Merge pull request #2498 from Microsoft/iteratorSpreadDestructure

Support spreading and destructuring of iterators in ES6

Author: JsonFreeman

src/compiler/checker.ts

@@ -344,8 +344,8 @@ module ts {
         The_left_hand_side_of_a_for_of_statement_cannot_be_a_previously_defined_constant: { code: 2485, category: DiagnosticCategory.Error, key: "The left-hand side of a 'for...of' statement cannot be a previously defined constant." },
         The_left_hand_side_of_a_for_in_statement_cannot_be_a_previously_defined_constant: { code: 2486, category: DiagnosticCategory.Error, key: "The left-hand side of a 'for...in' statement cannot be a previously defined constant." },
         Invalid_left_hand_side_in_for_of_statement: { code: 2487, category: DiagnosticCategory.Error, key: "Invalid left-hand side in 'for...of' statement." },
-        The_right_hand_side_of_a_for_of_statement_must_have_a_Symbol_iterator_method_that_returns_an_iterator: { code: 2488, category: DiagnosticCategory.Error, key: "The right-hand side of a 'for...of' statement must have a '[Symbol.iterator]()' method that returns an iterator." },
-        The_iterator_returned_by_the_right_hand_side_of_a_for_of_statement_must_have_a_next_method: { code: 2489, category: DiagnosticCategory.Error, key: "The iterator returned by the right-hand side of a 'for...of' statement must have a 'next()' method." },
+        Type_must_have_a_Symbol_iterator_method_that_returns_an_iterator: { code: 2488, category: DiagnosticCategory.Error, key: "Type must have a '[Symbol.iterator]()' method that returns an iterator." },
+        An_iterator_must_have_a_next_method: { code: 2489, category: DiagnosticCategory.Error, key: "An iterator must have a 'next()' method." },
         The_type_returned_by_the_next_method_of_an_iterator_must_have_a_value_property: { code: 2490, category: DiagnosticCategory.Error, key: "The type returned by the 'next()' method of an iterator must have a 'value' property." },
         The_left_hand_side_of_a_for_in_statement_cannot_be_a_destructuring_pattern: { code: 2491, category: DiagnosticCategory.Error, key: "The left-hand side of a 'for...in' statement cannot be a destructuring pattern." },
         Cannot_redeclare_identifier_0_in_catch_clause: { code: 2492, category: DiagnosticCategory.Error, key: "Cannot redeclare identifier '{0}' in catch clause" },

src/compiler/diagnosticInformationMap.generated.ts

@@ -1367,11 +1367,11 @@
         "category": "Error",
         "code": 2487
     },
-    "The right-hand side of a 'for...of' statement must have a '[Symbol.iterator]()' method that returns an iterator.": {
+    "Type must have a '[Symbol.iterator]()' method that returns an iterator.": {
         "category": "Error",
         "code": 2488
     },
-    "The iterator returned by the right-hand side of a 'for...of' statement must have a 'next()' method.": {
+    "An iterator must have a 'next()' method.": {
         "category": "Error",
         "code": 2489
     },

src/compiler/diagnosticMessages.json

@@ -52,6 +52,7 @@ class TypeWriterWalker {
             case ts.SyntaxKind.PostfixUnaryExpression:
             case ts.SyntaxKind.BinaryExpression:
             case ts.SyntaxKind.ConditionalExpression:
+            case ts.SyntaxKind.SpreadElementExpression:
                 this.log(node, this.getTypeOfNode(node));
                 break;
 

src/harness/typeWriter.ts

@@ -1,12 +1,18 @@
 tests/cases/conformance/statements/for-ofStatements/ES5For-of30.ts(3,6): error TS2461: Type 'string | number' is not an array type.
+tests/cases/conformance/statements/for-ofStatements/ES5For-of30.ts(3,7): error TS2322: Type 'number' is not assignable to type 'string'.
+tests/cases/conformance/statements/for-ofStatements/ES5For-of30.ts(3,14): error TS2322: Type 'string' is not assignable to type 'number'.
 
 
-==== tests/cases/conformance/statements/for-ofStatements/ES5For-of30.ts (1 errors) ====
+==== tests/cases/conformance/statements/for-ofStatements/ES5For-of30.ts (3 errors) ====
     var a: string, b: number;
     var tuple: [number, string] = [2, "3"];
     for ([a = 1, b = ""] of tuple) {
          ~~~~~~~~~~~~~~~
 !!! error TS2461: Type 'string | number' is not an array type.
+          ~
+!!! error TS2322: Type 'number' is not assignable to type 'string'.
+                 ~
+!!! error TS2322: Type 'string' is not assignable to type 'number'.
         a;
         b;
     }

tests/baselines/reference/ES5For-of30.errors.txt

@@ -9,44 +9,55 @@ function f0() {
     var a1 = [...a];
 >a1 : number[]
 >[...a] : number[]
+>...a : number
 >a : number[]
 
     var a2 = [1, ...a];
 >a2 : number[]
 >[1, ...a] : number[]
+>...a : number
 >a : number[]
 
     var a3 = [1, 2, ...a];
 >a3 : number[]
 >[1, 2, ...a] : number[]
+>...a : number
 >a : number[]
 
     var a4 = [...a, 1];
 >a4 : number[]
 >[...a, 1] : number[]
+>...a : number
 >a : number[]
 
     var a5 = [...a, 1, 2];
 >a5 : number[]
 >[...a, 1, 2] : number[]
+>...a : number
 >a : number[]
 
     var a6 = [1, 2, ...a, 1, 2];
 >a6 : number[]
 >[1, 2, ...a, 1, 2] : number[]
+>...a : number
 >a : number[]
 
     var a7 = [1, ...a, 2, ...a];
 >a7 : number[]
 >[1, ...a, 2, ...a] : number[]
+>...a : number
 >a : number[]
+>...a : number
 >a : number[]
 
     var a8 = [...a, ...a, ...a];
 >a8 : number[]
 >[...a, ...a, ...a] : number[]
+>...a : number
 >a : number[]
+>...a : number
 >a : number[]
+>...a : number
 >a : number[]
 }
 
@@ -60,6 +71,7 @@ function f1() {
     var b = ["hello", ...a, true];
 >b : (string | number | boolean)[]
 >["hello", ...a, true] : (string | number | boolean)[]
+>...a : number
 >a : number[]
 
     var b: (string | number | boolean)[];
@@ -72,19 +84,29 @@ function f2() {
     var a = [...[...[...[...[...[]]]]]];
 >a : any[]
 >[...[...[...[...[...[]]]]]] : undefined[]
+>...[...[...[...[...[]]]]] : undefined
 >[...[...[...[...[]]]]] : undefined[]
+>...[...[...[...[]]]] : undefined
 >[...[...[...[]]]] : undefined[]
+>...[...[...[]]] : undefined
 >[...[...[]]] : undefined[]
+>...[...[]] : undefined
 >[...[]] : undefined[]
+>...[] : undefined
 >[] : undefined[]
 
     var b = [...[...[...[...[...[5]]]]]];
 >b : number[]
 >[...[...[...[...[...[5]]]]]] : number[]
+>...[...[...[...[...[5]]]]] : number
 >[...[...[...[...[5]]]]] : number[]
+>...[...[...[...[5]]]] : number
 >[...[...[...[5]]]] : number[]
+>...[...[...[5]]] : number
 >[...[...[5]]] : number[]
+>...[...[5]] : number
 >[...[5]] : number[]
+>...[5] : number
 >[5] : number[]
 }
 

tests/baselines/reference/arrayLiteralSpread.types

@@ -38,11 +38,13 @@ foo(1, 2, "abc");
 foo(1, 2, ...a);
 >foo(1, 2, ...a) : void
 >foo : (x: number, y: number, ...z: string[]) => void
+>...a : string
 >a : string[]
 
 foo(1, 2, ...a, "abc");
 >foo(1, 2, ...a, "abc") : void
 >foo : (x: number, y: number, ...z: string[]) => void
+>...a : string
 >a : string[]
 
 obj.foo(1, 2, "abc");
@@ -56,13 +58,15 @@ obj.foo(1, 2, ...a);
 >obj.foo : (x: number, y: number, ...z: string[]) => any
 >obj : X
 >foo : (x: number, y: number, ...z: string[]) => any
+>...a : string
 >a : string[]
 
 obj.foo(1, 2, ...a, "abc");
 >obj.foo(1, 2, ...a, "abc") : any
 >obj.foo : (x: number, y: number, ...z: string[]) => any
 >obj : X
 >foo : (x: number, y: number, ...z: string[]) => any
+>...a : string
 >a : string[]
 
 (obj.foo)(1, 2, "abc");
@@ -78,6 +82,7 @@ obj.foo(1, 2, ...a, "abc");
 >obj.foo : (x: number, y: number, ...z: string[]) => any
 >obj : X
 >foo : (x: number, y: number, ...z: string[]) => any
+>...a : string
 >a : string[]
 
 (obj.foo)(1, 2, ...a, "abc");
@@ -86,6 +91,7 @@ obj.foo(1, 2, ...a, "abc");
 >obj.foo : (x: number, y: number, ...z: string[]) => any
 >obj : X
 >foo : (x: number, y: number, ...z: string[]) => any
+>...a : string
 >a : string[]
 
 xa[1].foo(1, 2, "abc");
@@ -101,6 +107,7 @@ xa[1].foo(1, 2, ...a);
 >xa[1] : X
 >xa : X[]
 >foo : (x: number, y: number, ...z: string[]) => any
+>...a : string
 >a : string[]
 
 xa[1].foo(1, 2, ...a, "abc");
@@ -109,6 +116,7 @@ xa[1].foo(1, 2, ...a, "abc");
 >xa[1] : X
 >xa : X[]
 >foo : (x: number, y: number, ...z: string[]) => any
+>...a : string
 >a : string[]
 
 (<Function>xa[1].foo)(...[1, 2, "abc"]);
@@ -120,6 +128,7 @@ xa[1].foo(1, 2, ...a, "abc");
 >xa[1] : X
 >xa : X[]
 >foo : (x: number, y: number, ...z: string[]) => any
+>...[1, 2, "abc"] : string | number
 >[1, 2, "abc"] : (string | number)[]
 
 class C {
@@ -145,6 +154,7 @@ class C {
 >foo : (x: number, y: number, ...z: string[]) => void
 >x : number
 >y : number
+>...z : string
 >z : string[]
     }
     foo(x: number, y: number, ...z: string[]) {
@@ -167,6 +177,7 @@ class D extends C {
         super(1, 2, ...a);
 >super(1, 2, ...a) : void
 >super : typeof C
+>...a : string
 >a : string[]
     }
     foo() {
@@ -183,6 +194,7 @@ class D extends C {
 >super.foo : (x: number, y: number, ...z: string[]) => void
 >super : C
 >foo : (x: number, y: number, ...z: string[]) => void
+>...a : string
 >a : string[]
     }
 }
@@ -192,5 +204,6 @@ var c = new C(1, 2, ...a);
 >c : C
 >new C(1, 2, ...a) : C
 >C : typeof C
+>...a : string
 >a : string[]
 

tests/baselines/reference/callWithSpreadES6.types

@@ -1,11 +1,11 @@
-tests/cases/conformance/es6/for-ofStatements/for-of14.ts(2,11): error TS2488: The right-hand side of a 'for...of' statement must have a '[Symbol.iterator]()' method that returns an iterator.
+tests/cases/conformance/es6/for-ofStatements/for-of14.ts(2,11): error TS2488: Type must have a '[Symbol.iterator]()' method that returns an iterator.
 
 
 ==== tests/cases/conformance/es6/for-ofStatements/for-of14.ts (1 errors) ====
     var v: string;
     for (v of new StringIterator) { } // Should fail because the iterator is not iterable
               ~~~~~~~~~~~~~~~~~~
-!!! error TS2488: The right-hand side of a 'for...of' statement must have a '[Symbol.iterator]()' method that returns an iterator.
+!!! error TS2488: Type must have a '[Symbol.iterator]()' method that returns an iterator.
 
     class StringIterator {
         next() {

tests/baselines/reference/for-of14.errors.txt

@@ -1,11 +1,11 @@
-tests/cases/conformance/es6/for-ofStatements/for-of16.ts(2,11): error TS2489: The iterator returned by the right-hand side of a 'for...of' statement must have a 'next()' method.
+tests/cases/conformance/es6/for-ofStatements/for-of16.ts(2,11): error TS2489: An iterator must have a 'next()' method.
 
 
 ==== tests/cases/conformance/es6/for-ofStatements/for-of16.ts (1 errors) ====
     var v: string;
     for (v of new StringIterator) { } // Should fail
               ~~~~~~~~~~~~~~~~~~
-!!! error TS2489: The iterator returned by the right-hand side of a 'for...of' statement must have a 'next()' method.
+!!! error TS2489: An iterator must have a 'next()' method.
 
     class StringIterator {
         [Symbol.iterator]() {

tests/baselines/reference/for-of16.errors.txt

@@ -0,0 +1,7 @@
+//// [for-of57.ts]
+var iter: Iterable<number>;
+for (let num of iter) { }
+
+//// [for-of57.js]
+var iter;
+for (let num of iter) { }

tests/baselines/reference/for-of57.js

@@ -0,0 +1,9 @@
+=== tests/cases/conformance/es6/for-ofStatements/for-of57.ts ===
+var iter: Iterable<number>;
+>iter : Iterable<number>
+>Iterable : Iterable<T>
+
+for (let num of iter) { }
+>num : number
+>iter : Iterable<number>
+

tests/baselines/reference/for-of57.types

@@ -0,0 +1,28 @@
+//// [iterableArrayPattern1.ts]
+var [a, b] = new SymbolIterator;
+class SymbolIterator {
+    next() {
+        return {
+            value: Symbol(),
+            done: false
+        };
+    }
+
+    [Symbol.iterator]() {
+        return this;
+    }
+}
+
+//// [iterableArrayPattern1.js]
+var [a, b] = new SymbolIterator;
+class SymbolIterator {
+    next() {
+        return {
+            value: Symbol(),
+            done: false
+        };
+    }
+    [Symbol.iterator]() {
+        return this;
+    }
+}

tests/baselines/reference/iterableArrayPattern1.js

@@ -0,0 +1,36 @@
+=== tests/cases/conformance/es6/destructuring/iterableArrayPattern1.ts ===
+var [a, b] = new SymbolIterator;
+>a : symbol
+>b : symbol
+>new SymbolIterator : SymbolIterator
+>SymbolIterator : typeof SymbolIterator
+
+class SymbolIterator {
+>SymbolIterator : SymbolIterator
+
+    next() {
+>next : () => { value: symbol; done: boolean; }
+
+        return {
+>{            value: Symbol(),            done: false        } : { value: symbol; done: boolean; }
+
+            value: Symbol(),
+>value : symbol
+>Symbol() : symbol
+>Symbol : SymbolConstructor
+
+            done: false
+>done : boolean
+
+        };
+    }
+
+    [Symbol.iterator]() {
+>Symbol.iterator : symbol
+>Symbol : SymbolConstructor
+>iterator : symbol
+
+        return this;
+>this : SymbolIterator
+    }
+}

tests/baselines/reference/iterableArrayPattern1.types

@@ -0,0 +1,24 @@
+tests/cases/conformance/es6/destructuring/iterableArrayPattern10.ts(2,5): error TS2345: Argument of type 'FooIterator' is not assignable to parameter of type '[any, any]'.
+  Property '0' is missing in type 'FooIterator'.
+
+
+==== tests/cases/conformance/es6/destructuring/iterableArrayPattern10.ts (1 errors) ====
+    function fun([a, b]) { }
+    fun(new FooIterator);
+        ~~~~~~~~~~~~~~~
+!!! error TS2345: Argument of type 'FooIterator' is not assignable to parameter of type '[any, any]'.
+!!! error TS2345:   Property '0' is missing in type 'FooIterator'.
+    class Bar { x }
+    class Foo extends Bar { y }
+    class FooIterator {
+        next() {
+            return {
+                value: new Foo,
+                done: false
+            };
+        }
+    
+        [Symbol.iterator]() {
+            return this;
+        }
+    }