Add command syntax highlighting.

include/internal/io/tokens.h

@@ -5,8 +5,8 @@
 
 namespace bed::internal::io {
 struct Token {
-  uint32_t start;
+  uint64_t start;
-  uint32_t end;
+  uint64_t end;
   enum Kind : uint8_t {
     TempCurrent,
     BufferName,
@@ -24,7 +24,6 @@ struct Token {
     Shell,
     Ruby,
     File,
-    Regex,
     Replacement,
     Suffix,
     Color1,

include/internal/parser/parser.h

@@ -85,12 +85,12 @@ struct Parser {
   std::string_view cmd;
   uint16_t i;
   Command *command;
-  std::vector<ui::Token> *tokens;
+  std::vector<io::Token> *tokens;
   CompletionContext *completion;
 
   explicit Parser(
     std::string_view cmd, BEd &bed, Command *command,
-    std::vector<ui::Token> *tokens, CompletionContext *completion
+    std::vector<io::Token> *tokens, CompletionContext *completion
   );
 
   char peek(uint16_t = 0); // == \0 if at eof.
@@ -107,7 +107,7 @@ struct Parser {
   void operation();
 
   void parse();
-
+  static std::vector<io::Token> get_highlight(std::string_view cmd, BEd &bed);
   static Command get_command(std::string_view, BEd &);
   static std::vector<AddressPromise> get_addresses(std::string_view cmd, BEd &bed);
 };

include/internal/ui/command.h

@@ -4,31 +4,6 @@
 #include "pch.h"
 
 namespace bed::internal::ui {
-struct Token {
-  enum struct Type : uint8_t {
-    TempCurrent,      // @
-    AddressSeperator, // ; ,
-    Address,          // . $ % [ ] ^ ~
-    Offset,           // +N -N + -
-    AddressRegex,     // /re/ ?re?
-    AddressSymbol,    // >s> <s< <s>
-    Number,           // 10
-    Mark,             // 'm
-    RubyFunction,     // (func:arg)
-    RubyArg,
-    Function,
-    Any,
-    Shell,
-    Ruby,
-    File,
-    Regex,
-    Replacement,
-    Suffix
-  } type;
-  uint16_t start;
-  uint16_t end;
-};
-
 struct CommandIO {
   std::string cmd;
   uint16_t cursor;

src/internal/buffer/shard.cc

@@ -29,8 +29,6 @@ uint64_t ShardBuffer::find_prev(std::string_view pattern, uint64_t start) {
 uint64_t ShardBuffer::next_closing(uint64_t start) {
   if (parse.lang) {
     uint64_t closing = syntax::next_closing(parse, start - 1);
-    if (closing == UINT64_MAX)
-      return lines();
     return closing + 1;
   } else {
     start += 10;

src/internal/functions/extended.cc

@@ -170,6 +170,27 @@ void Function::register_extented(BEd &ctx) {
                 ) {},
     }
   );
+  ctx.functions.insert(
+    "`",
+    Function{
+      .address_kind = Function::AddressKind::None,
+      .argument_kind = Function::ArgumentKind::Ruby,
+      .input_mode = Function::InputMode::None,
+      .desc = "Execute some ruby code",
+      .default_address = "",
+      .accept_zero = false,
+      .pre_text_mode = nullptr,
+      .handle = [](
+                  BEd &,
+                  const buffer::Address &,
+                  vase::Shard *,
+                  const Argument &,
+                  std::vector<buffer::Line> *
+                ) {
+        // TODO: connect up to mruby.
+      },
+    }
+  );
   ctx.functions.insert(
     "echo",
     Function{

src/internal/parser/address.cc

@@ -6,34 +6,74 @@ void Parser::locator(AddressPromise &addr) {
   addr.base = AddressPromise::None{};
   switch (peek()) {
   case '.':
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     addr.base = AddressPromise::Current{};
     break;
   case '$':
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     addr.base = AddressPromise::Last{};
     break;
   case '%':
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     addr.base = AddressPromise::LastRange{};
     break;
   case '[':
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     addr.base = AddressPromise::Block{Direction::Backward};
     break;
   case ']':
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     addr.base = AddressPromise::Block{Direction::Forward};
     break;
   case '^':
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     addr.base = AddressPromise::Diagnostic{Direction::Backward};
     break;
   case '~':
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     addr.base = AddressPromise::Diagnostic{Direction::Forward};
     break;
   case '\'':
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)2,
+       .type = io::Token::Mark}
+    );
     advance();
     if (('a' <= peek() && peek() <= 'z')
         || ('A' <= peek() && peek() <= 'Z'))
@@ -43,6 +83,11 @@ void Parser::locator(AddressPromise &addr) {
     advance();
     break;
   case '{': {
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     uint16_t j = 0;
     std::string func;
@@ -64,8 +109,24 @@ void Parser::locator(AddressPromise &addr) {
       arg = peek_str(j);
     else
       func = peek_str(j);
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)func.size(),
+       .type = io::Token::RubyFunction}
+    );
+    if (arg.size())
+      tokens->push_back(
+        {.start = i + (uint64_t)func.size() + 1,
+         .end = i + (uint64_t)func.size() + 1 + (uint64_t)arg.size(),
+         .type = io::Token::RubyFunction}
+      );
     addr.base = AddressPromise::Scripted{std::move(func), std::move(arg)};
     advance(j + 1);
+    tokens->push_back(
+      {.start = i,
+       .end = i - (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
   } break;
   case '/': {
     advance();
@@ -87,9 +148,19 @@ void Parser::locator(AddressPromise &addr) {
       Direction::Forward,
       std::string(peek_str(j))
     );
+    tokens->push_back(
+      {.start = (uint64_t)i - 1,
+       .end = (uint64_t)i + j + 1,
+       .type = io::Token::Regexp}
+    );
     advance(j + 1);
   } break;
   case '?': {
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     uint16_t j = 0;
     while (true) {
@@ -109,6 +180,11 @@ void Parser::locator(AddressPromise &addr) {
       Direction::Backward,
       std::string(peek_str(j))
     );
+    tokens->push_back(
+      {.start = (uint64_t)i - 1,
+       .end = (uint64_t)i + j + 1,
+       .type = io::Token::Regexp}
+    );
     advance(j + 1);
   } break;
   case '<': {
@@ -132,6 +208,11 @@ void Parser::locator(AddressPromise &addr) {
       };
       break;
     }
+    tokens->push_back(
+      {.start = (uint64_t)i - 1,
+       .end = (uint64_t)i + j + 1,
+       .type = io::Token::AddressSymbol}
+    );
     advance(j + 1);
   } break;
   case '>': {
@@ -149,9 +230,19 @@ void Parser::locator(AddressPromise &addr) {
       };
       break;
     }
+    tokens->push_back(
+      {.start = (uint64_t)i - 1,
+       .end = (uint64_t)i + j + 1,
+       .type = io::Token::AddressSymbol}
+    );
     advance(j + 1);
   } break;
   case '+': {
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     addr.base = AddressPromise::Current{};
     uint16_t j = 0;
@@ -162,10 +253,20 @@ void Parser::locator(AddressPromise &addr) {
     }
     if (j == 0)
       num = 1;
+    tokens->push_back(
+      {.start = (uint64_t)i,
+       .end = (uint64_t)i + j,
+       .type = io::Token::Number}
+    );
     advance(j);
     addr.offset += num;
   } break;
   case '-': {
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSymbol}
+    );
     advance();
     addr.base = AddressPromise::Current{};
     uint16_t j = 0;
@@ -176,17 +277,28 @@ void Parser::locator(AddressPromise &addr) {
     }
     if (j == 0)
       num = 1;
+    tokens->push_back(
+      {.start = (uint64_t)i,
+       .end = (uint64_t)i + j,
+       .type = io::Token::Number}
+    );
     advance(j);
     addr.offset -= num;
   } break;
   default:
     if ('0' <= peek() && peek() <= '9') {
+      uint16_t start = i;
       uint64_t num = 0;
       while ('0' <= peek() && peek() <= '9') {
         num = num * 10 + (peek() - '0');
         advance();
       }
       addr.base = AddressPromise::Number{num};
+      tokens->push_back(
+        {.start = (uint64_t)start,
+         .end = (uint64_t)i,
+         .type = io::Token::Number}
+      );
     }
   }
 }
@@ -196,14 +308,25 @@ int64_t Parser::offset() {
   while (peek() == '+' || peek() == '-'
          || ('0' <= peek() && peek() <= '9')) {
     bool positive = peek() != '-';
-    if (peek() == '+' || peek() == '-')
+    if (peek() == '+' || peek() == '-') {
+      tokens->push_back(
+        {.start = i,
+         .end = i + (uint64_t)1,
+         .type = io::Token::AddressSymbol}
+      );
       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;
+    tokens->push_back(
+      {.start = (uint64_t)i,
+       .end = (uint64_t)i + j,
+       .type = io::Token::Number}
+    );
     advance(j);
     offset += positive ? num : -num;
     skip_ws();
@@ -214,6 +337,7 @@ int64_t Parser::offset() {
 
 void Parser::address(AddressPromise &addr) {
   if (peek() == ':') {
+    uint16_t start = i;
     advance();
     uint16_t j = 0;
     while (peek(j) != ':' && peek(j) != '\0')
@@ -222,6 +346,11 @@ void Parser::address(AddressPromise &addr) {
     advance(j);
     if (peek() == ':')
       advance();
+    tokens->push_back(
+      {.start = start,
+       .end = i,
+       .type = io::Token::BufferName}
+    );
   }
   skip_ws();
   if (peek() == '\0')
@@ -238,6 +367,11 @@ void Parser::addresses(std::vector<AddressPromise> &addresses) {
   address(*addr);
   while (peek() == ',' || peek() == ';') {
     addr->jumping = peek() == ';';
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::AddressSeperator}
+    );
     advance();
     skip_ws();
     addresses.push_back({});

src/internal/parser/operation.cc

@@ -11,6 +11,11 @@ void Parser::operation() {
   if (len == 0)
     throw ed_error("Function not found.");
   functions::Function *function = bed.functions.get_ptr(peek_str(len));
+  tokens->push_back(
+    {.start = i,
+     .end = i + len,
+     .type = io::Token::Function}
+  );
   advance(len);
   command->function = function;
   char suffix = '\0';
@@ -27,10 +32,20 @@ void Parser::operation() {
       command->argument = peek();
     else
       throw ed_error("Valid mark needed.");
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::Mark}
+    );
     advance();
     break;
   case functions::Function::ArgumentKind::Any:
     command->argument = std::string(peek_str());
+    tokens->push_back(
+      {.start = i,
+       .end = i + peek_str().size(),
+       .type = io::Token::Any}
+    );
     advance(peek_str().size());
     break;
   case functions::Function::ArgumentKind::Global: {
@@ -108,8 +123,18 @@ void Parser::operation() {
     skip_ws();
     switch (peek()) {
     case '!':
+      tokens->push_back(
+        {.start = i,
+         .end = (uint64_t)i + 1,
+         .type = io::Token::Error}
+      );
       advance();
       command->argument = functions::Function::ShellArg(std::string(peek_str()));
+      tokens->push_back(
+        {.start = i,
+         .end = i + peek_str().size(),
+         .type = io::Token::Shell}
+      );
       advance(peek_str().size());
       break;
     case '\0':
@@ -117,6 +142,11 @@ void Parser::operation() {
       break;
     default:
       command->argument = std::filesystem::path(peek_str());
+      tokens->push_back(
+        {.start = i,
+         .end = i + peek_str().size(),
+         .type = io::Token::File}
+      );
       advance(peek_str().size());
       break;
     }
@@ -133,6 +163,7 @@ void Parser::operation() {
     char delim = peek();
     if (delim == '\0')
       throw ed_error("regex expected");
+    uint16_t start = i;
     advance();
     uint16_t j = 0;
     while (true) {
@@ -172,8 +203,18 @@ void Parser::operation() {
       advance(j);
       options = "p";
     }
+    tokens->push_back(
+      {.start = start,
+       .end = i,
+       .type = io::Token::Regexp}
+    );
     if (peek() != '\0') {
       options = std::string(peek_str());
+      tokens->push_back(
+        {.start = i,
+         .end = i + peek_str().size(),
+         .type = io::Token::Suffix}
+      );
       advance(peek_str().size());
     }
     std::erase_if(options, [&](char c) {
@@ -185,17 +226,38 @@ void Parser::operation() {
     });
     command->argument = functions::Function::RegexArg(expression, replacement, options);
   } break;
-  case functions::Function::ArgumentKind::Ruby:
+  case functions::Function::ArgumentKind::Ruby: {
     command->argument = functions::Function::RubyArg(std::string(peek_str()));
+    auto *ruby_parser = bed.languages["ruby"];
+    void *state = ruby_parser->none_state();
+    std::vector<syntax::ParseEvent> events;
+    std::vector<io::Token> tokens_;
+    ruby_parser->parse(&state, peek_str(), false, &tokens_, &events);
+    for (auto &token : tokens_) {
+      token.start += i;
+      token.end += i;
+      tokens->push_back(token);
+    }
+    ruby_parser->destroy(state);
     advance(peek_str().size());
-    break;
+  } break;
   case functions::Function::ArgumentKind::Shell:
     command->argument = functions::Function::ShellArg(std::string(peek_str()));
+    tokens->push_back(
+      {.start = i,
+       .end = i + peek_str().size(),
+       .type = io::Token::Shell}
+    );
     advance(peek_str().size());
     break;
   }
   if (!suffix) {
     suffix = peek();
+    tokens->push_back(
+      {.start = i,
+       .end = i + (uint64_t)1,
+       .type = io::Token::Suffix}
+    );
     advance();
   }
   if (suffix) {

src/internal/parser/parser.cc

@@ -22,6 +22,11 @@ void Parser::skip_ws() {
 void Parser::parse() {
   skip_ws();
   if (peek() == '@') {
+    tokens->push_back(
+      {.start = 0,
+       .end = 1,
+       .type = io::Token::TempCurrent}
+    );
     advance();
     command->temp_address = true;
   } else {
@@ -37,14 +42,26 @@ void Parser::parse() {
 
 Parser::Parser(
   std::string_view cmd, BEd &bed, Command *command,
-  std::vector<ui::Token> *tokens, CompletionContext *completion
+  std::vector<io::Token> *tokens, CompletionContext *completion
 ) : bed(bed), cmd(cmd), command(command), tokens(tokens), completion(completion) {
   i = 0;
 }
 
+std::vector<io::Token> Parser::get_highlight(std::string_view cmd, BEd &bed) {
+  Command c;
+  std::vector<io::Token> tokens;
+  CompletionContext completion;
+  try {
+    Parser p(cmd, bed, &c, &tokens, &completion);
+    p.parse();
+  } catch (const ed_error &e) {
+  }
+  return tokens;
+}
+
 Command Parser::get_command(std::string_view cmd, BEd &bed) {
   Command c;
-  std::vector<ui::Token> tokens;
+  std::vector<io::Token> tokens;
   CompletionContext completion;
   Parser p(cmd, bed, &c, &tokens, &completion);
   p.parse();
@@ -53,7 +70,7 @@ 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<ui::Token> tokens;
+  std::vector<io::Token> tokens;
   CompletionContext completion;
   Parser p(cmd, bed, nullptr, &tokens, &completion);
   p.addresses(result);

src/internal/syntax/parser.cc

@@ -50,7 +50,7 @@ uint64_t next_closing(const ParserSnapshot &snap, uint64_t line) {
     c.next();
     first_leaf = false;
   }
-  return (snap.root->lines() - line > 10 ? line + 10 : snap.root->lines());
+  return (snap.root->lines() - line > 10 ? line + 10 : snap.root->lines() - 1);
 }
 
 uint64_t prev_opening(const ParserSnapshot &snap, uint64_t line) {

src/internal/theme/theme.cc

@@ -15,53 +15,54 @@ io::Highlight Theme::get(const io::Token::Kind &token) const {
 
 Theme Theme::default_theme() {
   Theme theme;
+
   theme.hl[io::Token::TempCurrent] = {
-    .fg = 0x7DCFFF,
+    .fg = 0x7AA2F7,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::BufferName] = {
-    .fg = 0xAAD94C,
+    .fg = 0xBB9AF7,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::AddressSeperator] = {
-    .fg = 0xFF8F40,
+    .fg = 0xA9B1D6,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::Address] = {
-    .fg = 0xD2A6FF,
+    .fg = 0xE0AF68,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::Offset] = {
-    .fg = 0xEF5168,
+    .fg = 0xFFAF70,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::AddressRegex] = {
-    .fg = 0x7DCFFF,
-    .bg = 0x000000,
-    .flags = io::Highlight::None,
-  };
-  theme.hl[io::Token::AddressSymbol] = {
-    .fg = 0xAAD94C,
-    .bg = 0x000000,
-    .flags = io::Highlight::None,
-  };
-  theme.hl[io::Token::Mark] = {
-    .fg = 0xFF8F40,
-    .bg = 0x000000,
-    .flags = io::Highlight::None,
-  };
-  theme.hl[io::Token::RubyFunction] = {
     .fg = 0xD2A6FF,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
+  theme.hl[io::Token::AddressSymbol] = {
+    .fg = 0xFF9E64,
+    .bg = 0x000000,
+    .flags = io::Highlight::None,
+  };
+  theme.hl[io::Token::Mark] = {
+    .fg = 0xFF757F,
+    .bg = 0x000000,
+    .flags = io::Highlight::None,
+  };
+  theme.hl[io::Token::RubyFunction] = {
+    .fg = 0x7DCFFF,
+    .bg = 0x000000,
+    .flags = io::Highlight::None,
+  };
   theme.hl[io::Token::RubyArg] = {
-    .fg = 0xEF5168,
+    .fg = 0xA9B1D6,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
@@ -71,37 +72,32 @@ Theme Theme::default_theme() {
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::Shell] = {
-    .fg = 0xAAD94C,
+    .fg = 0x89DDFF,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::Ruby] = {
-    .fg = 0xFF8F40,
+    .fg = 0x95E6CB,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::File] = {
-    .fg = 0xD2A6FF,
-    .bg = 0x000000,
-    .flags = io::Highlight::None,
-  };
-  theme.hl[io::Token::Regex] = {
-    .fg = 0xEF5168,
-    .bg = 0x000000,
-    .flags = io::Highlight::None,
-  };
-  theme.hl[io::Token::Replacement] = {
-    .fg = 0x7DCFFF,
-    .bg = 0x000000,
-    .flags = io::Highlight::None,
-  };
-  theme.hl[io::Token::Suffix] = {
     .fg = 0xAAD94C,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
+  theme.hl[io::Token::Replacement] = {
+    .fg = 0x9ECE6A,
+    .bg = 0x000000,
+    .flags = io::Highlight::None,
+  };
+  theme.hl[io::Token::Suffix] = {
+    .fg = 0xF07178,
+    .bg = 0x000000,
+    .flags = io::Highlight::None,
+  };
   theme.hl[io::Token::Color1] = {
-    .fg = 0x7DCFFF,
+    .fg = 0x7AA2F7,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
@@ -111,17 +107,17 @@ Theme Theme::default_theme() {
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::Color3] = {
-    .fg = 0xFF8F40,
+    .fg = 0xFF9E64,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::Color4] = {
-    .fg = 0xD2A6FF,
+    .fg = 0xBB9AF7,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::Color5] = {
-    .fg = 0xEF5168,
+    .fg = 0xFF757F,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };
@@ -162,7 +158,7 @@ Theme Theme::default_theme() {
     .flags = io::Highlight::None,
   };
   theme.hl[io::Token::Regexp] = {
-    .fg = 0xD2A6FF,
+    .fg = 0x7DCFFF,
     .bg = 0x000000,
     .flags = io::Highlight::None,
   };

src/internal/ui/command/command.cc

@@ -1,5 +1,6 @@
 #include "internal/ui/command.h"
 #include "bed.h"
+#include "internal/parser/parser.h"
 
 namespace bed::internal::ui {
 /*template <typename F>
@@ -162,7 +163,22 @@ void CommandIO::redraw() {
   bed.io.write("\x1b[2K", 4);
   bed.io.move_cursor(start, 1);
   bed.io.write(prompt);
-  bed.io.write(cmd);
+  const auto tokens = parser::Parser::get_highlight(cmd, bed);
+  uint32_t pos = 0;
+  for (const auto &token : tokens) {
+    const uint32_t tstart = token.start;
+    const uint32_t tend = token.end;
+    if (tstart > cmd.size())
+      break;
+    if (pos < tstart)
+      bed.io.write(cmd.data() + pos, tstart - pos);
+    bed.io.apply(token.type);
+    bed.io.write(cmd.data() + tstart, tend - tstart);
+    bed.io.reset();
+    pos = tend;
+  }
+  if (pos < cmd.size())
+    bed.io.write(cmd.data() + pos, cmd.size() - pos);
   bed.io.move_cursor(start, prompt.size() + cursor + 1);
 }
 } // namespace bed::internal::ui

src/internal/vase/shard.cc

@@ -289,6 +289,8 @@ Shard *Shard::from_command(const char *cmd, bool posix_ending) {
         last = nullptr;
         if (!pieces.empty())
           last = (Petal *)pieces.back();
+        else
+          return nullptr;
       }
       if (last && ending[0] == '\r')
         last->length--;