Add some basic support for for-of loops

The support is basically at the same level as for for-in
at the moment.

Currently unimplemented:
* Destructuring
* Proper lexical scoping
* calling iterator.throw()/return() when required

Change-Id: If193ce0b054c4315fc16b7e174334a31b2730dcf
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

15 files changed, 81 insertions, 73 deletions

diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index 3e31693593..3543ddb177 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -2593,11 +2593,20 @@ bool Codegen::visit(ForEachStatement *ast)
         return true;
 
     expr.loadInAccumulator();
-    Instruction::ForeachIteratorObject iteratorObjInstr;
+    Instruction::GetIterator iteratorObjInstr;
+    iteratorObjInstr.iterator = (ast->type == ForEachType::Of) ? 1 : 0;
     bytecodeGenerator->addInstruction(iteratorObjInstr);
     iterator.storeConsumeAccumulator();
 
-    Reference lhs = expression(ast->initialiser).asLValue();
+    Reference lhs = expression(ast->initialiser);
+    if (hasError)
+        return false;
+    if (!lhs.isLValue()) {
+        throwSyntaxError(ast->forToken, QLatin1String("Destructuring not supported with for-in and for-of loops."));
+        return false;
+    }
+
+    lhs = lhs.asLValue();
 
     foreachBody(lhs, ast->statement, ast->forToken, iterator);
     return false;
@@ -2618,7 +2627,8 @@ bool Codegen::visit(LocalForEachStatement *ast)
     variableDeclaration(ast->declaration);
 
     expr.loadInAccumulator();
-    Instruction::ForeachIteratorObject iteratorObjInstr;
+    Instruction::GetIterator iteratorObjInstr;
+    iteratorObjInstr.iterator = (ast->type == ForEachType::Of) ? 1 : 0;
     bytecodeGenerator->addInstruction(iteratorObjInstr);
     iterator.storeConsumeAccumulator();
 
diff --git a/src/qml/compiler/qv4instr_moth.cpp b/src/qml/compiler/qv4instr_moth.cpp
index 49d8455617..6ef4e79344 100644
--- a/src/qml/compiler/qv4instr_moth.cpp
+++ b/src/qml/compiler/qv4instr_moth.cpp
@@ -419,11 +419,9 @@ void dumpBytecode(const char *code, int len, int nLocals, int nFormals, int /*st
             d << dumpRegister(reg, nFormals);
         MOTH_END_INSTR(PopContext)
 
-        MOTH_BEGIN_INSTR(ForeachIteratorObject)
-        MOTH_END_INSTR(ForeachIteratorObject)
-
-        MOTH_BEGIN_INSTR(ForeachNextPropertyName)
-        MOTH_END_INSTR(ForeachNextPropertyName)
+        MOTH_BEGIN_INSTR(GetIterator)
+            d << iterator;
+        MOTH_END_INSTR(GetIterator)
 
         MOTH_BEGIN_INSTR(DeleteMember)
             d << dumpRegister(base, nFormals) << "[" << member << "]";
diff --git a/src/qml/compiler/qv4instr_moth_p.h b/src/qml/compiler/qv4instr_moth_p.h
index 2e3d118e52..546e8fd2de 100644
--- a/src/qml/compiler/qv4instr_moth_p.h
+++ b/src/qml/compiler/qv4instr_moth_p.h
@@ -118,8 +118,7 @@ QT_BEGIN_NAMESPACE
 #define INSTR_PushWithContext(op) INSTRUCTION(op, PushWithContext, 1, reg)
 #define INSTR_PushBlockContext(op) INSTRUCTION(op, PushBlockContext, 2, reg, index)
 #define INSTR_PopContext(op) INSTRUCTION(op, PopContext, 1, reg)
-#define INSTR_ForeachIteratorObject(op) INSTRUCTION(op, ForeachIteratorObject, 0)
-#define INSTR_ForeachNextPropertyName(op) INSTRUCTION(op, ForeachNextPropertyName, 0)
+#define INSTR_GetIterator(op) INSTRUCTION(op, GetIterator, 1, iterator)
 #define INSTR_DeleteMember(op) INSTRUCTION(op, DeleteMember, 2, member, base)
 #define INSTR_DeleteSubscript(op) INSTRUCTION(op, DeleteSubscript, 2, base, index)
 #define INSTR_DeleteName(op) INSTRUCTION(op, DeleteName, 1, name)
@@ -242,8 +241,7 @@ QT_BEGIN_NAMESPACE
     F(PushWithContext) \
     F(PushBlockContext) \
     F(PopContext) \
-    F(ForeachIteratorObject) \
-    F(ForeachNextPropertyName) \
+    F(GetIterator) \
     F(DeleteMember) \
     F(DeleteSubscript) \
     F(DeleteName) \
diff --git a/src/qml/jit/qv4jit.cpp b/src/qml/jit/qv4jit.cpp
index 87c3642479..16b6b5fb94 100644
--- a/src/qml/jit/qv4jit.cpp
+++ b/src/qml/jit/qv4jit.cpp
@@ -662,23 +662,14 @@ void BaselineJIT::generate_PushBlockContext(int reg, int index)
 
 void BaselineJIT::generate_PopContext(int reg) { as->popContext(reg); }
 
-void BaselineJIT::generate_ForeachIteratorObject()
+void BaselineJIT::generate_GetIterator(int iterator)
 {
     as->saveAccumulatorInFrame();
-    as->prepareCallWithArgCount(2);
+    as->prepareCallWithArgCount(3);
+    as->passInt32AsArg(iterator, 2);
     as->passAccumulatorAsArg(1);
     as->passEngineAsArg(0);
-    JIT_GENERATE_RUNTIME_CALL(Runtime::method_foreachIterator, Assembler::ResultInAccumulator);
-    as->checkException();
-}
-
-void BaselineJIT::generate_ForeachNextPropertyName()
-{
-    as->saveAccumulatorInFrame();
-    as->prepareCallWithArgCount(1);
-    as->passAccumulatorAsArg(0);
-    JIT_GENERATE_RUNTIME_CALL(Runtime::method_foreachNextPropertyName,
-                              Assembler::ResultInAccumulator);
+    JIT_GENERATE_RUNTIME_CALL(Runtime::method_getIterator, Assembler::ResultInAccumulator);
     as->checkException();
 }
 
@@ -1220,11 +1211,8 @@ void BaselineJIT::collectLabelsInBytecode()
         MOTH_BEGIN_INSTR(PopContext)
         MOTH_END_INSTR(PopContext)
 
-        MOTH_BEGIN_INSTR(ForeachIteratorObject)
-        MOTH_END_INSTR(ForeachIteratorObject)
-
-        MOTH_BEGIN_INSTR(ForeachNextPropertyName)
-        MOTH_END_INSTR(ForeachNextPropertyName)
+        MOTH_BEGIN_INSTR(GetIterator)
+        MOTH_END_INSTR(GetIterator)
 
         MOTH_BEGIN_INSTR(DeleteMember)
         MOTH_END_INSTR(DeleteMember)
diff --git a/src/qml/jit/qv4jit_p.h b/src/qml/jit/qv4jit_p.h
index bf11e69cbb..157fbffeb1 100644
--- a/src/qml/jit/qv4jit_p.h
+++ b/src/qml/jit/qv4jit_p.h
@@ -182,8 +182,7 @@ public:
     void generate_PushWithContext(int reg) override;
     void generate_PushBlockContext(int reg, int index) override;
     void generate_PopContext(int reg) override;
-    void generate_ForeachIteratorObject() override;
-    void generate_ForeachNextPropertyName() override;
+    void generate_GetIterator(int iterator) override;
     void generate_DeleteMember(int member, int base) override;
     void generate_DeleteSubscript(int base, int index) override;
     void generate_DeleteName(int name) override;
diff --git a/src/qml/jsruntime/qv4managed.cpp b/src/qml/jsruntime/qv4managed.cpp
index f96e3c87d8..bd22e2bc04 100644
--- a/src/qml/jsruntime/qv4managed.cpp
+++ b/src/qml/jsruntime/qv4managed.cpp
@@ -131,8 +131,8 @@ QString Managed::className() const
     case Type_StringIteratorObject:
         s = "String Iterator";
         break;
-    case Type_ForeachIteratorObject:
-        s = "__ForeachIterator";
+    case Type_ForInIterator:
+        s = "__ForIn Iterator";
         break;
     case Type_InternalClass:
         s = "__InternalClass";
diff --git a/src/qml/jsruntime/qv4managed_p.h b/src/qml/jsruntime/qv4managed_p.h
index 1b67aacd7b..020e61f014 100644
--- a/src/qml/jsruntime/qv4managed_p.h
+++ b/src/qml/jsruntime/qv4managed_p.h
@@ -201,7 +201,7 @@ public:
         Type_InternalClass,
         Type_ArrayIteratorObject,
         Type_StringIteratorObject,
-        Type_ForeachIteratorObject,
+        Type_ForInIterator,
         Type_RegExp,
 
         Type_QmlSequence
diff --git a/src/qml/jsruntime/qv4objectiterator_p.h b/src/qml/jsruntime/qv4objectiterator_p.h
index 2b2410bf1f..462bd9a114 100644
--- a/src/qml/jsruntime/qv4objectiterator_p.h
+++ b/src/qml/jsruntime/qv4objectiterator_p.h
@@ -133,7 +133,7 @@ struct ForInIteratorPrototype : Object
 
 struct ForInIteratorObject: Object {
     V4_OBJECT2(ForInIteratorObject, Object)
-    Q_MANAGED_TYPE(ForeachIteratorObject)
+    Q_MANAGED_TYPE(ForInIterator)
     V4_PROTOTYPE(forInIteratorPrototype)
 
     ReturnedValue nextPropertyName() const { return d()->it().nextPropertyNameAsString(); }
diff --git a/src/qml/jsruntime/qv4runtime.cpp b/src/qml/jsruntime/qv4runtime.cpp
index 1c1c3c3802..a83edfaed6 100644
--- a/src/qml/jsruntime/qv4runtime.cpp
+++ b/src/qml/jsruntime/qv4runtime.cpp
@@ -695,26 +695,26 @@ bool Runtime::method_storeElement(ExecutionEngine *engine, const Value &object,
     return setElementFallback(engine, object, index, value);
 }
 
-ReturnedValue Runtime::method_foreachIterator(ExecutionEngine *engine, const Value &in)
+ReturnedValue Runtime::method_getIterator(ExecutionEngine *engine, const Value &in, int iterator)
 {
     Scope scope(engine);
     ScopedObject o(scope, (Object *)nullptr);
     if (!in.isNullOrUndefined())
         o = in.toObject(engine);
+    if (engine->hasException)
+        return Encode::undefined();
+    if (iterator) {
+        if (!o)
+            return engine->throwTypeError();
+        ScopedFunctionObject f(scope, o->get(engine->symbol_iterator()));
+        if (!f)
+            return engine->throwTypeError();
+        JSCallData cData(scope, 0, nullptr, o);
+        return f->call(cData);
+    }
     return engine->newForInIteratorObject(o)->asReturnedValue();
 }
 
-ReturnedValue Runtime::method_foreachNextPropertyName(const Value &foreach_iterator)
-{
-    Q_ASSERT(foreach_iterator.isObject());
-
-    ForInIteratorObject *it = static_cast<ForInIteratorObject *>(foreach_iterator.objectValue());
-    Q_ASSERT(it->as<ForInIteratorObject>());
-
-    return it->nextPropertyName();
-}
-
-
 void Runtime::method_storeNameSloppy(ExecutionEngine *engine, int nameIndex, const Value &value)
 {
     Scope scope(engine);
diff --git a/src/qml/jsruntime/qv4runtimeapi_p.h b/src/qml/jsruntime/qv4runtimeapi_p.h
index ac456283cb..4d4112bf0c 100644
--- a/src/qml/jsruntime/qv4runtimeapi_p.h
+++ b/src/qml/jsruntime/qv4runtimeapi_p.h
@@ -141,9 +141,8 @@ struct ExceptionCheck<void (*)(QV4::NoThrowEngine *, A, B, C)> {
     F(ReturnedValue, arrayLiteral, (ExecutionEngine *engine, Value *values, uint length)) \
     F(ReturnedValue, objectLiteral, (ExecutionEngine *engine, const Value *args, int classId, int arrayValueCount, int arrayGetterSetterCountAndFlags)) \
     \
-    /* foreach */ \
-    F(ReturnedValue, foreachIterator, (ExecutionEngine *engine, const Value &in)) \
-    F(ReturnedValue, foreachNextPropertyName, (const Value &foreach_iterator)) \
+    /* for-in and for-of */ \
+    F(ReturnedValue, getIterator, (ExecutionEngine *engine, const Value &in, int iterator)) \
     \
     /* unary operators */ \
     F(ReturnedValue, uMinus, (const Value &value)) \
diff --git a/src/qml/jsruntime/qv4vme_moth.cpp b/src/qml/jsruntime/qv4vme_moth.cpp
index 08a085c90d..7f27619d08 100644
--- a/src/qml/jsruntime/qv4vme_moth.cpp
+++ b/src/qml/jsruntime/qv4vme_moth.cpp
@@ -938,17 +938,11 @@ QV4::ReturnedValue VME::interpret(CppStackFrame &frame, const uchar *code)
         STACK_VALUE(CallData::Context) = STACK_VALUE(reg);
     MOTH_END_INSTR(PopContext)
 
-    MOTH_BEGIN_INSTR(ForeachIteratorObject)
+    MOTH_BEGIN_INSTR(GetIterator)
         STORE_ACC();
-        acc = Runtime::method_foreachIterator(engine, accumulator);
+        acc = Runtime::method_getIterator(engine, accumulator, iterator);
         CHECK_EXCEPTION;
-    MOTH_END_INSTR(ForeachIteratorObject)
-
-    MOTH_BEGIN_INSTR(ForeachNextPropertyName)
-        STORE_ACC();
-        acc = Runtime::method_foreachNextPropertyName(accumulator);
-        CHECK_EXCEPTION;
-    MOTH_END_INSTR(ForeachNextPropertyName)
+    MOTH_END_INSTR(GetIterator)
 
     MOTH_BEGIN_INSTR(DeleteMember)
         if (!Runtime::method_deleteMember(engine, STACK_VALUE(base), member)) {
diff --git a/src/qml/parser/qqmljs.g b/src/qml/parser/qqmljs.g
index c25f3395e2..8e71b8a42b 100644
--- a/src/qml/parser/qqmljs.g
+++ b/src/qml/parser/qqmljs.g
@@ -262,6 +262,7 @@ public:
       int ival;
       double dval;
       AST::VariableScope scope;
+      AST::ForEachType forEachType;
       AST::ArgumentList *ArgumentList;
       AST::CaseBlock *CaseBlock;
       AST::CaseClause *CaseClause;
@@ -3125,37 +3126,47 @@ IterationStatement: T_FOR T_LPAREN LexicalDeclaration T_SEMICOLON ExpressionOpt_
     } break;
 ./
 
-IterationStatement: T_FOR T_LPAREN LeftHandSideExpression T_IN Expression_In T_RPAREN Statement;
+InOrOf: T_IN;
+/.
+    case $rule_number: {
+        sym(1).forEachType = AST::ForEachType::In;
+    } break;
+./
+
+InOrOf: T_OF;
+/.
+    case $rule_number: {
+        sym(1).forEachType = AST::ForEachType::Of;
+    } break;
+./
+
+IterationStatement: T_FOR T_LPAREN LeftHandSideExpression InOrOf Expression_In T_RPAREN Statement;
 /.
     case $rule_number: {
         AST::ForEachStatement *node = new (pool) AST::ForEachStatement(sym(3).Expression, sym(5).Expression, sym(7).Statement);
         node->forToken = loc(1);
         node->lparenToken = loc(2);
-        node->inToken = loc(4);
+        node->inOfToken = loc(4);
         node->rparenToken = loc(6);
+        node->type = sym(4).forEachType;
         sym(1).Node = node;
     } break;
 ./
 
-IterationStatement: T_FOR T_LPAREN ForDeclaration T_IN Expression_In T_RPAREN Statement;
+IterationStatement: T_FOR T_LPAREN ForDeclaration InOrOf Expression_In T_RPAREN Statement;
 /.
     case $rule_number: {
         AST::LocalForEachStatement *node = new (pool) AST::LocalForEachStatement(sym(3).PatternElement, sym(5).Expression, sym(7).Statement);
         node->forToken = loc(1);
         node->lparenToken = loc(2);
         node->varToken = loc(3);
-        node->inToken = loc(4);
+        node->inOfToken = loc(4);
         node->rparenToken = loc(6);
+        node->type = sym(4).forEachType;
         sym(1).Node = node;
     } break;
 ./
 
-
-IterationStatement: T_FOR T_LPAREN LeftHandSideExpression T_OF AssignmentExpression_In T_RPAREN Statement; -- [lookahead ≠ let]
-/.  case $rule_number: { UNIMPLEMENTED; } ./
-IterationStatement: T_FOR T_LPAREN ForDeclaration T_OF Expression_In T_RPAREN Statement;
-/.  case $rule_number: { UNIMPLEMENTED; } ./
-
 ForDeclaration: LetOrConst ForBinding;
 /.  case $rule_number: Q_FALLTHROUGH(); ./
 ForDeclaration: Var ForBinding;
diff --git a/src/qml/parser/qqmljsast_p.h b/src/qml/parser/qqmljsast_p.h
index c83a459506..e54d1aea31 100644
--- a/src/qml/parser/qqmljsast_p.h
+++ b/src/qml/parser/qqmljsast_p.h
@@ -1701,6 +1701,11 @@ public:
     SourceLocation rparenToken;
 };
 
+enum class ForEachType {
+    In,
+    Of
+};
+
 class QML_PARSER_EXPORT ForEachStatement: public Statement
 {
 public:
@@ -1724,8 +1729,9 @@ public:
     Statement *statement;
     SourceLocation forToken;
     SourceLocation lparenToken;
-    SourceLocation inToken;
+    SourceLocation inOfToken;
     SourceLocation rparenToken;
+    ForEachType type;
 };
 
 class QML_PARSER_EXPORT LocalForEachStatement: public Statement
@@ -1752,8 +1758,9 @@ public:
     SourceLocation forToken;
     SourceLocation lparenToken;
     SourceLocation varToken;
-    SourceLocation inToken;
+    SourceLocation inOfToken;
     SourceLocation rparenToken;
+    ForEachType type;
 };
 
 class QML_PARSER_EXPORT ContinueStatement: public Statement
diff --git a/src/qml/parser/qqmljskeywords_p.h b/src/qml/parser/qqmljskeywords_p.h
index 9cc47469e5..40094ecdf8 100644
--- a/src/qml/parser/qqmljskeywords_p.h
+++ b/src/qml/parser/qqmljskeywords_p.h
@@ -76,10 +76,13 @@ static inline int classify2(const QChar *s, int parseModeFlags) {
       return Lexer::T_IN;
     }
   }
-  else if ((parseModeFlags & Lexer::QmlMode) && s[0].unicode() == 'o') {
+  else if (s[0].unicode() == 'o') {
     if (s[1].unicode() == 'n') {
       return (parseModeFlags & Lexer::QmlMode) ? Lexer::T_ON : Lexer::T_IDENTIFIER;
     }
+    else if (s[1].unicode() == 'f') {
+      return Lexer::T_OF;
+    }
   }
   return Lexer::T_IDENTIFIER;
 }
diff --git a/src/qml/parser/qqmljslexer.cpp b/src/qml/parser/qqmljslexer.cpp
index 3dbe535bcf..69e73f1374 100644
--- a/src/qml/parser/qqmljslexer.cpp
+++ b/src/qml/parser/qqmljslexer.cpp
@@ -1343,6 +1343,7 @@ static const int uriTokens[] = {
     QQmlJSGrammar::T_FUNCTION,
     QQmlJSGrammar::T_IF,
     QQmlJSGrammar::T_IN,
+    QQmlJSGrammar::T_OF,
     QQmlJSGrammar::T_INSTANCEOF,
     QQmlJSGrammar::T_NEW,
     QQmlJSGrammar::T_NULL,