optimized splatting assignment

lib/nodes.js

@@ -933,15 +933,15 @@
       return o.level <= LEVEL_LIST ? val : "(" + val + ")";
     };
     Assign.prototype.compilePatternMatch = function(o) {
-      var _len, _ref2, _ref3, _ref4, _ref5, _ref6, _ref7, acc, assigns, code, i, idx, isObject, ivar, obj, objects, olength, ref, rest, splat, top, val, valVar, value;
+      var _len, _ref2, _ref3, _ref4, _ref5, _ref6, _ref7, acc, assigns, code, i, idx, isObject, ivar, obj, objects, olen, ref, rest, splat, top, val, value, vvar;
       top = o.level === LEVEL_TOP;
       value = this.value;
       objects = this.variable.base.objects;
-      if (!(olength = objects.length)) {
+      if (!(olen = objects.length)) {
         return value.compile(o);
       }
       isObject = this.variable.isObject();
-      if (top && olength === 1 && !((obj = objects[0]) instanceof Splat)) {
+      if (top && olen === 1 && !((obj = objects[0]) instanceof Splat)) {
         if (obj instanceof Assign) {
           _ref2 = obj, (_ref3 = _ref2.variable, idx = _ref3.base, _ref3), obj = _ref2.value;
         } else {
@@ -956,12 +956,12 @@
         value.properties.push(new (acc ? Accessor : Index)(idx));
         return new Assign(obj, value).compile(o);
       }
-      valVar = value.compile(o, LEVEL_LIST);
+      vvar = value.compile(o, LEVEL_LIST);
       assigns = [];
       splat = false;
-      if (!IDENTIFIER.test(valVar) || this.variable.assigns(valVar)) {
-        assigns.push("" + (ref = o.scope.freeVariable('ref')) + " = " + valVar);
-        valVar = ref;
+      if (!IDENTIFIER.test(vvar) || this.variable.assigns(vvar)) {
+        assigns.push("" + (ref = o.scope.freeVariable('ref')) + " = " + vvar);
+        vvar = ref;
       }
       for (i = 0, _len = objects.length; i < _len; i++) {
         obj = objects[i];
@@ -978,12 +978,15 @@
           }
         }
         if (!splat && obj instanceof Splat) {
-          if (rest = olength - i - 1 || '') {
+          val = "" + olen + " <= " + vvar + ".length ? " + (utility('slice')) + ".call(" + vvar + ", " + i;
+          if (rest = olen - i - 1) {
             ivar = o.scope.freeVariable('i');
-            rest = ", " + ivar + " = " + valVar + ".length - " + rest;
+            val += ", " + ivar + " = " + vvar + ".length - " + rest + ") : (" + ivar + " = " + i + ", [])";
+          } else {
+            val += ") : []";
           }
-          val = new Literal(utility('slice') + (".call(" + valVar + ", " + i + rest + ")"));
-          splat = "" + ivar + " < " + i + " ? " + ivar + " = " + i + " : " + ivar + "++";
+          val = new Literal(val);
+          splat = "" + ivar + "++";
         } else {
           if (obj instanceof Splat) {
             obj = obj.name.compile(o);
@@ -995,12 +998,12 @@
           } else {
             acc = isObject && IDENTIFIER.test(idx.unwrap().value || 0);
           }
-          val = new Value(new Literal(valVar), [new (acc ? Accessor : Index)(idx)]);
+          val = new Value(new Literal(vvar), [new (acc ? Accessor : Index)(idx)]);
         }
         assigns.push(new Assign(obj, val).compile(o, LEVEL_LIST));
       }
       if (!top) {
-        assigns.push(valVar);
+        assigns.push(vvar);
       }
       code = assigns.join(', ');
       return o.level < LEVEL_LIST ? code : "(" + code + ")";

src/nodes.coffee

@@ -764,9 +764,9 @@ exports.Assign = class Assign extends Base
     top       = o.level is LEVEL_TOP
     {value}   = this
     {objects} = @variable.base
-    return value.compile o unless olength = objects.length
+    return value.compile o unless olen = objects.length
     isObject = @variable.isObject()
-    if top and olength is 1 and (obj = objects[0]) not instanceof Splat
+    if top and olen is 1 and (obj = objects[0]) not instanceof Splat
       # Unroll simplest cases: `{v} = x` -> `v = x.v`
       if obj instanceof Assign
         {variable: {base: idx}, value: obj} = obj
@@ -781,12 +781,12 @@ exports.Assign = class Assign extends Base
       value = new Value value
       value.properties.push new (if acc then Accessor else Index) idx
       return new Assign(obj, value).compile o
-    valVar  = value.compile o, LEVEL_LIST
+    vvar    = value.compile o, LEVEL_LIST
     assigns = []
     splat   = false
-    if not IDENTIFIER.test(valVar) or @variable.assigns(valVar)
-      assigns.push "#{ ref = o.scope.freeVariable 'ref' } = #{valVar}"
-      valVar = ref
+    if not IDENTIFIER.test(vvar) or @variable.assigns(vvar)
+      assigns.push "#{ ref = o.scope.freeVariable 'ref' } = #{vvar}"
+      vvar = ref
     for obj, i in objects
       # A regular array pattern-match.
       idx = i
@@ -800,11 +800,14 @@ exports.Assign = class Assign extends Base
           then [obj, idx] = new Value(obj.unwrapAll()).cacheReference o
           else idx = if obj.tags.this then obj.properties[0].name else obj
       if not splat and obj instanceof Splat
-        if rest = olength - i - 1 or ''
+        val = "#{olen} <= #{vvar}.length ? #{ utility 'slice' }.call(#{vvar}, #{i}"
+        if rest = olen - i - 1
           ivar = o.scope.freeVariable 'i'
-          rest = ", #{ivar} = #{valVar}.length - #{rest}"
-        val   = new Literal utility('slice') + ".call(#{valVar}, #{i}#{rest})"
-        splat = "#{ivar} < #{i} ? #{ivar} = #{i} : #{ivar}++"
+          val += ", #{ivar} = #{vvar}.length - #{rest}) : (#{ivar} = #{i}, [])"
+        else
+          val += ") : []"
+        val   = new Literal val
+        splat = "#{ivar}++"
       else
         if obj instanceof Splat
           obj = obj.name.compile o
@@ -815,9 +818,9 @@ exports.Assign = class Assign extends Base
           acc = no
         else
           acc = isObject and IDENTIFIER.test idx.unwrap().value or 0
-        val = new Value new Literal(valVar), [new (if acc then Accessor else Index) idx]
+        val = new Value new Literal(vvar), [new (if acc then Accessor else Index) idx]
       assigns.push new Assign(obj, val).compile o, LEVEL_LIST
-    assigns.push valVar unless top
+    assigns.push vvar unless top
     code = assigns.join ', '
     if o.level < LEVEL_LIST then code else "(#{code})"
 

test/test_arguments.coffee

@@ -29,21 +29,28 @@ ok sumOfArgs(1, 2, 3, 4, 5) is 15
 ok context.arg is 1
 
 ((splat..., @arg) ->).call context, 1, 2, 3
-ok context.arg is 3
+eq context.arg, 3
 
 ((@arg...) ->).call context, 1, 2, 3
-ok context.arg.join ' ' is '1 2 3'
+eq context.arg.join(' '), '1 2 3'
 
 class Klass
   constructor: (@one, @two) ->
 
 obj = new Klass 1, 2
 
-ok obj.one is 1
-ok obj.two is 2
+eq obj.one, 1
+eq obj.two, 2
 
 
 # Default arguments.
 obj = f: (q = 123, @p = 456) -> q
 eq obj.f(), 123
 eq obj.p  , 456
+
+withSplats = (a = 2, b..., c = 3, d = 5) -> a * (b.length + 1) * c * d
+eq 30, withSplats()
+eq 15, withSplats 1
+eq  5, withSplats 1, 1
+eq  1, withSplats 1, 1, 1
+eq  2, withSplats 1, 1, 1, 1