js_compiler_single.rb

#!ruby
# coding: utf-8
# 
# js_compiler.rb
#
# Created by Erik Österlund on 1/14/10.
# Copyright 2010 Växjö Universitet. All rights reserved.
#

require 'table_generator'
require 'set'

module LALR
  
  class InterpreterGenerator
    
    def generate_compiler_single
      token_to_num = {}
      @tokens.size.times do |i|
        token_to_num[@tokens[i]] = i + 1 # Start symbol is 0
      end
      known_token_set = Set.new
      @token_lit.each do |str, num|
        known_token_set << num
      end
      
      <<-end.here_with_pipe
        |
        |#{@name}_parser.prototype.compile = function(t, o){
          |var di = o.length;
          |var ti = t.length;
          |#{@compiler}
          |function N(){
            |this.$0=t[--ti];
          |}
          |N.prototype.e = function(){$.push(this.$0);};
          |var R = [#{
            all_rules = @rules | @deleted_rules
            all_rules.size.times.map do |i|
              rule = all_rules[i]
              prods = rule.productions
              
              str = "function N#{i}(){"
              if i == 0
                str << "{if(o.length > 0)this.$1=new R[o[--di]];this.e = function(){if(this.$1)this.$1.e();};}"
              else
                if rule.original_rule and not rule.epsilon? # Cloned rule
                  deleted_indices = rule.epsilon_indices
                  oprods = rule.original_rule.productions
                  
                  oprods.size.times.reverse_each do |p|
                    if deleted_indices.include?(p)
                      del_prod = rule.original_rule.productions[p]
                      del_rule = @deleted_rules.select{|x|x.name == del_prod}.first
                      child_index = all_rules.index del_rule
                      str << "this.$#{p+1} = new R[#{child_index}]();" unless del_prod == Epsilon.instance
                    else
                      product = oprods[p]
                      case product
                        when Symbol
                          str << "this.$#{p+1}=new R[o[--di]]();"
                        when Regexp
                          if not known_token_set.include? token_to_num[p]
                            str << "this.$#{p+1}=new N();"
                          else
                            str << "ti--;"
                          end
                      end
                    end
                  end
                elsif rule.epsilon?() and rule.original_rule # deleted rule
                  del_prod = rule.original_rule.productions[rule.epsilon_indices.first]
                  del_rule = @deleted_rules.select{|x| x.name == del_prod}.first
                  child_index = all_rules.index del_rule
                  str << "this.$1 = new R[#{child_index}];" unless del_prod == Epsilon.instance
                else
                  prods.size.times.reverse_each do |p|
                    product = prods[p]
                    case product
                      when Symbol
                        str << "this.$#{p+1}=new R[o[--di]]();"
                      when Regexp
                        if not known_token_set.include? token_to_num[p]
                          str << "this.$#{p+1}=new N();"
                        else
                          str << "ti--;"
                        end
                    end
                  end
                end
              end
              str << "}"
              str
            end.join(",")
          }];
          |#{
            (1...all_rules.size).each.map do |i|
              rule = all_rules[i]
              rule = rule.original_rule while rule.original_rule
              evaluator = @rule_evaluators[rule]
              "R[#{i}].prototype.e = function(){#{evaluator}};"
            end.join("")
          }
          |var $ = [];
          |#{@compiler_name ? "var context = new #{@compiler_name}();" : ""}
          |var start = new Date().getTime();
          |var tree = new R[0]();
          |#{
          #console.log("Constructing tree: " + (new Date().getTime() - start));
          }
          |var start = new Date().getTime();
          |tree.e();
          |#{
          #console.log("Evaluating tree: " + (new Date().getTime() - start));
          }
          |return [$.join(""), context._dependencies];
        |}
      end
      
    end
    
  end
  
end