Implement @-prefixed parameters.

lib/grammar.js

@@ -139,8 +139,12 @@
     Param: [
       o("PARAM", function() {
         return new LiteralNode($1);
-      }), o("Param . . .", function() {
+      }), o("@ PARAM", function() {
-        return new SplatNode($1);
+        return new ParamNode($2, true);
+      }), o("PARAM . . .", function() {
+        return new ParamNode($1, false, true);
+      }), o("@ PARAM . . .", function() {
+        return new ParamNode($2, true, true);
       })
     ],
     Splat: [

lib/nodes.js

@@ -1,5 +1,5 @@
 (function() {
-  var AccessorNode, ArrayNode, AssignNode, BaseNode, CallNode, ClassNode, ClosureNode, CodeNode, CommentNode, DOUBLE_PARENS, ExistenceNode, Expressions, ExtendsNode, ForNode, IDENTIFIER, IS_STRING, IfNode, InNode, IndexNode, LiteralNode, NUMBER, ObjectNode, OpNode, ParentheticalNode, PushNode, RangeNode, ReturnNode, SIMPLENUM, Scope, SliceNode, SplatNode, TAB, TRAILING_WHITESPACE, ThrowNode, TryNode, UTILITIES, ValueNode, WhileNode, _a, compact, del, ends, flatten, helpers, include, indexOf, literal, merge, starts, utility;
+  var AccessorNode, ArrayNode, AssignNode, BaseNode, CallNode, ClassNode, ClosureNode, CodeNode, CommentNode, DOUBLE_PARENS, ExistenceNode, Expressions, ExtendsNode, ForNode, IDENTIFIER, IS_STRING, IfNode, InNode, IndexNode, LiteralNode, NUMBER, ObjectNode, OpNode, ParamNode, ParentheticalNode, PushNode, RangeNode, ReturnNode, SIMPLENUM, Scope, SliceNode, SplatNode, TAB, TRAILING_WHITESPACE, ThrowNode, TryNode, UTILITIES, ValueNode, WhileNode, _a, compact, del, ends, flatten, helpers, include, indexOf, literal, merge, starts, utility;
   var __extends = function(child, parent) {
     var ctor = function(){};
     ctor.prototype = parent.prototype;
@@ -958,7 +958,7 @@
     CodeNode.prototype['class'] = 'CodeNode';
     CodeNode.prototype.children = ['params', 'body'];
     CodeNode.prototype.compileNode = function(o) {
-      var _b, _c, _d, _e, _f, _g, _h, _i, _j, _k, code, func, i, param, params, sharedScope, splat, top;
+      var _b, _c, _d, _e, _f, _g, _h, _i, _j, code, func, i, name, param, params, sharedScope, splat, top;
       sharedScope = del(o, 'sharedScope');
       top = del(o, 'top');
       o.scope = sharedScope || new Scope(o.scope, this.body, this);
@@ -966,37 +966,46 @@
       o.indent = this.idt(1);
       del(o, 'noWrap');
       del(o, 'globals');
-      i = 0;
       splat = undefined;
       params = [];
-      _c = this.params;
+      _b = this.params;
-      for (_b = 0, _d = _c.length; _b < _d; _b++) {
+      for (i = 0, _c = _b.length; i < _c; i++) {
-        param = _c[_b];
+        param = _b[i];
-        if (param instanceof SplatNode && !(typeof splat !== "undefined" && splat !== null)) {
+        if (typeof splat !== "undefined" && splat !== null) {
-          splat = param;
+          if (param.attach) {
-          splat.index = i;
+            param.assign = new AssignNode(new ValueNode(literal('this'), [new AccessorNode(param.name)]));
-          splat.trailings = [];
+            this.body.expressions.splice(splat.index + 1, 0, param.assign);
-          splat.arglength = this.params.length;
+          }
-          this.body.unshift(splat);
-        } else if (typeof splat !== "undefined" && splat !== null) {
           splat.trailings.push(param);
         } else {
-          params.push(param);
+          if (param.attach) {
+            name = param.name;
+            param = literal(o.scope.freeVariable());
+            this.body.unshift(new AssignNode(new ValueNode(literal('this'), [new AccessorNode(name)]), param));
+          }
+          if (param.splat) {
+            splat = new SplatNode(param.name);
+            splat.index = i;
+            splat.trailings = [];
+            splat.arglength = this.params.length;
+            this.body.unshift(splat);
+          } else {
+            params.push(param);
+          }
         }
-        i += 1;
       }
       params = (function() {
-        _e = []; _g = params;
+        _d = []; _f = params;
-        for (_f = 0, _h = _g.length; _f < _h; _f++) {
+        for (_e = 0, _g = _f.length; _e < _g; _e++) {
-          param = _g[_f];
+          param = _f[_e];
-          _e.push(param.compile(o));
+          _d.push(param.compile(o));
         }
-        return _e;
+        return _d;
       })();
       this.body.makeReturn();
-      _j = params;
+      _i = params;
-      for (_i = 0, _k = _j.length; _i < _k; _i++) {
+      for (_h = 0, _j = _i.length; _h < _j; _h++) {
-        param = _j[_i];
+        param = _i[_h];
         (o.scope.parameter(param));
       }
       code = this.body.expressions.length ? ("\n" + (this.body.compileWithDeclarations(o)) + "\n") : '';
@@ -1029,6 +1038,24 @@
     };
     return CodeNode;
   })();
+  exports.ParamNode = (function() {
+    ParamNode = function(name, attach, splat) {
+      this.name = literal(name);
+      this.attach = attach;
+      this.splat = splat;
+      return this;
+    };
+    __extends(ParamNode, BaseNode);
+    ParamNode.prototype['class'] = 'ParamNode';
+    ParamNode.prototype.children = ['name'];
+    ParamNode.prototype.compileNode = function(o) {
+      return this.name.compile(o);
+    };
+    ParamNode.prototype.toString = function(idt) {
+      return this.type === 'this' ? (literal("@" + name)).toString(idt) : this.name.toString(idt);
+    };
+    return ParamNode;
+  })();
   exports.SplatNode = (function() {
     SplatNode = function(name) {
       if (!(name.compile)) {
@@ -1045,7 +1072,7 @@
       return (typeof (_b = this.index) !== "undefined" && _b !== null) ? this.compileParam(o) : this.name.compile(o);
     };
     SplatNode.prototype.compileParam = function(o) {
-      var _b, _c, end, idx, len, name, pos, trailing, variadic;
+      var _b, _c, assign, end, idx, len, name, pos, trailing, variadic;
       name = this.name.compile(o);
       o.scope.find(name);
       end = '';
@@ -1058,6 +1085,11 @@
         _b = this.trailings;
         for (idx = 0, _c = _b.length; idx < _c; idx++) {
           trailing = _b[idx];
+          if (trailing.attach) {
+            assign = trailing.assign;
+            trailing = literal(o.scope.freeVariable());
+            assign.value = trailing;
+          }
           pos = this.trailings.length - idx;
           o.scope.assign(trailing.compile(o), ("arguments[" + variadic + " ? " + len + " - " + pos + " : " + (this.index + idx) + "]"));
         }

src/grammar.coffee

@@ -203,7 +203,9 @@ grammar =
   # that hoovers up the remaining arguments.
   Param: [
     o "PARAM",                                  -> new LiteralNode $1
-    o "Param . . .",                            -> new SplatNode $1
+    o "@ PARAM",                                -> new ParamNode $2, true
+    o "PARAM . . .",                            -> new ParamNode $1, false, true
+    o "@ PARAM . . .",                          -> new ParamNode $2, true, true
   ]
 
   # A splat that occurs outside of a parameter list.

src/nodes.coffee

@@ -871,21 +871,27 @@ exports.CodeNode = class CodeNode extends BaseNode
     o.indent    = @idt(1)
     del o, 'noWrap'
     del o, 'globals'
-    i = 0
     splat = undefined
     params = []
-    for param in @params
+    for param, i in @params
-      if param instanceof SplatNode and not splat?
+      if splat?
-        splat           = param
+        if param.attach
-        splat.index     = i
+          param.assign = new AssignNode new ValueNode literal('this'), [new AccessorNode param.name]
-        splat.trailings = []
+          @body.expressions.splice splat.index + 1, 0, param.assign
-        splat.arglength = @params.length
+        splat.trailings.push param
-        @body.unshift(splat)
-      else if splat?
-        splat.trailings.push(param)
       else
-        params.push(param)
+        if param.attach
-      i += 1
+          name  = param.name
+          param = literal o.scope.freeVariable()
+          @body.unshift new AssignNode new ValueNode(literal('this'), [new AccessorNode name]), param
+        if param.splat
+          splat           = new SplatNode param.name
+          splat.index     = i
+          splat.trailings = []
+          splat.arglength = @params.length
+          @body.unshift(splat)
+        else
+          params.push(param)
     params = (param.compile(o) for param in params)
     @body.makeReturn()
     (o.scope.parameter(param)) for param in params
@@ -906,6 +912,26 @@ exports.CodeNode = class CodeNode extends BaseNode
     children = (child.toString(idt + TAB) for child in @collectChildren()).join('')
     "\n#idt#children"
 
+#### ParamNode
+
+# A parameter in a function definition. Special parameters have a particular
+# type - either 'this', meaning it assigns straight to the current context, or
+# 'splat', where it gathers up a block of the parameters into an array.
+exports.ParamNode = class ParamNode extends BaseNode
+
+  class:     'ParamNode'
+  children: ['name']
+
+  constructor: (name, attach, splat) ->
+    @name = literal name
+    @attach = attach
+    @splat = splat
+
+  compileNode: (o) -> @name.compile o
+
+  toString: (idt) ->
+    if @type is 'this' then (literal "@#name").toString idt else @name.toString idt
+
 #### SplatNode
 
 # A splat, either as a parameter to a function, an argument to a call,
@@ -935,6 +961,10 @@ exports.SplatNode = class SplatNode extends BaseNode
       o.scope.assign variadic, "#len >= #@arglength"
       end = if @trailings.length then ", #len - #{@trailings.length}"
       for trailing, idx in @trailings
+        if trailing.attach
+          assign   = trailing.assign
+          trailing = literal o.scope.freeVariable()
+          assign.value = trailing
         pos = @trailings.length - idx
         o.scope.assign(trailing.compile(o), "arguments[#variadic ? #len - #pos : #{@index + idx}]")
     "#name = #{utility('slice')}.call(arguments, #@index#end)"

test/test_arguments.coffee

@@ -22,4 +22,11 @@ sumOfArgs = ->
   sum += val for val in arguments
   sum
 
-ok sumOfArgs(1, 2, 3, 4, 5) is 15
+ok sumOfArgs(1, 2, 3, 4, 5) is 15
+
+
+((@arg) ->).call context = {}, 1
+ok context.arg is 1
+
+((splat..., @arg) ->).call context, 1, 2, 3
+ok context.arg is 3