Make r fucntion allow zero.

- except global and history ones

include/bed.h

@@ -4,11 +4,11 @@
 #include "internal/buffer/buffer.h"
 #include "internal/functions/functions.h"
 #include "internal/functions/suffixes.h"
-#include "internal/io/command.h"
 #include "internal/io/io.h"
 #include "internal/marks/marks.h"
 #include "internal/theme/theme.h"
-#include "internal/ui/autocomp.h"
+#include "internal/ui/command.h"
+#include "internal/ui/text_mode.h"
 #include "pch.h"
 
 namespace bed {
@@ -23,17 +23,20 @@ struct BEd {
   internal::vase::AppendStorage append{"/tmp"};
 
   bool help_mode = false;
-  std::string last_help = "";
   bool prompt_mode = true;
   std::function<std::string(BEd &)> prompt = nullptr;
   bool suppress_mode = false;
+  bool temporary_current = false;
+  std::string last_help = "";
   std::string last_regex = "";
   std::string last_symbol = "";
   std::string last_replacement = "";
+  std::string last_shell = "";
 
   std::unordered_map<std::string, internal::buffer::Buffer *> buffers;
 
-  internal::buffer::Range prev;
+  internal::buffer::Range prev_1;
+  internal::buffer::Range prev_2;
   internal::marks::MarksEngine marks;
 
   BEd(std::vector<std::string> args, internal::io::IO &io);
@@ -41,10 +44,12 @@ struct BEd {
 
   internal::buffer::Buffer &buffer(const std::string &);
   internal::buffer::Line &current();
-  void mark(char, internal::buffer::Line);
+  internal::buffer::Range &prev();
+  void mark(uint8_t, internal::buffer::Line);
 
   void handle(std::string_view cmd, bool eof);
   void run();
   void suffix_handle(char s);
+  bool escape_command(std::string &cmd, std::string_view filename);
 };
 } // namespace bed

include/internal/buffer/buffer.h

@@ -1,74 +1,6 @@
 #pragma once
 
-#include "definitions.h"
-#include "internal/syntax/parser.h"
-#include "internal/syntax/ruby/parser.h"
-#include "internal/theme/theme.h"
+#include "clip.h"
+#include "decl.h"
+#include "generic.h"
 #include "pch.h"
-
-namespace bed::internal::buffer {
-struct Buffer {
-  enum {
-    Unmodified,
-    Modified,
-    Warned
-  } state;
-  std::filesystem::path save_path = "";
-
-  vase::Shard *root;
-
-  std::string name;
-  std::string language;
-  std::optional<syntax::Parser> parser;
-
-  explicit Buffer(std::string name);
-  ~Buffer();
-
-  uint64_t lines();
-  vase::Shard *copy(uint64_t start_line, uint64_t end_line);
-  void substitute(
-    BEd &ctx, uint64_t start_line, uint64_t end_line,
-    std::string &regex, std::string &replacement, std::string &options
-  );
-  void join(BEd &ctx, uint64_t start_line, uint64_t end_line);
-  void remove(BEd &ctx, uint64_t start_line, uint64_t end_line);
-  void append(BEd &ctx, vase::Shard *text, uint64_t line);
-  void print(BEd &ctx, uint64_t start_line, uint64_t end_line);
-  void number_print(BEd &ctx, uint64_t start_line, uint64_t end_line);
-  std::string list_string(std::string_view s);
-};
-
-struct Line {
-  std::string buffername;
-  uint64_t number;
-};
-
-struct Range {
-  std::string buffername;
-  uint64_t start;
-  uint64_t end;
-
-  explicit Range(const Line &a, const Line &b) {
-    if (a.buffername != b.buffername)
-      throw ed_error("Invalid range.");
-    if (a.number > b.number)
-      throw ed_error("Invalid range.");
-    buffername = a.buffername;
-    start = a.number;
-    end = b.number;
-  };
-
-  explicit Range(std::string buffername, uint64_t start, uint64_t end)
-      : buffername(buffername), start(start), end(end) {
-    if (start > end)
-      throw ed_error("Invalid range.");
-  };
-
-  explicit Range() : buffername("default"), start(0), end(0) {};
-};
-
-using Address = std::variant<
-  std::string,
-  buffer::Range,
-  buffer::Line>;
-} // namespace bed::internal::buffer

include/internal/buffer/clip.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include "decl.h"
+#include "pch.h"
+
+namespace bed::internal::buffer {
+struct ClipBuffer : Buffer {
+  ClipBuffer(std::string name)
+      : Buffer(name, Kind::Clip) {};
+  ~ClipBuffer();
+
+  void clip_write(vase::Shard *text);
+  bool waste() override;
+  uint64_t lines() override;
+  uint64_t bytes() override;
+  void load(BEd &ctx, vase::Shard *text) override;
+  void set_filename(std::filesystem::path path) override;
+  std::filesystem::path filename() override;
+  vase::Shard *copy(uint64_t start_line, uint64_t end_line) override;
+  void substitute(
+    BEd &ctx, uint64_t start_line, uint64_t end_line,
+    std::string &regex, std::string &replacement, std::string &options
+  ) override;
+  void join(BEd &ctx, uint64_t start_line, uint64_t end_line) override;
+  void remove(BEd &ctx, uint64_t start_line, uint64_t end_line) override;
+  void append(BEd &ctx, vase::Shard *text, uint64_t line) override;
+  void print(BEd &ctx, uint64_t start_line, uint64_t end_line) override;
+  void number_print(BEd &ctx, uint64_t start_line, uint64_t end_line) override;
+  void list_print(BEd &ctx, uint64_t start_line, uint64_t end_line) override;
+  uint64_t next_closing(uint64_t start) override;
+  uint64_t prev_closing(uint64_t start) override;
+  uint64_t find_next(std::string_view pattern, uint64_t start) override;
+  uint64_t find_prev(std::string_view pattern, uint64_t start) override;
+};
+} // namespace bed::internal::buffer

include/internal/buffer/decl.h

@@ -0,0 +1,146 @@
+#pragma once
+
+#include "definitions.h"
+#include "internal/syntax/parser.h"
+#include "internal/syntax/ruby/parser.h"
+#include "internal/theme/theme.h"
+#include "pch.h"
+
+namespace bed::internal::buffer {
+struct Buffer {
+  enum struct Kind : uint8_t {
+    Generic,
+    Null,
+    Clip,
+    Cancel,
+    Shell,
+  } kind;
+
+  enum : uint8_t {
+    Special,
+    Unmodified,
+    Modified,
+    Warned
+  } state;
+
+  std::string name;
+
+  explicit Buffer(std::string name, Kind kind)
+      : kind(kind), state(Unmodified), name(name) {};
+  virtual ~Buffer() = default;
+
+  virtual bool waste() = 0;
+  virtual uint64_t lines() = 0;
+  virtual uint64_t bytes() = 0;
+  virtual void set_filename(std::filesystem::path path) = 0;
+  virtual std::filesystem::path filename() = 0;
+  virtual void load(BEd &ctx, vase::Shard *text) = 0;
+  virtual vase::Shard *copy(uint64_t start_line, uint64_t end_line) = 0;
+  virtual void substitute(
+    BEd &ctx, uint64_t start_line, uint64_t end_line,
+    std::string &regex, std::string &replacement, std::string &options
+  ) = 0;
+  virtual void join(BEd &ctx, uint64_t start_line, uint64_t end_line) = 0;
+  virtual void remove(BEd &ctx, uint64_t start_line, uint64_t end_line) = 0;
+  virtual void append(BEd &ctx, vase::Shard *text, uint64_t line) = 0;
+  virtual void print(BEd &ctx, uint64_t start_line, uint64_t end_line) = 0;
+  virtual void number_print(BEd &ctx, uint64_t start_line, uint64_t end_line) = 0;
+  virtual void list_print(BEd &ctx, uint64_t start_line, uint64_t end_line) = 0;
+  virtual uint64_t find_next(std::string_view pattern, uint64_t start) = 0;
+  virtual uint64_t find_prev(std::string_view pattern, uint64_t start) = 0;
+  virtual uint64_t next_closing(uint64_t start) = 0;
+  virtual uint64_t prev_closing(uint64_t start) = 0;
+};
+
+struct Line {
+  std::string buffername;
+  uint64_t number;
+};
+
+struct Range {
+  std::string buffername;
+  uint64_t start;
+  uint64_t end;
+
+  explicit Range(const Line &a, const Line &b) {
+    if (a.buffername != b.buffername)
+      throw ed_error("Invalid range.");
+    if (a.number > b.number)
+      throw ed_error("Invalid range.");
+    buffername = a.buffername;
+    start = a.number;
+    end = b.number;
+  };
+
+  explicit Range(std::string buffername, uint64_t start, uint64_t end)
+      : buffername(buffername), start(start), end(end) {
+    if (start > end)
+      throw ed_error("Invalid range.");
+  };
+
+  explicit Range() : buffername("default"), start(0), end(0) {};
+};
+
+using Address = std::variant<
+  std::string,
+  buffer::Range,
+  buffer::Line>;
+
+inline static std::string list_string(std::string_view s) {
+  uint32_t width = 80;
+  winsize ws{};
+  if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == 0 && ws.ws_col != 0)
+    width = ws.ws_col;
+  std::string out;
+  out.reserve(s.size());
+  const uint32_t max_width = width > 1 ? width - 1 : 1;
+  uint32_t column = 0;
+  auto append = [&](std::string_view text) {
+    if (column + text.size() > max_width) {
+      out += "\\\n";
+      column = 0;
+    }
+    out += text;
+    column += text.size();
+  };
+  for (unsigned char c : s) {
+    switch (c) {
+    case '\\':
+      append("\\\\");
+      break;
+    case '$':
+      append("\\$");
+      break;
+    case '\a':
+      append("\\a");
+      break;
+    case '\b':
+      append("\\b");
+      break;
+    case '\f':
+      append("\\f");
+      break;
+    case '\r':
+      append("\\r");
+      break;
+    case '\t':
+      append("\\t");
+      break;
+    case '\v':
+      append("\\v");
+      break;
+    default:
+      if (!std::isprint(c)) {
+        char buf[5];
+        std::snprintf(buf, sizeof(buf), "\\%03o", c);
+        append(buf);
+      } else {
+        append(std::string_view((const char *)&c, 1));
+      }
+      break;
+    }
+  }
+  out += '$';
+  return out;
+}
+} // namespace bed::internal::buffer

include/internal/buffer/generic.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include "decl.h"
+#include "pch.h"
+
+namespace bed::internal::buffer {
+struct GenericBuffer : Buffer {
+  vase::Shard *root;
+  std::filesystem::path save_path{};
+  std::string language{};
+  std::optional<syntax::Parser> parser{};
+
+  GenericBuffer(std::string name)
+      : Buffer(name, Kind::Generic), root(nullptr) {};
+  ~GenericBuffer();
+
+  bool waste() override;
+  uint64_t lines() override;
+  uint64_t bytes() override;
+  void load(BEd &ctx, vase::Shard *text) override;
+  void set_filename(std::filesystem::path path) override;
+  std::filesystem::path filename() override;
+  vase::Shard *copy(uint64_t start_line, uint64_t end_line) override;
+  void substitute(
+    BEd &ctx, uint64_t start_line, uint64_t end_line,
+    std::string &regex, std::string &replacement, std::string &options
+  ) override;
+  void join(BEd &ctx, uint64_t start_line, uint64_t end_line) override;
+  void remove(BEd &ctx, uint64_t start_line, uint64_t end_line) override;
+  void append(BEd &ctx, vase::Shard *text, uint64_t line) override;
+  void print(BEd &ctx, uint64_t start_line, uint64_t end_line) override;
+  void number_print(BEd &ctx, uint64_t start_line, uint64_t end_line) override;
+  void list_print(BEd &ctx, uint64_t start_line, uint64_t end_line) override;
+  uint64_t next_closing(uint64_t start) override;
+  uint64_t prev_closing(uint64_t start) override;
+  uint64_t find_next(std::string_view pattern, uint64_t start) override;
+  uint64_t find_prev(std::string_view pattern, uint64_t start) override;
+};
+} // namespace bed::internal::buffer

include/internal/functions/functions.h

@@ -81,5 +81,6 @@ struct Function {
     handle;
 
   static void register_posix(BEd &ctx);
+  static void register_extented(BEd &ctx);
 };
 } // namespace bed::internal::functions

include/internal/io/io.h

@@ -50,6 +50,14 @@ struct KeyEvent {
 };
 
 struct IO {
+  static termios orig_termios;
+  static termios raw_termios;
+  static bool cleaned;
+  static void cleanup();
+  static void enable_raw();
+  static volatile std::atomic_bool resized;
+  static void handle_sigwinch(int);
+
   IO();
   ~IO();
 
@@ -63,19 +71,11 @@ struct IO {
   std::pair<uint16_t, uint16_t> cursor_position();
   void move_cursor(uint16_t row, uint16_t col);
 
-  std::pair<std::string, bool> get_command(BEd &);
-  std::pair<std::string, bool> get_text(BEd &);
-
   KeyEvent read_key();
   void write(const char *, uint64_t);
   void write(std::string_view);
-
-private:
-  static termios orig_termios;
-  static bool cleaned;
-  static void cleanup();
-  static volatile std::atomic_bool resized;
-  static void handle_sigwinch(int);
+  void write_line(std::string_view);
+  void run_pty(const std::string &);
 
   std::deque<char> input_queue;
 

include/internal/marks/marks.h

@@ -48,8 +48,8 @@ struct MarksEngine {
         continue;
       if (marks[i].number == UINT64_MAX)
         continue;
-      if (marks[i].number >= start) {
-        if (marks[i].number < start + count)
+      if (marks[i].number > start) {
+        if (marks[i].number <= start + count)
           marks[i].number = start;
         else
           marks[i].number -= count;

include/internal/parser/parser.h

@@ -2,7 +2,7 @@
 
 #include "internal/functions/functions.h"
 #include "internal/functions/suffixes.h"
-#include "internal/io/command.h"
+#include "internal/ui/command.h"
 #include "pch.h"
 
 namespace bed::internal::parser {
@@ -65,10 +65,10 @@ struct AddressPromise {
 struct Command {
   bool temp_address{false};
   std::vector<AddressPromise> addresses{};
-  functions::Function *function;
-  functions::Function::Argument argument;
+  functions::Function *function{nullptr};
+  functions::Function::Argument argument{std::monostate()};
   std::vector<AddressPromise> argument_addresses{};
-  functions::Suffix *suffix;
+  functions::Suffix *suffix{nullptr};
 };
 
 struct CompletionContext {
@@ -85,12 +85,12 @@ struct Parser {
   std::string_view cmd;
   uint16_t i;
   Command *command;
-  std::vector<io::Token> *tokens;
+  std::vector<ui::Token> *tokens;
   CompletionContext *completion;
 
   explicit Parser(
     std::string_view cmd, BEd &bed, Command *command,
-    std::vector<io::Token> *tokens, CompletionContext *completion
+    std::vector<ui::Token> *tokens, CompletionContext *completion
   );
 
   char peek(uint16_t = 0); // == \0 if at eof.

include/internal/syntax/parser.h

@@ -5,13 +5,15 @@
 #include "pch.h"
 
 namespace bed::internal::syntax {
-void dump_events(ParseState *node);
-
 struct Parser {
   static constexpr uint64_t MAX_CHUNK = 512;
 
   ParseState *root;
   Language lang;
+  bool in_edit = false;
+  bool dirty = false;
+  uint64_t dirty_start = 0;
+  uint64_t dirty_end = 0;
 
   Parser(vase::Shard *, uint64_t, Language);
   ~Parser();
@@ -23,6 +25,12 @@ struct Parser {
   void insert(vase::Shard *, uint64_t, uint64_t);
   void modify(vase::Shard *, uint64_t, uint64_t);
 
+  void begin_edit();
+  void erase(uint64_t start, uint64_t count);
+  void insert(uint64_t start, uint64_t count);
+  void end_edit(vase::Shard *vase);
+  void mark_dirty(uint64_t start, uint64_t end);
+
   uint64_t next_closing(uint64_t line);
   uint64_t prev_opening(uint64_t line);
 

include/internal/ui/command.h

@@ -1,10 +1,9 @@
 #pragma once
 
-#include "internal/io/io.h"
-#include "internal/ui/autocomp.h"
+#include "definitions.h"
 #include "pch.h"
 
-namespace bed::internal::io {
+namespace bed::internal::ui {
 struct Token {
   enum struct Type : uint8_t {
     TempCurrent,      // @
@@ -39,10 +38,9 @@ struct CommandIO {
   uint16_t term_height;
   uint16_t term_width;
   BEd &bed;
-  IO &io;
 
-  CommandIO(BEd &, IO &);
+  CommandIO(BEd &);
   std::pair<std::string, bool> run();
   void redraw();
 };
-} // namespace bed::internal::io
+} // namespace bed::internal::ui

include/internal/ui/text_mode.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include "definitions.h"
+#include "pch.h"
+
+namespace bed::internal::ui {
+struct TextMode {
+  std::string cmd;
+  uint16_t cursor;
+  uint16_t start;
+  uint16_t height;
+  uint16_t term_height;
+  uint16_t term_width;
+  BEd &bed;
+
+  TextMode(BEd &);
+  std::pair<vase::Shard *, bool> run();
+  void grow(size_t required_height);
+  void redraw();
+};
+} // namespace bed::internal::ui

include/internal/vase/shard.h

@@ -27,14 +27,12 @@ struct Shard {
   static Shard *from_file(const std::filesystem::path &path, bool posix_ending);
   static Shard *from_string(const char *data, uint64_t len, bool posix_ending);
   static Shard *from_command(const char *cmd, bool posix_ending);
-  // static std::vector<Shard *> from_swap(std::filesystem::path &path, OriginalStorage *b);
 
   static std::pair<Shard *, Shard *> split(Shard *n, uint64_t offset);
   static Shard *concat(Shard *a, Shard *b);
   static Shard *merge_leaves(Shard *a, Shard *b);
   static Shard *append(Shard *root, Shard *leaf);
   static Shard *build(Shard **pieces, uint64_t lo, uint64_t hi);
-  static void dump(Shard *node, int depth = 0);
 };
 
 struct Branch : Shard {

include/internal/vase/vase.h

@@ -20,8 +20,8 @@ struct Range {
 };
 
 struct RegexGroup {
-  uint64_t start{0};
-  uint64_t end{0};
+  uint64_t start{UINT64_MAX};
+  uint64_t end{UINT64_MAX};
 };
 
 struct RegexMatch {
@@ -48,7 +48,10 @@ std::string to_string(Shard *root, Range range);
 
 Shard *insert(AppendStorage *ap, Shard *root, Shard *text, uint64_t line);
 Shard *erase(Shard *root, uint64_t start, uint64_t end);
+Shard *join(Shard *root, uint64_t start, uint64_t end);
 Shard *copy(Shard *root, uint64_t start, uint64_t end);
+void write_file(std::filesystem::path path, Shard *text);
+void write_command(const char *cmd, Shard *text);
 
 uint64_t find_next(Shard *root, std::string_view pattern, uint64_t start);
 uint64_t find_prev(Shard *root, std::string_view pattern, uint64_t start);
@@ -56,7 +59,10 @@ uint64_t find_prev(Shard *root, std::string_view pattern, uint64_t start);
 Shard *substitute(
   AppendStorage *ap, Shard *root,
   std::string_view pattern, uint64_t start, uint64_t end,
-  std::string_view replace, std::string_view options
+  std::string_view replace, std::string_view options,
+  const std::function<void(
+    uint64_t line, uint64_t old_lines, uint64_t new_lines
+  )> &on_edit = nullptr
 );
 
 // internal

include/pch.h

@@ -29,12 +29,12 @@ extern "C" {
 #include <filesystem>
 #include <fstream>
 #include <functional>
-#include <iostream>
 #include <limits.h>
 #include <map>
 #include <mutex>
 #include <optional>
 #include <poll.h>
+#include <pty.h>
 #include <queue>
 #include <set>
 #include <shared_mutex>

src/bed/run.cc

@@ -5,6 +5,7 @@ namespace bed {
 BEd::BEd(std::vector<std::string> args, internal::io::IO &io)
     : theme(internal::theme::Theme::default_theme()), io(io) {
   internal::functions::Function::register_posix(*this);
+  internal::functions::Function::register_extented(*this);
   internal::functions::Suffix::register_suffixes(*this);
   std::string prompt_ = "";
   std::string file = "";
@@ -17,6 +18,8 @@ BEd::BEd(std::vector<std::string> args, internal::io::IO &io)
       prompt_ = args[i];
     } else if (args[i] == "-s") {
       suppress = true;
+    } else if (args[i] == "-v" || args[i] == "--verbose") {
+      help_mode = true;
     } else {
       if (file.size())
         throw fatal_error("Invalid arguments given.", 1);
@@ -28,13 +31,15 @@ BEd::BEd(std::vector<std::string> args, internal::io::IO &io)
   else
     prompt_mode = false;
   suppress_mode = suppress;
+  buffers["clip"] = new internal::buffer::ClipBuffer("clip");
+  current() = {"default", 0};
   try {
     if (file != "")
       handle(":default:E " + file, false);
   } catch (ed_error &e) {
-    std::cout << "?" << std::endl;
+    io.write_line("?");
     if (help_mode)
-      std::cout << e.what() << std::endl;
+      io.write_line(e.what());
     last_help = e.what();
   }
 }
@@ -46,13 +51,14 @@ BEd::~BEd() {
 
 void BEd::run() {
   while (true) {
-    auto [cmd, eof] = io.get_command(*this);
+    internal::ui::CommandIO command(*this);
+    auto [cmd, eof] = command.run();
     try {
       handle(cmd, eof);
     } catch (ed_error &e) {
-      std::cout << "?" << std::endl;
+      io.write_line("?");
       if (help_mode)
-        std::cout << e.what() << std::endl;
+        io.write_line(e.what());
       last_help = e.what();
     }
   }
@@ -64,71 +70,144 @@ void BEd::handle(std::string_view cmd, bool eof) {
     return;
   }
   internal::parser::Command c = internal::parser::Parser::get_command(cmd, *this);
+  if (c.temp_address) {
+    marks.get(251) = marks.get(250);
+    prev_2 = prev_1;
+    temporary_current = true;
+  }
   internal::buffer::Address address;
   switch (c.function->address_kind) {
   case internal::functions::Function::AddressKind::None: {
     auto a = internal::parser::AddressPromise::get_line(*this, c.addresses);
-    if (a.has_value()) {
-      address = a->buffername;
-    } else {
+    if (!a.has_value()) {
       auto vec = internal::parser::Parser::get_addresses(c.function->default_address, *this);
       a = internal::parser::AddressPromise::get_line(*this, vec);
-      address = a->buffername;
+      if (!a.has_value())
+        a = current();
     }
+    address = a->buffername;
   } break;
   case internal::functions::Function::AddressKind::Line: {
     auto a = internal::parser::AddressPromise::get_line(*this, c.addresses);
-    if (a.has_value()) {
-      address = *a;
-    } else {
+    if (!a.has_value()) {
       auto vec = internal::parser::Parser::get_addresses(c.function->default_address, *this);
       a = internal::parser::AddressPromise::get_line(*this, vec);
-      address = *a;
+      if (!a.has_value())
+        a = current();
     }
+    address = *a;
   } break;
   case internal::functions::Function::AddressKind::Range: {
     auto a = internal::parser::AddressPromise::get_range(*this, c.addresses);
-    if (a.has_value()) {
-      address = *a;
-    } else {
+    if (!a.has_value()) {
       auto vec = internal::parser::Parser::get_addresses(c.function->default_address, *this);
       a = internal::parser::AddressPromise::get_range(*this, vec);
-      address = *a;
+      if (!a.has_value())
+        a = internal::buffer::Range(current(), current());
     }
+    address = *a;
   } break;
   }
   if (std::holds_alternative<internal::buffer::Line>(c.argument)) {
+    if (c.argument_addresses.empty())
+      throw ed_error("Function needs address argument.");
     auto a = internal::parser::AddressPromise::get_line(*this, c.argument_addresses);
     if (a.has_value())
       c.argument = *a;
     else
       c.argument = current();
   } else if (std::holds_alternative<internal::buffer::Range>(c.argument)) {
+    if (c.argument_addresses.empty())
+      throw ed_error("Function needs address argument.");
     auto a = internal::parser::AddressPromise::get_range(*this, c.argument_addresses);
     if (a.has_value())
       c.argument = *a;
     else
       c.argument = internal::buffer::Range(current(), current());
   }
-  c.function->handle(*this, address, nullptr, c.argument, nullptr);
+  if (!c.function->accept_zero) {
+    if (std::holds_alternative<internal::buffer::Line>(address)) {
+      if (std::get<internal::buffer::Line>(address).number == 0)
+        throw ed_error("Line number can't be zero.");
+    } else if (std::holds_alternative<internal::buffer::Range>(address)) {
+      auto r = std::get<internal::buffer::Range>(address);
+      if (r.start == 0 || r.end == 0)
+        throw ed_error("Line number can't be zero.");
+    }
+  }
+  internal::vase::Shard *text = nullptr;
+  if (c.function->input_mode == internal::functions::Function::InputMode::Text) {
+    internal::ui::TextMode tm(*this);
+    auto [a, b] = tm.run();
+    if (!b)
+      text = a;
+  }
+  if (c.function->handle)
+    c.function->handle(*this, address, text, c.argument, nullptr);
   if (c.suffix)
     c.suffix->handle(*this);
+  if (c.temp_address)
+    temporary_current = false;
+  for (auto it = buffers.begin(); it != buffers.end();) {
+    internal::buffer::Buffer *buf = it->second;
+    if (buf->waste()) {
+      delete buf;
+      it = buffers.erase(it);
+    } else {
+      ++it;
+    }
+  }
 }
 
 internal::buffer::Buffer &BEd::buffer(const std::string &name) {
+  if (name.empty())
+    throw ed_error("can't have empty buffer name");
   auto it = buffers.find(name);
   if (it != buffers.end())
     return *it->second;
-  auto *buf = new internal::buffer::Buffer(name);
+  auto *buf = new internal::buffer::GenericBuffer(name);
   buffers.emplace(name, buf);
   return *buf;
 }
 
 internal::buffer::Line &BEd::current() {
-  return marks.get(250);
+  return marks.get(250 + temporary_current);
 }
 
-void BEd::mark(char m, internal::buffer::Line line) {
+internal::buffer::Range &BEd::prev() {
+  if (temporary_current)
+    return prev_2;
+  else
+    return prev_1;
+}
+
+void BEd::mark(uint8_t m, internal::buffer::Line line) {
   marks.get(m) = line;
 }
+
+bool BEd::escape_command(std::string &cmd, std::string_view filename) {
+  bool modified = false;
+  if (cmd == "!") {
+    cmd = last_shell;
+    modified = true;
+  }
+  last_shell = cmd;
+  for (size_t i = 0; i < cmd.size();) {
+    if (cmd[i] == '\\') {
+      if (i + 1 >= cmd.size())
+        break;
+      cmd.erase(i++, 1);
+      continue;
+    }
+    if (cmd[i] == '%') {
+      cmd.erase(i, 1);
+      cmd.insert(i, filename);
+      i += filename.size();
+      modified = true;
+      continue;
+    }
+    i++;
+  }
+  return modified;
+}
 } // namespace bed

src/internal/buffer/buffer.cc

@@ -1,250 +0,0 @@
-#include "internal/buffer/buffer.h"
-#include "bed.h"
-
-namespace bed::internal::buffer {
-Buffer::Buffer(std::string name)
-    : state(Unmodified), root(nullptr), name(name) {
-  parser.emplace(root, lines(), syntax::ruby::lang_ruby()); // just for debug.
-}
-
-Buffer::~Buffer() {
-  vase::Shard::release(root);
-}
-
-uint64_t Buffer::lines() {
-  if (root)
-    return root->lines + 1;
-  return 0;
-}
-
-void Buffer::append(BEd &ctx, vase::Shard *text, uint64_t line) {
-  ctx.prev.buffername = name;
-  ctx.prev.start = line;
-  ctx.prev.end = line + text->lines;
-  root = vase::insert(&ctx.append, root, text, line);
-  ctx.marks.insert(name, ctx.prev.start, ctx.prev.end);
-  if (parser)
-    parser->insert(root, ctx.prev.start, ctx.prev.end);
-  state = Modified;
-}
-
-void Buffer::remove(BEd &ctx, uint64_t start_line, uint64_t end_line) {
-  root = vase::erase(root, start_line, end_line);
-  ctx.prev.buffername = name;
-  ctx.prev.start = start_line;
-  ctx.prev.end = start_line;
-  ctx.marks.erase(name, start_line, end_line - start_line + 1);
-  if (parser)
-    parser->erase(root, start_line, end_line - start_line + 1);
-  state = Modified;
-}
-
-void Buffer::join(BEd &ctx, uint64_t start_line, uint64_t end_line) {
-  root = vase::substitute(&ctx.append, root, R"(\n)", start_line, end_line, "", "g");
-  ctx.prev.buffername = name;
-  ctx.prev.start = start_line;
-  ctx.prev.end = start_line;
-  ctx.marks.collapse(name, start_line, end_line - start_line);
-  if (parser)
-    parser->erase(root, start_line, end_line - start_line);
-  state = Modified;
-}
-
-void Buffer::substitute(
-  BEd &ctx, uint64_t start_line, uint64_t end_line,
-  std::string &regex, std::string &replacement, std::string &options
-) {
-  // make substitue return a list of modifications made.
-  root = vase::substitute(&ctx.append, root, regex, start_line, end_line, replacement, options);
-  /*prev_range.start = start_line;
-  prev_range.end = start_line;
-  marks.collapse(start_line, end_line - start_line);
-  if (parser)
-    parser->erase(vase, start_line, end_line - start_line);*/
-  state = Modified;
-}
-
-vase::Shard *Buffer::copy(uint64_t start_line, uint64_t end_line) {
-  return vase::copy(root, start_line, end_line);
-}
-
-inline void apply(std::ostream &out, const Highlight &hl) {
-  out << "\x1b[0m";
-  const uint8_t r = (hl.fg >> 16) & 0xff;
-  const uint8_t g = (hl.fg >> 8) & 0xff;
-  const uint8_t b = hl.fg & 0xff;
-  out << "\x1b[38;2;"
-      << (unsigned)r << ';'
-      << (unsigned)g << ';'
-      << (unsigned)b << 'm';
-  if (hl.bg != 0) {
-    const uint8_t br = (hl.bg >> 16) & 0xff;
-    const uint8_t bg = (hl.bg >> 8) & 0xff;
-    const uint8_t bb = hl.bg & 0xff;
-    out << "\x1b[48;2;"
-        << (unsigned)br << ';'
-        << (unsigned)bg << ';'
-        << (unsigned)bb << 'm';
-  }
-  if (hl.flags & Highlight::Bold)
-    out << "\x1b[1m";
-  if (hl.flags & Highlight::Italic)
-    out << "\x1b[3m";
-  if (hl.flags & Highlight::Underline)
-    out << "\x1b[4m";
-  if (hl.flags & Highlight::Strikethrough)
-    out << "\x1b[9m";
-}
-
-inline void reset(std::ostream &out) {
-  out << "\x1b[0m";
-}
-
-void Buffer::print(BEd &ctx, uint64_t start_line, uint64_t end_line) {
-  ctx.prev.buffername = name;
-  ctx.prev.start = start_line;
-  ctx.prev.end = end_line;
-  if (parser) {
-    std::optional<syntax::Parser::Iterator> it_o = parser->get_hl(root, start_line - 1);
-    auto &it = *it_o;
-    while (start_line <= end_line) {
-      it.next();
-      const std::string &line = it.it->line;
-      const auto &tokens = it.tokens;
-      uint32_t cursor = 0;
-      for (const auto &token : tokens) {
-        const uint32_t start = token.start;
-        const uint32_t end = token.end;
-        if (start > line.size())
-          break;
-        if (end > line.size())
-          break;
-        if (cursor < start) {
-          std::cout.write(
-            line.data() + cursor,
-            start - cursor
-          );
-        }
-        const auto highlight = ctx.theme.get(token);
-        apply(std::cout, highlight);
-        std::cout.write(line.data() + start, end - start);
-        reset(std::cout);
-        cursor = end;
-      }
-      if (cursor < line.size())
-        std::cout.write(line.data() + cursor, line.size() - cursor);
-      std::cout << std::endl;
-      ++start_line;
-    }
-  } else {
-    vase::Iterator it(root, start_line - 1, Direction::Forward);
-    while (it.next() && start_line++ <= end_line)
-      std::cout << it.line << std::endl;
-  }
-}
-
-void Buffer::number_print(BEd &ctx, uint64_t start_line, uint64_t end_line) {
-  ctx.prev.buffername = name;
-  ctx.prev.start = start_line;
-  ctx.prev.end = end_line;
-  uint8_t width = 1;
-  for (uint64_t n = end_line; n >= 10; n /= 10)
-    ++width;
-  if (parser) {
-    std::optional<syntax::Parser::Iterator> it_o = parser->get_hl(root, start_line - 1);
-    auto &it = *it_o;
-    while (start_line <= end_line) {
-      it.next();
-      std::cout << std::setw(width) << start_line << "\t";
-      const std::string &line = it.it->line;
-      const auto &tokens = it.tokens;
-      uint32_t cursor = 0;
-      for (const auto &token : tokens) {
-        const uint32_t start = token.start;
-        const uint32_t end = token.end;
-        if (start > line.size())
-          break;
-        if (end > line.size())
-          break;
-        if (cursor < start) {
-          std::cout.write(
-            line.data() + cursor,
-            start - cursor
-          );
-        }
-        const auto highlight = ctx.theme.get(token);
-        apply(std::cout, highlight);
-        std::cout.write(line.data() + start, end - start);
-        reset(std::cout);
-        cursor = end;
-      }
-      if (cursor < line.size())
-        std::cout.write(line.data() + cursor, line.size() - cursor);
-      std::cout << std::endl;
-      ++start_line;
-    }
-  } else {
-    vase::Iterator it(root, start_line - 1, Direction::Forward);
-    while (it.next() && start_line <= end_line)
-      std::cout << std::setw(width) << start_line++ << "\t" << it.line << std::endl;
-  }
-}
-
-std::string Buffer::list_string(std::string_view s) {
-  uint32_t width = 80;
-  winsize ws{};
-  if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == 0 && ws.ws_col != 0)
-    width = ws.ws_col;
-  std::string out;
-  out.reserve(s.size());
-  const uint32_t max_width = width > 1 ? width - 1 : 1;
-  uint32_t column = 0;
-  auto append = [&](std::string_view text) {
-    if (column + text.size() > max_width) {
-      out += "\\\n";
-      column = 0;
-    }
-    out += text;
-    column += text.size();
-  };
-  for (unsigned char c : s) {
-    switch (c) {
-    case '\\':
-      append("\\\\");
-      break;
-    case '$':
-      append("\\$");
-      break;
-    case '\a':
-      append("\\a");
-      break;
-    case '\b':
-      append("\\b");
-      break;
-    case '\f':
-      append("\\f");
-      break;
-    case '\r':
-      append("\\r");
-      break;
-    case '\t':
-      append("\\t");
-      break;
-    case '\v':
-      append("\\v");
-      break;
-    default:
-      if (!std::isprint(c)) {
-        char buf[5];
-        std::snprintf(buf, sizeof(buf), "\\%03o", c);
-        append(buf);
-      } else {
-        append(std::string_view((const char *)&c, 1));
-      }
-      break;
-    }
-  }
-  out += '$';
-  return out;
-}
-} // namespace bed::internal::buffer

src/internal/buffer/generic.cc

@@ -0,0 +1,270 @@
+#include "bed.h"
+#include "internal/buffer/buffer.h"
+
+namespace bed::internal::buffer {
+GenericBuffer::~GenericBuffer() {
+  vase::Shard::release(root);
+}
+
+bool GenericBuffer::waste() {
+  return save_path.empty()
+         && root == nullptr;
+}
+
+uint64_t GenericBuffer::lines() {
+  if (root)
+    return root->lines + 1;
+  return 0;
+}
+
+uint64_t GenericBuffer::bytes() {
+  if (root)
+    return root->length + 1;
+  return 0;
+}
+
+void GenericBuffer::load(BEd &ctx, vase::Shard *text) {
+  if (lines())
+    ctx.marks.erase(name, 1, lines());
+  vase::Shard::release(root);
+  vase::Shard::retain(text);
+  root = text;
+  state = buffer::GenericBuffer::Unmodified;
+  if (!text) {
+    ctx.prev().buffername = name;
+    ctx.prev().start = 0;
+    ctx.prev().end = 0;
+  } else {
+    ctx.prev().buffername = name;
+    ctx.prev().start = 1;
+    ctx.prev().end = text->lines + 1;
+  }
+  parser.emplace(root, lines(), syntax::ruby::lang_ruby());
+}
+
+void GenericBuffer::set_filename(std::filesystem::path path) {
+  save_path = path;
+}
+
+std::filesystem::path GenericBuffer::filename() {
+  return save_path;
+};
+
+void GenericBuffer::append(BEd &ctx, vase::Shard *text, uint64_t line) {
+  ctx.prev().buffername = name;
+  ctx.prev().start = line + 1;
+  ctx.prev().end = line + text->lines + 1;
+  root = vase::insert(&ctx.append, root, text, line);
+  ctx.marks.insert(name, ctx.prev().start, ctx.prev().end);
+  if (parser)
+    parser->insert(root, ctx.prev().start, ctx.prev().end);
+  state = Modified;
+}
+
+void GenericBuffer::remove(BEd &ctx, uint64_t start_line, uint64_t end_line) {
+  root = vase::erase(root, start_line, end_line);
+  ctx.prev().buffername = name;
+  ctx.prev().start = std::min(start_line, lines());
+  ctx.prev().end = std::min(start_line, lines());
+  ctx.marks.erase(name, start_line, end_line - start_line + 1);
+  if (parser)
+    parser->erase(root, start_line, end_line - start_line + 1);
+  state = Modified;
+}
+
+void GenericBuffer::join(BEd &ctx, uint64_t start_line, uint64_t end_line) {
+  root = vase::join(root, start_line, end_line);
+  ctx.prev().buffername = name;
+  ctx.prev().start = start_line;
+  ctx.prev().end = start_line;
+  ctx.marks.collapse(name, start_line, end_line - start_line);
+  if (parser)
+    parser->erase(root, start_line, end_line - start_line);
+  state = Modified;
+}
+
+void GenericBuffer::substitute(
+  BEd &ctx, uint64_t start_line, uint64_t end_line,
+  std::string &regex, std::string &replacement, std::string &options
+) {
+  ctx.prev().buffername = name;
+  ctx.prev().start = start_line;
+  ctx.prev().end = end_line;
+  if (parser)
+    parser->begin_edit();
+  root = vase::substitute(
+    &ctx.append,
+    root,
+    regex,
+    start_line,
+    end_line,
+    replacement,
+    options,
+    [&](uint64_t line, uint64_t old_lines, uint64_t new_lines) {
+      if (old_lines) {
+        ctx.marks.erase(name, line, old_lines);
+        if (parser)
+          parser->erase(line, old_lines);
+      }
+      if (new_lines) {
+        ctx.marks.insert(name, line, line + new_lines - 1);
+        if (parser)
+          parser->insert(line, line + new_lines - 1);
+      }
+    }
+  );
+  if (parser)
+    parser->end_edit(root);
+  ctx.prev().buffername = name;
+  state = Modified;
+}
+
+vase::Shard *GenericBuffer::copy(uint64_t start_line, uint64_t end_line) {
+  return vase::copy(root, start_line, end_line);
+}
+
+uint64_t GenericBuffer::find_next(std::string_view pattern, uint64_t start) {
+  return vase::find_next(root, pattern, start);
+}
+
+uint64_t GenericBuffer::find_prev(std::string_view pattern, uint64_t start) {
+  return vase::find_prev(root, pattern, start);
+}
+
+uint64_t GenericBuffer::next_closing(uint64_t start) {
+  if (parser.has_value()) {
+    uint64_t closing = parser->next_closing(start - 1);
+    if (closing == UINT64_MAX)
+      return lines();
+    return closing + 1;
+  } else {
+    start += 10;
+    if (start > lines())
+      return lines();
+    return start;
+  }
+}
+
+uint64_t GenericBuffer::prev_closing(uint64_t start) {
+  if (parser.has_value()) {
+    return parser->prev_opening(start - 1) + 1;
+  } else {
+    if (start > 10)
+      return start - 10;
+    return 0;
+  }
+}
+
+inline void apply(io::IO &io, const Highlight &hl) {
+  io.write("\x1b[0m");
+  const uint8_t r = (hl.fg >> 16) & 0xff;
+  const uint8_t g = (hl.fg >> 8) & 0xff;
+  const uint8_t b = hl.fg & 0xff;
+  io.write(std::format("\x1b[38;2;{};{};{}m", r, g, b));
+  if (hl.bg != 0) {
+    const uint8_t br = (hl.bg >> 16) & 0xff;
+    const uint8_t bg = (hl.bg >> 8) & 0xff;
+    const uint8_t bb = hl.bg & 0xff;
+    io.write(std::format("\x1b[48;2;{};{};{}m", br, bg, bb));
+  }
+  if (hl.flags & Highlight::Bold)
+    io.write("\x1b[1m");
+  if (hl.flags & Highlight::Italic)
+    io.write("\x1b[3m");
+  if (hl.flags & Highlight::Underline)
+    io.write("\x1b[4m");
+  if (hl.flags & Highlight::Strikethrough)
+    io.write("\x1b[9m");
+}
+
+inline void reset(io::IO &io) {
+  io.write("\x1b[0m");
+}
+
+void GenericBuffer::print(BEd &ctx, uint64_t start_line, uint64_t end_line) {
+  ctx.prev().buffername = name;
+  ctx.prev().start = start_line;
+  ctx.prev().end = end_line;
+  if (parser) {
+    auto it_o = parser->get_hl(root, start_line - 1);
+    auto &it = *it_o;
+    while (start_line <= end_line) {
+      it.next();
+      const std::string &line = it.it->line;
+      const auto &tokens = it.tokens;
+      uint32_t cursor = 0;
+      for (const auto &token : tokens) {
+        const uint32_t start = token.start;
+        const uint32_t end = token.end;
+        if (start > line.size() || end > line.size())
+          break;
+        if (cursor < start)
+          ctx.io.write(line.data() + cursor, start - cursor);
+        const auto highlight = ctx.theme.get(token);
+        apply(ctx.io, highlight);
+        ctx.io.write(line.data() + start, end - start);
+        reset(ctx.io);
+        cursor = end;
+      }
+      if (cursor < line.size())
+        ctx.io.write(line.data() + cursor, line.size() - cursor);
+      ctx.io.write_line("");
+      ++start_line;
+    }
+  } else {
+    vase::Iterator it(root, start_line - 1, Direction::Forward);
+    while (it.next() && start_line++ <= end_line)
+      ctx.io.write_line(it.line);
+  }
+}
+
+void GenericBuffer::number_print(BEd &ctx, uint64_t start_line, uint64_t end_line) {
+  ctx.prev().buffername = name;
+  ctx.prev().start = start_line;
+  ctx.prev().end = end_line;
+  uint8_t width = 1;
+  for (uint64_t n = end_line; n >= 10; n /= 10)
+    ++width;
+  if (parser) {
+    std::optional<syntax::Parser::Iterator> it_o = parser->get_hl(root, start_line - 1);
+    auto &it = *it_o;
+    while (start_line <= end_line) {
+      it.next();
+      ctx.io.write(std::format("{:>{}}\t", start_line, width));
+      const std::string &line = it.it->line;
+      const auto &tokens = it.tokens;
+      uint32_t cursor = 0;
+      for (const auto &token : tokens) {
+        const uint32_t start = token.start;
+        const uint32_t end = token.end;
+        if (start > line.size() || end > line.size())
+          break;
+        if (cursor < start)
+          ctx.io.write(line.data() + cursor, start - cursor);
+        const auto highlight = ctx.theme.get(token);
+        apply(ctx.io, highlight);
+        ctx.io.write(line.data() + start, end - start);
+        reset(ctx.io);
+        cursor = end;
+      }
+      if (cursor < line.size())
+        ctx.io.write(line.data() + cursor, line.size() - cursor);
+      ctx.io.write_line("");
+      ++start_line;
+    }
+  } else {
+    vase::Iterator it(root, start_line - 1, Direction::Forward);
+    while (it.next() && start_line <= end_line)
+      ctx.io.write_line(std::format("{:>{}}\t{}", start_line++, width, it.line));
+  }
+}
+
+void GenericBuffer::list_print(BEd &ctx, uint64_t start_line, uint64_t end_line) {
+  ctx.prev().buffername = name;
+  ctx.prev().start = start_line;
+  ctx.prev().end = end_line;
+  vase::Iterator it(root, start_line - 1, Direction::Forward);
+  while (it.next() && start_line++ <= end_line)
+    ctx.io.write_line(list_string(it.line));
+}
+} // namespace bed::internal::buffer

src/internal/buffer/special/clip.cc

@@ -0,0 +1,185 @@
+#include "bed.h"
+#include "internal/buffer/buffer.h"
+
+namespace bed::internal::buffer {
+ClipBuffer::~ClipBuffer() {}
+
+bool ClipBuffer::waste() {
+  return false;
+}
+
+uint64_t ClipBuffer::lines() {
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  uint64_t lines = s ? s->lines + 1 : 0;
+  vase::Shard::release(s);
+  return lines;
+}
+
+uint64_t ClipBuffer::bytes() {
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  uint64_t length = s ? s->length + 1 : 0;
+  vase::Shard::release(s);
+  return length;
+}
+
+void ClipBuffer::clip_write(vase::Shard *text) {
+  FILE *pipe = popen("xclip -selection clipboard -i", "w");
+  if (!pipe)
+    throw ed_error("can't access clipboard");
+  auto s = vase::to_string(text);
+  fwrite(s.data(), 1, s.length(), pipe);
+  if (pclose(pipe) != 0)
+    throw ed_error("can't write clipboard");
+}
+
+void ClipBuffer::load(BEd &ctx, vase::Shard *text) {
+  clip_write(text);
+  if (!text) {
+    ctx.prev().buffername = name;
+    ctx.prev().start = 0;
+    ctx.prev().end = 0;
+  } else {
+    ctx.prev().buffername = name;
+    ctx.prev().start = 1;
+    ctx.prev().end = text->lines + 1;
+  }
+}
+
+void ClipBuffer::set_filename(std::filesystem::path) {}
+
+std::filesystem::path ClipBuffer::filename() {
+  return "";
+};
+
+void ClipBuffer::append(BEd &ctx, vase::Shard *text, uint64_t line) {
+  ctx.prev().buffername = name;
+  ctx.prev().start = line + 1;
+  ctx.prev().end = line + text->lines + 1;
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  s = vase::insert(&ctx.append, s, text, line);
+  clip_write(s);
+  vase::Shard::release(s);
+  ctx.marks.insert(name, ctx.prev().start, ctx.prev().end);
+}
+
+void ClipBuffer::remove(BEd &ctx, uint64_t start_line, uint64_t end_line) {
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  s = vase::erase(s, start_line, end_line);
+  clip_write(s);
+  ctx.prev().buffername = name;
+  ctx.prev().start = std::min(start_line, s ? s->lines + 1 : 0);
+  ctx.prev().end = std::min(start_line, s ? s->lines + 1 : 0);
+  vase::Shard::release(s);
+  ctx.marks.erase(name, start_line, end_line - start_line + 1);
+}
+
+void ClipBuffer::join(BEd &ctx, uint64_t start_line, uint64_t end_line) {
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  s = vase::join(s, start_line, end_line);
+  clip_write(s);
+  vase::Shard::release(s);
+  ctx.prev().buffername = name;
+  ctx.prev().start = start_line;
+  ctx.prev().end = start_line;
+  ctx.marks.collapse(name, start_line, end_line - start_line);
+}
+
+void ClipBuffer::substitute(
+  BEd &ctx, uint64_t start_line, uint64_t end_line,
+  std::string &regex, std::string &replacement, std::string &options
+) {
+  ctx.prev().buffername = name;
+  ctx.prev().start = start_line;
+  ctx.prev().end = end_line;
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  s = vase::substitute(
+    &ctx.append,
+    s,
+    regex,
+    start_line,
+    end_line,
+    replacement,
+    options,
+    [&](uint64_t line, uint64_t old_lines, uint64_t new_lines) {
+      if (old_lines)
+        ctx.marks.erase(name, line, old_lines);
+      if (new_lines)
+        ctx.marks.insert(name, line, line + new_lines - 1);
+    }
+  );
+  clip_write(s);
+  vase::Shard::release(s);
+  ctx.prev().buffername = name;
+}
+
+vase::Shard *ClipBuffer::copy(uint64_t start_line, uint64_t end_line) {
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  vase::Shard *o = vase::copy(s, start_line, end_line);
+  vase::Shard::release(s);
+  return o;
+}
+
+uint64_t ClipBuffer::find_next(std::string_view pattern, uint64_t start) {
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  uint64_t line = vase::find_next(s, pattern, start);
+  vase::Shard::release(s);
+  return line;
+}
+
+uint64_t ClipBuffer::find_prev(std::string_view pattern, uint64_t start) {
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  uint64_t line = vase::find_prev(s, pattern, start);
+  vase::Shard::release(s);
+  return line;
+}
+
+uint64_t ClipBuffer::next_closing(uint64_t start) {
+  start += 10;
+  uint64_t line = lines();
+  if (start > line)
+    return line;
+  return start;
+}
+
+uint64_t ClipBuffer::prev_closing(uint64_t start) {
+  if (start > 10)
+    return start - 10;
+  return 0;
+}
+
+void ClipBuffer::print(BEd &ctx, uint64_t start_line, uint64_t end_line) {
+  ctx.prev().buffername = name;
+  ctx.prev().start = start_line;
+  ctx.prev().end = end_line;
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  vase::Iterator it(s, start_line - 1, Direction::Forward);
+  while (it.next() && start_line++ <= end_line)
+    ctx.io.write_line(it.line);
+  vase::Shard::release(s);
+}
+
+void ClipBuffer::number_print(BEd &ctx, uint64_t start_line, uint64_t end_line) {
+  ctx.prev().buffername = name;
+  ctx.prev().start = start_line;
+  ctx.prev().end = end_line;
+  uint8_t width = 1;
+  for (uint64_t n = end_line; n >= 10; n /= 10)
+    ++width;
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  vase::Iterator it(s, start_line - 1, Direction::Forward);
+  while (it.next() && start_line <= end_line)
+    ctx.io.write_line(std::format("{:>{}}\t{}", start_line++, width, it.line));
+  vase::Shard::release(s);
+}
+
+void ClipBuffer::list_print(BEd &ctx, uint64_t start_line, uint64_t end_line) {
+  ctx.prev().buffername = name;
+  ctx.prev().start = start_line;
+  ctx.prev().end = end_line;
+  auto s = vase::Shard::from_command("xclip -selection clipboard -o", true);
+  vase::Iterator it(s, start_line - 1, Direction::Forward);
+  while (it.next() && start_line++ <= end_line)
+    ctx.io.write_line(list_string(it.line));
+  vase::Shard::release(s);
+}
+} // namespace bed::internal::buffer

src/internal/functions/extended.cc

@@ -0,0 +1,58 @@
+#include "bed.h"
+#include "internal/functions/functions.h"
+#include "internal/functions/suffixes.h"
+
+namespace bed::internal::functions {
+void Function::register_extented(BEd &ctx) {
+  ctx.functions.insert(
+    "cd",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::Any,
+      .input_mode = Function::InputMode::None,
+      .desc = "Change directory.",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &, const buffer::Address &, vase::Shard *, const Argument &arg_, std::vector<buffer::Line> *) {
+        auto path = std::get<std::string>(arg_);
+        const auto first = path.find_first_not_of(" \t");
+        const auto last = path.find_last_not_of(" \t");
+        if (first == std::string::npos)
+          path.clear();
+        else
+          path = path.substr(first, last - first + 1);
+        if (path.empty())
+          path = getenv("HOME");
+        if (path == "~")
+          path = getenv("HOME");
+        if (path.starts_with("~/")) {
+          const char *home = getenv("HOME");
+          if (home)
+            path = std::string(home) + path.substr(1);
+        }
+        if (chdir(path.c_str()) == -1)
+          throw ed_error("Can't change directory.");
+      },
+    }
+  );
+  ctx.functions.insert(
+    "pwd",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Print directory.",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        char cwd[PATH_MAX];
+        if (!getcwd(cwd, sizeof(cwd)))
+          throw ed_error("Can't determine current directory.");
+        ctx.io.write_line(cwd);
+      },
+    }
+  );
+}
+} // namespace bed::internal::functions

src/internal/functions/functions.cc

@@ -1,295 +0,0 @@
-#include "internal/functions/functions.h"
-#include "bed.h"
-#include "internal/functions/suffixes.h"
-
-namespace bed::internal::functions {
-void Suffix::register_suffixes(BEd &ctx) {
-  ctx.suffixes['p' - 'a'] = Suffix{
-    .desc = "Prints current line.",
-    .handle = [](BEd &ctx) {
-      auto &addr = ctx.current();
-      ctx.buffer(addr.buffername).print(ctx, addr.number, addr.number);
-    }
-  };
-  ctx.suffixes['n' - 'a'] = Suffix{
-    .desc = "Prints current line with line number.",
-    .handle = [](BEd &ctx) {
-      auto &addr = ctx.current();
-      ctx.buffer(addr.buffername).number_print(ctx, addr.number, addr.number);
-    }
-  };
-}
-
-void Function::register_posix(BEd &ctx) {
-  ctx.no_op = Function{
-    .address_kind = Function::AddressKind::Line,
-    .argument_kind = Function::ArgumentKind::None,
-    .input_mode = Function::InputMode::None,
-    .desc = "Prints a line and jumps to it.",
-    .default_address = ".+1",
-    .accept_zero = false,
-    .pre_text_mode = nullptr,
-    .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
-      auto addr = std::get<buffer::Line>(addr_);
-      ctx.buffer(addr.buffername).print(ctx, addr.number, addr.number);
-      ctx.current() = addr;
-    }
-  };
-  ctx.eof_op = Function{
-    .address_kind = Function::AddressKind::None,
-    .argument_kind = Function::ArgumentKind::None,
-    .input_mode = Function::InputMode::None,
-    .desc = "Try quitting.",
-    .default_address = "",
-    .accept_zero = false,
-    .pre_text_mode = nullptr,
-    .handle = [](BEd &ctx, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
-      for (auto &[name, buffer] : ctx.buffers) {
-        if (buffer->state == buffer::Buffer::Modified) {
-          buffer->state = buffer::Buffer::Warned;
-          throw ed_error("Buffer " + name + " modified.");
-        }
-      }
-      throw fatal_error("Quitting", 0);
-    }
-  };
-  ctx.functions.insert(
-    "j",
-    Function{
-      .address_kind = Function::AddressKind::Range,
-      .argument_kind = Function::ArgumentKind::None,
-      .input_mode = Function::InputMode::None,
-      .desc = "Join a set of lines.",
-      .default_address = ".,.+1",
-      .accept_zero = false,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
-        auto addr = std::get<buffer::Range>(addr_);
-        ctx.buffer(addr.buffername).join(ctx, addr.start, addr.end);
-        ctx.current() = {addr.buffername, addr.start};
-      }
-    }
-  );
-  ctx.functions.insert(
-    "q",
-    Function{
-      .address_kind = Function::AddressKind::None,
-      .argument_kind = Function::ArgumentKind::None,
-      .input_mode = Function::InputMode::None,
-      .desc = "Try quitting.",
-      .default_address = "",
-      .accept_zero = false,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &ctx, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
-        for (auto &[name, buffer] : ctx.buffers) {
-          if (buffer->state == buffer::Buffer::Modified) {
-            buffer->state = buffer::Buffer::Warned;
-            throw ed_error("Buffer " + name + " modified.");
-          }
-        }
-        throw fatal_error("Quitting", 0);
-      }
-    }
-  );
-  ctx.functions.insert(
-    "Q",
-    Function{
-      .address_kind = Function::AddressKind::None,
-      .argument_kind = Function::ArgumentKind::None,
-      .input_mode = Function::InputMode::None,
-      .desc = "Force quit.",
-      .default_address = "",
-      .accept_zero = false,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
-        throw fatal_error("Force Quitting", 0);
-      }
-    }
-  );
-  ctx.functions.insert(
-    "p",
-    Function{
-      .address_kind = Function::AddressKind::Range,
-      .argument_kind = Function::ArgumentKind::None,
-      .input_mode = Function::InputMode::None,
-      .desc = "Print range",
-      .default_address = ".,.",
-      .accept_zero = false,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
-        auto addr = std::get<buffer::Range>(addr_);
-        ctx.buffer(addr.buffername).print(ctx, addr.start, addr.end);
-        ctx.current() = {addr.buffername, addr.end};
-      },
-    }
-  );
-  ctx.functions.insert(
-    "n",
-    Function{
-      .address_kind = Function::AddressKind::Range,
-      .argument_kind = Function::ArgumentKind::None,
-      .input_mode = Function::InputMode::None,
-      .desc = "Print range with line numbers",
-      .default_address = ".,.",
-      .accept_zero = false,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
-        auto addr = std::get<buffer::Range>(addr_);
-        ctx.buffer(addr.buffername).number_print(ctx, addr.start, addr.end);
-        ctx.current() = {addr.buffername, addr.end};
-      },
-    }
-  );
-  ctx.functions.insert(
-    "=",
-    Function{
-      .address_kind = Function::AddressKind::Range,
-      .argument_kind = Function::ArgumentKind::None,
-      .input_mode = Function::InputMode::None,
-      .desc = "Print line numbers",
-      .default_address = "$",
-      .accept_zero = true,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
-        auto addr = std::get<buffer::Range>(addr_);
-        if (addr.start == addr.end)
-          std::cout << ':' << addr.buffername << ':' << addr.start << "\n";
-        else
-          std::cout << ':' << addr.buffername << ':' << addr.start << "," << addr.end << "\n";
-      },
-    }
-  );
-  ctx.functions.insert(
-    "k",
-    Function{
-      .address_kind = Function::AddressKind::Line,
-      .argument_kind = Function::ArgumentKind::Mark,
-      .input_mode = Function::InputMode::None,
-      .desc = "Mark a line.",
-      .default_address = ".",
-      .accept_zero = false,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg, std::vector<buffer::Line> *) {
-        auto addr = std::get<buffer::Line>(addr_);
-        ctx.mark(std::get<char>(arg), addr);
-      }
-    }
-  );
-  ctx.functions.insert(
-    "e",
-    Function{
-      .address_kind = Function::AddressKind::None,
-      .argument_kind = Function::ArgumentKind::File,
-      .input_mode = Function::InputMode::None,
-      .desc = "Try load a file into the current buffer.",
-      .default_address = "",
-      .accept_zero = false,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg, std::vector<buffer::Line> *) {
-        auto &addr = std::get<std::string>(addr_);
-        auto &buf = ctx.buffer(addr);
-        if (buf.state == buffer::Buffer::Modified) {
-          buf.state = buffer::Buffer::Warned;
-          throw ed_error("Buffer modified.");
-        }
-        vase::Shard *s = nullptr;
-        if (std::holds_alternative<std::filesystem::path>(arg)) {
-          s = vase::Shard::from_file(std::get<std::filesystem::path>(arg), true);
-          buf.save_path = std::get<std::filesystem::path>(arg);
-        } else if (std::holds_alternative<ShellArg>(arg)) {
-          s = vase::Shard::from_command(std::get<ShellArg>(arg).cmd.c_str(), true);
-        } else if (std::holds_alternative<std::monostate>(arg)) {
-          if (buf.save_path != "")
-            s = vase::Shard::from_file(buf.save_path, true);
-          else
-            throw ed_error("Need filename to load.");
-        }
-        try {
-          if (buf.lines())
-            buf.remove(ctx, 1, buf.lines());
-          buf.append(ctx, s, 0);
-          buf.state = buffer::Buffer::Unmodified;
-        } catch (...) {
-          vase::Shard::release(s);
-          throw;
-        }
-        std::cout << (s->length + 1) << std::endl;
-        vase::Shard::release(s);
-        ctx.current() = {addr, buf.lines()};
-      }
-    }
-  );
-  ctx.functions.insert(
-    "E",
-    Function{
-      .address_kind = Function::AddressKind::None,
-      .argument_kind = Function::ArgumentKind::File,
-      .input_mode = Function::InputMode::None,
-      .desc = "Load a file into the current buffer.",
-      .default_address = "",
-      .accept_zero = false,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg, std::vector<buffer::Line> *) {
-        auto &addr = std::get<std::string>(addr_);
-        auto &buf = ctx.buffer(addr);
-        vase::Shard *s = nullptr;
-        if (std::holds_alternative<std::filesystem::path>(arg)) {
-          s = vase::Shard::from_file(std::get<std::filesystem::path>(arg), true);
-          buf.save_path = std::get<std::filesystem::path>(arg);
-        } else if (std::holds_alternative<ShellArg>(arg)) {
-          s = vase::Shard::from_command(std::get<ShellArg>(arg).cmd.c_str(), true);
-        } else if (std::holds_alternative<std::monostate>(arg)) {
-          if (buf.save_path != "")
-            s = vase::Shard::from_file(buf.save_path, true);
-          else
-            throw ed_error("Need filename to load.");
-        }
-        try {
-          if (buf.lines())
-            buf.remove(ctx, 1, buf.lines());
-          buf.append(ctx, s, 0);
-          buf.state = buffer::Buffer::Unmodified;
-        } catch (...) {
-          vase::Shard::release(s);
-          throw;
-        }
-        std::cout << (s->length + 1) << std::endl;
-        vase::Shard::release(s);
-        ctx.current() = {addr, buf.lines()};
-      }
-    }
-  );
-  ctx.functions.insert(
-    "H",
-    Function{
-      .address_kind = Function::AddressKind::None,
-      .argument_kind = Function::ArgumentKind::None,
-      .input_mode = Function::InputMode::None,
-      .desc = "Toggle help mode.",
-      .default_address = "",
-      .accept_zero = false,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &ctx, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
-        ctx.help_mode = !ctx.help_mode;
-        if (ctx.help_mode)
-          std::cout << ctx.last_help << std::endl;
-      }
-    }
-  );
-  ctx.functions.insert(
-    "h",
-    Function{
-      .address_kind = Function::AddressKind::None,
-      .argument_kind = Function::ArgumentKind::None,
-      .input_mode = Function::InputMode::None,
-      .desc = "Print last help message",
-      .default_address = "",
-      .accept_zero = false,
-      .pre_text_mode = nullptr,
-      .handle = [](BEd &ctx, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
-        std::cout << ctx.last_help << std::endl;
-      }
-    }
-  );
-}
-} // namespace bed::internal::functions

src/internal/functions/posix.cc

@@ -0,0 +1,657 @@
+#include "bed.h"
+#include "internal/functions/functions.h"
+#include "internal/functions/suffixes.h"
+
+namespace bed::internal::functions {
+void Suffix::register_suffixes(BEd &ctx) {
+  ctx.suffixes['p' - 'a'] = Suffix{
+    .desc = "Prints current line.",
+    .handle = [](BEd &ctx) {
+      auto &addr = ctx.current();
+      ctx.buffer(addr.buffername).print(ctx, addr.number, addr.number);
+    }
+  };
+  ctx.suffixes['n' - 'a'] = Suffix{
+    .desc = "Prints current line with line number.",
+    .handle = [](BEd &ctx) {
+      auto &addr = ctx.current();
+      ctx.buffer(addr.buffername).number_print(ctx, addr.number, addr.number);
+    }
+  };
+  ctx.suffixes['l' - 'a'] = Suffix{
+    .desc = "Prints current line unambiguously.",
+    .handle = [](BEd &ctx) {
+      auto &addr = ctx.current();
+      ctx.buffer(addr.buffername).list_print(ctx, addr.number, addr.number);
+    }
+  };
+}
+
+void Function::register_posix(BEd &ctx) {
+  ctx.functions.insert(
+    "a",
+    Function{
+      .address_kind = Function::AddressKind::Line,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::Text,
+      .desc = "Append text to a line.",
+      .default_address = ".",
+      .accept_zero = true,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *text, const Argument &, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Line>(addr_);
+        ctx.buffer(addr.buffername).append(ctx, text, addr.number);
+        ctx.current() = {ctx.prev().buffername, ctx.prev().end};
+        vase::Shard::release(text);
+      }
+    }
+  );
+  ctx.functions.insert(
+    "c",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::Text,
+      .desc = "Change set of lines.",
+      .default_address = ".,.",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *text, const Argument &, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Range>(addr_);
+        ctx.buffer(addr.buffername).remove(ctx, addr.start, addr.end);
+        ctx.buffer(addr.buffername).append(ctx, text, addr.start - 1);
+        ctx.current() = {ctx.prev().buffername, ctx.prev().end};
+        vase::Shard::release(text);
+      }
+    }
+  );
+  ctx.functions.insert(
+    "d",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Delete set of lines.",
+      .default_address = ".,.",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Range>(addr_);
+        ctx.buffer(addr.buffername).remove(ctx, addr.start, addr.end);
+        ctx.current() = {addr.buffername, addr.start};
+      }
+    }
+  );
+  ctx.functions.insert(
+    "e",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::File,
+      .input_mode = Function::InputMode::None,
+      .desc = "Try load a file into the current buffer.",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg, std::vector<buffer::Line> *) {
+        auto &addr = std::get<std::string>(addr_);
+        auto &buf = ctx.buffer(addr);
+        if (buf.state == buffer::Buffer::Modified) {
+          buf.state = buffer::Buffer::Warned;
+          throw ed_error("Buffer modified.");
+        }
+        vase::Shard *s = nullptr;
+        if (std::holds_alternative<std::filesystem::path>(arg)) {
+          auto path = std::get<std::filesystem::path>(arg);
+          s = vase::Shard::from_file(path, true);
+          buf.set_filename(path);
+        } else if (std::holds_alternative<ShellArg>(arg)) {
+          auto cmd = std::get<ShellArg>(arg).cmd;
+          ctx.escape_command(cmd, buf.filename().string());
+          s = vase::Shard::from_command(cmd.c_str(), true);
+        } else {
+          auto path = buf.filename();
+          if (path.empty())
+            throw ed_error("Need filename.");
+          s = vase::Shard::from_file(path, true);
+        };
+        try {
+          buf.load(ctx, s);
+          vase::Shard::release(s);
+        } catch (...) {
+          vase::Shard::release(s);
+          throw;
+        }
+        ctx.io.write_line(std::format("{}", buf.bytes()));
+        ctx.current() = {addr, buf.lines()};
+      }
+    }
+  );
+  ctx.functions.insert(
+    "E",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::File,
+      .input_mode = Function::InputMode::None,
+      .desc = "Load a file into the current buffer.",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg, std::vector<buffer::Line> *) {
+        auto &addr = std::get<std::string>(addr_);
+        auto &buf = ctx.buffer(addr);
+        vase::Shard *s = nullptr;
+        if (std::holds_alternative<std::filesystem::path>(arg)) {
+          auto path = std::get<std::filesystem::path>(arg);
+          s = vase::Shard::from_file(path, true);
+          buf.set_filename(path);
+        } else if (std::holds_alternative<ShellArg>(arg)) {
+          auto cmd = std::get<ShellArg>(arg).cmd;
+          ctx.escape_command(cmd, buf.filename().string());
+          s = vase::Shard::from_command(cmd.c_str(), true);
+        } else {
+          auto path = buf.filename();
+          if (path.empty())
+            throw ed_error("Need filename.");
+          s = vase::Shard::from_file(path, true);
+        };
+        try {
+          buf.load(ctx, s);
+          vase::Shard::release(s);
+        } catch (...) {
+          vase::Shard::release(s);
+          throw;
+        }
+        ctx.io.write_line(std::format("{}", buf.bytes()));
+        ctx.current() = {addr, buf.lines()};
+      }
+    }
+  );
+  ctx.functions.insert(
+    "f",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::File,
+      .input_mode = Function::InputMode::None,
+      .desc = "Set a save path.",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg, std::vector<buffer::Line> *) {
+        auto &addr = std::get<std::string>(addr_);
+        auto &buf_ = ctx.buffer(addr);
+        if (buf_.kind != buffer::Buffer::Kind::Generic)
+          return;
+        auto &buf = *(buffer::GenericBuffer *)&buf_;
+        if (std::holds_alternative<std::filesystem::path>(arg))
+          buf.set_filename(std::get<std::filesystem::path>(arg));
+        else if (std::holds_alternative<ShellArg>(arg))
+          throw ed_error("Can't save shell command as save path.");
+        if (buf.filename().empty())
+          throw ed_error("Filename needed.");
+        ctx.io.write_line(buf.filename().string());
+      }
+    }
+  );
+  ctx.functions.insert(
+    "h",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Print last help message",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        ctx.io.write_line(ctx.last_help);
+      }
+    }
+  );
+  ctx.functions.insert(
+    "H",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Toggle help mode.",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        ctx.help_mode = !ctx.help_mode;
+        if (ctx.help_mode)
+          ctx.io.write_line(ctx.last_help);
+      }
+    }
+  );
+  ctx.functions.insert(
+    "i",
+    Function{
+      .address_kind = Function::AddressKind::Line,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::Text,
+      .desc = "Insert text before a line.",
+      .default_address = ".",
+      .accept_zero = true,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *text, const Argument &, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Line>(addr_);
+        if (addr.number)
+          addr.number--;
+        ctx.buffer(addr.buffername).append(ctx, text, addr.number);
+        ctx.current() = {ctx.prev().buffername, ctx.prev().end};
+        vase::Shard::release(text);
+      }
+    }
+  );
+  ctx.functions.insert(
+    "j",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Join a set of lines.",
+      .default_address = ".,.+1",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Range>(addr_);
+        ctx.buffer(addr.buffername).join(ctx, addr.start, addr.end);
+        ctx.current() = {addr.buffername, addr.start};
+      }
+    }
+  );
+  ctx.functions.insert(
+    "k",
+    Function{
+      .address_kind = Function::AddressKind::Line,
+      .argument_kind = Function::ArgumentKind::Mark,
+      .input_mode = Function::InputMode::None,
+      .desc = "Mark a line.",
+      .default_address = ".",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg, std::vector<buffer::Line> *) {
+        auto &addr = std::get<buffer::Line>(addr_);
+        ctx.mark(std::get<char>(arg), addr);
+      }
+    }
+  );
+  ctx.functions.insert(
+    "l",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "List (print unambiguous) range",
+      .default_address = ".,.",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Range>(addr_);
+        ctx.buffer(addr.buffername).list_print(ctx, addr.start, addr.end);
+        ctx.current() = {addr.buffername, addr.end};
+      },
+    }
+  );
+  ctx.functions.insert(
+    "m",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::Line,
+      .input_mode = Function::InputMode::None,
+      .desc = "Move a range of lines.",
+      .default_address = ".,.",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg_, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Range>(addr_);
+        auto arg = std::get<buffer::Line>(arg_);
+        if (arg.buffername == addr.buffername
+            && addr.start <= arg.number
+            && addr.end < arg.number)
+          throw ed_error("Can't move lines within themselves.");
+        auto text = ctx.buffer(addr.buffername).copy(addr.start, addr.end);
+        ctx.mark(252, arg);
+        ctx.buffer(addr.buffername).remove(ctx, addr.start, addr.end);
+        arg = ctx.marks.get(252);
+        try {
+          if (arg.number == UINT64_MAX)
+            throw ed_error("Unexpected error when moving lines.");
+          ctx.buffer(arg.buffername).append(ctx, text, arg.number);
+          vase::Shard::release(text);
+        } catch (...) {
+          if (!addr.start) {
+            vase::Shard::release(text);
+            throw;
+          }
+          ctx.buffer(addr.buffername).append(ctx, text, --addr.start);
+          vase::Shard::release(text);
+          throw;
+        }
+        ctx.current() = {arg.buffername, arg.number + addr.end - addr.start + 1};
+      },
+    }
+  );
+  ctx.functions.insert(
+    "n",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Print range with line numbers",
+      .default_address = ".,.",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Range>(addr_);
+        ctx.buffer(addr.buffername).number_print(ctx, addr.start, addr.end);
+        ctx.current() = {addr.buffername, addr.end};
+      },
+    }
+  );
+  ctx.functions.insert(
+    "p",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Print range",
+      .default_address = ".,.",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Range>(addr_);
+        ctx.buffer(addr.buffername).print(ctx, addr.start, addr.end);
+        ctx.current() = {addr.buffername, addr.end};
+      },
+    }
+  );
+  ctx.functions.insert(
+    "P",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Toggle prompt.",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        ctx.prompt_mode = !ctx.prompt_mode;
+        if (ctx.prompt_mode && !ctx.prompt) {
+          ctx.prompt = [](BEd &) { return "*"; };
+        }
+      }
+    }
+  );
+  ctx.functions.insert(
+    "q",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Try quitting.",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        std::string modified_buffers;
+        for (auto &[name, buffer] : ctx.buffers) {
+          if (buffer->state == buffer::Buffer::Modified) {
+            buffer->state = buffer::Buffer::Warned;
+            modified_buffers.append(name + ", ");
+          }
+        }
+        if (!modified_buffers.size())
+          throw fatal_error("Quitting", 0);
+        modified_buffers.erase(modified_buffers.size() - 2);
+        throw ed_error("Buffer(s) " + modified_buffers + " modified.");
+      }
+    }
+  );
+  ctx.functions.insert(
+    "Q",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Force quit.",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        throw fatal_error("Force Quitting", 0);
+      }
+    }
+  );
+  ctx.functions.insert(
+    "r",
+    Function{
+      .address_kind = Function::AddressKind::Line,
+      .argument_kind = Function::ArgumentKind::File,
+      .input_mode = Function::InputMode::None,
+      .desc = "Read from file into buffer.",
+      .default_address = "$",
+      .accept_zero = true,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg, std::vector<buffer::Line> *) {
+        auto &addr = std::get<buffer::Line>(addr_);
+        auto &buf = ctx.buffer(addr.buffername);
+        vase::Shard *s = nullptr;
+        if (std::holds_alternative<std::filesystem::path>(arg)) {
+          auto path = std::get<std::filesystem::path>(arg);
+          s = vase::Shard::from_file(path, true);
+          if (buf.filename().empty())
+            buf.set_filename(path);
+        } else if (std::holds_alternative<ShellArg>(arg)) {
+          auto cmd = std::get<ShellArg>(arg).cmd;
+          ctx.escape_command(cmd, buf.filename().string());
+          s = vase::Shard::from_command(cmd.c_str(), true);
+        } else {
+          auto path = buf.filename();
+          if (path.empty())
+            throw ed_error("Need filename.");
+          s = vase::Shard::from_file(path, true);
+        };
+        try {
+          buf.append(ctx, s, addr.number);
+          ctx.io.write_line(std::format("{}", s ? s->length + 1 : 0));
+          ctx.current() = {addr.buffername, addr.number + (s ? s->lines + 1 : 0)};
+          vase::Shard::release(s);
+        } catch (...) {
+          vase::Shard::release(s);
+          throw;
+        }
+      }
+    }
+  );
+  ctx.functions.insert(
+    "s",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::Regex,
+      .input_mode = Function::InputMode::None,
+      .desc = "Substitute regex.",
+      .default_address = ".,.",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg_, std::vector<buffer::Line> *) {
+        auto &addr = std::get<buffer::Range>(addr_);
+        auto arg = std::get<RegexArg>(arg_);
+        if (arg.expression == "")
+          arg.expression = ctx.last_regex;
+        else
+          ctx.last_regex = arg.expression;
+        if (arg.replacement == "%")
+          arg.replacement = ctx.last_replacement;
+        else
+          ctx.last_replacement = arg.replacement;
+        ctx.buffer(addr.buffername)
+          .substitute(
+            ctx,
+            addr.start,
+            addr.end,
+            arg.expression,
+            arg.replacement,
+            arg.options
+          );
+      }
+    }
+  );
+  ctx.functions.insert(
+    "t",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::Line,
+      .input_mode = Function::InputMode::None,
+      .desc = "Copy a range of lines.",
+      .default_address = ".,.",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg_, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Range>(addr_);
+        auto arg = std::get<buffer::Line>(arg_);
+        auto text = ctx.buffer(addr.buffername).copy(addr.start, addr.end);
+        try {
+          ctx.buffer(arg.buffername).append(ctx, text, arg.number);
+          vase::Shard::release(text);
+        } catch (...) {
+          if (!addr.start) {
+            vase::Shard::release(text);
+            throw;
+          }
+          ctx.buffer(addr.buffername).append(ctx, text, --addr.start);
+          vase::Shard::release(text);
+          throw;
+        }
+        ctx.current() = {arg.buffername, arg.number + addr.end - addr.start + 1};
+      },
+    }
+  );
+  ctx.functions.insert(
+    "w",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::File,
+      .input_mode = Function::InputMode::None,
+      .desc = "Write buffer to disk.",
+      .default_address = "0,$",
+      .accept_zero = true,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg, std::vector<buffer::Line> *) {
+        auto addr = std::get<buffer::Range>(addr_);
+        auto &buf = ctx.buffer(addr.buffername);
+        vase::Shard *text;
+        if (!addr.start && !addr.end) {
+          text = nullptr;
+        } else {
+          if (!addr.start && addr.end)
+            addr.start = 1;
+          text = buf.copy(addr.start, addr.end);
+        }
+        try {
+          if (std::holds_alternative<std::filesystem::path>(arg)) {
+            auto path = std::get<std::filesystem::path>(arg);
+            vase::write_file(path, text);
+            buf.set_filename(path);
+          } else if (std::holds_alternative<ShellArg>(arg)) {
+            auto cmd = std::get<ShellArg>(arg).cmd;
+            ctx.escape_command(cmd, buf.filename().string());
+            vase::write_command(cmd.c_str(), text);
+          } else {
+            auto path = buf.filename();
+            if (path.empty())
+              throw ed_error("Need filename.");
+            vase::write_file(path, text);
+          };
+          ctx.io.write(std::format("{}\n", text ? text->length + 1 : 0));
+          vase::Shard::release(text);
+        } catch (...) {
+          vase::Shard::release(text);
+          throw;
+        }
+      }
+    }
+  );
+  ctx.functions.insert(
+    "=",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Print line numbers",
+      .default_address = "$",
+      .accept_zero = true,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+        auto &addr = std::get<buffer::Range>(addr_);
+        if (addr.start == addr.end)
+          ctx.io.write_line(std::format(":{}:{}", addr.buffername, addr.start));
+        else
+          ctx.io.write_line(std::format(":{}:{},{}", addr.buffername, addr.start, addr.end));
+        ctx.current() = {addr.buffername, addr.end};
+      },
+    }
+  );
+  ctx.functions.insert(
+    "!",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::Shell,
+      .input_mode = Function::InputMode::None,
+      .desc = "Run a shell command.",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &arg_, std::vector<buffer::Line> *) {
+        auto &addr = std::get<std::string>(addr_);
+        auto filename = ctx.buffer(addr).filename();
+        auto &arg = std::get<ShellArg>(arg_);
+        auto cmd = arg.cmd;
+        if (ctx.escape_command(cmd, filename.string()))
+          ctx.io.write(cmd + "\n");
+        ctx.io.run_pty(cmd);
+        ctx.io.write("!\n");
+      },
+    }
+  );
+  ctx.no_op = Function{
+    .address_kind = Function::AddressKind::Line,
+    .argument_kind = Function::ArgumentKind::None,
+    .input_mode = Function::InputMode::None,
+    .desc = "Prints a line and jumps to it.",
+    .default_address = ".+1",
+    .accept_zero = true,
+    .pre_text_mode = nullptr,
+    .handle = [](BEd &ctx, const buffer::Address &addr_, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+      auto addr = std::get<buffer::Line>(addr_);
+      if (addr.number != 0)
+        ctx.buffer(addr.buffername).print(ctx, addr.number, addr.number);
+      ctx.current() = addr;
+    }
+  };
+  ctx.eof_op = Function{
+    .address_kind = Function::AddressKind::None,
+    .argument_kind = Function::ArgumentKind::None,
+    .input_mode = Function::InputMode::None,
+    .desc = "Try quitting.",
+    .default_address = "",
+    .accept_zero = false,
+    .pre_text_mode = nullptr,
+    .handle = [](BEd &ctx, const buffer::Address &, vase::Shard *, const Argument &, std::vector<buffer::Line> *) {
+      std::string modified_buffers;
+      for (auto &[name, buffer] : ctx.buffers) {
+        if (buffer->state == buffer::Buffer::Modified) {
+          buffer->state = buffer::Buffer::Warned;
+          modified_buffers.append(name + ", ");
+        }
+      }
+      if (!modified_buffers.size())
+        throw fatal_error("Quitting", 0);
+      modified_buffers.erase(modified_buffers.size() - 2);
+      throw ed_error("Buffer(s) " + modified_buffers + " modified.");
+    }
+  };
+}
+} // namespace bed::internal::functions

src/internal/io/_command.cc

@@ -1,10 +0,0 @@
-#include "bed.h"
-#include "internal/io/command.h"
-#include "internal/io/io.h"
-
-namespace bed::internal::io {
-std::pair<std::string, bool> IO::get_command(BEd &ctx) {
-  CommandIO cio(ctx, *this);
-  return cio.run();
-}
-} // namespace bed::internal::io

src/internal/io/io.cc

@@ -2,7 +2,8 @@
 
 namespace bed::internal::io {
 termios IO::orig_termios{};
-bool IO::cleaned = false;
+termios IO::raw_termios{};
+bool IO::cleaned = true;
 volatile std::atomic_bool IO::resized(false);
 
 IO::IO() {
@@ -14,16 +15,13 @@ IO::IO() {
   sa.sa_flags = 0;
   if (sigaction(SIGWINCH, &sa, nullptr) == -1)
     throw fatal_error("Can't install SIGWINCH handler.", 1);
-  struct termios raw = orig_termios;
-  raw.c_iflag &= ~(BRKINT | ISTRIP | IXON);
-  raw.c_cflag |= (CS8);
-  raw.c_lflag &= ~(ECHO | ICANON | ISIG);
-  raw.c_cc[VMIN] = 1;
-  raw.c_cc[VTIME] = 0;
-  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1)
-    throw fatal_error("Can't set terminal state.", 1);
-  std::string os = "\x1b[?2004h";
-  write_all(STDOUT_FILENO, os.c_str(), os.size());
+  raw_termios = orig_termios;
+  raw_termios.c_iflag &= ~(BRKINT | ISTRIP | IXON);
+  raw_termios.c_cflag |= (CS8);
+  raw_termios.c_lflag &= ~(ECHO | ICANON | ISIG);
+  raw_termios.c_cc[VMIN] = 1;
+  raw_termios.c_cc[VTIME] = 0;
+  enable_raw();
   atexit(cleanup);
 }
 
@@ -70,6 +68,16 @@ std::pair<uint16_t, uint16_t> IO::cursor_position() {
   return {(uint16_t)row, (uint16_t)col};
 }
 
+void IO::enable_raw() {
+  if (!cleaned)
+    return;
+  std::string os = "\x1b[?2004h";
+  write_all(STDOUT_FILENO, os.c_str(), os.size());
+  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw_termios) == -1)
+    throw fatal_error("Can't set raw terminal state.", 1);
+  cleaned = false;
+}
+
 void IO::cleanup() {
   if (cleaned)
     return;
@@ -97,4 +105,76 @@ void IO::write(const char *buf, uint64_t n) {
 void IO::write(std::string_view s) {
   write_all(STDOUT_FILENO, s.data(), s.size());
 }
+
+void IO::write_line(std::string_view s) {
+  write(s);
+  write("\n", 1);
+}
+
+void IO::run_pty(const std::string &cmd) {
+  int master_fd = -1;
+  struct winsize ws{};
+  if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == -1)
+    throw fatal_error("Can't get terminal size.", 1);
+  pid_t pid = forkpty(
+    &master_fd,
+    nullptr,
+    &orig_termios,
+    &ws
+  );
+  if (pid == -1)
+    throw fatal_error("Can't create PTY.", 1);
+  if (pid == 0) {
+    const char *shell = getenv("BED_SHELL");
+    if (!shell || !*shell)
+      shell = getenv("SHELL");
+    if (!shell || !*shell)
+      shell = "/bin/sh";
+    execl(shell, shell, "-i", "-c", cmd.c_str(), (char *)nullptr);
+    _exit(127);
+  }
+  struct pollfd fds[2];
+  while (true) {
+    fds[0].fd = STDIN_FILENO;
+    fds[0].events = POLLIN;
+    fds[1].fd = master_fd;
+    fds[1].events = POLLIN;
+    int rc = poll(fds, 2, -1);
+    if (rc == -1) {
+      if (errno == EINTR)
+        continue;
+      break;
+    }
+    if (resized.exchange(false)) {
+      struct winsize new_ws{};
+      if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &new_ws) == 0)
+        ioctl(master_fd, TIOCSWINSZ, &new_ws);
+    }
+    if (fds[0].revents & POLLIN) {
+      char buf[4096];
+      ssize_t n = read(STDIN_FILENO, buf, sizeof(buf));
+      if (n > 0)
+        write_all(master_fd, buf, n);
+      else if (n == 0)
+        break;
+    }
+    if (fds[1].revents & POLLIN) {
+      char buf[8192];
+      ssize_t n = read(master_fd, buf, sizeof(buf));
+      if (n > 0)
+        write_all(STDOUT_FILENO, buf, n);
+      else
+        break;
+    }
+    if (fds[0].revents & (POLLERR | POLLHUP | POLLNVAL))
+      break;
+    if (fds[1].revents & (POLLERR | POLLHUP | POLLNVAL))
+      break;
+  }
+  close(master_fd);
+  int status;
+  while (waitpid(pid, &status, 0) == -1)
+    if (errno != EINTR)
+      break;
+}
 } // namespace bed::internal::io

src/internal/io/text_mode.cc

@@ -1,28 +0,0 @@
-#include "bed.h"
-#include "internal/io/io.h"
-
-namespace bed::internal::io {
-std::pair<std::string, bool> IO::get_text(BEd &) {
-  uint16_t start;
-  uint16_t height;
-  {
-    auto [row, col] = cursor_position();
-    auto [rows, cols] = terminal_size();
-    if (row > rows)
-      throw fatal_error("Invalid cursor position.", 1);
-    start = row;
-    height = rows - row + 1;
-  }
-  enable_mouse();
-  // uint16_t width = cols;
-
-  disable_mouse();
-  for (uint16_t i = 1; i < height; ++i) {
-    move_cursor(start + i, 1);
-    write_all(STDOUT_FILENO, "\x1b[2K", 4);
-  }
-  move_cursor(start, 1);
-  write_all(STDOUT_FILENO, "\n", 1);
-  return {"", true};
-}
-} // namespace bed::internal::io

src/internal/parser/address.cc

@@ -0,0 +1,252 @@
+#include "bed.h"
+#include "internal/parser/parser.h"
+
+namespace bed::internal::parser {
+void Parser::locator(AddressPromise &addr) {
+  addr.base = AddressPromise::None{};
+  switch (peek()) {
+  case '.':
+    advance();
+    addr.base = AddressPromise::Current{};
+    break;
+  case '$':
+    advance();
+    addr.base = AddressPromise::Last{};
+    break;
+  case '%':
+    advance();
+    addr.base = AddressPromise::LastRange{};
+    break;
+  case '[':
+    advance();
+    addr.base = AddressPromise::Block{Direction::Backward};
+    break;
+  case ']':
+    advance();
+    addr.base = AddressPromise::Block{Direction::Forward};
+    break;
+  case '^':
+    advance();
+    addr.base = AddressPromise::Diagnostic{Direction::Backward};
+    break;
+  case '~':
+    advance();
+    addr.base = AddressPromise::Diagnostic{Direction::Forward};
+    break;
+  case '\'':
+    advance();
+    if (('a' <= peek() && peek() <= 'z')
+        || ('A' <= peek() && peek() <= 'Z'))
+      addr.base = AddressPromise::Mark{peek()};
+    else
+      throw ed_error("Valid mark needed after \'");
+    advance();
+    break;
+  case '{': {
+    advance();
+    uint16_t j = 0;
+    std::string func;
+    std::string arg;
+    while (peek(j) != '}') {
+      if (peek(j) == '\0')
+        throw ed_error("Scripted address not terminated");
+      if (peek(j) == '\\')
+        ++j;
+      if (peek(j) == ':') {
+        func = peek_str(j);
+        advance(j + 1);
+        j = 0;
+        continue;
+      }
+      ++j;
+    }
+    if (func.size())
+      arg = peek_str(j);
+    else
+      func = peek_str(j);
+    addr.base = AddressPromise::Scripted{std::move(func), std::move(arg)};
+    advance(j + 1);
+  } break;
+  case '/': {
+    advance();
+    uint64_t j = 0;
+    while (true) {
+      if (peek(j) == '\0')
+        break;
+      if (peek(j) == '/')
+        break;
+      else if (peek(j) == '\\')
+        j += 2;
+      else if (peek(j) == '[')
+        while (peek(j) != '\0' && cmd[i] != ']')
+          j++;
+      else
+        j++;
+    }
+    addr.base = AddressPromise::Regex(
+      Direction::Forward,
+      std::string(peek_str(j))
+    );
+    advance(j + 1);
+  } break;
+  case '?': {
+    advance();
+    uint16_t j = 0;
+    while (true) {
+      if (peek(j) == '\0')
+        break;
+      if (peek(j) == '?')
+        break;
+      else if (peek(j) == '\\')
+        j += 2;
+      else if (peek(j) == '[')
+        while (peek(j) != '\0' && cmd[i] != ']')
+          j++;
+      else
+        j++;
+    }
+    addr.base = AddressPromise::Regex(
+      Direction::Backward,
+      std::string(peek_str(j))
+    );
+    advance(j + 1);
+  } break;
+  case '<': {
+    advance();
+    uint16_t j = 0;
+    while (peek(j) != '>'
+           && peek(j) != '<'
+           && peek(j) != '\0')
+      j++;
+    switch (peek(j)) {
+    case '\0':
+    case '>':
+      addr.base = AddressPromise::SymbolDefinition{
+        std::string(peek_str(j))
+      };
+      break;
+    case '<':
+      addr.base = AddressPromise::SymbolReference{
+        Direction::Backward,
+        std::string(peek_str(j))
+      };
+      break;
+    }
+    advance(j + 1);
+  } break;
+  case '>': {
+    advance();
+    uint16_t j = 0;
+    while (peek(j) != '>' && peek(j) != '\0')
+      j++;
+    switch (peek(j)) {
+    case '\0':
+      throw ed_error("Unterminated symbol reference addressing.");
+    case '>':
+      addr.base = AddressPromise::SymbolReference{
+        Direction::Forward,
+        std::string(peek_str(j))
+      };
+      break;
+    }
+    advance(j + 1);
+  } break;
+  case '+': {
+    advance();
+    addr.base = AddressPromise::Current{};
+    uint16_t j = 0;
+    uint64_t num = 0;
+    while ('0' <= peek(j) && peek(j) <= '9') {
+      num = num * 10 + (peek(j) - '0');
+      j++;
+    }
+    if (j == 0)
+      num = 1;
+    advance(j);
+    addr.offset += num;
+  } break;
+  case '-': {
+    advance();
+    addr.base = AddressPromise::Current{};
+    uint16_t j = 0;
+    uint64_t num = 0;
+    while ('0' <= peek(j) && peek(j) <= '9') {
+      num = num * 10 + (peek(j) - '0');
+      j++;
+    }
+    if (j == 0)
+      num = 1;
+    advance(j);
+    addr.offset -= num;
+  } break;
+  default:
+    if ('0' <= peek() && peek() <= '9') {
+      uint64_t num = 0;
+      while ('0' <= peek() && peek() <= '9') {
+        num = num * 10 + (peek() - '0');
+        advance();
+      }
+      addr.base = AddressPromise::Number{num};
+    }
+  }
+}
+
+int64_t Parser::offset() {
+  int64_t offset = 0;
+  while (peek() == '+' || peek() == '-'
+         || ('0' <= peek() && peek() <= '9')) {
+    bool positive = peek() != '-';
+    if (peek() == '+' || peek() == '-')
+      advance();
+    uint16_t j = 0;
+    int64_t num = 0;
+    while ('0' <= peek(j) && peek(j) <= '9')
+      num = num * 10 + (peek(j++) - '0');
+    if (j == 0)
+      num = 1;
+    advance(j);
+    offset += positive ? num : -num;
+    skip_ws();
+  }
+  skip_ws();
+  return offset;
+}
+
+void Parser::address(AddressPromise &addr) {
+  if (peek() == ':') {
+    advance();
+    uint16_t j = 0;
+    while (peek(j) != ':' && peek(j) != '\0')
+      j++;
+    addr.bufname = peek_str(j);
+    advance(j);
+    if (peek() == ':')
+      advance();
+  }
+  skip_ws();
+  if (peek() == '\0')
+    return;
+  locator(addr);
+  skip_ws();
+  addr.offset += offset();
+}
+
+void Parser::addresses(std::vector<AddressPromise> &addresses) {
+  skip_ws();
+  addresses.push_back({});
+  auto *addr = &addresses.back();
+  address(*addr);
+  while (peek() == ',' || peek() == ';') {
+    addr->jumping = peek() == ';';
+    advance();
+    skip_ws();
+    addresses.push_back({});
+    addr = &addresses.back();
+    address(*addr);
+  }
+  if (addresses.size() == 1
+      && addr->offset == 0 && !addr->bufname.has_value()
+      && std::holds_alternative<AddressPromise::None>(addr->base))
+    addresses.pop_back();
+}
+} // namespace bed::internal::parser

src/internal/parser/address_promise.cc

@@ -6,13 +6,16 @@ namespace bed::internal::parser {
 buffer::Line AddressPromise::resolve(BEd &ctx) {
   buffer::Line result = std::visit(
     [&](auto const &addr) -> buffer::Line {
-      if (!bufname.has_value())
+      if (!bufname.has_value() || bufname->empty())
         throw ed_error("Buffer name can't be empty.");
       buffer::Line line = {*bufname, 0};
       auto &buf = ctx.buffer(line.buffername);
       using T = std::decay_t<decltype(addr)>;
       if constexpr (std::is_same_v<T, None>) {
-        throw ed_error("no address");
+        if (line.buffername == ctx.current().buffername)
+          line.number = ctx.current().number;
+        else
+          line.number = buf.lines();
       } else if constexpr (std::is_same_v<T, Current>) {
         if (line.buffername == ctx.current().buffername)
           line.number = ctx.current().number;
@@ -41,9 +44,9 @@ buffer::Line AddressPromise::resolve(BEd &ctx) {
         if (re.size() == 0)
           throw ed_error("No regex given.");
         if (addr.dir == Direction::Forward)
-          line.number = vase::find_next(buf.root, re, line.number);
+          line.number = buf.find_next(re, line.number);
         else
-          line.number = vase::find_prev(buf.root, re, line.number);
+          line.number = buf.find_prev(re, line.number);
         ctx.last_regex = re;
       } else if constexpr (std::is_same_v<T, Block>) {
         if (line.buffername == ctx.current().buffername)
@@ -52,28 +55,10 @@ buffer::Line AddressPromise::resolve(BEd &ctx) {
           line.number = buf.lines();
         if (buf.lines() > 0 && line.number == 0)
           line.number = 1;
-        if (addr.dir == Direction::Forward) {
-          if (buf.parser.has_value()) {
-            uint64_t closing = buf.parser->next_closing(line.number - 1);
-            if (closing == UINT64_MAX)
-              line.number = buf.lines();
-            else
-              line.number = closing + 1;
-          } else {
-            line.number += 10;
-            if (line.number > buf.lines())
-              line.number = buf.lines();
-          }
-        } else {
-          if (buf.parser.has_value()) {
-            line.number = buf.parser->prev_opening(line.number - 1) + 1;
-          } else {
-            if (line.number > 10)
-              line.number -= 10;
-            else
-              line.number = 0;
-          }
-        }
+        if (addr.dir == Direction::Forward)
+          line.number = buf.next_closing(line.number);
+        else
+          line.number = buf.prev_closing(line.number);
       } else {
         throw ed_error("Unhandled address given.");
       }
@@ -116,8 +101,8 @@ std::optional<buffer::Line> AddressPromise::get_line(BEd &ctx, std::vector<Addre
         curr.offset = 0;
         prev_given = false;
       } else if (std::holds_alternative<LastRange>(curr.base)) {
-        curr.bufname = ctx.prev.buffername;
-        curr.base = Number(ctx.prev.end);
+        curr.bufname = ctx.prev().buffername;
+        curr.base = Number(ctx.prev().end);
         prev_given = true;
       } else {
         prev_given = true;
@@ -133,15 +118,18 @@ std::optional<buffer::Line> AddressPromise::get_line(BEd &ctx, std::vector<Addre
       prev_set = true;
     } else {
       if (std::holds_alternative<None>(curr.base)) {
-        if (!prev_set)
-          return std::nullopt;
-        if (prev_given) {
-          curr.base = prev.base;
-          curr.offset = prev.offset;
-        } else {
-          curr.base = Last();
-          curr.offset = 0;
+        if (prev_set) {
+          if (prev_given) {
+            curr.base = prev.base;
+            curr.offset = prev.offset;
+          } else {
+            curr.base = Last();
+            curr.offset = 0;
+          }
         }
+      } else if (std::holds_alternative<LastRange>(curr.base)) {
+        curr.bufname = ctx.prev().buffername;
+        curr.base = Number(ctx.prev().end);
       }
       return curr.resolve(ctx);
     }
@@ -176,8 +164,8 @@ std::optional<buffer::Range> AddressPromise::get_range(BEd &ctx, std::vector<Add
         curr.offset = 0;
         prev_given = false;
       } else if (std::holds_alternative<LastRange>(curr.base)) {
-        curr.bufname = ctx.prev.buffername;
-        curr.base = Number(ctx.prev.end);
+        curr.bufname = ctx.prev().buffername;
+        curr.base = Number(ctx.prev().end);
         prev_given = true;
       } else {
         prev_given = true;
@@ -193,16 +181,30 @@ std::optional<buffer::Range> AddressPromise::get_range(BEd &ctx, std::vector<Add
       prev_set = true;
     } else {
       if (std::holds_alternative<None>(curr.base)) {
-        if (!prev_set)
-          return std::nullopt;
-        if (prev_given) {
-          curr.base = prev.base;
-          curr.offset = prev.offset;
-        } else {
-          curr.base = Last();
-          curr.offset = 0;
+        if (prev_set) {
+          if (prev_given) {
+            curr.base = prev.base;
+            curr.offset = prev.offset;
+          } else {
+            curr.base = Last();
+            curr.offset = 0;
+          }
+          return buffer::Range(prev.resolve(ctx), curr.resolve(ctx));
         }
-        return buffer::Range(prev.resolve(ctx), curr.resolve(ctx));
+      } else if (std::holds_alternative<LastRange>(curr.base)) {
+        auto previous = ctx.prev();
+        auto &buf = ctx.buffer(previous.buffername);
+        if (curr.offset < 0 && previous.start < (uint64_t)-curr.offset)
+          throw ed_error("Can't have negative addresses");
+        previous.start += curr.offset;
+        if (previous.start > buf.lines())
+          throw ed_error("Line number too high.");
+        if (curr.offset < 0 && previous.end < (uint64_t)-curr.offset)
+          throw ed_error("Can't have negative addresses");
+        previous.end += curr.offset;
+        if (previous.end > buf.lines())
+          throw ed_error("Line number too high.");
+        return previous;
       }
       if (prev_given)
         return buffer::Range(prev.resolve(ctx), curr.resolve(ctx));

src/internal/parser/operation.cc

@@ -0,0 +1,208 @@
+#include "bed.h"
+#include "internal/parser/parser.h"
+
+namespace bed::internal::parser {
+void Parser::operation() {
+  if (peek() == '\0') {
+    command->function = &bed.no_op;
+    return;
+  }
+  uint64_t len = bed.functions.longest_match(peek_str());
+  if (len == 0)
+    throw ed_error("Function not found.");
+  functions::Function *function = bed.functions.get_ptr(peek_str(len));
+  advance(len);
+  command->function = function;
+  char suffix = '\0';
+  switch (command->function->argument_kind) {
+  case functions::Function::ArgumentKind::None:
+    break;
+  case functions::Function::ArgumentKind::Number:
+    skip_ws();
+    command->argument = offset();
+    break;
+  case functions::Function::ArgumentKind::Mark:
+    if (('a' <= peek() && peek() <= 'z')
+        || ('A' <= peek() && peek() <= 'Z'))
+      command->argument = peek();
+    else
+      throw ed_error("Valid mark needed.");
+    advance();
+    break;
+  case functions::Function::ArgumentKind::Any:
+    command->argument = std::string(peek_str());
+    advance(peek_str().size());
+    break;
+  case functions::Function::ArgumentKind::Global: {
+    char delim;
+    std::string val;
+    switch (peek()) {
+    case '\0':
+      throw ed_error("Command needs a delimited value.");
+    case '{': {
+      advance();
+      delim = '}';
+      uint16_t j = 0;
+      while (peek(j) != '}' && peek(j) != '\0') {
+        if (peek(j) == '\\')
+          j++;
+        j++;
+      }
+      switch (peek(j)) {
+      case '\0':
+        throw ed_error("Unterminated {");
+      case '}':
+        val = peek_str(j);
+        break;
+      }
+      advance(j + 1);
+    } break;
+    case '<': {
+      advance();
+      delim = '<';
+      uint16_t j = 0;
+      while (peek(j) != '>' || peek(j) != '\0') {
+        if (peek(j) == '\\')
+          j++;
+        j++;
+      }
+      switch (peek(j)) {
+      case '\0':
+        throw ed_error("Unterminated <");
+      case '>':
+        val = peek_str(j);
+        break;
+      }
+      advance(j + 1);
+    } break;
+    case '^':
+    case '~':
+      advance();
+      delim = '^';
+      break;
+    default:
+      delim = peek();
+      advance();
+      uint64_t j = 0;
+      while (true) {
+        if (peek(j) == '\0')
+          break;
+        if (peek(j) == delim)
+          break;
+        else if (peek(j) == '\\')
+          j += 2;
+        else if (peek(j) == '[')
+          while (peek(j) != '\0' && cmd[i] != ']')
+            j++;
+        else
+          j++;
+      }
+      val = peek_str(j);
+      advance(j + 1);
+    }
+    command->argument = functions::Function::GlobalArg(delim, std::move(val));
+  } break;
+  case functions::Function::ArgumentKind::File:
+    if (!(peek() == '\t' || peek() == ' ' || peek() == '\0'))
+      throw ed_error("Incorrect file input usage.");
+    skip_ws();
+    switch (peek()) {
+    case '!':
+      advance();
+      command->argument = functions::Function::ShellArg(std::string(peek_str()));
+      advance(peek_str().size());
+      break;
+    case '\0':
+      command->argument = std::monostate();
+      break;
+    default:
+      command->argument = std::filesystem::path(peek_str());
+      advance(peek_str().size());
+      break;
+    }
+    break;
+  case functions::Function::ArgumentKind::Line:
+    command->argument = buffer::Line();
+    addresses(command->argument_addresses);
+    break;
+  case functions::Function::ArgumentKind::Range:
+    command->argument = buffer::Range();
+    addresses(command->argument_addresses);
+    break;
+  case functions::Function::ArgumentKind::Regex: {
+    char delim = peek();
+    if (delim == '\0')
+      throw ed_error("regex expected");
+    advance();
+    uint16_t j = 0;
+    while (true) {
+      if (peek(j) == '\0')
+        throw ed_error("Unterminated regex");
+      if (peek(j) == delim)
+        break;
+      else if (peek(j) == '\\')
+        j += 2;
+      else if (peek(j) == '[')
+        while (peek(j) != '\0' && peek(j) != ']')
+          j++;
+      else
+        j++;
+    }
+    std::string expression(peek_str(j));
+    advance(j + 1);
+    j = 0;
+    while (true) {
+      if (peek(j) == '\0')
+        break;
+      if (peek(j) == delim)
+        break;
+      else if (peek(j) == '\\')
+        j += 2;
+      else if (peek(j) == '[')
+        while (peek(j) != '\0' && peek(j) != ']')
+          j++;
+      else
+        j++;
+    }
+    std::string replacement(peek_str(j));
+    if (peek(j) != '\0') {
+      advance(j + 1);
+    } else {
+      advance(j);
+    }
+    std::string options;
+    if (peek() != '\0') {
+      options = std::string(peek_str());
+      advance(peek_str().size());
+    }
+    std::erase_if(options, [&](char c) {
+      if (bed.suffixes[c - 'a'].has_value()) {
+        suffix = c;
+        return true;
+      }
+      return false;
+    });
+    command->argument = functions::Function::RegexArg(expression, replacement, options);
+  } break;
+  case functions::Function::ArgumentKind::Ruby:
+    command->argument = functions::Function::RubyArg(std::string(peek_str()));
+    advance(peek_str().size());
+    break;
+  case functions::Function::ArgumentKind::Shell:
+    command->argument = functions::Function::ShellArg(std::string(peek_str()));
+    advance(peek_str().size());
+    break;
+  }
+  if (!suffix) {
+    suffix = peek();
+    advance();
+  }
+  if (suffix) {
+    auto &s = bed.suffixes[suffix - 'a'];
+    if (s.has_value())
+      command->suffix = &s.value();
+    else
+      throw ed_error("Invalid suffix.");
+  }
+}
+} // namespace bed::internal::parser

src/internal/parser/parser.cc

@@ -19,455 +19,6 @@ void Parser::skip_ws() {
     advance();
 }
 
-void Parser::locator(AddressPromise &addr) {
-  addr.base = AddressPromise::None{};
-  switch (peek()) {
-  case '.':
-    advance();
-    addr.base = AddressPromise::Current{};
-    break;
-  case '$':
-    advance();
-    addr.base = AddressPromise::Last{};
-    break;
-  case '%':
-    advance();
-    addr.base = AddressPromise::LastRange{};
-    break;
-  case '[':
-    advance();
-    addr.base = AddressPromise::Block{Direction::Backward};
-    break;
-  case ']':
-    advance();
-    addr.base = AddressPromise::Block{Direction::Forward};
-    break;
-  case '^':
-    advance();
-    addr.base = AddressPromise::Diagnostic{Direction::Backward};
-    break;
-  case '~':
-    advance();
-    addr.base = AddressPromise::Diagnostic{Direction::Forward};
-    break;
-  case '\'':
-    advance();
-    if (('a' <= peek() && peek() <= 'z')
-        || ('A' <= peek() && peek() <= 'Z'))
-      addr.base = AddressPromise::Mark{peek()};
-    else
-      throw ed_error("Valid mark needed after \'");
-    advance();
-    break;
-  case '{': {
-    advance();
-    uint16_t j = 0;
-    std::string func;
-    std::string arg;
-    while (peek(j) != '}') {
-      if (peek(j) == '\0')
-        throw ed_error("Scripted address not terminated");
-      if (peek(j) == '\\')
-        ++j;
-      if (peek(j) == ':') {
-        func = peek_str(j);
-        advance(j + 1);
-        j = 0;
-        continue;
-      }
-      ++j;
-    }
-    if (func.size())
-      arg = peek_str(j);
-    else
-      func = peek_str(j);
-    addr.base = AddressPromise::Scripted{std::move(func), std::move(arg)};
-    advance(j + 1);
-  } break;
-  case '/': {
-    advance();
-    uint64_t j = 0;
-    while (true) {
-      if (peek(j) == '\0')
-        break;
-      if (peek(j) == '/')
-        break;
-      else if (peek(j) == '\\')
-        j += 2;
-      else if (peek(j) == '[')
-        while (peek(j) != '\0' && cmd[i] != ']')
-          j++;
-      else
-        j++;
-    }
-    addr.base = AddressPromise::Regex(
-      Direction::Forward,
-      std::string(peek_str(j))
-    );
-    advance(j + 1);
-  } break;
-  case '?': {
-    advance();
-    uint16_t j = 0;
-    while (true) {
-      if (peek(j) == '\0')
-        break;
-      if (peek(j) == '?')
-        break;
-      else if (peek(j) == '\\')
-        j += 2;
-      else if (peek(j) == '[')
-        while (peek(j) != '\0' && cmd[i] != ']')
-          j++;
-      else
-        j++;
-    }
-    addr.base = AddressPromise::Regex(
-      Direction::Backward,
-      std::string(peek_str(j))
-    );
-    advance(j + 1);
-  } break;
-  case '<': {
-    advance();
-    uint16_t j = 0;
-    while (peek(j) != '>'
-           && peek(j) != '<'
-           && peek(j) != '\0')
-      j++;
-    switch (peek(j)) {
-    case '\0':
-    case '>':
-      addr.base = AddressPromise::SymbolDefinition{
-        std::string(peek_str(j))
-      };
-      break;
-    case '<':
-      addr.base = AddressPromise::SymbolReference{
-        Direction::Backward,
-        std::string(peek_str(j))
-      };
-      break;
-    }
-    advance(j + 1);
-  } break;
-  case '>': {
-    advance();
-    uint16_t j = 0;
-    while (peek(j) != '>' && peek(j) != '\0')
-      j++;
-    switch (peek(j)) {
-    case '\0':
-      throw ed_error("Unterminated symbol reference addressing.");
-    case '>':
-      addr.base = AddressPromise::SymbolReference{
-        Direction::Forward,
-        std::string(peek_str(j))
-      };
-      break;
-    }
-    advance(j + 1);
-  } break;
-  case '+': {
-    advance();
-    addr.base = AddressPromise::Current{};
-    uint16_t j = 0;
-    uint64_t num = 0;
-    while ('0' <= peek(j) && peek(j) <= '9') {
-      num = num * 10 + (peek(j) - '0');
-      j++;
-    }
-    if (j == 0)
-      num = 1;
-    advance(j);
-    addr.offset += num;
-  } break;
-  case '-': {
-    advance();
-    addr.base = AddressPromise::Current{};
-    uint16_t j = 0;
-    uint64_t num = 0;
-    while ('0' <= peek(j) && peek(j) <= '9') {
-      num = num * 10 + (peek(j) - '0');
-      j++;
-    }
-    if (j == 0)
-      num = 1;
-    advance(j);
-    addr.offset -= num;
-  } break;
-  default:
-    if ('0' <= peek() && peek() <= '9') {
-      uint64_t num = 0;
-      while ('0' <= peek() && peek() <= '9') {
-        num = num * 10 + (peek() - '0');
-        advance();
-      }
-      addr.base = AddressPromise::Number{num};
-    }
-  }
-}
-
-int64_t Parser::offset() {
-  int64_t offset = 0;
-  while (peek() == '+' || peek() == '-'
-         || ('0' <= peek() && peek() <= '9')) {
-    bool positive = peek() != '-';
-    if (peek() == '+' || peek() == '-')
-      advance();
-    uint16_t j = 0;
-    int64_t num = 0;
-    while ('0' <= peek(j) && peek(j) <= '9')
-      num = num * 10 + (peek(j++) - '0');
-    if (j == 0)
-      num = 1;
-    advance(j);
-    offset += positive ? num : -num;
-    skip_ws();
-  }
-  skip_ws();
-  return offset;
-}
-
-void Parser::address(AddressPromise &addr) {
-  if (peek() == ':') {
-    advance();
-    uint16_t j = 0;
-    while (peek(j) != ':' && peek(j) != '\0')
-      j++;
-    addr.bufname = peek_str(j);
-    advance(j);
-    if (peek() == ':')
-      advance();
-  }
-  skip_ws();
-  if (peek() == '\0')
-    return;
-  locator(addr);
-  skip_ws();
-  addr.offset += offset();
-}
-
-void Parser::addresses(std::vector<AddressPromise> &addresses) {
-  skip_ws();
-  addresses.push_back({});
-  auto *addr = &addresses.back();
-  address(*addr);
-  while (peek() == ',' || peek() == ';') {
-    addr->jumping = peek() == ';';
-    advance();
-    skip_ws();
-    addresses.push_back({});
-    addr = &addresses.back();
-    address(*addr);
-  }
-  if (addresses.size() == 1
-      && addr->offset == 0 && addr->bufname.has_value()
-      && std::holds_alternative<AddressPromise::None>(addr->base))
-    addresses.pop_back();
-}
-
-void Parser::operation() {
-  if (peek() == '\0') {
-    command->function = &bed.no_op;
-    return;
-  }
-  uint64_t len = bed.functions.longest_match(peek_str());
-  if (len == 0)
-    throw ed_error("Function not found.");
-  functions::Function *function = bed.functions.get_ptr(peek_str(len));
-  advance(len);
-  command->function = function;
-  char suffix = '\0';
-  switch (command->function->argument_kind) {
-  case functions::Function::ArgumentKind::None:
-    break;
-  case functions::Function::ArgumentKind::Number:
-    skip_ws();
-    command->argument = offset();
-    break;
-  case functions::Function::ArgumentKind::Mark:
-    if (('a' <= peek() && peek() <= 'z')
-        || ('A' <= peek() && peek() <= 'Z'))
-      command->argument = peek();
-    else
-      throw ed_error("Valid mark needed.");
-    advance();
-    break;
-  case functions::Function::ArgumentKind::Any:
-    command->argument = std::string(peek_str());
-    advance(peek_str().size());
-    break;
-  case functions::Function::ArgumentKind::Global: {
-    char delim;
-    std::string val;
-    switch (peek()) {
-    case '\0':
-      throw ed_error("Command needs a delimited value.");
-    case '{': {
-      advance();
-      delim = '}';
-      uint16_t j = 0;
-      while (peek(j) != '}' && peek(j) != '\0') {
-        if (peek(j) == '\\')
-          j++;
-        j++;
-      }
-      switch (peek(j)) {
-      case '\0':
-        throw ed_error("Unterminated {");
-      case '}':
-        val = peek_str(j);
-        break;
-      }
-      advance(j + 1);
-    } break;
-    case '<': {
-      advance();
-      delim = '<';
-      uint16_t j = 0;
-      while (peek(j) != '>' || peek(j) != '\0') {
-        if (peek(j) == '\\')
-          j++;
-        j++;
-      }
-      switch (peek(j)) {
-      case '\0':
-        throw ed_error("Unterminated <");
-      case '>':
-        val = peek_str(j);
-        break;
-      }
-      advance(j + 1);
-    } break;
-    case '^':
-    case '~':
-      advance();
-      delim = '^';
-      break;
-    default:
-      delim = peek();
-      advance();
-      uint64_t j = 0;
-      while (true) {
-        if (peek(j) == '\0')
-          break;
-        if (peek(j) == delim)
-          break;
-        else if (peek(j) == '\\')
-          j += 2;
-        else if (peek(j) == '[')
-          while (peek(j) != '\0' && cmd[i] != ']')
-            j++;
-        else
-          j++;
-      }
-      val = peek_str(j);
-      advance(j + 1);
-    }
-    command->argument = functions::Function::GlobalArg(delim, std::move(val));
-  } break;
-  case functions::Function::ArgumentKind::File:
-    skip_ws();
-    switch (peek()) {
-    case '!':
-      advance();
-      command->argument = functions::Function::ShellArg(std::string(peek_str()));
-      advance(peek_str().size());
-      break;
-    case '\0':
-      command->argument = std::monostate();
-      break;
-    default:
-      command->argument = std::filesystem::path(peek_str());
-      advance(peek_str().size());
-      break;
-    }
-    break;
-  case functions::Function::ArgumentKind::Line:
-    command->argument = buffer::Line();
-    addresses(command->argument_addresses);
-    break;
-  case functions::Function::ArgumentKind::Range:
-    command->argument = buffer::Range();
-    addresses(command->argument_addresses);
-    break;
-  case functions::Function::ArgumentKind::Regex: {
-    char delim = peek();
-    if (delim == '\0')
-      throw ed_error("regex expected");
-    advance();
-    uint64_t j = 0;
-    while (true) {
-      if (peek(j) == '\0')
-        throw ed_error("Unterminated regex");
-      if (peek(j) == delim)
-        break;
-      else if (peek(j) == '\\')
-        j += 2;
-      else if (peek(j) == '[')
-        while (peek(j) != '\0' && cmd[i] != ']')
-          j++;
-      else
-        j++;
-    }
-    std::string expression(peek_str(j));
-    advance(j + 1);
-    j = 0;
-    while (true) {
-      if (peek(j) == '\0')
-        break;
-      if (peek(j) == delim)
-        break;
-      else if (peek(j) == '\\')
-        j += 2;
-      else if (peek(j) == '[')
-        while (peek(j) != '\0' && cmd[i] != ']')
-          j++;
-      else
-        j++;
-    }
-    std::string replacement;
-    if (peek(j) != '\0') {
-      replacement = peek_str(j);
-      advance(j + 1);
-    }
-    std::string options;
-    if (peek() != '\0') {
-      options = std::string(peek_str());
-      advance(peek_str().size());
-    }
-    std::erase_if(options, [&](char c) {
-      if (bed.suffixes[c - 'a'].has_value()) {
-        suffix = c;
-        return true;
-      }
-      return false;
-    });
-    command->argument = functions::Function::RegexArg(expression, replacement, options);
-  } break;
-  case functions::Function::ArgumentKind::Ruby:
-    command->argument = functions::Function::RubyArg(std::string(peek_str()));
-    advance(peek_str().size());
-    break;
-  case functions::Function::ArgumentKind::Shell:
-    command->argument = functions::Function::ShellArg(std::string(peek_str()));
-    advance(peek_str().size());
-    break;
-  }
-  if (!suffix) {
-    suffix = peek();
-    advance();
-  }
-  if (suffix) {
-    auto &s = bed.suffixes[suffix - 'a'];
-    if (s.has_value())
-      command->suffix = &s.value();
-    else
-      throw ed_error("Invalid suffix.");
-  }
-}
-
 void Parser::parse() {
   skip_ws();
   if (peek() == '@') {
@@ -486,14 +37,14 @@ void Parser::parse() {
 
 Parser::Parser(
   std::string_view cmd, BEd &bed, Command *command,
-  std::vector<io::Token> *tokens, CompletionContext *completion
+  std::vector<ui::Token> *tokens, CompletionContext *completion
 ) : bed(bed), cmd(cmd), command(command), tokens(tokens), completion(completion) {
   i = 0;
 }
 
 Command Parser::get_command(std::string_view cmd, BEd &bed) {
   Command c;
-  std::vector<io::Token> tokens;
+  std::vector<ui::Token> tokens;
   CompletionContext completion;
   Parser p(cmd, bed, &c, &tokens, &completion);
   p.parse();
@@ -502,7 +53,7 @@ Command Parser::get_command(std::string_view cmd, BEd &bed) {
 
 std::vector<AddressPromise> Parser::get_addresses(std::string_view cmd, BEd &bed) {
   std::vector<AddressPromise> result;
-  std::vector<io::Token> tokens;
+  std::vector<ui::Token> tokens;
   CompletionContext completion;
   Parser p(cmd, bed, nullptr, &tokens, &completion);
   p.addresses(result);

src/internal/syntax/parser.cc

@@ -1,42 +1,6 @@
 #include "internal/syntax/parser.h"
 
 namespace bed::internal::syntax {
-void dump_events(ParseState *root) {
-  if (!root)
-    return;
-  uint64_t offset = 0;
-  TreeCursor c(root, 0, &offset);
-  uint64_t line_offset = 0;
-  int depth = 0;
-  while (c.leaf) {
-    auto *leaf = c.leaf;
-    for (uint32_t i = 0; i < leaf->n; ++i) {
-      uint32_t block = leaf->blocks[i];
-      uint32_t pos = block & ParseStateLeaf::LINE_MASK;
-      bool closing = block & ParseStateLeaf::IS_CLOSING;
-      if (closing) {
-        if (depth > 0)
-          --depth;
-        else
-          std::cout << "!! UNMATCHED CLOSE !! ";
-      }
-      std::cout << std::string(static_cast<size_t>(depth) * 2, ' ')
-                << (closing ? "}" : "{")
-                << " line " << (line_offset + pos)
-                << '\n';
-      if (!closing)
-        ++depth;
-    }
-    line_offset += leaf->lines();
-    c.next();
-  }
-  if (depth != 0) {
-    std::cout << "!! UNBALANCED: depth = "
-              << depth
-              << " !!\n";
-  }
-}
-
 static void destroy_tree(ParseState *node, Language &lang) {
   if (!node)
     return;
@@ -159,36 +123,15 @@ ParseState *Parser::join_tree(ParseState *a, ParseState *b) {
 }
 
 void Parser::erase(vase::Shard *vase, uint64_t start, uint64_t count) {
-  if (count == 0 || !root)
-    return;
-  auto [a, remaining] = split_tree(root, start);
-  auto [waste, b] = split_tree(remaining, count);
-  destroy_tree(waste, lang);
-  root = join_tree(a, b);
-  modify(vase, start, 1);
+  begin_edit();
+  erase(start, count);
+  end_edit(vase);
 }
 
 void Parser::insert(vase::Shard *vase, uint64_t start, uint64_t count) {
-  if (count == 0)
-    return;
-  std::vector<ParseStateLeaf *> leaves;
-  leaves.reserve((count + MAX_CHUNK - 1) / MAX_CHUNK);
-  uint64_t consumed = 0;
-  while (consumed < count) {
-    auto *leaf = (ParseStateLeaf *)malloc(sizeof(ParseStateLeaf));
-    leaf->state = nullptr;
-    leaf->blocks = nullptr;
-    leaf->n = 0;
-    leaf->cap = 0;
-    uint64_t chunk = std::min(MAX_CHUNK, count - consumed);
-    leaf->header = chunk;
-    consumed += chunk;
-    leaves.push_back(leaf);
-  }
-  ParseState *subtree = build_tree(leaves, 0, leaves.size());
-  auto [left, right] = split_tree(root, start);
-  root = join_tree(join_tree(left, subtree), right);
-  modify(vase, start, count);
+  begin_edit();
+  insert(start, count);
+  end_edit(vase);
 }
 
 void Parser::modify(vase::Shard *vase, uint64_t target, uint64_t count) {
@@ -255,6 +198,63 @@ void Parser::modify(vase::Shard *vase, uint64_t target, uint64_t count) {
   lang.destroy(state);
 }
 
+void Parser::begin_edit() {
+  in_edit = true;
+}
+
+void Parser::mark_dirty(uint64_t start, uint64_t end) {
+  if (!dirty) {
+    dirty_start = start;
+    dirty_end = end;
+    dirty = true;
+  } else {
+    dirty_start = std::min(dirty_start, start);
+    dirty_end = std::max(dirty_end, end);
+  }
+}
+
+void Parser::erase(uint64_t start, uint64_t count) {
+  if (count == 0 || !root)
+    return;
+  auto [a, remaining] = split_tree(root, start);
+  auto [waste, b] = split_tree(remaining, count);
+  destroy_tree(waste, lang);
+  root = join_tree(a, b);
+  mark_dirty(start, start + 1);
+}
+
+void Parser::insert(uint64_t start, uint64_t count) {
+  if (count == 0)
+    return;
+  std::vector<ParseStateLeaf *> leaves;
+  leaves.reserve((count + MAX_CHUNK - 1) / MAX_CHUNK);
+  uint64_t consumed = 0;
+  while (consumed < count) {
+    auto *leaf = (ParseStateLeaf *)malloc(sizeof(ParseStateLeaf));
+    leaf->state = nullptr;
+    leaf->blocks = nullptr;
+    leaf->n = 0;
+    leaf->cap = 0;
+    uint64_t chunk = std::min(MAX_CHUNK, count - consumed);
+    leaf->header = chunk;
+    consumed += chunk;
+    leaves.push_back(leaf);
+  }
+  ParseState *subtree = build_tree(leaves, 0, leaves.size());
+  auto [left, right] = split_tree(root, start);
+  root = join_tree(join_tree(left, subtree), right);
+  mark_dirty(start, start + count);
+}
+
+void Parser::end_edit(vase::Shard *vase) {
+  in_edit = false;
+  if (!dirty)
+    return;
+  uint64_t count = dirty_end > dirty_start ? dirty_end - dirty_start : 1;
+  modify(vase, dirty_start, count);
+  dirty = false;
+}
+
 uint64_t Parser::next_closing(uint64_t line) {
   if (!root)
     return UINT64_MAX;

src/internal/ui/command/command.cc

@@ -1,6 +1,7 @@
+#include "internal/ui/command.h"
 #include "bed.h"
 
-namespace bed::internal::io {
+namespace bed::internal::ui {
 /*template <typename F>
 static void for_each_cluster(std::string_view s, F &&f) {
   unicode_width_state_t state;
@@ -61,14 +62,15 @@ static std::string current_word(const std::string &line, size_t byte_pos) {
   return line.substr(start, byte_pos - start);
 }*/
 
-CommandIO::CommandIO(BEd &bed, IO &io) : bed(bed), io(io) {
-  prompt = bed.prompt(bed);
+CommandIO::CommandIO(BEd &bed) : bed(bed) {
+  if (bed.prompt_mode)
+    prompt = bed.prompt(bed);
   cursor = 0;
 }
 
 std::pair<std::string, bool> CommandIO::run() {
-  auto [row, col] = io.cursor_position();
-  auto [rows, cols] = io.terminal_size();
+  auto [row, col] = bed.io.cursor_position();
+  auto [rows, cols] = bed.io.terminal_size();
   if (row > rows)
     throw fatal_error("Invalid cursor position.", 1);
   start = row;
@@ -77,26 +79,25 @@ std::pair<std::string, bool> CommandIO::run() {
   term_height = rows;
   redraw();
 
-  // main loop.
-  KeyEvent res;
+  io::KeyEvent res;
   bool running = true;
   while (running) {
-    res = io.read_key();
+    res = bed.io.read_key();
     switch (res.type) {
-    case KeyEvent::KeyType::EOF_:
+    case io::KeyEvent::KeyType::EOF_:
       running = false;
       break;
-    case KeyEvent::KeyType::MOUSE:
-    case KeyEvent::KeyType::RESIZE:
+    case io::KeyEvent::KeyType::MOUSE:
+    case io::KeyEvent::KeyType::RESIZE:
       break;
-    case KeyEvent::KeyType::CHAR:
+    case io::KeyEvent::KeyType::CHAR:
       switch (res.modifier) {
-      case KeyEvent::Modifier::SHIFT:
-      case KeyEvent::Modifier::ALT:
-      case KeyEvent::Modifier::CTRL_ALT:
-      case KeyEvent::Modifier::CTRL:
+      case io::KeyEvent::Modifier::SHIFT:
+      case io::KeyEvent::Modifier::ALT:
+      case io::KeyEvent::Modifier::CTRL_ALT:
+      case io::KeyEvent::Modifier::CTRL:
         break;
-      case KeyEvent::Modifier::NONE:
+      case io::KeyEvent::Modifier::NONE:
         if (res.text[0] == '\b' || res.text[0] == 0x7f) {
           if (cursor > 0)
             cmd.erase(--cursor, 1);
@@ -108,25 +109,25 @@ std::pair<std::string, bool> CommandIO::run() {
         break;
       }
       break;
-    case KeyEvent::KeyType::PASTE:
+    case io::KeyEvent::KeyType::PASTE:
       cmd.insert(cursor, res.text);
       cursor += res.text.size();
       break;
-    case KeyEvent::KeyType::SPECIAL:
+    case io::KeyEvent::KeyType::SPECIAL:
       switch (res.special_key) {
-      case KeyEvent::SpecialKey::UNKNOWN:
-      case KeyEvent::SpecialKey::UP:
-      case KeyEvent::SpecialKey::DOWN:
+      case io::KeyEvent::SpecialKey::UNKNOWN:
+      case io::KeyEvent::SpecialKey::UP:
+      case io::KeyEvent::SpecialKey::DOWN:
         break;
-      case KeyEvent::SpecialKey::RIGHT:
+      case io::KeyEvent::SpecialKey::RIGHT:
         if (cursor < cmd.size())
           cursor++;
         break;
-      case KeyEvent::SpecialKey::LEFT:
+      case io::KeyEvent::SpecialKey::LEFT:
         if (cursor > 0)
           cursor--;
         break;
-      case KeyEvent::SpecialKey::DELETE:
+      case io::KeyEvent::SpecialKey::DELETE:
         if (cursor < cmd.size())
           cmd.erase(cursor, 1);
         break;
@@ -137,20 +138,20 @@ std::pair<std::string, bool> CommandIO::run() {
   }
 
   for (uint16_t i = 1; i < height; ++i) {
-    io.move_cursor(start + i, 1);
-    io.write("\x1b[2K", 4);
+    bed.io.move_cursor(start + i, 1);
+    bed.io.write("\x1b[2K", 4);
   }
-  io.move_cursor(start, 1);
-  io.write("\n", 1);
+  bed.io.move_cursor(start, 1);
+  bed.io.write("\n", 1);
   return {cmd, false};
 }
 
 void CommandIO::redraw() {
-  io.move_cursor(start, 1);
-  io.write("\x1b[2K", 4);
-  io.move_cursor(start, 1);
-  io.write(prompt);
-  io.write(cmd);
-  io.move_cursor(start, prompt.size() + cursor + 1);
+  bed.io.move_cursor(start, 1);
+  bed.io.write("\x1b[2K", 4);
+  bed.io.move_cursor(start, 1);
+  bed.io.write(prompt);
+  bed.io.write(cmd);
+  bed.io.move_cursor(start, prompt.size() + cursor + 1);
 }
-} // namespace bed::internal::io
+} // namespace bed::internal::ui

src/internal/ui/text_mode/text_mode.cc

@@ -0,0 +1,188 @@
+#include "internal/ui/text_mode.h"
+#include "bed.h"
+
+namespace bed::internal::ui {
+TextMode::TextMode(BEd &bed) : bed(bed) {
+  cursor = 0;
+}
+
+std::pair<vase::Shard *, bool> TextMode::run() {
+  auto [row, col] = bed.io.cursor_position();
+  auto [rows, cols] = bed.io.terminal_size();
+  if (row > rows)
+    throw fatal_error("Invalid cursor position.", 1);
+  start = row;
+  height = rows - row + 1;
+  term_width = cols;
+  term_height = rows;
+  cmd.clear();
+  cursor = 0;
+  redraw();
+  bool running = true;
+
+  while (running) {
+    io::KeyEvent res = bed.io.read_key();
+    switch (res.type) {
+    case io::KeyEvent::KeyType::EOF_:
+      running = false;
+      break;
+    case io::KeyEvent::KeyType::MOUSE:
+    case io::KeyEvent::KeyType::RESIZE:
+      break;
+    case io::KeyEvent::KeyType::CHAR:
+      switch (res.modifier) {
+      case io::KeyEvent::Modifier::SHIFT:
+      case io::KeyEvent::Modifier::ALT:
+      case io::KeyEvent::Modifier::CTRL_ALT:
+      case io::KeyEvent::Modifier::CTRL:
+        break;
+      case io::KeyEvent::Modifier::NONE:
+        if (res.text[0] == '\b' || res.text[0] == 0x7f) {
+          if (cursor > 0) {
+            cmd.erase(--cursor, 1);
+          }
+        } else if (res.text[0] == '\n') {
+          size_t lines = 1 + std::count(cmd.begin(), cmd.end(), '\n');
+          grow(lines + 1);
+          cmd.insert(cursor++, 1, '\n');
+        } else {
+          cmd.insert(cursor, res.text);
+          cursor += res.text.size();
+        }
+        break;
+      }
+      break;
+    case io::KeyEvent::KeyType::PASTE:
+      cmd.insert(cursor, res.text);
+      cursor += res.text.size();
+      break;
+    case io::KeyEvent::KeyType::SPECIAL:
+      switch (res.special_key) {
+      case io::KeyEvent::SpecialKey::UNKNOWN:
+        break;
+      case io::KeyEvent::SpecialKey::RIGHT:
+        if (cursor < cmd.size())
+          ++cursor;
+        break;
+      case io::KeyEvent::SpecialKey::LEFT:
+        if (cursor > 0)
+          --cursor;
+        break;
+      case io::KeyEvent::SpecialKey::UP: {
+        size_t line_start =
+          cmd.rfind('\n', cursor == 0 ? 0 : cursor - 1);
+        if (line_start == std::string::npos)
+          line_start = 0;
+        else
+          ++line_start;
+        size_t col = cursor - line_start;
+        if (line_start == 0)
+          break;
+        size_t prev_end = line_start - 1;
+        size_t prev_start =
+          cmd.rfind('\n', prev_end == 0 ? 0 : prev_end - 1);
+        if (prev_start == std::string::npos)
+          prev_start = 0;
+        else
+          ++prev_start;
+        size_t prev_len = prev_end - prev_start;
+        cursor = prev_start + std::min(col, prev_len);
+        break;
+      }
+      case io::KeyEvent::SpecialKey::DOWN: {
+        size_t line_start =
+          cmd.rfind('\n', cursor == 0 ? 0 : cursor - 1);
+        if (line_start == std::string::npos)
+          line_start = 0;
+        else
+          ++line_start;
+        size_t col = cursor - line_start;
+        size_t line_end = cmd.find('\n', cursor);
+        if (line_end == std::string::npos)
+          line_end = cmd.size();
+        if (line_end == cmd.size())
+          break;
+        size_t next_start = line_end + 1;
+        size_t next_end = cmd.find('\n', next_start);
+        if (next_end == std::string::npos)
+          next_end = cmd.size();
+        size_t next_len = next_end - next_start;
+        cursor = next_start + std::min(col, next_len);
+        break;
+      }
+      case io::KeyEvent::SpecialKey::DELETE:
+        if (cursor < cmd.size())
+          cmd.erase(cursor, 1);
+        break;
+      }
+      break;
+    }
+    redraw();
+    if (cmd.size() >= 3 && cmd.compare(cmd.size() - 3, 3, "\n.\n") == 0) {
+      cmd.erase(cmd.size() - 3);
+      cursor = cmd.size();
+      running = false;
+    }
+  }
+
+  size_t total_lines = 1 + std::count(cmd.begin(), cmd.end(), '\n');
+  uint16_t last_row = start + total_lines;
+  bed.io.move_cursor(last_row, 1);
+  bed.io.write("\n", 1);
+  return {vase::Shard::from_string(cmd.data(), cmd.length(), true), false};
+}
+
+void TextMode::grow(size_t required_height) {
+  auto [rows, cols] = bed.io.terminal_size();
+  term_height = rows;
+  term_width = cols;
+  if (required_height > height)
+    height = required_height;
+  long overflow = long(start) + long(height) - 1 - long(rows);
+  if (overflow <= 0)
+    return;
+  bed.io.move_cursor(rows, 1);
+  for (long i = 0; i < overflow; ++i)
+    bed.io.write("\n", 1);
+  start -= overflow;
+  if (start < 1)
+    start = 1;
+}
+
+void TextMode::redraw() {
+  auto [rows, cols] = bed.io.terminal_size();
+  term_height = rows;
+  term_width = cols;
+  for (uint16_t i = 0; i < height; ++i) {
+    bed.io.move_cursor(start + i, 1);
+    bed.io.write("\x1b[2K", 4);
+  }
+  size_t line = 0;
+  size_t line_start = 0;
+  for (size_t i = 0; i < cursor; ++i) {
+    if (cmd[i] == '\n') {
+      ++line;
+      line_start = i + 1;
+    }
+  }
+  size_t col = cursor - line_start;
+  size_t pos = 0;
+  uint16_t screen_line = start;
+  while (pos <= cmd.size()) {
+    size_t end = cmd.find('\n', pos);
+    if (end == std::string::npos)
+      end = cmd.size();
+    if (screen_line < start + height) {
+      size_t len = std::min(end - pos, size_t(term_width));
+      bed.io.move_cursor(screen_line, 1);
+      bed.io.write(cmd.substr(pos, len));
+    }
+    if (end == cmd.size())
+      break;
+    pos = end + 1;
+    ++screen_line;
+  }
+  size_t vis_col = std::min(col, size_t(term_width - 1));
+  bed.io.move_cursor(start + line, vis_col + 1);
+}
+} // namespace bed::internal::ui

src/internal/vase/regex/api.cc

@@ -25,12 +25,7 @@ std::vector<ReplacePart> parse_replace(AppendStorage *ap, std::string_view s) {
   };
   for (size_t i = 0; i < s.size(); ++i) {
     char c = s[i];
-    if (c == '\\' && i + 1 < s.size() && s[i + 1] == '$') {
-      constant.push_back('$');
-      ++i;
-      continue;
-    }
-    if (c == '$' && i + 1 < s.size()) {
+    if (c == '\\' && i + 1 < s.size()) {
       char next = s[i + 1];
       if (next == '0') {
         flush_constant();
@@ -40,10 +35,7 @@ std::vector<ReplacePart> parse_replace(AppendStorage *ap, std::string_view s) {
             .value = (uint8_t)0
           }
         );
-        ++i;
-        continue;
-      }
-      if (next >= '1' && next <= '9') {
+      } else if (next >= '1' && next <= '9') {
         flush_constant();
         parts.push_back(
           ReplacePart{
@@ -51,9 +43,22 @@ std::vector<ReplacePart> parse_replace(AppendStorage *ap, std::string_view s) {
             .value = (uint8_t)(next - '0')
           }
         );
-        ++i;
-        continue;
+      } else if (next == 'n') {
+        constant.push_back('\n');
+      } else {
+        constant.push_back(next);
       }
+      ++i;
+      continue;
+    }
+    if (c == '&') {
+      flush_constant();
+      parts.push_back(
+        ReplacePart{
+          .type = ReplacePart::PartType::FullMatch,
+          .value = (uint8_t)0
+        }
+      );
     }
     constant.push_back(c);
   }
@@ -64,7 +69,8 @@ std::vector<ReplacePart> parse_replace(AppendStorage *ap, std::string_view s) {
 Shard *substitute(
   AppendStorage *ap, Shard *root,
   std::string_view pattern, uint64_t start, uint64_t end,
-  std::string_view replace, std::string_view options
+  std::string_view replace, std::string_view options,
+  const std::function<void(uint64_t line, uint64_t old_lines, uint64_t new_lines)> &on_edit
 ) {
   if (!start || !end)
     throw ed_error("Invalid range.");
@@ -79,21 +85,23 @@ Shard *substitute(
   uint64_t end_offset =
     (end + 1 == line_count)
       ? root->length
-      : offset_of(root, end + 1);
-
+      : offset_of(root, end + 1) - 1;
   std::vector<RegexMatch> matches = _regex_search(root, pattern, start_offset, end_offset, options);
   if (matches.empty())
     return root;
-
   std::vector<ReplacePart> replace_parts = parse_replace(ap, replace);
-
+  struct Edit {
+    uint64_t line;
+    uint64_t old_lines;
+    uint64_t new_lines;
+  };
+  uint64_t orig_line = start;
+  int64_t line_delta = 0;
   std::vector<Shard *> pieces;
   pieces.reserve(matches.size() * 2 + 1);
-
   Shard *remaining = root;
   Shard::retain(remaining);
   uint64_t cursor = 0;
-
   for (const RegexMatch &match : matches) {
     uint64_t gap = match.start - cursor;
     if (gap > 0) {
@@ -101,28 +109,33 @@ Shard *substitute(
       Shard::release(remaining);
       pieces.push_back(keep);
       remaining = rest;
+      orig_line += keep ? keep->lines : 0;
     }
-
     auto [dropped, rest2] = Shard::split(remaining, match.end - match.start);
     Shard::release(remaining);
     remaining = rest2;
-
+    uint64_t old_lines = dropped ? dropped->lines : 0;
+    uint64_t new_lines = 0;
     for (size_t i = 0; i < replace_parts.size(); ++i) {
       const ReplacePart &part = replace_parts[i];
       switch (part.type) {
-      case ReplacePart::PartType::Constant:
-        Shard::retain(std::get<Shard *>(part.value));
-        pieces.push_back(std::get<Shard *>(part.value));
+      case ReplacePart::PartType::Constant: {
+        Shard *c = std::get<Shard *>(part.value);
+        Shard::retain(c);
+        pieces.push_back(c);
+        new_lines += c ? c->lines : 0;
         break;
+      }
       case ReplacePart::PartType::FullMatch:
         Shard::retain(dropped);
         pieces.push_back(dropped);
+        new_lines += dropped ? dropped->lines : 0;
         break;
       case ReplacePart::PartType::CaptureGroup: {
         uint8_t idx = std::get<uint8_t>(part.value);
         if (idx <= 9) {
           const RegexGroup &group = match.groups[idx - 1];
-          if (group.start > group.end) {
+          if (group.start != UINT64_MAX) {
             uint64_t ls = group.start - match.start;
             uint64_t le = group.end - match.start;
             auto [a, b] = Shard::split(dropped, ls);
@@ -131,6 +144,7 @@ Shard *substitute(
             Shard::release(b);
             Shard::release(c);
             pieces.push_back(g);
+            new_lines += g ? g->lines : 0;
           }
         }
         break;
@@ -138,14 +152,19 @@ Shard *substitute(
       }
     }
     Shard::release(dropped);
+    if (old_lines || new_lines) {
+      uint64_t report_line = (uint64_t)((int64_t)orig_line + line_delta);
+      if (on_edit)
+        on_edit(report_line, old_lines, new_lines);
+      line_delta += (int64_t)new_lines - (int64_t)old_lines;
+    }
+    orig_line += old_lines;
     cursor = match.end;
   }
   pieces.push_back(remaining);
-
   for (auto &part : replace_parts)
     if (part.type == ReplacePart::PartType::Constant)
       Shard::release(std::get<Shard *>(part.value));
-
   std::vector<Shard *> compact;
   compact.reserve(pieces.size());
   for (Shard *p : pieces) {
@@ -154,14 +173,15 @@ Shard *substitute(
     else if (p)
       Shard::release(p);
   }
-
   Shard *new_root = compact.empty() ? nullptr : Shard::build(compact.data(), 0, compact.size());
   Shard::release(root);
   return new_root;
 }
 
 uint64_t find_next(Shard *root, std::string_view pattern, uint64_t start) {
-  if (start == 0 || start > root->lines)
+  if (!root)
+    throw ed_error("Invalid line number.");
+  if (start == 0 || start > root->lines + 1)
     throw ed_error("Invalid line number.");
   start--;
   std::vector<RegexMatch> results;
@@ -190,7 +210,7 @@ uint64_t find_next(Shard *root, std::string_view pattern, uint64_t start) {
     if (rc >= 0) {
       pcre2_match_data_free(match_data);
       pcre2_code_free(re);
-      return at;
+      return at + 1;
     }
     if (rc != PCRE2_ERROR_NOMATCH) {
       pcre2_match_data_free(match_data);
@@ -208,7 +228,7 @@ uint64_t find_next(Shard *root, std::string_view pattern, uint64_t start) {
     if (rc >= 0) {
       pcre2_match_data_free(match_data);
       pcre2_code_free(re);
-      return at;
+      return at + 1;
     }
     if (rc != PCRE2_ERROR_NOMATCH) {
       pcre2_match_data_free(match_data);
@@ -223,7 +243,9 @@ uint64_t find_next(Shard *root, std::string_view pattern, uint64_t start) {
 }
 
 uint64_t find_prev(Shard *root, std::string_view pattern, uint64_t start) {
-  if (start == 0 || start > root->lines)
+  if (!root)
+    throw ed_error("Invalid line number.");
+  if (start == 0 || start > root->lines + 1)
     throw ed_error("Invalid line number.");
   start--;
   std::vector<RegexMatch> results;
@@ -252,7 +274,7 @@ uint64_t find_prev(Shard *root, std::string_view pattern, uint64_t start) {
     if (rc >= 0) {
       pcre2_match_data_free(match_data);
       pcre2_code_free(re);
-      return at;
+      return at + 1;
     }
     if (rc != PCRE2_ERROR_NOMATCH) {
       pcre2_match_data_free(match_data);
@@ -270,7 +292,7 @@ uint64_t find_prev(Shard *root, std::string_view pattern, uint64_t start) {
     if (rc >= 0) {
       pcre2_match_data_free(match_data);
       pcre2_code_free(re);
-      return at;
+      return at + 1;
     }
     if (rc != PCRE2_ERROR_NOMATCH) {
       pcre2_match_data_free(match_data);

src/internal/vase/regex/core.cc

@@ -64,7 +64,7 @@ std::vector<RegexMatch> _regex_search(
   uint64_t offset = UINT64_MAX;
 
   auto record_match = [&](int rc, PCRE2_SIZE *ovector) {
-    if (global_offset + (uint64_t)ovector[1] > end_offset || ovector[0] == ovector[1])
+    if (global_offset + (uint64_t)ovector[1] > end_offset)
       return;
     RegexMatch match{
       .start = global_offset + (uint64_t)ovector[0],
@@ -74,8 +74,8 @@ std::vector<RegexMatch> _regex_search(
       PCRE2_SIZE s = ovector[2 * i];
       PCRE2_SIZE e = ovector[2 * i + 1];
       if (s != PCRE2_UNSET) {
-        match.groups[i].start = global_offset + (uint64_t)s;
-        match.groups[i].end = global_offset + (uint64_t)e;
+        match.groups[i - 1].start = global_offset + (uint64_t)s;
+        match.groups[i - 1].end = global_offset + (uint64_t)e;
       }
     }
     results.push_back(std::move(match));

src/internal/vase/shard.cc

@@ -1,3 +1,4 @@
+#include "internal/io/io.h"
 #include "internal/vase/vase.h"
 
 namespace bed::internal::vase {
@@ -192,10 +193,10 @@ Shard *Shard::append(Shard *root, Shard *leaf) {
 Shard *Shard::build(Shard **pieces, uint64_t lo, uint64_t hi) {
   if (hi - lo == 1)
     return pieces[lo];
-  size_t mid = lo + (hi - lo) / 2;
+  uint64_t mid = lo + (hi - lo) / 2;
   Shard *left = build(pieces, lo, mid);
   Shard *right = build(pieces, mid, hi);
-  Shard *node = new Branch(left, right);
+  Shard *node = Shard::concat(left, right);
   Shard::release(left);
   Shard::release(right);
   return node;
@@ -208,9 +209,11 @@ Shard *Shard::from_command(const char *cmd, bool posix_ending) {
     delete o;
     return nullptr;
   }
+  io::IO::cleanup();
   FILE *pipe = popen(cmd, "r");
   if (!pipe) {
     delete o;
+    io::IO::enable_raw();
     return nullptr;
   }
   std::vector<Shard *> pieces;
@@ -245,6 +248,7 @@ Shard *Shard::from_command(const char *cmd, bool posix_ending) {
       if (!write_all(dest_fd, buf, buf_cursor)) {
         pclose(pipe);
         delete o;
+        io::IO::enable_raw();
         return nullptr;
       }
       pieces.push_back(new Petal(buf_cursor, lines, o, pos));
@@ -254,20 +258,24 @@ Shard *Shard::from_command(const char *cmd, bool posix_ending) {
       break;
     if (ferror(pipe)) {
       delete o;
+      io::IO::enable_raw();
       return nullptr;
     }
   }
   int status = pclose(pipe);
   if (status == -1) {
     delete o;
+    io::IO::enable_raw();
     return nullptr;
   }
   if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
     delete o;
+    io::IO::enable_raw();
     return nullptr;
   }
   if (pieces.empty()) {
     delete o;
+    io::IO::enable_raw();
     return nullptr;
   }
   if (posix_ending) {
@@ -287,6 +295,7 @@ Shard *Shard::from_command(const char *cmd, bool posix_ending) {
     }
   }
   o->initialize();
+  io::IO::enable_raw();
   if (pieces.size() == 1)
     return pieces[0];
   return build(pieces.data(), 0, pieces.size());
@@ -421,54 +430,4 @@ Shard *Shard::from_string(const char *data, uint64_t len, bool posix_ending) {
     return pieces[0];
   return build(pieces.data(), 0, pieces.size());
 }
-
-void Shard::dump(Shard *node, int depth) {
-  if (!node) {
-    std::cout << std::string(depth * 2, ' ') << "<null>\n";
-    return;
-  }
-  std::string indent(depth * 2, ' ');
-  std::cout << indent
-            << "Shard@" << node
-            << " kind=";
-  switch (node->kind) {
-  case Shard::Kind::Branch:
-    std::cout << "Branch";
-    break;
-  case Shard::Kind::Petal:
-    std::cout << "Petal";
-    break;
-  }
-  std::cout
-    << " height=" << unsigned(node->height)
-    << " length=" << node->length
-    << " lines=" << node->lines
-    << " refs=" << node->refs.load()
-    << "\n";
-  if (node->kind == Shard::Kind::Branch) {
-    auto *branch = (Branch *)node;
-    std::cout << indent << "  left:\n";
-    dump(branch->left, depth + 2);
-    std::cout << indent << "  right:\n";
-    dump(branch->right, depth + 2);
-  } else {
-    auto *petal = static_cast<Petal *>(node);
-    constexpr auto clean = [](const std::string &text) {
-      std::string result = text;
-      size_t pos = 0;
-      while ((pos = result.find('\n', pos)) != std::string::npos) {
-        result.replace(pos, 1, "\\n");
-        pos += 2;
-      }
-      return result;
-    };
-    std::cout
-      << indent << "  source=" << petal->source
-      << " pos=" << petal->pos
-      << " length=" << petal->length
-      << " lines=" << petal->lines
-      << " text=\"" << clean(std::string(petal->source->read(petal->pos), petal->length))
-      << "\"\n";
-  }
-}
 } // namespace bed::internal::vase

src/internal/vase/vase.cc

@@ -1,4 +1,5 @@
 #include "internal/vase/vase.h"
+#include "internal/io/io.h"
 
 namespace bed::internal::vase {
 std::string to_string(Shard *root) {
@@ -128,7 +129,11 @@ uint64_t offset_of(Shard *root, Point point) {
 uint64_t offset_of(Shard *root, uint64_t line) {
   if (!root)
     return 0;
-  if (line > root->lines)
+  if (line == 0)
+    return 0;
+  if (line == root->lines + 1)
+    return root->length;
+  if (line > root->lines + 1)
     throw ed_error("line out of range");
   uint64_t offset = 0;
   Shard *curr = root;
@@ -207,10 +212,9 @@ Shard *erase(Shard *root, uint64_t start, uint64_t end) {
   if (start > end || end >= line_count)
     throw ed_error("line range out of bounds");
   uint64_t start_offset = offset_of(root, start);
-  uint64_t end_offset =
-    (end + 1 == line_count)
-      ? root->length
-      : offset_of(root, end + 1);
+  uint64_t end_offset = offset_of(root, end + 1);
+  if (end == root->lines && start_offset)
+    start_offset--;
   auto [left, rest] = Shard::split(root, start_offset);
   auto [middle, right] = Shard::split(rest, end_offset - start_offset);
   Shard *new_root = Shard::concat(left, right);
@@ -222,6 +226,37 @@ Shard *erase(Shard *root, uint64_t start, uint64_t end) {
   return new_root;
 }
 
+Shard *join(Shard *root, uint64_t start, uint64_t end) {
+  if (!start || !end)
+    throw ed_error("Invalid range.");
+  start--;
+  end--;
+  if (!root)
+    throw ed_error("line range out of bounds");
+  uint64_t line_count = root->lines + 1;
+  if (start >= end || end >= line_count)
+    throw ed_error("line range out of bounds");
+  uint64_t offset = offset_of(root, start);
+  std::vector<Shard *> pieces;
+  pieces.reserve(end - start + 3);
+  auto [a, b] = Shard::split(root, offset);
+  pieces.push_back(a);
+  for (uint64_t line = start; line < end; line++) {
+    uint64_t nl_pos = offset_of(b, 1) - 1;
+    auto [content, rest] = Shard::split(b, nl_pos);
+    Shard::release(b);
+    auto [nl, next_b] = Shard::split(rest, 1);
+    Shard::release(rest);
+    Shard::release(nl);
+    pieces.push_back(content);
+    b = next_b;
+  }
+  pieces.push_back(b);
+  Shard *joined = Shard::build(pieces.data(), 0, pieces.size());
+  Shard::release(root);
+  return joined;
+}
+
 Shard *copy(Shard *root, uint64_t start, uint64_t end) {
   if (!start || !end)
     throw ed_error("Invalid range.");
@@ -236,13 +271,57 @@ Shard *copy(Shard *root, uint64_t start, uint64_t end) {
   uint64_t end_offset =
     (end + 1 == line_count)
       ? root->length
-      : offset_of(root, end + 1);
+      : offset_of(root, end + 1) - 1;
   auto [left, rest] = Shard::split(root, start_offset);
   auto [middle, right] = Shard::split(rest, end_offset - start_offset);
   Shard::release(left);
   Shard::release(rest);
   Shard::release(right);
-  Shard::release(root);
   return middle;
 }
+
+void write_file(std::filesystem::path path, Shard *text) {
+  std::ofstream file(path, std::ios::binary);
+  if (!text)
+    return;
+  PetalIterator it(text, Direction::Forward);
+  it.seek_offset(0);
+  const char *data;
+  uint64_t len;
+  while (it.next(&data, &len)) {
+    if (!file)
+      throw ed_error("Failed while writing file: " + path.string());
+    file.write(data, len);
+  }
+  file.write("\n", 1);
+  if (!file)
+    throw ed_error("Failed while writing file: " + path.string());
+}
+
+void write_command(const char *cmd, Shard *text) {
+  io::IO::cleanup();
+  FILE *pipe = popen(cmd, "w");
+  if (!pipe) {
+    io::IO::enable_raw();
+    throw ed_error("Failed to start command: " + std::string(cmd));
+  }
+  if (!text) {
+    int status = pclose(pipe);
+    if (status == -1)
+      throw ed_error("Failed to wait for command: " + std::string(cmd));
+    return;
+  }
+  PetalIterator it(text, Direction::Forward);
+  it.seek_offset(0);
+  const char *data;
+  uint64_t len;
+  while (it.next(&data, &len))
+    fwrite(data, 1, len, pipe);
+  fwrite("\n", 1, 1, pipe);
+  int status = pclose(pipe);
+  io::IO::enable_raw();
+  if (status == -1)
+    throw ed_error("Failed to wait for command: " + std::string(cmd));
+  return;
+}
 } // namespace bed::internal::vase

src/main.cc

@@ -9,12 +9,12 @@ int main(int argc, char *argv[]) {
     ed.run();
   } catch (bed::fatal_error &e) {
     if (e.code)
-      std::cout << "Fatal error: " << e.what() << std::endl;
+      printf("Fatal error: %s\n", e.what());
     return e.code;
   }
 #ifndef DEBUG
   catch (...) {
-    std::cout << "Unexpected error." << std::endl;
+    printf("Unexpected error.\n");
     return 1;
   }
 #endif