Add ->* and yield

Slakefile

@@ -138,7 +138,13 @@ function runTests global.LiveScript
     else tint message
     if failedTests
       process.exit 1
-  dir(\test)forEach (file) ->
+
+  files = dir \test
+  unless '--harmony' in process.execArgv or '--harmony-generators' in process.execArgv
+    say "Skipping --harmony tests"
+    files.splice (files.indexOf 'generators.ls'), 1
+
+  files.forEach (file) ->
     return unless /\.ls$/i.test file
     code = slurp filename = path.join \test file
     try LiveScript.run code, {filename} catch

package.json

@@ -40,6 +40,7 @@
   "scripts": {
     "pretest": "bin/slake build && bin/slake build:parser && bin/slake build",
     "test": "bin/slake test",
+    "test-harmony": "node --harmony ./bin/slake test",
     "posttest": "git checkout -- lib"
   },
   "preferGlobal": true,

package.json.ls

@@ -36,6 +36,7 @@ bin  :
 scripts:
   pretest: "bin/slake build && bin/slake build:parser && bin/slake build"
   test: "bin/slake test"
+  \test-harmony : "node --harmony ./bin/slake test"
   posttest: "git checkout -- lib"
 
 preferGlobal: true

src/ast.ls

@@ -1012,7 +1012,8 @@ class exports.Unary extends Node
               #{ it.compile o, LEVEL_LIST }).slice(8, -1)"
     code = it.compile o, LEVEL_OP + PREC.unary
     if @post then code += op else
-      op += ' ' if op in <[ new typeof delete ]>
+      op = 'yield* ' if op is \yieldfrom
+      op += ' ' if op in <[ new typeof delete yield ]>
                 or op in <[ + - ]> and op is code.charAt!
       code = op + code
     if o.level < LEVEL_CALL then code else "(#code)"
@@ -1591,7 +1592,7 @@ class exports.Existence extends Node implements Negatable
 #### Fun
 # A function definition. This is the only node that creates a `new Scope`.
 class exports.Fun extends Node
-  (@params or [], @body or Block!, @bound and \this$, @curried or false, @hushed = false) ~>
+  (@params or [], @body or Block!, @bound and \this$, @curried or false, @hushed = false, @generator = false) ~>
 
   children: <[ params body ]>
 
@@ -1623,6 +1624,10 @@ class exports.Fun extends Node
     o.indent += TAB
     {body, name, tab} = this
     code = \function
+    if @generator
+      @ctor and @carp "a constructor can't be a generator"
+      @hushed and @carp "a generator is hushed by default"
+      code += \*
     if @bound is \this$
       if @ctor
         scope.assign \this$ 'this instanceof ctor$ ? this : new ctor$'
@@ -1637,7 +1642,7 @@ class exports.Fun extends Node
       pscope.add name, \function, this
     if @statement or name and @labeled
       code += ' ' + scope.add name, \function, this
-    @hushed or @ctor or @newed or body.makeReturn!
+    @hushed or @ctor or @newed or @generator or body.makeReturn!
     code += "(#{ @compileParams o, scope }){"
     code += "\n#that\n#tab" if body.compileWithDeclarations o
     code += \}

src/grammar.ls

@@ -245,7 +245,7 @@ bnf =
 
     # The function literal can be either anonymous with `->`,
     o 'PARAM( ArgList OptComma )PARAM -> Block'
-    , -> L Fun $2, $6, /~/.test($5), /--|~~/.test($5), /!/.test($5)
+    , -> L Fun $2, $6, /~/.test($5), /--|~~/.test($5), /!/.test($5), /\*/.test($5)
     # or named with `function`.
     o 'FUNCTION CALL( ArgList OptComma )CALL Block' -> L Fun($3, $6)named $1
 

src/lexer.ls

@@ -123,7 +123,7 @@ exports import
     switch id
     case <[ true false on off yes no null void arguments debugger ]>
       tag = \LITERAL
-    case \new \do \typeof \delete                      then tag = \UNARY
+    case <[ new do typeof delete yield ]>              then tag = \UNARY
     case \return \throw                                then tag = \HURL
     case \break  \continue                             then tag = \JUMP
     case \this \eval \super then return @token(\LITERAL id, true)length
@@ -211,7 +211,11 @@ exports import
         or last.1 is \import and \All
           last.1 += that
           return 3
-      case \from then @forange! and tag = \FROM
+      case \from
+        if last.1 is \yield
+          last.1 += \from
+          return 4
+        @forange! and tag = \FROM
       case \to \til
         @forange! and @tokens.push [\FROM '' @line] [\STRNUM \0 @line]
         if @fget \from
@@ -539,6 +543,9 @@ exports import
       @token \IMPORT \<<
       return sym.length
     case \*
+      if @last.0 is \->
+        @last.1 += \* if @last.0 is \->
+        return 1
       if @last.0 in <[ NEWLINE INDENT THEN => ]> and
          (INLINEDENT <<< lastIndex: index+1)exec code .0.length
         @tokens.push [\LITERAL \void @line] [\ASSIGN \= @line]
@@ -1215,13 +1222,13 @@ KEYWORDS_SHARED = <[
   true false null this void super return throw break continue
   if else for while switch case default try catch finally
   function class extends implements new do delete typeof in instanceof
-  let with var const import export debugger
+  let with var const import export debugger yield
 ]>
 
 # The list of keywords that are reserved by JavaScript, but not used.
 # We throw a syntax error for these to avoid runtime errors.
 KEYWORDS_UNUSED =
-  <[ enum interface package private protected public static yield ]>
+  <[ enum interface package private protected public static ]>
 
 JS_KEYWORDS = KEYWORDS_SHARED ++ KEYWORDS_UNUSED
 

test/compilation.ls

@@ -197,5 +197,12 @@ eq "var a, b, c;\na = require('a');\nb = require('b');\nc = require('c');" bare
 # JS literal
 eq 'some js code!' bare '``some js code!``'
 
+# generators
+compileThrows "a constructor can't be a generator" 1 'class => ->*'
+compileThrows "a generator is hushed by default" 1 '!->*'
+
+# https://github.com/jashkenas/coffee-script/pull/3240#issuecomment-38344281
+eq '(function*(){\n  var body;\n  body = (yield fn).body;\n});' bare '->* {body} = yield fn'
+
 # [livescript#279](https://github.com/gkz/LiveScript/issues/279)
-################################################################
+################################################################

test/generators.ls

@@ -0,0 +1,68 @@
+# Generators
+# -----------------
+#
+# * Generator Definition
+
+# generator as argument
+ok ->* 1
+
+# named generator function
+ok <| :fn ->* 2
+
+# generator definition
+x = ->*
+  yield 0
+  yield 1
+  yield 2
+
+y = x!
+z = y.next!
+eq z.value, 0
+eq z.done, false
+z = y.next!
+eq z.value, 1
+eq z.done, false
+z = y.next!
+eq z.value, 2
+eq z.done, false
+z = y.next!
+eq z.value, void
+eq z.done, true
+
+# yield from
+first = ->*
+  i = 0
+  loop => yield i++
+second = ->*
+  yield from first!
+list = second!
+for i to 3 
+  {value} = list.next!
+  eq value, i
+
+# curried bound generators
+class A
+  val: 5
+  curried: (x, y) ~~>*
+    yield @val + x + y
+fn = (new A).curried
+yield-add = fn 2
+y = yield-add 3
+z = y.next!
+eq z.value, 10
+eq z.done, false
+z = y.next!
+eq z.value, void
+eq z.done, true
+
+# bound generator
+obj =
+  bound: ->
+    do ~>*
+      return this
+  unbound: ->
+    do ->*
+      return this
+
+eq obj, obj.bound().next().value
+ok obj isnt obj.unbound().next().value