Class: BabelBridge::Parser

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

Overview

Used to parse with .parse

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Parser

Returns a new instance of Parser.



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# File 'lib/parser.rb', line 173

def initialize
  reset_parser_tracking
end

Class Attribute Details

.delimiter_pattern ⇒ Object

Returns the value of attribute delimiter_pattern.



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# File 'lib/parser.rb', line 11

def delimiter_pattern
  @delimiter_pattern
end

.module_name ⇒ Object

Returns the value of attribute module_name.



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# File 'lib/parser.rb', line 11

def module_name
  @module_name
end

.root_rule ⇒ Object

Returns the value of attribute root_rule.



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# File 'lib/parser.rb', line 11

def root_rule
  @root_rule
end

.rules ⇒ Object

Returns the value of attribute rules.



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# File 'lib/parser.rb', line 11

def rules
  @rules
end

Instance Attribute Details

#expecting_list ⇒ Object

Returns the value of attribute expecting_list.



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# File 'lib/parser.rb', line 168

def expecting_list
  @expecting_list
end

#failed_parse ⇒ Object

gets set if the entire input was not matched



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# File 'lib/parser.rb', line 171

def failed_parse
  @failed_parse
end

#failure_index ⇒ Object

********************************************* ********************************************* parser instance implementation this methods are used for each actual parse run they are tied to an instnace of the Parser Sub-class to you can have more than one parser active at a time



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# File 'lib/parser.rb', line 167

def failure_index
  @failure_index
end

#parse_cache ⇒ Object

Returns the value of attribute parse_cache.



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# File 'lib/parser.rb', line 170

def parse_cache
  @parse_cache
end

#src ⇒ Object

Returns the value of attribute src.



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# File 'lib/parser.rb', line 169

def src
  @src
end

Class Method Details

.[](i) ⇒ Object 



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# File 'lib/parser.rb', line 89

def [](i)
  rules[i]
end

.binary_operators_rule(name, operand_rule_name, operators, options = {}, &block) ⇒ Object

options

> right_operators: list of all operators that should be evaluated right to left instead of left-to-write

typical example is the "**" exponentiation operator which should be evaluated right-to-left.



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# File 'lib/parser.rb', line 51

def binary_operators_rule(name,operand_rule_name,operators,options={},&block)
  right_operators = options[:right_operators]
  rule name, many(operand_rule_name,Tools::array_to_or_regexp(operators)).delimiter_name(:operators).as(:operands) do
    self.class_eval &block if block
    class <<self
      attr_accessor :operators_from_rule, :right_operators
      def operator_processor
        @operator_processor||=BinaryOperatorProcessor.new(operators_from_rule,self,right_operators)
      end
    end
    self.right_operators = right_operators
    self.operators_from_rule = operators

    def operator
      @operator||=operator_node.to_s.to_sym
    end

    def operator_processor
      self.class.operator_processor
    end

    # Override the on_post_match method to take the results of the "many" match
    # and restructure it into a binary tree of nodes based on the precidence of
    # the "operators".
    # TODO - Should on_post_match be run after the whole tree matches? If not, will this screw up caching?
    def post_match_processing
      super
      operator_processor.generate_tree operands, operators, parent
    end
  end
end

.could ⇒ Object 



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# File 'lib/parser.rb', line 156

def could; PatternElementHash.new.could end

.custom_parser(&block) ⇒ Object 



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# File 'lib/parser.rb', line 157

def custom_parser(&block); PatternElementHash.new.parser(lambda &block) end

.delimiter(*pattern) ⇒ Object 



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# File 'lib/parser.rb', line 104

def delimiter(*pattern)
  @delimiter = pattern
end

.dont ⇒ Object 



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# File 'lib/parser.rb', line 154

def dont; PatternElementHash.new.dont end

.ignore_whitespace ⇒ Object 



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# File 'lib/parser.rb', line 100

def ignore_whitespace
  delimiter /\s*/
end

.many(m, delimiter = nil) ⇒ Object 



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# File 'lib/parser.rb', line 146

def many(m,delimiter=nil) PatternElementHash.new.match.many(m).delimiter(delimiter) end

.many!(m, delimiter = nil) ⇒ Object 



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# File 'lib/parser.rb', line 148

def many!(m,delimiter=nil) PatternElementHash.new.dont.match.many(m).delimiter(delimiter) end

.many?(m, delimiter = nil) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/parser.rb', line 147

def many?(m,delimiter=nil) PatternElementHash.new.optionally.match.many(m).delimiter(delimiter) end

.match(*args) ⇒ Object 



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# File 'lib/parser.rb', line 151

def match(*args) PatternElementHash.new.match(*args) end

.match!(*args) ⇒ Object 



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# File 'lib/parser.rb', line 152

def match!(*args) PatternElementHash.new.dont.match(*args) end

.match?(*args) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/parser.rb', line 150

def match?(*args) PatternElementHash.new.optionally.match(*args) end

.node_class(name, &block) ⇒ Object 



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# File 'lib/parser.rb', line 83

def node_class(name,&block)
  klass=self.rules[name].node_class
  return klass unless block
  klass.class_eval &block
end

.optionally ⇒ Object 



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# File 'lib/parser.rb', line 155

def optionally; PatternElementHash.new.optionally end

.rule(name, *pattern, &block) ⇒ Object

Add a rule to the parser

rules can be specified as:

rule :name, to_match1, to_match2, etc...

Can define rules INSIDE class:

class MyParser < BabelBridge::Parser
  rule :name, to_match1, to_match2, etc...
end

Or can define rules OUTSIDE class:

class MyParser < BabelBridge::Parser
end
MyParser.rule :name, to_match1, to_match2, etc...

The first rule added is the root-rule for the parser. You can override by:

class MyParser < BabelBridge::Parser
  root_rule = :new_root_rool
end

The block is executed in the context of the rule-varient’s node type, a subclass of: RuleNode This allows you to add whatever functionality you want to a your nodes in the final parse tree. Also note you can override the on_post_match method. This allows you to restructure the parse tree as it is parsed.



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# File 'lib/parser.rb', line 41

def rule(name,*pattern,&block)
  rule = self.rules[name] ||= Rule.new(name,self)
  @root_rule ||= name
  options =  pattern[-1].kind_of?(Hash) ? pattern.pop : {}
  rule.add_variant options.merge(:pattern => pattern), &block
end

Instance Method Details

#cache_match(rule_class, match) ⇒ Object 



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# File 'lib/parser.rb', line 190

def cache_match(rule_class,match)
  (parse_cache[rule_class]||={})[match.offset]=match
end

#cache_no_match(rule_class, offset) ⇒ Object 



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# File 'lib/parser.rb', line 194

def cache_no_match(rule_class,offset)
  (parse_cache[rule_class]||={})[offset]=:no_match
end

#cached(rule_class, offset) ⇒ Object 



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# File 'lib/parser.rb', line 186

def cached(rule_class,offset)
  (parse_cache[rule_class]||={})[offset]
end

#delimiter_pattern ⇒ Object 



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# File 'lib/parser.rb', line 113

def delimiter_pattern
  self.class.delimiter_pattern
end

#expecting_output(options = {}) ⇒ Object

options => false



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# File 'lib/parser.rb', line 291

def expecting_output(options={})
  return "" if expecting_list.length==0
  common_root=nil
  expecting_list.values.each do |e|
    node=e[:node]
    pl=nodes_interesting_parse_path(node)
    pl.pop # ignore the node itself
    if common_root
      common_root.each_index do |i|
        if pl[i]!=common_root[i]
          common_root=common_root[0..i-1]
          break
        end
      end
    else
      common_root=pl
    end
  end
  <<ENDTXT

Parse path at failure:
#{node_list_string(common_root,[],:verbose=>true)}

Expecting#{expecting_list.length>1 ? ' one of' : ''}:
#{Tools.uniform_tabs(Tools.indent(expecting_list.values.collect do |a|
  list=node_list_string(nodes_interesting_parse_path(a[:node]),common_root,options)
  "#{a[:pattern].inspect}\t#{list}"
end.sort.join("\n"),"  "))}
ENDTXT
end

#log_parsing_failure(index, expecting) ⇒ Object 



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# File 'lib/parser.rb', line 198

def log_parsing_failure(index,expecting)
  if matching_negative?
    # ignored
  elsif index>failure_index
    @expecting_list = {expecting[:pattern] => expecting}
    @failure_index = index
  elsif index == failure_index
    @expecting_list[expecting[:pattern]] = expecting
  else
    # ignored
  end
end

#matching_negative ⇒ Object 



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# File 'lib/parser.rb', line 211

def matching_negative
  @matching_negative_depth||=0
  @matching_negative_depth+=1
end

#matching_negative? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/parser.rb', line 220

def matching_negative?
  (@matching_negative_depth||0) > 0
end

#node_list_string(node_list, common_root = [], options = {}) ⇒ Object

options => false



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# File 'lib/parser.rb', line 269

def node_list_string(node_list,common_root=[],options={})
  return unless node_list
  if options[:verbose]
    node_list[common_root.length..-1]
  else
    [node_list[-1]]
  end.select do |p|
    p.class.to_s.index(BabelBridge.to_s)!=0
  end.map do |p|
    "#{p.relative_class_name}"
  end.join(" > ")
end

#nodes_interesting_parse_path(node) ⇒ Object 



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# File 'lib/parser.rb', line 282

def nodes_interesting_parse_path(node)
  path = node.parent_list
  path << node
  path.pop while path[-1] && !path[-1].kind_of?(RuleNode)
  path
end

#parse(src, options = {}) ⇒ Object

parse a string, return the root node of the parse tree. If nil is returned, parsing failed. Call .parser_failure_info after failure for a human-readable description of the failure. src: the string to parse options:

offset: where to start in the string for parsing
rule: lets you specify the root rule for matching
partial_match: allow partial matching



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# File 'lib/parser.rb', line 231

def parse(src, options={})
  offset = options[:offset] || 0
  rule = options[:rule] || self.class.root_rule
  reset_parser_tracking
  @start_time = Time.now
  self.src = src
  root_node = RootNode.new(self)
  raise "No root rule defined." unless rule
  ret = rules[rule].parse(root_node)
  if ret
    if ret.next<src.length && !options[:partial_match] # parse only succeeds if the whole input is matched
      if ret.next >= @failure_index
        @parsing_did_not_match_entire_input=true
        @failure_index = ret.next
        @failed_parse = ret
      end
      ret=nil
    else
      reset_parser_tracking
    end
  end
  @end_time=Time.now
  ret
end

#parse_and_puts_errors(src, out = $stdout) ⇒ Object 



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# File 'lib/parser.rb', line 260

def parse_and_puts_errors(src,out=$stdout)
  ret=parse(src)
  unless ret
    out.puts parser_failure_info
  end
  ret
end

#parse_time ⇒ Object 



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# File 'lib/parser.rb', line 256

def parse_time
  @end_time-@start_time
end

#parser_failure_info(options = {}) ⇒ Object

option: :verbose => true



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# File 'lib/parser.rb', line 323

def parser_failure_info(options={})
  return unless src
  verbose = options[:verbose]
  bracketing_lines=5
  line,col = Tools.line_column(src, failure_index)
  ret=<<-ENDTXT
Parsing error at line #{line} column #{col} offset #{failure_index}

Source:
...
#{(failure_index==0 ? "" : src[0..(failure_index-1)]).last_lines(bracketing_lines)}<HERE>#{src[(failure_index)..-1].first_lines(bracketing_lines)}
...
ENDTXT

  if @parsing_did_not_match_entire_input
    ret+="\nParser did not match entire input.\n"
    if verbose
      ret+="\nParsed:\n#{Tools::indent failed_parse.inspect||"(nothing)"}\n"
    end
  end

  ret+expecting_output
end

#reset_parser_tracking ⇒ Object 



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# File 'lib/parser.rb', line 177

def reset_parser_tracking
  @matching_negative_depth = 0
  @parsing_did_not_match_entire_input = false
  @src = nil
  @failure_index = 0
  @expecting_list = {}
  @parse_cache = {}
end

#rules ⇒ Object 



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# File 'lib/parser.rb', line 117

def rules
  self.class.rules
end

#unmatching_negative ⇒ Object 



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# File 'lib/parser.rb', line 216

def unmatching_negative
  @matching_negative_depth-=1
end