Contents

module Vernacular
  # Represents a modification that will be performed against the AST between the
  # time that the source code is read and the time that it is compiled down to
  # YARV instruction sequences.
  class ASTModifier
    BuilderExtension =
      Struct.new(:method, :block) do
        def components
          [method, block.source_location]
        end
      end
    attr_reader :builder_extensions

    ParserExtension =
      Struct.new(:symbol, :pattern, :code) do
        def components
          [symbol, pattern, code]
        end
      end
    attr_reader :parser_extensions

    attr_reader :rewriter_block

    def initialize
      @builder_extensions = []
      @parser_extensions = []
      yield self if block_given?
    end

    def build_rewriter(&block)
      @rewriter_block = block
    end

    def extend_builder(method, &block)
      builder_extensions << BuilderExtension.new(method, block)
    end

    def extend_parser(symbol, pattern, code)
      parser_extensions << ParserExtension.new(symbol, pattern, code)
    end

    def modify(source)
      raise 'You must first configure a rewriter!' unless rewriter_block

      rewriter = Class.new(Parser::Rewriter, &rewriter_block).new
      rewriter.instance_variable_set(:@parser, ASTParser.parser)

      buffer = Parser::Source::Buffer.new('<dynamic>')
      buffer.source = source

      ast = ASTParser.parse(source)
      rewriter.rewrite(buffer, ast)
    end

    def components
      (builder_extensions + parser_extensions).flat_map(&:components) +
        rewriter_block.source_location
    end
  end
end

Version data entries

5 entries across 5 versions & 1 rubygems

Version	Path
vernacular-0.1.2	lib/vernacular/ast_modifier.rb
vernacular-0.1.1	lib/vernacular/ast_modifier.rb
vernacular-0.1.0	lib/vernacular/ast_modifier.rb
vernacular-0.0.2	lib/vernacular/ast_modifier.rb
vernacular-0.0.1	lib/vernacular/ast_modifier.rb