Moved prim methods into a module, cleaned up compiling words

src/rforth.rb

@@ -1,5 +1,74 @@
 require 'pp'
 
+module PrimitiveWords
+
+  def dup
+    @stack << @stack.last
+  end
+
+  def q_dup
+    @stack << @stack.last unless @stack.last == 0 
+  end
+
+  def drop
+    @stack.pop
+  end
+
+  def swap
+    @stack += [@stack.pop, @stack.pop]
+  end
+
+  def over
+    a = @stack.pop
+    b = @stack.pop
+    @stack << b << a << b
+  end
+
+  def rot
+    a = @stack.pop
+    b = @stack.pop
+    c = @stack.pop
+    @stack << b << a << c
+  end
+
+  def plus
+    @stack << (@stack.pop + @stack.pop)
+  end
+
+  def mult
+    @stack << (@stack.pop * @stack.pop) 
+  end
+
+  def subtract
+    a = @stack.pop
+    b = @stack.pop
+    @stack << b - a
+  end
+
+  def divide
+    a = @stack.pop
+    b = @stack.pop
+    @stack << b / a
+  end
+
+  def dot 
+    @s_out.print( @stack.pop )
+  end
+
+  def cr
+    @s_out.puts
+  end
+
+  def dot_s
+    @s_out.print( "#{@stack}\n" )
+  end
+
+  def dot_d
+    pp @dictionary
+  end
+
+end
+
 class Dictionary
   def initialize( &block )
     @entries = {}
@@ -16,64 +85,85 @@ class Dictionary
     self
   end
 
+  def alias_word( name, old_name )
+    entry = self[old_name]
+    raise "No such word #{old_name}" unless entry
+    new_entry = entry.dup
+    new_entry[:name] = name
+    @entries[name] = entry
+  end
+
   def []( name )
     @entries[name]
   end
 end
 
 class RForth
+  include PrimitiveWords
 
   def initialize( s_in = $stdin, s_out = $stdout )
     @s_in = s_in
     @s_out = s_out
-    @dictionary = initial_dictionary
+    @dictionary = Dictionary.new
     @stack = []
+    initialize_dictionary
   end
 
-  def initial_dictionary
-    Dictionary.new do |d|
-      d.word('dup')   { @stack << @stack.last }
-      d.word('?dup')  { @stack << @stack.last unless @stack.last == 0 }
-      d.word('drop')  { @stack.pop }
-      d.word('swap')  { @stack += [@stack.pop, @stack.pop] }
-      d.word('over') do
-        a = @stack.pop
-        b = @stack.pop
-        @stack << b << a << b
-      end
-      d.word('rot') do
-        a = @stack.pop
-        b = @stack.pop
-        c = @stack.pop
-        @stack << b << a << c
-      end
-      d.word(':')     { define_word }
-      d.word('+')     { @stack << (@stack.pop + @stack.pop) }
-      d.word('*')     { @stack << (@stack.pop * @stack.pop) }
-      d.word('-') do
-        a = @stack.pop
-        b = @stack.pop
-        @stack << b - a
-      end
-      d.word('/') do
-        a = @stack.pop
-        b = @stack.pop
-        @stack << b / a
-      end
-      d.word('.')     { @s_out.print( @stack.pop ) }
-      d.word('.S')    { @s_out.print( "#{@stack}\n" ) }
-      d.word('.D')    { pp @dictionary }
-      d.word('cr')    { @s_out.puts }
-      d.word('bye')   { exit }
+  # Create all of the initial words.
+  def initialize_dictionary
+    PrimitiveWords.public_instance_methods(false).each do |m|
+      method_clojure = method(m.to_sym)
+      word( m.to_s, &method_clojure )
     end
+
+    alias_word( '?dup', 'q_dup' )
+    alias_word( '+', 'plus' )
+    alias_word( '*', 'mult' )
+    alias_word( '-', 'subtract' )
+    alias_word( '/', 'divide' )
+    alias_word( '.', 'dot' )
+    alias_word( '.S', 'dot_s' )
+    alias_word( '.D', 'dot_d' )
+
+    word(':')     { read_and_define_word }
+    word('bye')   { exit }
+
+    immediate_word( '\\' ) { @s_in.readline }
   end
 
-  def define_word
-    name = read_word
+  # Convience method that takes a word and a closure
+  # and defines the word in the dictionary
+  def word( name, &block )
+    @dictionary.word( name, &block )
+  end
+
+  # Convience method that takes a word and a closure
+  # and defines an immediate word in the dictionary
+  def immediate_word( name, &block )
+    @dictionary.immediate_word( name, &block )
+  end
+
+  # Convience method that takes an existing dict.
+  # word and a new word and aliases the new word to
+  # the old.
+  def alias_word( name, old_name )
+    @dictionary.alias_word( name, old_name )
+  end
+
+  # Given the name of a new words and the words
+  # that make up its definition, define the
+  # new word.
+  def define_word( name, *words )
+    @dictionary.word( name, &compile_words( *words ) )
+  end
+
+  # Give an array of (string) words, return
+  # A block which will run all of those words.
+  # Executes all immedate words, well, immediately.
+  def compile_words( *words )
     blocks = []
-    while (word = read_word)
-      break if word == ';'
-      entry = @dictionary[word]
+    words.each do |word|
+      entry = resolve_word( word )
       raise "no such word: #{word}" unless entry
       if entry[:immediate]
         entry[:block].call
@@ -81,22 +171,49 @@ class RForth
         blocks << entry[:block]
       end
     end
-
-    @dictionary.word(name) do
+    proc do
       blocks.each {|b| b.call}
     end
   end
 
+  # Read a word definition from input and
+  # define the word
+  # Definition looks like:
+  #  new-word w1 w2 w3 ;
+  def read_and_define_word
+    name = read_word
+    words = []
+    while (word = read_word)
+      break if word == ';'
+      words << word
+    end
+    @dictionary.word(name, &compile_words( *words ))
+  end
+
+  # Given a (string) word, return the dictionary
+  # entry for that word or nil.
+  def resolve_word( word )
+    return @dictionary[word] if @dictionary[word]
+    x = to_number(word)
+    if x
+      block = proc { @stack << x }
+      return { :name => word, :block => block, :immediate => false }
+    end
+    nil
+  end
+
+  # Evaluate the given word.
   def forth_eval( word )
-    if @dictionary[word]
-      @dictionary[word][:block].call
-    elsif (x = to_number(word))
-      @stack << x
+    entry = resolve_word(word)
+    if entry
+      entry[:block].call
     else
       @s_out.puts "#{word} ??"
     end
   end
 
+  # Try to turn the word into a number, return nil if
+  # conversion fails
   def to_number( word )
     begin
       return Integer( word )
@@ -111,15 +228,11 @@ class RForth
     nil
   end
 
-  def read_char
-    @s_in.readchar
-  end
-
   def read_word
     result = nil
     ch = nil
     until @s_in.eof?
-      ch = read_char
+      ch = @s_in.readchar
       if result and is_space?(ch)
         break
       elsif result.nil?