Class: BabelBridge::PatternElement

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

Overview

PatternElement provides optimized parsing for each Element of a pattern PatternElement provides all the logic for parsing:

:many
:optional

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(match, options = {}) ⇒ PatternElement

match can be: true, Hash, Symbol, String, Regexp options

:rule_varient
:parser



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# File 'lib/babel_bridge/pattern_element.rb', line 25

def initialize(match, options={})
  @init_options = options.clone
  @rule_variant = options[:rule_variant]
  @parser_class = options[:parser_class]
  @delimiter = options[:delimiter]
  @name = options[:name]
  raise "rule_variant or parser_class required" unless @rule_variant || @parser_class

  init match
  raise "pattern element cannot be both :dont and :optional" if negative && optional
end

Instance Attribute Details

#could_match ⇒ Object

Returns the value of attribute could_match.



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# File 'lib/babel_bridge/pattern_element.rb', line 14

def could_match
  @could_match
end

#delimiter ⇒ Object

true if this is a delimiter



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# File 'lib/babel_bridge/pattern_element.rb', line 18

def delimiter
  @delimiter
end

#match ⇒ Object

Returns the value of attribute match.



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# File 'lib/babel_bridge/pattern_element.rb', line 15

def match
  @match
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/babel_bridge/pattern_element.rb', line 14

def name
  @name
end

#negative ⇒ Object

Returns the value of attribute negative.



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# File 'lib/babel_bridge/pattern_element.rb', line 14

def negative
  @negative
end

#optional ⇒ Object

Returns the value of attribute optional.



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# File 'lib/babel_bridge/pattern_element.rb', line 14

def optional
  @optional
end

#parser ⇒ Object

Returns the value of attribute parser.



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# File 'lib/babel_bridge/pattern_element.rb', line 14

def parser
  @parser
end

#parser_class ⇒ Object

Returns the value of attribute parser_class.



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# File 'lib/babel_bridge/pattern_element.rb', line 15

def parser_class
  @parser_class
end

#rule_variant ⇒ Object

Returns the value of attribute rule_variant.



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# File 'lib/babel_bridge/pattern_element.rb', line 15

def rule_variant
  @rule_variant
end

#terminal ⇒ Object

Returns the value of attribute terminal.



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# File 'lib/babel_bridge/pattern_element.rb', line 14

def terminal
  @terminal
end

Instance Method Details

#inspect ⇒ Object 



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# File 'lib/babel_bridge/pattern_element.rb', line 37

def inspect
  "<PatternElement #{rule_variant && "rule_variant=#{rule_variant.variant_node_class} "}match=#{match.inspect}#{" delimiter" if delimiter}>"
end

#parse(parent_node) ⇒ Object

attempt to match the pattern defined in self.parser in parent_node.src starting at offset parent_node.next



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# File 'lib/babel_bridge/pattern_element.rb', line 54

def parse(parent_node)

  # run element parser
  begin
    parent_node.parser.matching_negative if negative
    match = parser.call(parent_node)
  ensure
    parent_node.parser.unmatching_negative if negative
  end

  # Negative patterns (PEG: !element)
  match = match ? nil : EmptyNode.new(parent_node) if negative

  # Optional patterns (PEG: element?)
  match = EmptyNode.new(parent_node) if !match && optional

  # Could-match patterns (PEG: &element)
  match.match_length = 0 if match && could_match

  if !match && (terminal || negative)
    # log failures on Terminal patterns for debug output if overall parse fails
    parent_node.parser.log_parsing_failure parent_node.next, :pattern => self.to_s, :node => parent_node
  end

  match.delimiter = delimiter if match

  # return match
  match
end

#rules ⇒ Object 



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# File 'lib/babel_bridge/pattern_element.rb', line 49

def rules
  parser_class.rules
end

#to_s ⇒ Object 



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# File 'lib/babel_bridge/pattern_element.rb', line 41

def to_s
  match.inspect
end