Implement return void, #218

lib/ast.js

@@ -1,4 +1,4 @@
-var Node, Negatable, Block, Atom, Literal, Var, Key, Index, Chain, Call, List, Obj, Prop, Arr, Unary, Binary, Assign, Import, Of, Existence, Fun, Class, Super, Parens, Splat, Jump, Throw, Return, While, For, Try, Switch, Case, If, Label, Pipe, JS, Util, Vars, DECLS, ref$, UTILS, LEVEL_TOP, LEVEL_PAREN, LEVEL_LIST, LEVEL_COND, LEVEL_OP, LEVEL_CALL, PREC, TAB, ID, SIMPLENUM, slice$ = [].slice, replace$ = ''.replace;
+var Node, Negatable, Block, Atom, Literal, Var, Key, Index, Chain, Call, List, Obj, Prop, Arr, Unary, Binary, Assign, Import, Of, Existence, Fun, Class, Super, Parens, Splat, Jump, Throw, Return, ReturnVoid, While, For, Try, Switch, Case, If, Label, Pipe, JS, Util, Vars, DECLS, ref$, UTILS, LEVEL_TOP, LEVEL_PAREN, LEVEL_LIST, LEVEL_COND, LEVEL_OP, LEVEL_CALL, PREC, TAB, ID, SIMPLENUM, slice$ = [].slice, replace$ = ''.replace;
 (Node = function(){
   throw Error('unimplemented');
 }).prototype = {
@@ -2623,6 +2623,23 @@ exports.Return = Return = (function(superclass){
   };
   return Return;
 }(Jump));
+exports.ReturnVoid = ReturnVoid = (function(superclass){
+  ReturnVoid.displayName = 'ReturnVoid';
+  var prototype = extend$(ReturnVoid, superclass).prototype, constructor = ReturnVoid;
+  function ReturnVoid(it){
+    var this$ = this instanceof ctor$ ? this : new ctor$;
+    this$.it = it;
+    return this$;
+  } function ctor$(){} ctor$.prototype = prototype;
+  prototype.getJump = THIS;
+  prototype.compileNode = function(o){
+    if (!this.it) {
+      this.carp("Can't hush a return without a value");
+    }
+    return "return void " + this.it.compile(o, LEVEL_PAREN) + ";";
+  };
+  return ReturnVoid;
+}(Jump));
 exports.While = While = (function(superclass){
   While.displayName = 'While';
   var prototype = extend$(While, superclass).prototype, constructor = While;

lib/lexer.js

@@ -124,10 +124,15 @@ exports.doID = function(code, index){
     return input.length;
   }
   switch (id) {
+  case 'void':
+    if (last[0] === 'HURL' && last[1] === 'return') {
+      last[1] = 'returnvoid';
+      return 4;
+    }
+    // fallthrough
   case 'true':
   case 'false':
   case 'null':
-  case 'void':
   case 'arguments':
   case 'debugger':
     tag = 'LITERAL';

src/ast.co

@@ -1608,6 +1608,17 @@ class exports.Return extends Jump
   compileNode: (o) ->
     "return#{ if @it then ' ' + that.compile o, LEVEL_PAREN else '' };"
 
+#### Return void
+class exports.ReturnVoid extends Jump
+  (@it) ~>
+
+  getJump: THIS
+
+  compileNode: (o) ->
+    @carp "Can't hush a return without a value" unless @it
+    "return void #{ @it.compile o, LEVEL_PAREN };"
+
+
 #### While
 # The traditional `while`/`for`/`do` loop.
 # Returns an array of values collected from the last expression when requested.

src/lexer.co

@@ -109,7 +109,12 @@ exports import
       return input.length
     # keywords
     switch id
-    case \true \false \null \void \arguments \debugger then tag = \LITERAL
+    case \void
+      if last.0 is \HURL and last.1 is \return
+        last.1 = \returnvoid
+        return 4
+      fallthrough
+    case \true \false \null \arguments \debugger       then tag = \LITERAL
     case \new \do \typeof \delete                      then tag = \UNARY
     case \return \throw                                then tag = \HURL
     case \break  \continue                             then tag = \JUMP

test/compilation.co

@@ -183,3 +183,6 @@ Coco.compile 'class A; class B; class C'
 
 # [livescript#279](https://github.com/gkz/LiveScript/issues/279)
 Coco.compile \################################################################
+
+# Can't hush an empty return
+compileThrows "Can't hush a return without a value" 1 '-> return void'

test/function.co

@@ -499,3 +499,7 @@ let
   eq a, b
   eq c, d
   eq e, f
+
+
+### can hush a return
+eq void, do -> return void true