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Diffstat (limited to 'lib/coderay/rule_based_scanner.rb')
| -rw-r--r-- | lib/coderay/rule_based_scanner.rb | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/lib/coderay/rule_based_scanner.rb b/lib/coderay/rule_based_scanner.rb new file mode 100644 index 0000000..670cb15 --- /dev/null +++ b/lib/coderay/rule_based_scanner.rb @@ -0,0 +1,221 @@ +module CodeRay + module Scanners + class RuleBasedScanner < Scanner + + Groups = Struct.new :token_kinds + Kind = Struct.new :token_kind + Push = Struct.new :state + Pop = Class.new + Check = Struct.new :condition + CheckIf = Class.new Check + CheckUnless = Class.new Check + ValueSetter = Struct.new :targets, :value + + class << self + attr_accessor :states + + def state *names, &block + @code ||= "" + + @code << "when #{names.map(&:inspect).join(', ')}\n" + + @first = true + instance_eval(&block) + @code << " else\n" + # @code << " raise 'no match for #{names.map(&:inspect).join(', ')}'\n" + @code << " encoder.text_token getch, :error\n" + @code << " end\n" + @code << " \n" + end + + def on? pattern + pattern_expression = pattern.inspect + @code << " #{'els' unless @first}if check(#{pattern_expression})\n" + + @first = true + yield + @code << " end\n" + + @first = false + end + + def on *pattern_and_actions + if index = pattern_and_actions.find_index { |item| !item.is_a?(Check) } + preconditions = pattern_and_actions[0..index - 1] if index > 0 + pattern = pattern_and_actions[index] or raise 'I need a pattern!' + actions = pattern_and_actions[index + 1..-1] or raise 'I need actions!' + end + + precondition_expression = '' + if preconditions + for precondition in preconditions + case precondition + when CheckIf + case precondition.condition + when Proc + precondition_expression << "#{make_callback(precondition.condition)} && " + when Symbol + precondition_expression << "#{precondition.condition} && " + else + raise "I don't know how to evaluate this check_if precondition: %p" % [precondition.condition] + end + when CheckUnless + case precondition.condition + when Proc + precondition_expression << "!#{make_callback(precondition.condition)} && " + when Symbol + precondition_expression << "!#{precondition.condition} && " + else + raise "I don't know how to evaluate this check_unless precondition: %p" % [precondition.condition] + end + else + raise "I don't know how to evaluate this precondition: %p" % [precondition] + end + end + end + + case pattern + when String + raise + pattern_expression = pattern + when Regexp + pattern_expression = pattern.inspect + when Proc + pattern_expression = make_callback(pattern) + else + raise "I don't know how to evaluate this pattern: %p" % [pattern] + end + + @code << " #{'els' unless @first}if #{precondition_expression}match = scan(#{pattern_expression})\n" + + for action in actions + case action + when String + raise + @code << " p 'evaluate #{action.inspect}'\n" if $DEBUG + @code << " #{action}\n" + + when Symbol + @code << " p 'text_token %p %p' % [match, #{action.inspect}]\n" if $DEBUG + @code << " encoder.text_token match, #{action.inspect}\n" + when Kind + case action.token_kind + when Proc + @code << " encoder.text_token match, #{make_callback(action.token_kind)}\n" + else + raise "I don't know how to evaluate this kind: %p" % [action.token_kind] + end + when Groups + @code << " p 'text_tokens %p in groups %p' % [match, #{action.token_kinds.inspect}]\n" if $DEBUG + action.token_kinds.each_with_index do |kind, i| + @code << " encoder.text_token self[#{i + 1}], #{kind.inspect} if self[#{i + 1}]\n" + end + + when Push + case action.state + when String + raise + @code << " p 'push %p' % [#{action.state}]\n" if $DEBUG + @code << " state = #{action.state}\n" + when Symbol + @code << " p 'push %p' % [#{action.state.inspect}]\n" if $DEBUG + @code << " state = #{action.state.inspect}\n" + when Proc + @code << " state = #{make_callback(action.state)}\n" + else + raise "I don't know how to evaluate this push state: %p" % [action.state] + end + @code << " states << state\n" + @code << " encoder.begin_group state\n" + when Pop + @code << " p 'pop %p' % [states.last]\n" if $DEBUG + @code << " encoder.end_group states.pop\n" + @code << " state = states.last\n" + + when ValueSetter + case action.value + when Proc + @code << " #{action.targets.join(' = ')} = #{make_callback(action.value)}\n" + else + @code << " #{action.targets.join(' = ')} = #{action.value.inspect}\n" + end + + when Proc + @code << " #{make_callback(action)}\n" + + else + raise "I don't know how to evaluate this action: %p" % [action] + end + end + + @first = false + end + + def groups *token_kinds + Groups.new token_kinds + end + + def kind token_kind = nil, &block + Kind.new token_kind || block + end + + def push state = nil, &block + raise 'push requires a state or a block; got nothing' unless state || block + Push.new state || block + end + + def pop + Pop.new + end + + def check_if value = nil, &callback + CheckIf.new value || callback + end + + def check_unless value = nil, &callback + CheckUnless.new value || callback + end + + def flag_on *flags + ValueSetter.new Array(flags), true + end + + def flag_off *flags + ValueSetter.new Array(flags), false + end + + def set flag, value = nil, &callback + ValueSetter.new [flag], value || callback + end + + def unset *flags + ValueSetter.new Array(flags), nil + end + + protected + + def make_callback block + @callbacks ||= {} + + base_name = "__callback_line_#{block.source_location.last}" + name = base_name + counter = 'a' + while @callbacks.key?(name) + name = "#{base_name}_#{counter}" + counter.succ! + end + + @callbacks[name] = define_method(name, &block) + + arguments = block.parameters.map(&:last) + + if arguments.empty? + name + else + "#{name}(#{arguments.join(', ')})" + end + end + end + end + end +end
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