Class: Rouge::RegexLexer Abstract

Inherits:
Lexer
  • Object
show all
Defined in:
lib/rouge/regex_lexer.rb

Overview

This class is abstract.

A stateful lexer that uses sets of regular expressions to tokenize a string. Most lexers are instances of RegexLexer.

Direct Known Subclasses

Lexers::ABAP, Lexers::Actionscript, Lexers::Ada, Lexers::Apache, Lexers::Apex, Lexers::AppleScript, Lexers::ArmAsm, Lexers::Augeas, Lexers::Awk, Lexers::BBCBASIC, Lexers::BPF, Lexers::Batchfile, Lexers::BibTeX, Lexers::Brainfuck, Lexers::Brightscript, Lexers::Bsl, Lexers::C, Lexers::CMHG, Lexers::CMake, Lexers::COBOL, Lexers::CSS, Lexers::CSVS, Lexers::CSharp, Lexers::Ceylon, Lexers::Cfscript, Lexers::CiscoIos, Lexers::Clean, Lexers::Clojure, Lexers::Codeowners, Lexers::Coffeescript, Lexers::CommonLisp, Lexers::Conf, Lexers::Coq, Lexers::Crystal, Lexers::Cypher, Lexers::D, Lexers::Dafny, Lexers::Dart, Lexers::Datastudio, Lexers::Diff, Lexers::Docker, Lexers::Dot, Lexers::ECL, Lexers::Eiffel, Lexers::Elixir, Lexers::Elm, Lexers::Email, Lexers::Erlang, Lexers::FSharp, Lexers::Factor, Lexers::Fluent, Lexers::Fortran, Lexers::GDScript, Lexers::GHCCmm, Lexers::GHCCore, Lexers::Gherkin, Lexers::Go, Lexers::GraphQL, Lexers::Groovy, Lexers::HTML, Lexers::HTTP, Lexers::Haml, Lexers::Haskell, Lexers::Haxe, Lexers::Hcl, Lexers::HyLang, Lexers::IDLang, Lexers::INI, Lexers::IO, Lexers::ISBL, Lexers::Idris, Lexers::IecST, Lexers::IgorPro, Lexers::Isabelle, Lexers::J, Lexers::JSL, Lexers::JSON, Lexers::Janet, Lexers::Java, Lexers::Javascript, Lexers::Jsonnet, Lexers::Julia, Lexers::Kotlin, Lexers::LLVM, Lexers::Lean, Lexers::Liquid, Lexers::LiterateCoffeescript, Lexers::LiterateHaskell, Lexers::Livescript, Lexers::Lua, Lexers::Lustre, Lexers::M68k, Lexers::MXML, Lexers::Magik, Lexers::Make, Lexers::Markdown, Lexers::Mathematica, Lexers::Matlab, Lexers::Meson, Lexers::MiniZinc, Lexers::Moonscript, Lexers::Mosel, Lexers::MsgTrans, Lexers::Nasm, Lexers::NesAsm, Lexers::Nginx, Lexers::Nial, Lexers::Nim, Lexers::Nix, Lexers::OCL, Lexers::OCamlCommon, Lexers::OpenEdge, Lexers::OpenTypeFeatureFile, Lexers::P4, Lexers::PLSQL, Lexers::Pascal, Lexers::Perl, Lexers::Plist, Lexers::Pony, Lexers::PostScript, Lexers::Powershell, Lexers::Praat, Lexers::Prolog, Lexers::Prometheus, Lexers::Properties, Lexers::Protobuf, Lexers::Puppet, Lexers::Python, Lexers::Q, Lexers::R, Lexers::RML, Lexers::Racket, Lexers::Rego, Lexers::RobotFramework, Lexers::Ruby, Lexers::Rust, Lexers::SAS, Lexers::SML, Lexers::SPARQL, Lexers::SQF, Lexers::SQL, Lexers::SSH, Lexers::SassCommon, Lexers::Scala, Lexers::Scheme, Lexers::Sed, Lexers::Sed::Regex, Lexers::Sed::Replacement, Lexers::Shell, Lexers::Sieve, Lexers::Slim, Lexers::Smalltalk, Lexers::Stan, Lexers::Stata, Lexers::SuperCollider, Lexers::Swift, Lexers::SystemD, Lexers::Syzlang, Lexers::Syzprog, Lexers::TCL, Lexers::TOML, Lexers::TTCN3, Lexers::Tap, Lexers::TeX, Lexers::Tulip, Lexers::Turtle, Lexers::VHDL, Lexers::Vala, Lexers::Varnish, Lexers::Verilog, Lexers::VimL, Lexers::VisualBasic, Lexers::Wollok, Lexers::XML, Lexers::XPath, Lexers::Xojo, Lexers::YAML, Lexers::YANG, Lexers::Zig, TemplateLexer

Defined Under Namespace

Classes: ClosedState, InvalidRegex, Rule, State, StateDSL

Constant Summary collapse

MAX_NULL_SCANS =

The number of successive scans permitted without consuming the input stream. If this is exceeded, the match fails.

5

Constants included from Token::Tokens

Token::Tokens::Num, Token::Tokens::Str

Instance Attribute Summary

Attributes inherited from Lexer

#options

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Lexer

aliases, all, #as_bool, #as_lexer, #as_list, #as_string, #as_token, assert_utf8!, #bool_option, continue_lex, #continue_lex, debug_enabled?, demo, demo_file, desc, detect?, detectable?, disable_debug!, enable_debug!, filenames, find, find_fancy, guess, guess_by_filename, guess_by_mimetype, guess_by_source, guesses, #hash_option, #initialize, #lex, lex, #lexer_option, #list_option, lookup_fancy, mimetypes, option, option_docs, #string_option, tag, #tag, title, #token_option, #with

Methods included from Token::Tokens

token

Constructor Details

This class inherits a constructor from Rouge::Lexer

Class Method Details

.append(name, &b) ⇒ Object 



264
265
266
267
268
 
# File 'lib/rouge/regex_lexer.rb', line 264

def self.append(name, &b)
  name = name.to_sym
  dsl = state_definitions[name] or raise "no such state #{name.inspect}"
  replace_state(name, dsl.appended(&b))
end

.get_state(name) ⇒ Object 



271
272
273
274
275
276
277
278
 
# File 'lib/rouge/regex_lexer.rb', line 271

def self.get_state(name)
  return name if name.is_a? State

  states[name.to_sym] ||= begin
    defn = state_definitions[name.to_sym] or raise "unknown state: #{name.inspect}"
    defn.to_state(self)
  end
end

.prepend(name, &b) ⇒ Object 



258
259
260
261
262
 
# File 'lib/rouge/regex_lexer.rb', line 258

def self.prepend(name, &b)
  name = name.to_sym
  dsl = state_definitions[name] or raise "no such state #{name.inspect}"
  replace_state(name, dsl.prepended(&b))
end

.replace_state(name, new_defn) ⇒ Object 



231
232
233
234
 
# File 'lib/rouge/regex_lexer.rb', line 231

def self.replace_state(name, new_defn)
  states[name] = nil
  state_definitions[name] = new_defn
end

.start(&b) ⇒ Object

Specify an action to be run every fresh lex.

Examples:

start { puts "I'm lexing a new string!" }


247
248
249
 
# File 'lib/rouge/regex_lexer.rb', line 247

def self.start(&b)
  start_procs << b
end

.start_procs ⇒ Object

The routines to run at the beginning of a fresh lex.

See Also:



238
239
240
 
# File 'lib/rouge/regex_lexer.rb', line 238

def self.start_procs
  @start_procs ||= InheritableList.new(superclass.start_procs)
end

.state(name, &b) ⇒ Object

Define a new state for this lexer with the given name. The block will be evaluated in the context of a StateDSL.



253
254
255
256
 
# File 'lib/rouge/regex_lexer.rb', line 253

def self.state(name, &b)
  name = name.to_sym
  state_definitions[name] = StateDSL.new(name, &b)
end

.state_definitions ⇒ Object 



226
227
228
 
# File 'lib/rouge/regex_lexer.rb', line 226

def self.state_definitions
  @state_definitions ||= InheritableHash.new(superclass.state_definitions)
end

.states ⇒ Object

The states hash for this lexer.

See Also:



222
223
224
 
# File 'lib/rouge/regex_lexer.rb', line 222

def self.states
  @states ||= {}
end

Instance Method Details

#delegate(lexer, text = nil) ⇒ Object

Delegate the lex to another lexer. We use the ‘continue_lex` method so that #reset! will not be called. In this way, a single lexer can be repeatedly delegated to while maintaining its own internal state stack.

Parameters:

  • lexer (#lex) —

    The lexer or lexer class to delegate to

  • text (String) (defaults to: nil) —

    The text to delegate. This defaults to the last matched string.



433
434
435
436
437
438
439
440
441
 
# File 'lib/rouge/regex_lexer.rb', line 433

def delegate(lexer, text=nil)
  puts "    delegating to: #{lexer.inspect}" if @debug
  text ||= @current_stream[0]

  lexer.continue_lex(text) do |tok, val|
    puts "    delegated token: #{tok.inspect}, #{val.inspect}" if @debug
    yield_token(tok, val)
  end
end

#get_state(state_name) ⇒ Object 



281
282
283
 
# File 'lib/rouge/regex_lexer.rb', line 281

def get_state(state_name)
  self.class.get_state(state_name)
end

#goto(state_name) ⇒ Object

replace the head of the stack with the given state



477
478
479
480
481
482
 
# File 'lib/rouge/regex_lexer.rb', line 477

def goto(state_name)
  raise 'empty stack!' if stack.empty?

  puts "    going to: state :#{state_name} " if @debug
  stack[-1] = get_state(state_name)
end

#group(tok) ⇒ Object

Deprecated.

Yield a token with the next matched group. Subsequent calls to this method will yield subsequent groups.



412
413
414
 
# File 'lib/rouge/regex_lexer.rb', line 412

def group(tok)
  raise "RegexLexer#group is deprecated: use #groups instead"
end

#groups(*tokens) ⇒ Object

Yield tokens corresponding to the matched groups of the current match.



418
419
420
421
422
 
# File 'lib/rouge/regex_lexer.rb', line 418

def groups(*tokens)
  tokens.each_with_index do |tok, i|
    yield_token(tok, @current_stream[i+1])
  end
end

#in_state?(state_name) ⇒ Boolean

Check if ‘state_name` is in the state stack.

Returns:

  • (Boolean) 


492
493
494
495
496
497
 
# File 'lib/rouge/regex_lexer.rb', line 492

def in_state?(state_name)
  state_name = state_name.to_sym
  stack.any? do |state|
    state.name == state_name.to_sym
  end
end

#pop!(times = 1) ⇒ Object

Pop the state stack. If a number is passed in, it will be popped that number of times.



466
467
468
469
470
471
472
473
474
 
# File 'lib/rouge/regex_lexer.rb', line 466

def pop!(times=1)
  raise 'empty stack!' if stack.empty?

  puts "    popping stack: #{times}" if @debug

  stack.pop(times)

  nil
end

#push(state_name = nil, &b) ⇒ Object

Push a state onto the stack. If no state name is given and you’ve passed a block, a state will be dynamically created using the StateDSL.



450
451
452
453
454
455
456
457
458
459
460
461
462
 
# File 'lib/rouge/regex_lexer.rb', line 450

def push(state_name=nil, &b)
  push_state = if state_name
    get_state(state_name)
  elsif block_given?
    StateDSL.new(b.inspect, &b).to_state(self.class)
  else
    # use the top of the stack by default
    self.state
  end

  puts "    pushing: :#{push_state.name}" if @debug
  stack.push(push_state)
end

#recurse(text = nil) ⇒ Object 



443
444
445
 
# File 'lib/rouge/regex_lexer.rb', line 443

def recurse(text=nil)
  delegate(self.class, text)
end

#reset! ⇒ Object

reset this lexer to its initial state. This runs all of the start_procs.



302
303
304
305
306
307
308
309
310
 
# File 'lib/rouge/regex_lexer.rb', line 302

def reset!
  @stack = nil
  @current_stream = nil

  puts "start blocks" if @debug && self.class.start_procs.any?
  self.class.start_procs.each do |pr|
    instance_eval(&pr)
  end
end

#reset_stack ⇒ Object

reset the stack back to ‘[:root]`.



485
486
487
488
489
 
# File 'lib/rouge/regex_lexer.rb', line 485

def reset_stack
  puts '    resetting stack' if @debug
  stack.clear
  stack.push get_state(:root)
end

#stack ⇒ Object

The state stack. This is initially the single state ‘[:root]`. It is an error for this stack to be empty.

See Also:



288
289
290
 
# File 'lib/rouge/regex_lexer.rb', line 288

def stack
  @stack ||= [get_state(:root)]
end

#state ⇒ Object

The current state - i.e. one on top of the state stack.

NB: if the state stack is empty, this will throw an error rather than returning nil.



296
297
298
 
# File 'lib/rouge/regex_lexer.rb', line 296

def state
  stack.last or raise 'empty stack!'
end

#state?(state_name) ⇒ Boolean

Check if ‘state_name` is the state on top of the state stack.

Returns:

  • (Boolean) 


500
501
502
 
# File 'lib/rouge/regex_lexer.rb', line 500

def state?(state_name)
  state_name.to_sym == state.name
end

#step(state, stream) ⇒ Object

Runs one step of the lex. Rules in the current state are tried until one matches, at which point its callback is called.

Returns:

  • true if a rule was tried successfully

  • false otherwise.



358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
 
# File 'lib/rouge/regex_lexer.rb', line 358

def step(state, stream)
  state.rules.each do |rule|
    if rule.is_a?(State)
      puts "  entering: mixin :#{rule.name}" if @debug
      return true if step(rule, stream)
      puts "  exiting: mixin :#{rule.name}" if @debug
    else
      puts "  trying: #{rule.inspect}" if @debug

      # XXX HACK XXX
      # StringScanner's implementation of ^ is b0rken.
      # see http://bugs.ruby-lang.org/issues/7092
      # TODO: this doesn't cover cases like /(a|^b)/, but it's
      # the most common, for now...
      next if rule.beginning_of_line && !stream.beginning_of_line?

      if (size = stream.skip(rule.re))
        puts "    got: #{stream[0].inspect}" if @debug

        instance_exec(stream, &rule.callback)

        if size.zero?
          @null_steps += 1
          if @null_steps > MAX_NULL_SCANS
            puts "    warning: too many scans without consuming the string!" if @debug
            return false
          end
        else
          @null_steps = 0
        end

        return true
      end
    end
  end

  false
end

#stream_tokens(str, &b) ⇒ Object

This implements the lexer protocol, by yielding [token, value] pairs.

The process for lexing works as follows, until the stream is empty:

  1. We look at the state on top of the stack (which by default is ‘[:root]`).

  2. Each rule in that state is tried until one is successful. If one is found, that rule’s callback is evaluated - which may yield tokens and manipulate the state stack. Otherwise, one character is consumed with an ‘’Error’‘ token, and we continue at (1.)

See Also:



324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
 
# File 'lib/rouge/regex_lexer.rb', line 324

def stream_tokens(str, &b)
  stream = StringScanner.new(str)

  @current_stream = stream
  @output_stream  = b
  @states         = self.class.states
  @null_steps     = 0

  until stream.eos?
    if @debug
      puts
      puts "lexer: #{self.class.tag}"
      puts "stack: #{stack.map(&:name).map(&:to_sym).inspect}"
      puts "stream: #{stream.peek(20).inspect}"
    end

    success = step(state, stream)

    if !success
      puts "    no match, yielding Error" if @debug
      b.call(Token::Tokens::Error, stream.getch)
    end
  end
end

#token(tok, val = ) ⇒ Object

Yield a token.

Parameters:

  • tok —

    the token type

  • val (defaults to: ) —

    (optional) the string value to yield. If absent, this defaults to the entire last match.



404
405
406
 
# File 'lib/rouge/regex_lexer.rb', line 404

def token(tok, val=@current_stream[0])
  yield_token(tok, val)
end