adding weepy's suggestion to use (for .. in) for array comprehensions, which means that they're now object comprehensions as well

lib/coffee_script/nodes.rb

@@ -325,10 +325,10 @@ module CoffeeScript
       @exclusive ? '>' : '>='
     end
 
-    def compile(o, fv, tv)
+    def compile(o, fv)
       fvv, tvv = @from.compile(o), @to.compile(o)
-      vars     = "#{fv}=#{fvv}, #{tv}=#{tvv}"
+      vars     = "#{fv}=#{fvv}"
-      compare  = "(#{fvv} <= #{tvv} ? #{fv} #{less_operator} #{tv} : #{fv} #{greater_operator} #{tv})"
+      compare  = "(#{fvv} <= #{tvv} ? #{fv} #{less_operator} #{tvv} : #{fv} #{greater_operator} #{tvv})"
       incr     = "(#{fvv} <= #{tvv} ? #{fv} += 1 : #{fv} -= 1)"
       "#{vars}; #{compare}; #{incr}"
     end
@@ -554,22 +554,22 @@ module CoffeeScript
       name_found    = scope.find(@name)
       index_found   = @index && scope.find(@index)
       svar          = scope.free_variable
-      ivar          = range ? name : scope.free_variable
+      ivar          = range ? name : @index ? @index : scope.free_variable
-      lvar          = scope.free_variable
       rvar          = scope.free_variable
-      index_name    = @index ? @index : nil
       if range
-        source_part = ''
+        body_dent   = o[:indent] + TAB
-        var_part    = ''
+        source_part, var_part = '', '', ''
-        index_part  = ''
+        pre_cond, post_cond = '', ''
         index_var   = scope.free_variable
-        for_part    = "#{index_var}=0, #{@source.compile(o, ivar, lvar)}, #{index_var}++"
+        for_part    = "#{index_var}=0, #{@source.compile(o, ivar)}, #{index_var}++"
       else
         index_var   = nil
+        body_dent   = o[:indent] + TAB + TAB
         source_part = "#{svar} = #{@source.compile(o)};\n#{o[:indent]}"
-        for_part    = "#{ivar}=0, #{lvar}=#{svar}.length; #{ivar}<#{lvar}; #{ivar}++"
+        for_part    = "#{ivar} in #{svar}"
-        var_part    = "\n#{o[:indent] + TAB}#{@name} = #{svar}[#{ivar}];"
+        pre_cond    = "\n#{o[:indent] + TAB}if (#{svar}.hasOwnProperty(#{ivar})) {"
-        index_part  = @index ? "\n#{o[:indent] + TAB}#{index_name} = #{ivar};" : ''
+        var_part    = "\n#{body_dent}#{@name} = #{svar}[#{ivar}];"
+        post_cond   = "\n#{o[:indent] + TAB}}"
       end
       body          = @body
       suffix        = ';'
@@ -593,9 +593,8 @@ module CoffeeScript
       end
 
       return_result = "\n#{o[:indent]}#{return_result};"
-      indent = o[:indent] + TAB
+      body = body.compile(o.merge(:indent => body_dent))
-      body = body.compile(o.merge(:indent => indent))
+      write("#{source_part}#{set_result}for (#{for_part}) {#{pre_cond}#{var_part}\n#{body_dent}#{save_result}#{body}#{suffix}#{post_cond}\n#{o[:indent]}}#{return_result}")
-      write("#{source_part}#{set_result}for (#{for_part}) {#{var_part}#{index_part}\n#{indent}#{save_result}#{body}#{suffix}\n#{o[:indent]}}#{return_result}")
     end
   end
 
@@ -694,7 +693,7 @@ module CoffeeScript
       @else_body ? @else_body << eb : @else_body = eb
       self
     end
-    
+
     def force_statement
       @tags[:statement] = true
       self

test/fixtures/generation/each.js

@@ -3,28 +3,31 @@
   // The cornerstone, an each implementation.
   // Handles objects implementing forEach, arrays, and raw objects.
   _.each = function each(obj, iterator, context) {
-    var __a, __b, __c, __d, __e, __f, __g, __h, i, index, item, key;
+    var __a, __b, __c, __d, __e, i, index, item, key;
     index = 0;
     try {
       if (obj.forEach) {
         obj.forEach(iterator, context);
       } else if (_.isArray(obj) || _.isArguments(obj)) {
         __a = obj;
-        __d = [];
+        __b = [];
-        for (__b=0, __c=__a.length; __b<__c; __b++) {
+        for (i in __a) {
-          item = __a[__b];
+          if (__a.hasOwnProperty(i)) {
-          i = __b;
+            item = __a[i];
-          __d[__b] = iterator.call(context, item, i, obj);
+            __b[i] = iterator.call(context, item, i, obj);
+          }
         }
-        __d;
+        __b;
       } else {
-        __e = _.keys(obj);
+        __c = _.keys(obj);
-        __h = [];
+        __e = [];
-        for (__f=0, __g=__e.length; __f<__g; __f++) {
+        for (__d in __c) {
-          key = __e[__f];
+          if (__c.hasOwnProperty(__d)) {
-          __h[__f] = iterator.call(context, obj[key], key, obj);
+            key = __c[__d];
+            __e[__d] = iterator.call(context, obj[key], key, obj);
+          }
         }
-        __h;
+        __e;
       }
     } catch (e) {
       if (e !== breaker) {

test/fixtures/generation/each_no_wrap.js

@@ -2,28 +2,31 @@
 // The cornerstone, an each implementation.
 // Handles objects implementing forEach, arrays, and raw objects.
 _.each = function each(obj, iterator, context) {
-  var __a, __b, __c, __d, __e, __f, __g, __h, i, index, item, key;
+  var __a, __b, __c, __d, __e, i, index, item, key;
   index = 0;
   try {
     if (obj.forEach) {
       obj.forEach(iterator, context);
     } else if (_.isArray(obj) || _.isArguments(obj)) {
       __a = obj;
-      __d = [];
+      __b = [];
-      for (__b=0, __c=__a.length; __b<__c; __b++) {
+      for (i in __a) {
-        item = __a[__b];
+        if (__a.hasOwnProperty(i)) {
-        i = __b;
+          item = __a[i];
-        __d[__b] = iterator.call(context, item, i, obj);
+          __b[i] = iterator.call(context, item, i, obj);
+        }
       }
-      __d;
+      __b;
     } else {
-      __e = _.keys(obj);
+      __c = _.keys(obj);
-      __h = [];
+      __e = [];
-      for (__f=0, __g=__e.length; __f<__g; __f++) {
+      for (__d in __c) {
-        key = __e[__f];
+        if (__c.hasOwnProperty(__d)) {
-        __h[__f] = iterator.call(context, obj[key], key, obj);
+          key = __c[__d];
+          __e[__d] = iterator.call(context, obj[key], key, obj);
+        }
       }
-      __h;
+      __e;
     }
   } catch (e) {
     if (e !== breaker) {