Class: Inform::Grammar::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/runtime/grammar_parser.rb

Overview

The Inform::Grammar::Parser class will parse inform-style grammar files rubocop: disable Metrics/ClassLength

Constant Summary collapse

CommentedOrBlankLine = 
%r{^\s*[^\#\n]}.freeze
TerminalLinePattern = 
%r{;$}.freeze
TokenPattern = 
%r{'[^\s']+'}.freeze
ArrowPattern = 
%r{->}.freeze

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/runtime/grammar_parser.rb', line 401

def initialize
  # Base state for block comment toggling
  @block_comment = false
end

Instance Method Details

#block_comment?(line) ⇒ Boolean

rubocop: enable Metrics/AbcSize rubocop: enable Metrics/CyclomaticComplexity rubocop: enable Metrics/MethodLength rubocop: enable Metrics/PerceivedComplexity rubocop: enable Style/RaiseArgs def parse

Returns:

  • (Boolean) 


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# File 'lib/runtime/grammar_parser.rb', line 537

def block_comment?(line)
  if line[/^=begin/]
    @block_comment = true
  elsif line[/^=end/]
    @block_comment = false
    true
  else
    @block_comment
  end
end

#parse(source, line) ⇒ Object

rubocop: disable Metrics/AbcSize rubocop: disable Metrics/CyclomaticComplexity rubocop: disable Metrics/MethodLength rubocop: disable Metrics/PerceivedComplexity rubocop: disable Style/RaiseArgs



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# File 'lib/runtime/grammar_parser.rb', line 433

def parse(source, line)
  return if block_comment?(line)
  terminal = /;$/.match(line)
  # terminal = TerminalLinePattern.match?(line)
  line.gsub!(/\#.*/, '')
  line.gsub!(/;$/, '')
  tokens = line.split
  return if tokens.empty?
  token = tokens.first
  @grammars ||= []
  case token
  when /^Verb/
    raise UnexpectedToken.new('*', 'Verb') unless @grammars.empty?
    tokens.shift
    meta  = tokens.delete 'meta'
    emote = tokens.delete 'emote'
    @first = false
    @last = true
    synonym = tokens.delete '='
    replace = tokens.delete 'replace' # rubocop: disable Lint/UselessAssignment
    tokens.delete_if { |a| !/'[^\s']+'/.match?(a) }
    # tokens.delete_if { |a| !TokenPattern.match?(a) }
    keys = tokens.map { |a| a[1..-2] }
    key = synonym ? keys.last : keys.first
    log.debug "Loading verb: #{key}"
    @verb = Inform::Grammar::Verbs.lookup(key)
    if @verb
      raise DuplicateVerb.new(key) unless synonym
      @verb.merge keys
    else
      @verb = Verb.new(keys, source, meta, emote)
    end
    keys.each do |k|
      Inform::Grammar::Verbs[k] = @verb
    end
  when /^Extend/
    raise UnexpectedToken.new('*', 'Extend') unless @grammars.empty?
    tokens.shift
    meta = tokens.delete('meta')
    emote = tokens.delete('emote')
    only = tokens.delete('only')
    @first = tokens.delete('first')
    @last = tokens.delete('last')
    replace = tokens.delete('replace')
    tokens.delete_if { |verb_token| !/'[^\s']+'/.match?(verb_token) }
    # tokens.delete_if { |token| !TokenPattern.match?(token) }
    keys = tokens.map { |verb_token| verb_token[1..-2] }
    key = keys.first
    existing_verb = Inform::Grammar::Verbs.lookup(key)
    if existing_verb.nil?
      @verb = Verb.new(keys, source, meta, emote)
    elsif only.nil?
      existing_verb.merge(keys)
      @verb = existing_verb
      unless replace.nil?
        @verb.source = source
        @verb.grammars.clear
      end
    else
      keys.each do |existing_key|
        Inform::Grammar::Verbs.delete(existing_key)
        existing_verb.delete(existing_key)
      end
      @verb = Verb.new(keys, source, meta, emote)
      @verb.grammars = existing_verb.grammars if replace.nil?
      keys.each do |new_key|
        Inform::Grammar::Verbs[new_key] = @verb
      end
    end
    Inform::Grammar::Verbs[key] = @verb
  when /\*/
    tokens, action = line.split(ArrowPattern)
    tokens = tokens.split
    tokens.shift
    reverse = false; reverse = true if /reverse/.match?(action)
    action = action.gsub(/;/, '').split.first.to_sym
    grammar = Verb::Grammar.new(tokens, source, action, reverse)
    @grammars.push(grammar)
  else
    unless @verb.nil?
      new_keys = tokens.map { |verb_token| verb_token[1..-2] }
      @verb.merge(new_keys) # Set#merge modifies in-place
      new_keys.each do |new_key|
        Inform::Grammar::Verbs[new_key] = @verb
      end
    end
  end

  return if terminal.nil?

  if @first.nil?
    @verb.grammars.concat(@grammars)
  else
    @verb.grammars.unshift(*@grammars)
  end
  @grammars.clear
end

#parse_grammar(grammar_module, lines, origin_path: nil, origin_line: 0) ⇒ Object

rubocop: disable Metrics/MethodLength



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# File 'lib/runtime/grammar_parser.rb', line 407

def parse_grammar(grammar_module, lines, origin_path: nil, origin_line: 0)
  line_index = Integer(origin_line || 0)
  lines.each do |line|
    line_index += 1
    next unless /^\s*[^\#\n]/.match?(line)
    begin
      parse(grammar_module, line)
    rescue DuplicateVerb => e
      e.file = File.basename(origin_path)
      e.line = line_index
      log.warn e
    rescue UnexpectedToken => e
      e.file = File.basename(origin_path)
      e.line = line_index
      raise e
    end
  end
  true
end