Add basic scripting support.

- Fix certain bugs in ruby parser
- And a lot more cleanup/minor fixes.

Makefile

@@ -36,7 +36,7 @@ CFLAGS_RELEASE :=\
 	-fomit-frame-pointer -DNDEBUG -s \
 	-I./include -I./libs/unicode_width
 
-CFLAGS_DEBUG += $(PCRE_CFLAGS) $(LIBGRAPHEME_CFLAGS) $(MRUBY_CFLAGS) $(C_SANITIZER)
+CFLAGS_DEBUG += $(PCRE_CFLAGS) $(LIBGRAPHEME_CFLAGS) $(MRUBY_CFLAGS)
 CFLAGS_RELEASE += $(PCRE_CFLAGS) $(LIBGRAPHEME_CFLAGS) $(MRUBY_CFLAGS)
 
 UNICODE_SRC := $(wildcard libs/unicode_width/*.c)

include/bed.h

@@ -6,6 +6,7 @@
 #include "internal/functions/suffixes.h"
 #include "internal/io/io.h"
 #include "internal/marks/marks.h"
+#include "internal/scripting/ruby.h"
 #include "internal/theme/theme.h"
 #include "internal/ui/command.h"
 #include "internal/ui/text_mode.h"
@@ -21,6 +22,8 @@ struct BEd {
   std::unordered_map<std::string, internal::syntax::Language *> languages;
   internal::io::IO io;
   internal::vase::AppendStorage append{"/tmp"};
+  mrb_state *mrb = nullptr;
+  int arena;
 
   bool help_mode = false;
   bool prompt_mode = true;

include/internal/buffer/types/generic.h

@@ -14,8 +14,8 @@ struct HistoryItem {
 
 struct GenericBuffer : ShardBuffer {
   uint64_t base_version{0};
-  std::chrono::system_clock::time_point timestamp;
-  std::string action;
+  std::chrono::system_clock::time_point timestamp{std::chrono::system_clock::now()};
+  std::string action{"Created buffer."};
   std::filesystem::path save_path{};
   std::vector<HistoryItem> undo_stack;
   std::vector<HistoryItem> redo_stack;
@@ -24,6 +24,7 @@ struct GenericBuffer : ShardBuffer {
       : ShardBuffer(name, nullptr, nullptr, Kind::Generic) {}
   ~GenericBuffer();
 
+  void language(BEd &ctx, std::string name);
   void list_history(BEd &ctx);
   ReadonlyBuffer *get_history(uint64_t version);
   void snapshot(std::string action);

include/internal/scripting/ruby.h

@@ -0,0 +1,43 @@
+#pragma once
+
+#include "definitions.h"
+#include "pch.h"
+
+namespace bed::internal::scripting {
+struct Block {
+  mrb_value proc;
+  mrb_state *mrb;
+
+  Block(mrb_state *mrb, mrb_value proc)
+      : proc(proc), mrb(mrb) {
+    mrb_gc_register(mrb, proc);
+  }
+
+  Block() : proc(mrb_nil_value()) {}
+
+  ~Block() {
+    if (!mrb_nil_p(proc))
+      mrb_gc_unregister(mrb, proc);
+  }
+
+  void set_proc(mrb_value new_proc) {
+    if (!mrb_nil_p(proc))
+      mrb_gc_unregister(mrb, proc);
+    proc = new_proc;
+    mrb_gc_register(mrb, proc);
+  }
+
+  Block(const Block &) = delete;
+  Block &operator=(const Block &) = delete;
+
+  mrb_value call(int argc = 0, mrb_value *argv = nullptr) const {
+    if (mrb_nil_p(proc))
+      return mrb_nil_value();
+    mrb_value result = mrb_funcall_argv(mrb, proc, mrb_intern_cstr(mrb, "call"), argc, argv);
+    return result;
+  }
+};
+
+void register_basic(BEd &ctx);
+void run(BEd &ctx, const std::string &str);
+}; // namespace bed::internal::scripting

include/internal/syntax/decl.h

@@ -48,6 +48,7 @@ struct ParseState {
     uint64_t line, uint64_t original, uint64_t final
   );
   static ParseState *concat(Language &lang, ParseState *a, ParseState *b);
+  static void *state_before(Language &lang, ParseState *root, vase::Shard *vase, uint64_t line);
 };
 
 struct ParseStateBranch : ParseState {
@@ -83,18 +84,25 @@ struct ParsePieceBuilder {
   std::vector<ParseState *> pieces;
   std::vector<uint16_t> blocks;
   void *piece_state{nullptr};
+  void *prev_state{nullptr};
   uint64_t chunk_start{0};
   uint64_t chunk_lines{0};
-  ParsePieceBuilder(Language &lang, uint64_t first_line)
-      : lang(lang), chunk_start(first_line) {}
-  void add(
-    void *state,
-    uint64_t line,
-    const std::vector<ParseEvent> &events
-  ) {
+  ParsePieceBuilder(Language &lang, uint64_t first_line, void *entry_state)
+      : lang(lang), chunk_start(first_line) {
+    prev_state = lang.copy(entry_state);
+  }
+  ~ParsePieceBuilder() {
+    if (prev_state)
+      lang.destroy(prev_state);
+    if (piece_state)
+      lang.destroy(piece_state);
+  }
+  ParsePieceBuilder(const ParsePieceBuilder &) = delete;
+  ParsePieceBuilder &operator=(const ParsePieceBuilder &) = delete;
+  void add(void *state, uint64_t line, const std::vector<ParseEvent> &events) {
     if (chunk_lines == 0) {
       chunk_start = line;
-      piece_state = lang.copy(state);
+      piece_state = lang.copy(prev_state);
     }
     for (const auto &ev : events) {
       blocks.push_back(
@@ -103,6 +111,9 @@ struct ParsePieceBuilder {
       );
     }
     ++chunk_lines;
+    if (prev_state)
+      lang.destroy(prev_state);
+    prev_state = lang.copy(state);
     if (chunk_lines == ParseStateLeaf::MAX_CHUNK)
       flush();
   }

include/internal/syntax/parser.h

@@ -13,6 +13,7 @@ ParserSnapshot make_parser(vase::Shard *vase, uint64_t lines, Language *lang);
 ParserSnapshot retain(const ParserSnapshot &snap);
 void release(ParserSnapshot &snap);
 
+void *state_before(const ParserSnapshot &snap, vase::Shard *vase, uint64_t line);
 uint64_t next_closing(const ParserSnapshot &snap, uint64_t line);
 uint64_t prev_opening(const ParserSnapshot &snap, uint64_t line);
 

include/pch.h

@@ -4,10 +4,29 @@
 
 #include <mruby.h>
 #include <mruby/array.h>
+#include <mruby/boxing_word.h>
+#include <mruby/class.h>
+#include <mruby/common.h>
 #include <mruby/compile.h>
+#include <mruby/data.h>
+#include <mruby/dump.h>
+#include <mruby/error.h>
+#include <mruby/gc.h>
 #include <mruby/hash.h>
+#include <mruby/internal.h>
 #include <mruby/irep.h>
+#include <mruby/numeric.h>
+#include <mruby/object.h>
+#include <mruby/opcode.h>
+#include <mruby/presym.h>
+#include <mruby/proc.h>
+#include <mruby/range.h>
+#include <mruby/re.h>
 #include <mruby/string.h>
+#include <mruby/throw.h>
+#include <mruby/value.h>
+#include <mruby/variable.h>
+#include <mruby/version.h>
 #include <pcre2.h>
 extern "C" {
 #include <grapheme.h>

src/bed/bed.cc

@@ -0,0 +1,84 @@
+#include "bed.h"
+
+namespace bed {
+BEd::BEd(std::vector<std::string> args)
+    : theme(internal::theme::Theme::default_theme()), io(*this) {
+  std::string prompt_ = "";
+  std::string file = "";
+  bool suppress = false;
+  bool color = true;
+  for (size_t i = 1; i < args.size(); i++) {
+    if (args[i] == "-p") {
+      i++;
+      if (i >= args.size())
+        throw fatal_error("Prompt not specified!", 1);
+      prompt_ = args[i];
+    } else if (args[i] == "-s") {
+      suppress = true;
+    } else if (args[i] == "--no-color") {
+      color = false;
+    } else if (args[i] == "-v" || args[i] == "--verbose") {
+      help_mode = true;
+    } else if (args[i] == "-h" || args[i] == "--help") {
+      print_help();
+      throw fatal_error("", 0);
+    } else {
+      if (file.size())
+        throw fatal_error("Invalid arguments given.", 1);
+      file = args[i];
+    }
+  }
+  if (prompt_ != "")
+    prompt = [p = std::move(prompt_)](BEd &) { return p; };
+  else
+    prompt_mode = false;
+  suppress_mode = suppress;
+  const char *no_color = getenv("NO_COLOR");
+  if (no_color && *no_color != '\0')
+    color = false;
+  const char *colorterm = getenv("COLORTERM");
+  if (colorterm
+      && strcmp(colorterm, "truecolor") != 0
+      && strcmp(colorterm, "24bit") != 0)
+    color = false;
+  color_mode = color;
+  mrb = mrb_open();
+  if (!mrb)
+    throw fatal_error("Failed to initialize mruby.", 1);
+  mrb->ud = this;
+  arena = mrb_gc_arena_save(mrb);
+  internal::functions::Function::register_posix(*this);
+  internal::functions::Function::register_extented(*this);
+  internal::functions::Suffix::register_suffixes(*this);
+  internal::scripting::register_basic(*this);
+  languages["ruby"] = new internal::syntax::Language(internal::syntax::ruby::lang_ruby());
+  buffers["clip"] = new internal::buffer::ClipBuffer("clip");
+  current() = {"default", 0};
+  try {
+    if (file != "")
+      handle(":default:E " + file, false);
+  } catch (ed_error &e) {
+    io.write_line("?");
+    if (help_mode)
+      io.write_line(e.what());
+    last_help = e.what();
+  }
+}
+
+BEd::~BEd() {
+  for (auto &[_, buffer] : buffers)
+    delete buffer;
+  for (auto &[_, lang] : languages)
+    delete lang;
+  mrb->ud = nullptr;
+  if (mrb) {
+    mrb_gc_arena_restore(mrb, arena);
+    mrb_full_gc(mrb);
+    mrb_close(mrb);
+  }
+}
+
+void BEd::print_help() {
+  io.write("BEd - A line editor.\n");
+}
+} // namespace bed

src/bed/handle.cc

@@ -0,0 +1,115 @@
+#include "bed.h"
+#include "internal/parser/parser.h"
+
+namespace bed {
+void BEd::handle(std::string_view cmd, bool eof) {
+  if (eof && cmd.empty()) {
+    eof_op.handle(*this, "", nullptr, std::monostate(), nullptr);
+    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()) {
+      auto vec = internal::parser::Parser::get_addresses(c.function->default_address, *this);
+      a = internal::parser::AddressPromise::get_line(*this, vec);
+      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()) {
+      auto vec = internal::parser::Parser::get_addresses(c.function->default_address, *this);
+      a = internal::parser::AddressPromise::get_line(*this, vec);
+      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()) {
+      auto vec = internal::parser::Parser::get_addresses(c.function->default_address, *this);
+      a = internal::parser::AddressPromise::get_range(*this, vec);
+      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());
+  }
+  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::vase::Shard *vase = nullptr;
+    internal::syntax::Language *lang = nullptr;
+    void *state = nullptr;
+    if (c.function->pre_text_mode)
+      std::tie(vase, lang, state) = c.function->pre_text_mode(*this, address, c.argument);
+    internal::ui::text_mode::TextMode tm(*this, vase, lang, state);
+    auto [a, b] = tm.run();
+    if (!b) {
+      text = a;
+    } else {
+      if (a) {
+        auto p = internal::syntax::make_parser(a, a->lines + 1, lang);
+        auto cancel_buf = new internal::buffer::ReadonlyBuffer("cancel", a, p);
+        internal::syntax::release(p);
+        buffers["cancel"] = cancel_buf;
+        cancel_buf->useless = false;
+        internal::vase::Shard::release(a);
+      }
+      throw ed_error("Operation cancelled.");
+    }
+  }
+  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;
+    }
+  }
+}
+} // namespace bed

src/bed/run.cc

@@ -2,82 +2,13 @@
 #include "internal/parser/parser.h"
 
 namespace bed {
-BEd::BEd(std::vector<std::string> args)
-    : theme(internal::theme::Theme::default_theme()), io(*this) {
-  std::string prompt_ = "";
-  std::string file = "";
-  bool suppress = false;
-  bool color = true;
-  for (size_t i = 1; i < args.size(); i++) {
-    if (args[i] == "-p") {
-      i++;
-      if (i >= args.size())
-        throw fatal_error("Prompt not specified!", 1);
-      prompt_ = args[i];
-    } else if (args[i] == "-s") {
-      suppress = true;
-    } else if (args[i] == "--no-color") {
-      color = false;
-    } else if (args[i] == "-v" || args[i] == "--verbose") {
-      help_mode = true;
-    } else if (args[i] == "-h" || args[i] == "--help") {
-      print_help();
-      throw fatal_error("", 0);
-    } else {
-      if (file.size())
-        throw fatal_error("Invalid arguments given.", 1);
-      file = args[i];
-    }
-  }
-  if (prompt_ != "")
-    prompt = [p = std::move(prompt_)](BEd &) { return p; };
-  else
-    prompt_mode = false;
-  suppress_mode = suppress;
-  const char *no_color = getenv("NO_COLOR");
-  if (no_color && *no_color != '\0')
-    color = false;
-  const char *colorterm = getenv("COLORTERM");
-  if (colorterm
-      && strcmp(colorterm, "truecolor") != 0
-      && strcmp(colorterm, "24bit") != 0)
-    color = false;
-  color_mode = color;
-  internal::functions::Function::register_posix(*this);
-  internal::functions::Function::register_extented(*this);
-  internal::functions::Suffix::register_suffixes(*this);
-  languages["ruby"] = new internal::syntax::Language(internal::syntax::ruby::lang_ruby());
-  buffers["clip"] = new internal::buffer::ClipBuffer("clip");
-  current() = {"default", 0};
-  try {
-    if (file != "")
-      handle(":default:E " + file, false);
-  } catch (ed_error &e) {
-    io.write_line("?");
-    if (help_mode)
-      io.write_line(e.what());
-    last_help = e.what();
-  }
-}
-
-BEd::~BEd() {
-  for (auto &[_, buffer] : buffers)
-    delete buffer;
-  for (auto &[_, lang] : languages)
-    delete lang;
-}
-
-void BEd::print_help() {
-  io.write("BEd - A line editor.\n");
-}
-
 void BEd::run() {
   while (true) {
     internal::ui::CommandIO command(*this);
     auto [cmd, eof] = command.run();
     try {
       handle(cmd, eof);
-    } catch (ed_error &e) {
+    } catch (const ed_error &e) {
       io.apply(internal::io::Token::Warning);
       io.write_line("?");
       if (help_mode)
@@ -88,117 +19,6 @@ void BEd::run() {
   }
 }
 
-void BEd::handle(std::string_view cmd, bool eof) {
-  if (eof && cmd.empty()) {
-    eof_op.handle(*this, "", nullptr, std::monostate(), nullptr);
-    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()) {
-      auto vec = internal::parser::Parser::get_addresses(c.function->default_address, *this);
-      a = internal::parser::AddressPromise::get_line(*this, vec);
-      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()) {
-      auto vec = internal::parser::Parser::get_addresses(c.function->default_address, *this);
-      a = internal::parser::AddressPromise::get_line(*this, vec);
-      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()) {
-      auto vec = internal::parser::Parser::get_addresses(c.function->default_address, *this);
-      a = internal::parser::AddressPromise::get_range(*this, vec);
-      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());
-  }
-  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::vase::Shard *vase = nullptr;
-    internal::syntax::Language *lang = nullptr;
-    void *state = nullptr;
-    if (c.function->pre_text_mode)
-      std::tie(vase, lang, state) = c.function->pre_text_mode(*this, address, c.argument);
-    internal::ui::text_mode::TextMode tm(*this, vase, lang, state);
-    auto [a, b] = tm.run();
-    if (!b) {
-      text = a;
-    } else {
-      if (a) {
-        auto p = internal::syntax::make_parser(a, a->lines + 1, lang);
-        auto cancel_buf = new internal::buffer::ReadonlyBuffer("cancel", a, p);
-        internal::syntax::release(p);
-        buffers["cancel"] = cancel_buf;
-        cancel_buf->useless = false;
-        internal::vase::Shard::release(a);
-      }
-      throw ed_error("Operation cancelled.");
-    }
-  }
-  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");

src/internal/buffer/generic.cc

@@ -203,7 +203,23 @@ uint64_t GenericBuffer::prune(int keep) {
 bool GenericBuffer::waste() {
   return save_path.empty()
          && root == nullptr
-         && undo_stack.empty();
+         && undo_stack.empty()
+         && parse.lang == nullptr;
+}
+
+void GenericBuffer::language(BEd &ctx, std::string name) {
+  syntax::Language *lang = nullptr;
+  if (name.size()) {
+    auto it = ctx.languages.find(name);
+    if (it == ctx.languages.end())
+      throw ed_error("Language not found.");
+    lang = it->second;
+  }
+  if (lang == parse.lang)
+    return;
+  snapshot("Change buffer language.");
+  syntax::release(parse);
+  parse = syntax::make_parser(root, lines(), lang);
 }
 
 void GenericBuffer::load(BEd &ctx, vase::Shard *text) {
@@ -225,7 +241,7 @@ void GenericBuffer::load(BEd &ctx, vase::Shard *text) {
   }
   ctx.current() = {name, lines()};
   syntax::release(parse);
-  parse = syntax::make_parser(root, lines(), ctx.languages["ruby"]);
+  parse = syntax::make_parser(root, lines(), nullptr);
 }
 
 void GenericBuffer::set_filename(std::filesystem::path path) {

src/internal/functions/extended.cc

@@ -173,24 +173,95 @@ void Function::register_extented(BEd &ctx) {
   ctx.functions.insert(
     "`",
     Function{
-      .address_kind = Function::AddressKind::None,
+      .address_kind = Function::AddressKind::Range,
       .argument_kind = Function::ArgumentKind::Ruby,
       .input_mode = Function::InputMode::None,
       .desc = "Execute some ruby code",
       .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::Range>(addr_);
+        auto &arg = std::get<RubyArg>(arg_);
+        auto pre_code = "$START=" + std::to_string(addr.start)
+                        + ";$END=" + std::to_string(addr.end)
+                        + ";$BUFNAME=\"" + addr.buffername + "\"";
+        scripting::run(ctx, pre_code);
+        scripting::run(ctx, arg.cmd);
+      },
+    }
+  );
+  ctx.functions.insert(
+    "``",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::None,
+      .desc = "Execute addressed lines as ruby code.",
+      .default_address = ".,.",
       .accept_zero = false,
       .pre_text_mode = nullptr,
       .handle = [](
-                  BEd &,
-                  const buffer::Address &,
+                  BEd &ctx,
+                  const buffer::Address &addr_,
                   vase::Shard *,
                   const Argument &,
                   std::vector<buffer::Line> *
                 ) {
-        // TODO: connect up to mruby.
+        auto &addr = std::get<buffer::Range>(addr_);
+        auto &buf = ctx.buffer(addr.buffername);
+        auto code = buf.copy(addr.start, addr.end);
+        ctx.prev().buffername = addr.buffername;
+        ctx.prev().start = addr.start;
+        ctx.prev().end = addr.end;
+        ctx.current() = {addr.buffername, addr.end};
+        auto pre_code = "$START=" + std::to_string(addr.start)
+                        + ";$END=" + std::to_string(addr.end)
+                        + ";$BUFNAME=\"" + addr.buffername + "\"";
+        scripting::run(ctx, pre_code);
+        scripting::run(ctx, vase::to_string(code));
+        vase::Shard::release(code);
       },
     }
   );
+  ctx.functions.insert(
+    "```",
+    Function{
+      .address_kind = Function::AddressKind::Range,
+      .argument_kind = Function::ArgumentKind::None,
+      .input_mode = Function::InputMode::Text,
+      .desc = "Execute some ruby code (taken from text mode)",
+      .default_address = "",
+      .accept_zero = true,
+      .pre_text_mode = [](
+                         BEd &ctx,
+                         const buffer::Address &,
+                         const Argument &
+                       ) -> std::tuple<vase::Shard *, syntax::Language *, void *> {
+        return {nullptr, ctx.languages["ruby"], nullptr};
+      },
+      .handle = [](
+                  BEd &ctx,
+                  const buffer::Address &addr_,
+                  vase::Shard *code,
+                  const Argument &,
+                  std::vector<buffer::Line> *
+                ) {
+        auto &addr = std::get<buffer::Range>(addr_);
+        auto pre_code = "$START=" + std::to_string(addr.start)
+                        + ";$END=" + std::to_string(addr.end)
+                        + ";$BUFNAME=\"" + addr.buffername + "\"";
+        scripting::run(ctx, pre_code);
+        scripting::run(ctx, vase::to_string(code));
+        vase::Shard::release(code); },
+    }
+  );
   ctx.functions.insert(
     "echo",
     Function{
@@ -432,5 +503,38 @@ void Function::register_extented(BEd &ctx) {
       }
     }
   );
+  ctx.functions.insert(
+    "lang",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::Any,
+      .input_mode = Function::InputMode::None,
+      .desc = "Set buffer language",
+      .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 name = std::get<std::string>(arg_);
+        const auto first = name.find_first_not_of(" \t");
+        const auto last = name.find_last_not_of(" \t");
+        if (first == std::string::npos)
+          name.clear();
+        else
+          name = name.substr(first, last - first + 1);
+        auto &buf_ = ctx.buffer(addr);
+        if (buf_.kind != buffer::Buffer::Kind::Generic)
+          throw ed_error("Can't set language to buffer.");
+        auto &buf = *(buffer::GenericBuffer *)&buf_;
+        buf.language(ctx, name);
+      }
+    }
+  );
 }
 } // namespace bed::internal::functions

src/internal/functions/posix.cc

@@ -37,7 +37,19 @@ void Function::register_posix(BEd &ctx) {
       .desc = "Append text to a line",
       .default_address = ".",
       .accept_zero = true,
-      .pre_text_mode = nullptr,
+      .pre_text_mode = [](
+                         BEd &ctx,
+                         const buffer::Address &addr_,
+                         const Argument &
+                       ) -> std::tuple<vase::Shard *, syntax::Language *, void *> {
+        const auto &addr = std::get<buffer::Line>(addr_);
+        auto &buf_ = ctx.buffer(addr.buffername);
+        if (buf_.kind != buffer::Buffer::Kind::Generic)
+          return {nullptr, nullptr, nullptr};
+        auto &buf = *(buffer::GenericBuffer *)&buf_;
+        void *state = syntax::state_before(buf.parse, buf.root, addr.number);
+        return {nullptr, buf.parse.lang, state};
+      },
       .handle = [](
                   BEd &ctx,
                   const buffer::Address &addr_,
@@ -47,8 +59,7 @@ void Function::register_posix(BEd &ctx) {
                 ) {
         auto addr = std::get<buffer::Line>(addr_);
         ctx.buffer(addr.buffername).append(ctx, text, addr.number);
-        vase::Shard::release(text);
-      }
+        vase::Shard::release(text); }
     }
   );
   ctx.functions.insert(
@@ -70,9 +81,7 @@ void Function::register_posix(BEd &ctx) {
         if (buf_.kind != buffer::Buffer::Kind::Generic)
           return {buf_.copy(addr.start, addr.end), nullptr, nullptr};
         auto &buf = *(buffer::GenericBuffer *)&buf_;
-        if (!buf.parse.lang)
-          return {buf.copy(addr.start, addr.end), nullptr, nullptr};
-        void *state = nullptr; // TODO: buf.parse.root.get_at(addr.start);
+        void *state = syntax::state_before(buf.parse, buf.root, addr.start - 1);
         return {buf.copy(addr.start, addr.end), buf.parse.lang, state};
       },
       .handle = [](
@@ -291,7 +300,21 @@ void Function::register_posix(BEd &ctx) {
       .desc = "Insert text before a line",
       .default_address = ".",
       .accept_zero = true,
-      .pre_text_mode = nullptr,
+      .pre_text_mode = [](
+                         BEd &ctx,
+                         const buffer::Address &addr_,
+                         const Argument &
+                       ) -> std::tuple<vase::Shard *, syntax::Language *, void *> {
+        auto addr = std::get<buffer::Line>(addr_);
+        if (addr.number)
+          addr.number--;
+        auto &buf_ = ctx.buffer(addr.buffername);
+        if (buf_.kind != buffer::Buffer::Kind::Generic)
+          return {nullptr, nullptr, nullptr};
+        auto &buf = *(buffer::GenericBuffer *)&buf_;
+        void *state = syntax::state_before(buf.parse, buf.root, addr.number);
+        return {nullptr, buf.parse.lang, state};
+      },
       .handle = [](
                   BEd &ctx,
                   const buffer::Address &addr_,
@@ -303,8 +326,7 @@ void Function::register_posix(BEd &ctx) {
         if (addr.number)
           addr.number--;
         ctx.buffer(addr.buffername).append(ctx, text, addr.number);
-        vase::Shard::release(text);
-      }
+        vase::Shard::release(text); }
     }
   );
   ctx.functions.insert(

src/internal/scripting/ruby.cc

@@ -0,0 +1,73 @@
+#include "internal/scripting/ruby.h"
+#include "bed.h"
+
+namespace bed::internal::scripting {
+static mrb_value mrb_bed_exit(mrb_state *mrb, mrb_value) {
+  mrb_raise(mrb, E_RUNTIME_ERROR, "Use `handle(\"q\")` to quit.");
+  return mrb_nil_value();
+}
+
+static void
+raise_fatal(mrb_state *mrb, const fatal_error &e) {
+  struct RClass *klass = mrb_class_get(mrb, "FatalError");
+  mrb_value exc = mrb_exc_new_str(mrb, klass, mrb_str_new_cstr(mrb, e.what()));
+  mrb_iv_set(mrb, exc, mrb_intern_lit(mrb, "@code"), mrb_fixnum_value(e.code));
+  mrb_exc_raise(mrb, exc);
+}
+
+static mrb_value mrb_bed_handle(mrb_state *mrb, mrb_value) {
+  auto &ctx = *(BEd *)mrb->ud;
+  const char *command;
+  mrb_int len;
+  mrb_get_args(mrb, "s", &command, &len);
+  std::string_view cmd(command, len);
+  try {
+    ctx.handle(cmd, false);
+  } catch (const ed_error &e) {
+    mrb_raise(mrb, mrb_class_get(mrb, "EdError"), e.what());
+  } catch (const fatal_error &f) {
+    raise_fatal(mrb, f);
+  } catch (...) {
+    mrb_raise(mrb, E_RUNTIME_ERROR, "Unexpected error.");
+  }
+  return mrb_nil_value();
+}
+
+void register_basic(BEd &ctx) {
+  auto *bed_error =
+    mrb_define_class(ctx.mrb, "EdError", mrb_exc_get_id(ctx.mrb, MRB_ERROR_SYM(RuntimeError)));
+  mrb_define_class(ctx.mrb, "FatalError", bed_error);
+
+  mrb_define_method(ctx.mrb, ctx.mrb->kernel_module, "exit", mrb_bed_exit, MRB_ARGS_NONE());
+  mrb_define_method(ctx.mrb, ctx.mrb->kernel_module, "handle", mrb_bed_handle, MRB_ARGS_REQ(1));
+}
+
+void run(BEd &ctx, const std::string &str) {
+  mrb_state *mrb = ctx.mrb;
+  mrb_load_nstring(mrb, str.data(), str.size());
+  if (!mrb->exc)
+    return;
+  mrb_value exc = mrb_obj_value(mrb->exc);
+  mrb_value msg = mrb_funcall(mrb, exc, "message", 0);
+  std::string error;
+  if (mrb_string_p(msg))
+    error.assign(RSTRING_PTR(msg), RSTRING_LEN(msg));
+  auto *fatal_class = mrb_class_get(mrb, "FatalError");
+  if (mrb_obj_is_kind_of(mrb, exc, fatal_class)) {
+    mrb_value code =
+      mrb_iv_get(mrb, exc, mrb_intern_lit(mrb, "@code"));
+    mrb->exc = nullptr;
+    int c = 1;
+    if (mrb_fixnum_p(code))
+      c = mrb_fixnum(code);
+    throw fatal_error(error, c);
+  }
+  auto *ed_class = mrb_class_get(mrb, "EdError");
+  if (mrb_obj_is_kind_of(mrb, exc, ed_class)) {
+    mrb->exc = nullptr;
+    throw ed_error(error);
+  }
+  mrb->exc = nullptr;
+  throw ed_error("Ruby Exception: " + error);
+}
+} // namespace bed::internal::scripting

src/internal/syntax/iterator.cc

@@ -2,19 +2,11 @@
 
 namespace bed::internal::syntax {
 Iterator::Iterator(uint64_t target, ParserSnapshot p, vase::Shard *vase)
-    : snap(p) {
-  uint64_t offset;
-  TreeCursor c = TreeCursor(*p.lang, p.root, target, &offset);
-  at = target - offset;
-  state = p.lang->copy(c.leaf->state);
+    : snap(p), at(target) {
+  at = target;
+  if (snap.lang)
+    state = ParseState::state_before(*snap.lang, snap.root, vase, at);
   it = vase::Iterator(vase, at, Direction::Forward);
-  while (at < target) {
-    it->next();
-    tokens.clear();
-    events.clear();
-    p.lang->parse(&state, it->line, at == 0, &tokens, &events);
-    at++;
-  }
 }
 
 Iterator::~Iterator() {
@@ -46,6 +38,8 @@ Iterator &Iterator::operator=(Iterator &&other) {
 }
 
 void Iterator::next() {
+  if (!state)
+    return;
   it->next();
   tokens.clear();
   events.clear();

src/internal/syntax/miniparser.cc

@@ -8,7 +8,7 @@ MiniParser::MiniParser(Language &lang, vase::Shard *vase, void *initial_state)
   void *state = lang.copy(start_state);
   std::vector<io::Token> tokens;
   std::vector<ParseEvent> events;
-  const uint64_t count = vase ? vase->lines + 1 : 0;
+  const uint64_t count = vase ? vase->lines + 1 : 1;
   lines.reserve(count);
   for (uint64_t i = 0; i < count; ++i) {
     it.next();

src/internal/syntax/parser.cc

@@ -22,6 +22,12 @@ void release(ParserSnapshot &snap) {
   snap.root = nullptr;
 }
 
+void *state_before(const ParserSnapshot &snap, vase::Shard *vase, uint64_t line) {
+  if (!snap.lang)
+    return nullptr;
+  return ParseState::state_before(*snap.lang, snap.root, vase, line);
+}
+
 uint64_t next_closing(const ParserSnapshot &snap, uint64_t line) {
   if (!snap.root || !snap.lang)
     return line + 10;

src/internal/syntax/parser_state.cc

@@ -108,7 +108,7 @@ ParseState *ParseState::splice(
     void *state = lang.none_state();
     std::vector<io::Token> tokens;
     std::vector<ParseEvent> events;
-    ParsePieceBuilder builder(lang, 0);
+    ParsePieceBuilder builder(lang, 0, state);
     for (uint64_t at = 0; at < final; ++at) {
       it.next();
       tokens.clear();
@@ -136,7 +136,7 @@ ParseState *ParseState::splice(
   uint64_t end_extra;
   TreeCursor c = TreeCursor(lang, root, end_in_tree, &end_extra);
   uint64_t end_in_vase = line + final;
-  ParsePieceBuilder builder(lang, at);
+  ParsePieceBuilder builder(lang, at, state);
   while (at < end_in_vase + end_extra) {
     it.next();
     tokens.clear();
@@ -192,4 +192,28 @@ ParseState *ParseState::concat(Language &lang, ParseState *a, ParseState *b) {
   }
   return balance(lang, new ParseStateBranch(a, b));
 }
+
+void *ParseState::state_before(Language &lang, ParseState *root, vase::Shard *vase, uint64_t line) {
+  uint64_t offset;
+  uint64_t at;
+  void *state;
+  if (!root) {
+    at = 0;
+    state = lang.none_state();
+  } else {
+    TreeCursor c = TreeCursor(lang, root, line, &offset);
+    at = line - offset;
+    state = lang.copy(c.leaf->state);
+  }
+  vase::Iterator it(vase, at, Direction::Forward);
+  std::vector<io::Token> tokens;
+  std::vector<ParseEvent> events;
+  for (; at < line; ++at) {
+    it.next();
+    tokens.clear();
+    events.clear();
+    lang.parse(&state, it.line, at == 0, &tokens, &events);
+  }
+  return state;
+}
 } // namespace bed::internal::syntax

src/internal/syntax/ruby/parse.cc

@@ -782,11 +782,6 @@ bool handle_syntax(RubyParser &p, std::vector<io::Token> *tokens, std::vector<Pa
       p.ending = false;
     p.advance();
     return false;
-  case '\0':
-    if (p.ending)
-      p.current().flags |= RubyState::RubyInternalState::EXPECTING_EXPRESSION;
-    p.advance();
-    return false;
   default:
     if ('0' <= p.peek() && p.peek() <= '9') {
       p.current().flags &= ~RubyState::RubyInternalState::EXPECTING_EXPRESSION;
@@ -981,6 +976,11 @@ bool handle_syntax(RubyParser &p, std::vector<io::Token> *tokens, std::vector<Pa
             | RubyState::RubyInternalState::DEF_NAME;
           return false;
         }
+        if (j > 3 && p.peek_str(3) == "to_") {
+          p.current().flags &= ~RubyState::RubyInternalState::EXPECTING_EXPRESSION;
+          tokens->push_back({p.i, p.i + j, io::Token::Function});
+          p.advance(j);
+        }
         uint32_t start = p.i;
         if (p.peek(j) == ':') {
           p.advance(j);
@@ -1008,8 +1008,9 @@ bool handle_syntax(RubyParser &p, std::vector<io::Token> *tokens, std::vector<Pa
             return false;
           if (p.peek(j) == '&'
               || p.peek(j) == '%'
-              || p.peek(j) == ':') {
-            if (p.peek(j + 1) == ' ' || p.peek(j + 1) == '>')
+              || p.peek(j) == ':'
+              || p.peek(j) == '?') {
+            if (p.peek(j + 1) == ' ' || p.peek(j + 1) == '\0')
               return false;
           } else if (p.peek(j) == '-') {
             if (p.peek(j + 1) != '>')
@@ -1025,7 +1026,6 @@ bool handle_syntax(RubyParser &p, std::vector<io::Token> *tokens, std::vector<Pa
             || p.peek(j) == '*'
             || p.peek(j) == '/'
             || p.peek(j) == '='
-            || p.peek(j) == '?'
             || p.peek(j) == '|'
             || p.peek(j) == '^'
             || p.peek(j) == '<'
@@ -1061,7 +1061,7 @@ void ruby_parse(
   std::vector<ParseEvent> *events
 ) {
   RubyParser p(v_state, line);
-  while (p.i <= p.len()) {
+  while (p.i < p.len()) {
     p.op_last = p.set_op_last;
     p.set_op_last = false;
     if (p.current().state == RubyState::RubyInternalState::END)
@@ -1099,6 +1099,13 @@ void ruby_parse(
       return;
     if (!handle_syntax(p, tokens, events))
       p.current().flags &= ~RubyState::RubyInternalState::NEWLINE;
+    if (p.peek() == '\0') {
+      if (p.ending)
+        p.current().flags |= RubyState::RubyInternalState::EXPECTING_EXPRESSION;
+      p.advance();
+      p.current().flags &= ~RubyState::RubyInternalState::NEWLINE;
+      break;
+    }
     continue;
   }
   if (p.ending)

src/internal/ui/text_mode/text_mode.cc

@@ -2,6 +2,8 @@
 #include "bed.h"
 
 namespace bed::internal::ui::text_mode {
+// TODO: make this into a proper layout engine, in order to avoid so many expensive calculations repeatedly.
+
 template <typename F>
 static void for_each_cluster(std::string_view s, F &&f) {
   size_t cluster_start = 0;
@@ -204,11 +206,13 @@ std::pair<vase::Shard *, bool> TextMode::run_terminal() {
             }
             vase::Range r = {last, cursor};
             vase = vase::erase(vase, r);
-            if (cursor.row == last.row) {
-              parser->dirty(vase, cursor.row, 1);
-            } else {
-              parser->erase(vase, cursor.row, 1);
-              parser->dirty(vase, last.row, 1);
+            if (parser) {
+              if (cursor.row == last.row) {
+                parser->dirty(vase, cursor.row, 1);
+              } else {
+                parser->erase(vase, cursor.row, 1);
+                parser->dirty(vase, last.row, 1);
+              }
             }
             cursor = last;
           }
@@ -222,10 +226,12 @@ std::pair<vase::Shard *, bool> TextMode::run_terminal() {
             }
           }
           vase = vase::insert(&bed.append, vase, &cursor, '\n');
-          parser->insert(vase, cursor.row - 1, 1);
+          if (parser)
+            parser->insert(vase, cursor.row - 1, 1);
         } else {
           vase = vase::insert(&bed.append, vase, &cursor, res.text.data(), res.text.size());
-          parser->dirty(vase, cursor.row, 1);
+          if (parser)
+            parser->dirty(vase, cursor.row, 1);
         }
         break;
       }
@@ -233,11 +239,13 @@ std::pair<vase::Shard *, bool> TextMode::run_terminal() {
     case io::KeyEvent::KeyType::PASTE: {
       auto lines = std::count(res.text.begin(), res.text.end(), '\n');
       vase = vase::insert(&bed.append, vase, &cursor, res.text.data(), res.text.size());
-      if (lines) {
-        parser->insert(vase, cursor.row - lines, lines);
-        parser->dirty(vase, cursor.row - lines, 1);
-      } else {
-        parser->dirty(vase, cursor.row, 1);
+      if (parser) {
+        if (lines) {
+          parser->insert(vase, cursor.row - lines, lines);
+          parser->dirty(vase, cursor.row - lines, 1);
+        } else {
+          parser->dirty(vase, cursor.row, 1);
+        }
       }
     } break;
     case io::KeyEvent::KeyType::SPECIAL:
@@ -302,9 +310,11 @@ std::pair<vase::Shard *, bool> TextMode::run_terminal() {
         }
         vase::Range r = {cursor, next};
         vase = vase::erase(vase, r);
-        if (cursor.row != next.row)
-          parser->erase(vase, cursor.row + 1, 1);
-        parser->dirty(vase, cursor.row, 1);
+        if (parser) {
+          if (cursor.row != next.row)
+            parser->erase(vase, cursor.row + 1, 1);
+          parser->dirty(vase, cursor.row, 1);
+        }
       }
       break;
     }