lib/voodoo/generators/dummy_generator.rb

   1 require 'set'
   2 require 'voodoo/symbol_tracker'
   3
   4 module Voodoo
   5   # Generator that does not generate code.
   6   class DummyGenerator
   7     def initialize *params
   8       @locals = Set.new
   9       @symbol_tracker = SymbolTracker.new
  10     end
  11
  12     def add section, *code
  13       analyze code
  14     end
  15
  16     # Returns a set of symbols that have been used, but not defined.
  17     def undefined_symbols
  18       @symbol_tracker.used_but_undefined_symbols
  19     end
  20
  21     def write *args
  22     end
  23
  24     private
  25
  26     def analyze statements
  27       statements.each { |code| analyze_statement code }
  28     end
  29
  30     def analyze_statement code
  31       case code[0]
  32       when :block
  33         old_locals = @locals
  34         @locals = Set.new @locals
  35         begin
  36           analyze code[1..-1]
  37         ensure
  38           @locals = old_locals
  39         end
  40       when :export
  41         use *code[1..-1]
  42       when :function
  43         old_locals = @locals
  44         @locals = Set.new @locals
  45         @locals.merge code[1]
  46         begin
  47           analyze code[2..-1]
  48         ensure
  49           @locals = old_locals
  50         end
  51       when :import
  52         define *code[1..-1]
  53       when :label
  54         define code[1]
  55       when :let
  56         define code[1]
  57         analyze_expr code[2..-1]
  58       when :return
  59         analyze_expr code[1..-1]
  60       when :set
  61         analyze_values [code[1]]
  62         analyze_expr code[2..-1]
  63       else
  64         if code[0].to_s[0...2] == "if"
  65           analyze_values code[1]
  66           analyze code[2]
  67           analyze code[3] if code.length > 3
  68         else
  69           analyze_values code[1..-1]
  70         end
  71       end
  72     end
  73
  74     def analyze_expr code
  75       if code.length == 1
  76         analyze_values code
  77       else
  78         analyze_values code[1..-1]
  79       end
  80     end
  81
  82     def analyze_values values
  83       values.each do |x|
  84         if x.kind_of? Symbol
  85           use x
  86         elsif x.respond_to?(:[]) && x[0] == :'@'
  87           analyze_values x[1]
  88         end
  89       end
  90     end
  91
  92     def define *symbols
  93       @symbol_tracker.define *symbols
  94     end
  95
  96     def use *symbols
  97       syms = Set.new symbols
  98       nonlocals = syms - @locals
  99       @symbol_tracker.use *nonlocals
 100     end
 101   end
 102 end