Class: Regexp::Lexer

Inherits:
Object
  • Object
show all
Defined in:
lib/regexp_parser/lexer.rb

Overview

A very thin wrapper around the scanner that breaks quantified literal runs, collects emitted tokens into an array, calculates their nesting depth, and normalizes tokens for the parser, and checks if they are implemented by the given syntax flavor.

Constant Summary collapse

OPENING_TOKENS = 
%i[
  capture passive lookahead nlookahead lookbehind nlookbehind
  atomic options options_switch named absence
].freeze
CLOSING_TOKENS = 
%i[close].freeze
CONDITION_TOKENS = 
%i[condition condition_close].freeze

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.lex(input, syntax = "ruby/#{RUBY_VERSION}", options: nil, &block) ⇒ Object Also known as: scan 



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# File 'lib/regexp_parser/lexer.rb', line 16

def self.lex(input, syntax = "ruby/#{RUBY_VERSION}", options: nil, &block)
  new.lex(input, syntax, options: options, &block)
end

Instance Method Details

#lex(input, syntax = "ruby/#{RUBY_VERSION}", options: nil, &block) ⇒ Object 



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# File 'lib/regexp_parser/lexer.rb', line 20

def lex(input, syntax = "ruby/#{RUBY_VERSION}", options: nil, &block)
  syntax = Regexp::Syntax.new(syntax)

  self.tokens = []
  self.nesting = 0
  self.set_nesting = 0
  self.conditional_nesting = 0
  self.shift = 0

  last = nil
  Regexp::Scanner.scan(input, options: options) do |type, token, text, ts, te|
    type, token = *syntax.normalize(type, token)
    syntax.check! type, token

    ascend(type, token)

    if type == :quantifier and last
      break_literal(last)        if last.type == :literal
      break_codepoint_list(last) if last.token == :codepoint_list
    end

    current = Regexp::Token.new(type, token, text, ts + shift, te + shift,
                                nesting, set_nesting, conditional_nesting)

    current = merge_condition(current) if type == :conditional and
      CONDITION_TOKENS.include?(token)

    last.next = current if last
    current.previous = last if last

    tokens << current
    last = current

    descend(type, token)
  end

  if block_given?
    tokens.map { |t| block.call(t) }
  else
    tokens
  end
end