Module: SrlRuby

Defined in:
lib/srl_ruby.rb,
lib/srl_ruby/grammar.rb,
lib/srl_ruby/version.rb,
lib/srl_ruby/srl_token.rb,
lib/srl_ruby/tokenizer.rb,
lib/srl_ruby/ast_builder.rb

Defined Under Namespace

Classes: ASTBuilder, Position, SrlToken, Tokenizer

Constant Summary collapse

Grammar =

And now build the grammar and make it accessible via a global constant [Rley::Syntax::Grammar]

builder.grammar
VERSION = 
'0.4.3'.freeze

Class Method Summary collapse

Class Method Details

.load_file(filename) ⇒ Regexp

Compile the SRL expression in given filename into a Regexp object.

Parameters:

  • filename (String) —

    Name of SRL file to parse

Returns:

  • (Regexp) —

    A regexp object equivalent to the SRL expression.



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# File 'lib/srl_ruby.rb', line 10

def self.load_file(filename)
  source = nil
  File.open(filename, 'r') { |f| source = f.read }
  return source if source.nil? || source.empty?

  return parse(source)
end

.parse(source) ⇒ Regexp

Compile the given SRL expression into its Regexp equivalent.

Examples:

Matching a (signed) integer literal

some_srl =<<-SRL
  begin with
    (one of "+-") optional,
    digit once or more,
  must end
SRL
regex = SrlRuby::API.parse(some_srl) # => regex == /^[+\-]?\d+$/

Parameters:

  • source (String) —

    SRL expression to parse

Returns:

  • (Regexp) —

    A regexp object equivalent to the SRL expression.



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# File 'lib/srl_ruby.rb', line 29

def self.parse(source)
  # Create a Rley facade object
  engine = Rley::Engine.new { |cfg| cfg.diagnose = true }

  # Step 1. Load SRL grammar
  engine.use_grammar(SrlRuby::Grammar)

  lexer = SrlRuby::Tokenizer.new(source)
  result = engine.parse(lexer.tokens)

  unless result.success?
    # Stop if the parse failed...
    line1 = "Parsing failed\n"
    line2 = "Reason: #{result.failure_reason.message}"
    raise StandardError, line1 + line2
  end

  # Generate an abstract syntax tree (AST) from the parse result
  engine.configuration.repr_builder = SrlRuby::ASTBuilder
  ast_ptree = engine.convert(result)

  # Now output the regexp literal
  root = ast_ptree.root
  options = root.is_a?(Regex::MatchOption) ? root.combine_opts : nil
  return Regexp.new(root.to_str, options)
end