1 #!/usr/bin/ruby 2 # encoding: utf-8 3 4 module ANTLR3 5 module Debug 6 =begin rdoc ANTLR3::Debug::RuleTracer 7 8 RuleTracer is simple debug event listener that writes the names of rule methods 9 as they are entered and exitted to an output stream. 10 11 =end 12 class RuleTracer 13 include EventListener 14 15 ARROW_IN = '--> '.freeze 16 ARROW_OUT = '<-- '.freeze 17 18 attr_reader :level 19 attr_accessor :spaces_per_indent, :device 20 21 def initialize( options = {} ) 22 @input = options[ :input ] 23 @level = 0 24 @spaces_per_indent = options[ :spaces_per_indent ] || 2 25 @device = options[ :device ] || options[ :output ] || $stderr 26 end 27 28 def enter_rule( grammar_file, name ) 29 indent = @level * @spaces_per_indent 30 31 @device.print( ' ' * indent, ARROW_IN, name ) 32 if @input 33 input_symbol = @input.look || :EOF 34 @device.puts( " look = %p" % input_symbol ) 35 else @device.print( "\n" ) 36 end 37 38 @level += 1 39 end 40 41 def exit_rule( grammar_file, name ) 42 @level -= 1 43 44 indent = @level * @spaces_per_indent 45 46 @device.print( ' ' * indent, ARROW_OUT, name ) 47 if @input 48 input_symbol = ( @input.look || :EOF ) 49 @device.puts( " look = %p" % input_symbol ) 50 else @device.print( "\n" ) 51 end 52 end 53 end 54 end 55 end 56
