Avoid swaps in for loops.

Better? Worse? Meh.

README

@@ -0,0 +1,9 @@
+
+rasp
+=====
+
+A VBScript runtime, running on the Rubinius VM.
+
+
+Untested, undocumented, and ill-advised.
+

bin/rasp

@@ -6,15 +6,19 @@ $: << File.join(File.dirname(File.dirname(__FILE__)), "lib")
 
 require 'rasp'
 
-filename = ARGV.shift || 't/math.vbs'
+filename = File.exist?(ARGV.first) ? ARGV.shift : 't/math.vbs'
 parse = Rasp::Parser.parse(File.read(filename), :consume => true)
 #puts parse.dump
 
-parse.value.graph
+parse.value.graph if ARGV.grep /^--graph$/
 #p parse.value
 
-$DEBUG = true
-compiled = Rasp::Compiler.new.compile(parse.value, filename)
+old_debug, $DEBUG = $DEBUG, ARGV.grep(/^--decode$/)
+begin
+  compiled = Rasp::Compiler.new.compile(parse.value, filename)
+ensure
+  $DEBUG = old_debug
+end
 
-#compiled.call
+compiled.call if ARGV.grep /^--run$/
 

lib/rasp/ast/expression.rb

@@ -6,6 +6,10 @@ def initialize(inner)
     @inner = inner
   end
 
+  def bytecode(g)
+    @inner.bytecode(g)
+    op_bytecode g
+  end
   def prescan(g)
     @inner.prescan(g)
   end
@@ -46,6 +50,9 @@ def op_bytecode(g)
   end
 end
 class NotOp < UnaryOp
+  def op_bytecode(g)
+    g.send_vcall :~
+  end
 end
 class Comparison < BinaryOp
   attr_accessor :operator
@@ -69,11 +76,10 @@ def bytecode(g)
 
     case @lhs
     when Rasp::AST::StringAppend
-      # Already dupped
       @lhs.bytecode(g)
     when Rasp::AST::String
-      # Was a literal
       @lhs.bytecode(g)
+      g.string_dup
     else
       @lhs.bytecode(g)
       g.send_vcall :to_s
@@ -95,12 +101,12 @@ def op_bytecode(g)
 end
 class UnaryPlus < UnaryOp
   def op_bytecode(g)
-    g.send_vcall :"@+"
+    g.send_vcall :+@
   end
 end
 class UnaryMinus < UnaryOp
   def op_bytecode(g)
-    g.send_vcall :"@-"
+    g.send_vcall :-@
   end
 end
 

lib/rasp/ast/flow.rb

@@ -88,7 +88,6 @@ def bytecode(g)
       unless Rasp::AST::Literal === @step
         g.dup
         g.meta_push_0
-        g.swap
         g.send :<, 1
       end
     end
@@ -110,7 +109,6 @@ def bytecode(g)
       if @step
         g.dup_many 2 # @step, @finish, ...
         loop_var.get_bytecode(g)
-        g.swap
         g.send :+, 1
       else
         g.dup # @finish, ...
@@ -121,18 +119,16 @@ def bytecode(g)
 
       if @step.nil? || @step.value > 0
         # Always working forwards
-        g.swap
-        g.send :>, 1
+        g.send :<=, 1
       elsif @step.value < 0
         # Always working backwards
-        g.swap
-        g.send :<, 1
+        g.send :>=, 1
       else
         # Constant step of zero?! Twit.
         raise "For loop cannot have a zero step"
       end
 
-      g.gif loop_body
+      g.git loop_body
 
       if @step
         g.pop_many 2
@@ -155,20 +151,17 @@ def bytecode(g)
 
       g.dup_many 3 # loop_backwards, @step, @finish, ...
       loop_var.get_bytecode(g)
-      g.swap
       g.send :+, 1
       loop_var.set_bytecode(g)
 
       g.git check_backwards
-      g.swap
-      g.send :>, 1
-      g.gif loop_body
+      g.send :<=, 1
+      g.git loop_body
       g.goto end_loop
 
       check_backwards.set!
-      g.swap
-      g.send :<, 1
-      g.gif loop_body
+      g.send :>=, 1
+      g.git loop_body
 
       end_loop.set!
       g.pop_many 3

t/math.vbs

@@ -5,13 +5,13 @@ Dim i,j
 Dim fib, n
 
 'Function fib(n)
-	If True Then n = 2
-	If 1 Then
-		x = 1
-		fib = 1
-	Else
-		fib = zfib(n - 2) + zfib(n - 1) + fizz(777)
-	End If
+'	If True Then n = 2
+'	If 1 Then
+'		x = 1
+'		fib = 1
+'	Else
+'		fib = zfib(n - 2) + zfib(n - 1) + fizz(777)
+'	End If
 'End Function
 
 Const MIN = -1
@@ -25,6 +25,6 @@ For i = MIN To MAX
 		WScript.Echo i & " Or "  & j & " = " & (i Or  j)
 		WScript.Echo i & " Xor " & j & " = " & (i Xor j)
 	Next
-'	WScript.Echo "Not " & i & " = " & (Not i)
+	WScript.Echo "Not " & i & " = " & (Not i)
 Next