Class: Ariel::RuleSet

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

Overview

A RuleSet acts as a container for a Node::Structure’s start and end rules. These are stored as an ordered array and are applied in turn until there is a successful match. A RuleSet takes responsibility for applying start and end rules to extract an Node::Extracted.

Instance Method Summary collapse

Constructor Details

#initialize(start_rules, end_rules) ⇒ RuleSet

Returns a new instance of RuleSet.



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# File 'lib/ariel/rule_set.rb', line 8

def initialize(start_rules, end_rules)
  @start_rules=start_rules
  @end_rules=end_rules
end

Instance Method Details

#apply_to(tokenstream) ⇒ Object

Returns an array of the extracted tokenstreams. An empty array is returned if the rules cannot be applied. TODO: Think more about the way list iteration rules are applied



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# File 'lib/ariel/rule_set.rb', line 16

def apply_to(tokenstream)
  start_idxs=nil
  end_idxs=nil
  @start_rules.each do |rule|
  start_idxs=rule.apply_to tokenstream
    break if !start_idxs.empty?
  end
  @end_rules.each do |rule|
    end_idxs=rule.apply_to tokenstream
    end_idxs.reverse! #So the start_idxs and end_idxs match up
    break if !end_idxs.empty?
  end
  result=[]
  unless start_idxs.empty? && end_idxs.empty?
    # Following expression deals with the case where the first start rule
    # matches after the first end rule, indicating that all tokens up to the
    # end rule match should be a list item
    if start_idxs.first > end_idxs.first
      start_idxs.insert(0, 0)
    end
    if end_idxs.last < start_idxs.last
      end_idxs << (tokenstream.size - 1)
    end
    Log.debug "RuleSet matched with start_idxs=#{start_idxs.inspect} and end_idxs=#{end_idxs.inspect}"
    start_idxs.zip(end_idxs) do |start_idx, end_idx|
      if start_idx && end_idx
        next if start_idx > end_idx
        result << tokenstream.slice_by_token_index(start_idx, end_idx)
        yield result.last if block_given?
      else
        break
      end
    end
  end
  return result
end