Re-enabling garbage collection of tempvars, only at function boundaries.

documentation/coffee/array_comprehensions.coffee

@@ -2,6 +2,6 @@
 lunch = eat food for food in ['toast', 'cheese', 'wine']
 
 # Naive collision detection.
-for roid, index in asteroids
+for roid, pos in asteroids
   for roid2 in asteroids when roid isnt roid2
     roid.explode() if roid.overlaps roid2

documentation/js/array_comprehensions.js

@@ -1,4 +1,4 @@
-var _i, _j, _len, _len2, _len3, _ref, _result, food, index, lunch, roid, roid2;
+var _i, _len, _len2, _ref, _result, food, lunch, pos, roid, roid2;
 lunch = (function() {
   _result = []; _ref = ['toast', 'cheese', 'wine'];
   for (_i = 0, _len = _ref.length; _i < _len; _i++) {
@@ -7,10 +7,10 @@ lunch = (function() {
   }
   return _result;
 })();
-for (index = 0, _len2 = asteroids.length; index < _len2; index++) {
-  roid = asteroids[index];
-  for (_j = 0, _len3 = asteroids.length; _j < _len3; _j++) {
-    roid2 = asteroids[_j];
+for (pos = 0, _len = asteroids.length; pos < _len; pos++) {
+  roid = asteroids[pos];
+  for (_i = 0, _len2 = asteroids.length; _i < _len2; _i++) {
+    roid2 = asteroids[_i];
     if (roid !== roid2) {
       if (roid.overlaps(roid2)) {
         roid.explode();

index.html

@@ -829,10 +829,10 @@ lyrics = (function() {
 lunch <span class="Keyword">=</span> eat food <span class="Keyword">for</span> food <span class="Keyword">in</span> [<span class="String"><span class="String">'</span>toast<span class="String">'</span></span>, <span class="String"><span class="String">'</span>cheese<span class="String">'</span></span>, <span class="String"><span class="String">'</span>wine<span class="String">'</span></span>]
 
 <span class="Comment"><span class="Comment">#</span> Naive collision detection.</span>
-<span class="Keyword">for</span> roid, index <span class="Keyword">in</span> asteroids
+<span class="Keyword">for</span> roid, pos <span class="Keyword">in</span> asteroids
   <span class="Keyword">for</span> roid2 <span class="Keyword">in</span> asteroids <span class="Keyword">when</span> roid <span class="Keyword">isnt</span> roid2
     roid.explode() <span class="Keyword">if</span> roid.overlaps roid2
-</pre><pre class="idle"><span class="Storage">var</span> _i, _j, _len, _len2, _len3, _ref, _result, food, index, lunch, roid, roid2;
+</pre><pre class="idle"><span class="Storage">var</span> _i, _len, _len2, _ref, _result, food, lunch, pos, roid, roid2;
 lunch <span class="Keyword">=</span> (<span class="Storage">function</span>() {
   _result <span class="Keyword">=</span> []; _ref <span class="Keyword">=</span> [<span class="String"><span class="String">'</span>toast<span class="String">'</span></span>, <span class="String"><span class="String">'</span>cheese<span class="String">'</span></span>, <span class="String"><span class="String">'</span>wine<span class="String">'</span></span>];
   <span class="Keyword">for</span> (_i <span class="Keyword">=</span> <span class="Number">0</span>, _len <span class="Keyword">=</span> _ref.<span class="LibraryConstant">length</span>; _i <span class="Keyword">&lt;</span> _len; _i<span class="Keyword">++</span>) {
@@ -841,10 +841,10 @@ lunch <span class="Keyword">=</span> (<span class="Storage">function</span>() {
   }
   <span class="Keyword">return</span> _result;
 })();
-<span class="Keyword">for</span> (index <span class="Keyword">=</span> <span class="Number">0</span>, _len2 <span class="Keyword">=</span> asteroids.<span class="LibraryConstant">length</span>; index <span class="Keyword">&lt;</span> _len2; index<span class="Keyword">++</span>) {
-  roid <span class="Keyword">=</span> asteroids[index];
-  <span class="Keyword">for</span> (_j <span class="Keyword">=</span> <span class="Number">0</span>, _len3 <span class="Keyword">=</span> asteroids.<span class="LibraryConstant">length</span>; _j <span class="Keyword">&lt;</span> _len3; _j<span class="Keyword">++</span>) {
-    roid2 <span class="Keyword">=</span> asteroids[_j];
+<span class="Keyword">for</span> (pos <span class="Keyword">=</span> <span class="Number">0</span>, _len <span class="Keyword">=</span> asteroids.<span class="LibraryConstant">length</span>; pos <span class="Keyword">&lt;</span> _len; pos<span class="Keyword">++</span>) {
+  roid <span class="Keyword">=</span> asteroids[pos];
+  <span class="Keyword">for</span> (_i <span class="Keyword">=</span> <span class="Number">0</span>, _len2 <span class="Keyword">=</span> asteroids.<span class="LibraryConstant">length</span>; _i <span class="Keyword">&lt;</span> _len2; _i<span class="Keyword">++</span>) {
+    roid2 <span class="Keyword">=</span> asteroids[_i];
     <span class="Keyword">if</span> (roid <span class="Keyword">!</span><span class="Keyword">==</span> roid2) {
       <span class="Keyword">if</span> (roid.overlaps(roid2)) {
         roid.explode();

lib/nodes.js

@@ -785,7 +785,7 @@
     ObjectNode.prototype.children = ['properties'];
     ObjectNode.prototype.topSensitive = YES;
     ObjectNode.prototype.compileNode = function(o) {
-      var _i, _len, _len2, _ref2, _ref3, _result, _result2, i, indent, join, lastNoncom, nonComments, obj, prop, props, top;
+      var _i, _len, _ref2, _result, i, indent, join, lastNoncom, nonComments, obj, prop, props, top;
       top = del(o, 'top');
       o.indent = this.idt(1);
       nonComments = (function() {
@@ -800,10 +800,10 @@
       }).call(this);
       lastNoncom = last(nonComments);
       props = (function() {
-        _result2 = []; _ref3 = this.properties;
-        for (i = 0, _len2 = _ref3.length; i < _len2; i++) {
-          prop = _ref3[i];
-          _result2.push((function() {
+        _result = []; _ref2 = this.properties;
+        for (i = 0, _len = _ref2.length; i < _len; i++) {
+          prop = _ref2[i];
+          _result.push((function() {
             join = ",\n";
             if ((prop === lastNoncom) || (prop instanceof CommentNode)) {
               join = "\n";
@@ -820,7 +820,7 @@
             return indent + prop.compile(o) + join;
           }).call(this));
         }
-        return _result2;
+        return _result;
       }).call(this);
       props = props.join('');
       obj = '{' + (props ? '\n' + props + '\n' + this.idt() : '') + '}';
@@ -1102,7 +1102,7 @@
     __extends(CodeNode, BaseNode);
     CodeNode.prototype.children = ['params', 'body'];
     CodeNode.prototype.compileNode = function(o) {
-      var _i, _j, _len, _len2, _len3, _ref2, _ref3, _result, close, code, empty, func, i, open, param, params, sharedScope, splat, top, value;
+      var _i, _len, _len2, _ref2, _ref3, _result, close, code, empty, func, i, open, param, params, sharedScope, splat, top, value;
       sharedScope = del(o, 'sharedScope');
       top = del(o, 'top');
       o.scope = sharedScope || new Scope(o.scope, this.body, this);
@@ -1139,6 +1139,7 @@
           }
         }
       }
+      o.scope.startLevel();
       params = (function() {
         _result = [];
         for (_i = 0, _len2 = params.length; _i < _len2; _i++) {
@@ -1150,8 +1151,8 @@
       if (!(empty)) {
         this.body.makeReturn();
       }
-      for (_j = 0, _len3 = params.length; _j < _len3; _j++) {
-        param = params[_j];
+      for (_i = 0, _len2 = params.length; _i < _len2; _i++) {
+        param = params[_i];
         (o.scope.parameter(param));
       }
       if (this.className) {
@@ -1161,6 +1162,7 @@
       open = this.className ? ("(function() {\n" + (this.idt(1)) + "return function " + (this.className) + "(") : "function(";
       close = this.className ? ("" + (code && this.idt(1)) + "};\n" + (this.tab) + "})()") : ("" + (code && this.tab) + "}");
       func = ("" + open + (params.join(', ')) + ") {" + code + close);
+      o.scope.endLevel();
       if (this.bound) {
         return ("" + (utility('bind')) + "(" + func + ", " + (this.context) + ")");
       }

lib/scope.js

@@ -11,13 +11,31 @@
         this.variables = {
           'arguments': 'arguments'
         };
-        if (!(this.parent)) {
+        if (this.parent) {
+          this.garbage = this.parent.garbage;
+        } else {
+          this.garbage = [];
           Scope.root = this;
         }
         return this;
       };
     })();
     Scope.root = null;
+    Scope.prototype.startLevel = function() {
+      return this.garbage.push([]);
+    };
+    Scope.prototype.endLevel = function() {
+      var _i, _len, _ref2, _result, name, vars;
+      vars = this.variables;
+      _result = []; _ref2 = this.garbage.pop();
+      for (_i = 0, _len = _ref2.length; _i < _len; _i++) {
+        name = _ref2[_i];
+        if (vars[name] === 'var') {
+          _result.push(vars[name] = 'reuse');
+        }
+      }
+      return _result;
+    };
     Scope.prototype.find = function(name, options) {
       if (this.check(name, options)) {
         return true;
@@ -54,10 +72,13 @@
     Scope.prototype.freeVariable = function(type) {
       var index, temp;
       index = 0;
-      while (this.check(temp = this.temporary(type, index))) {
+      while (this.check(temp = this.temporary(type, index)) && this.variables[temp] !== 'reuse') {
         index++;
       }
       this.variables[temp] = 'var';
+      if (this.garbage.length) {
+        last(this.garbage).push(temp);
+      }
       return temp;
     };
     Scope.prototype.assign = function(name, value) {
@@ -68,7 +89,7 @@
     };
     Scope.prototype.hasDeclarations = function(body) {
       return body === this.expressions && this.any(function(k, val) {
-        return val === 'var';
+        return ('var' === val || 'reuse' === val);
       });
     };
     Scope.prototype.hasAssignments = function(body) {
@@ -83,7 +104,7 @@
         for (key in _ref2) {
           if (!__hasProp.call(_ref2, key)) continue;
           val = _ref2[key];
-          if (val === 'var') {
+          if (('var' === val || 'reuse' === val)) {
             _result.push(key);
           }
         }

src/nodes.coffee

@@ -984,6 +984,7 @@ exports.CodeNode = class CodeNode extends BaseNode
           @body.unshift(splat)
         else
           params.push param
+    o.scope.startLevel()
     params = (param.compile(o) for param in params)
     @body.makeReturn() unless empty
     (o.scope.parameter(param)) for param in params
@@ -992,6 +993,7 @@ exports.CodeNode = class CodeNode extends BaseNode
     open  = if @className then "(function() {\n#{@idt(1)}return function #{@className}(" else "function("
     close = if @className then "#{code and @idt(1)}};\n#{@tab}})()" else "#{code and @tab}}"
     func  = "#{open}#{ params.join(', ') }) {#{code}#{close}"
+    o.scope.endLevel()
     return "#{utility 'bind'}(#{func}, #{@context})" if @bound
     if top then "(#{func})" else func
 

src/scope.coffee

@@ -19,7 +19,21 @@ exports.Scope = class Scope
   # it wraps.
   constructor: (@parent, @expressions, @method) ->
     @variables = {'arguments'}
-    Scope.root = this unless @parent
+    if @parent
+      @garbage = @parent.garbage
+    else
+      @garbage   = []
+      Scope.root = this
+
+  # Create a new garbage level
+  startLevel: ->
+    @garbage.push []
+
+  # Return to the previous garbage level and erase referenced temporary
+  # variables in current level from scope.
+  endLevel: ->
+    vars = @variables
+    (vars[name] = 'reuse') for name in @garbage.pop() when vars[name] is 'var'
 
   # Look up a variable name in lexical scope, and declare it if it does not
   # already exist.
@@ -57,8 +71,9 @@ exports.Scope = class Scope
   # compiler-generated variable. `_var`, `_var2`, and so on...
   freeVariable: (type) ->
     index = 0
-    index++ while @check(temp = @temporary type, index)
+    index++ while @check(temp = @temporary type, index) and @variables[temp] isnt 'reuse'
     @variables[temp] = 'var'
+    last(@garbage).push temp if @garbage.length
     temp
 
   # Ensure that an assignment is made at the top of this scope
@@ -69,7 +84,7 @@ exports.Scope = class Scope
   # Does this scope reference any variables that need to be declared in the
   # given function body?
   hasDeclarations: (body) ->
-    body is @expressions and @any (k, val) -> val is 'var'
+    body is @expressions and @any (k, val) -> val in ['var', 'reuse']
 
   # Does this scope reference any assignments that need to be declared at the
   # top of the given function body?
@@ -78,7 +93,7 @@ exports.Scope = class Scope
 
   # Return the list of variables first declared in this scope.
   declaredVariables: ->
-    (key for key, val of @variables when val is 'var').sort()
+    (key for key, val of @variables when val in ['var', 'reuse']).sort()
 
   # Return the list of assignments that are supposed to be made at the top
   # of this scope.