Support unpacking tuples in for ... in ... loops.

chunk.h

@@ -71,6 +71,7 @@ typedef enum {
 	OP_EXPAND_ARGS,
 	OP_FINALIZE,
 	OP_TUPLE,
+	OP_UNPACK_TUPLE,
 
 	OP_CONSTANT_LONG = 128,
 	OP_DEFINE_GLOBAL_LONG,
@@ -91,6 +92,7 @@ typedef enum {
 	OP_INC_LONG,
 	OP_KWARGS_LONG,
 	OP_TUPLE_LONG,
+	OP_UNPACK_TUPLE_LONG,
 } KrkOpCode;
 
 typedef struct {

compiler.c

@@ -1174,7 +1174,11 @@ static void forStatement() {
 	beginScope();
 
 	ssize_t loopInd = current->localCount;
-	varDeclaration();
+	ssize_t varCount = 0;
+	do {
+		varDeclaration();
+		varCount++;
+	} while (match(TOKEN_COMMA));
 
 	int loopStart;
 	int exitJump;
@@ -1212,17 +1216,27 @@ static void forStatement() {
 
 		/* Get the loop iterator again */
 		EMIT_CONSTANT_OP(OP_GET_LOCAL, indLoopIter);
-		emitBytes(OP_EQUAL, OP_NOT);
-		exitJump = emitJump(OP_JUMP_IF_FALSE);
+		emitByte(OP_EQUAL);
+		exitJump = emitJump(OP_JUMP_IF_TRUE);
 		emitByte(OP_POP);
 
+		if (varCount > 1) {
+			EMIT_CONSTANT_OP(OP_GET_LOCAL, loopInd);
+			EMIT_CONSTANT_OP(OP_UNPACK_TUPLE, varCount);
+			for (ssize_t i = loopInd + varCount - 1; i >= loopInd; i--) {
+				EMIT_CONSTANT_OP(OP_SET_LOCAL, i);
+				emitByte(OP_POP);
+			}
+		}
+
 	} else {
 		consume(TOKEN_SEMICOLON,"expect ; after var declaration in for loop");
 		loopStart = currentChunk()->count;
 
-
 		beginScope();
-		expression(); /* condition */
+		do {
+			expression(); /* condition */
+		} while (match(TOKEN_COMMA));
 		endScope();
 		exitJump = emitJump(OP_JUMP_IF_FALSE);
 		emitByte(OP_POP);
@@ -1232,7 +1246,9 @@ static void forStatement() {
 			int bodyJump = emitJump(OP_JUMP);
 			int incrementStart = currentChunk()->count;
 			beginScope();
-			expression();
+			do {
+				expression();
+			} while (match(TOKEN_COMMA));
 			endScope();
 			emitByte(OP_POP);
 

debug.c

@@ -140,6 +140,7 @@ size_t krk_disassembleInstruction(FILE * f, KrkFunction * func, size_t offset) {
 		OPERAND(OP_CALL, (void)0)
 		OPERAND(OP_INC, (void)0)
 		OPERAND(OP_TUPLE, (void)0)
+		OPERAND(OP_UNPACK_TUPLE, (void)0)
 		JUMP(OP_JUMP,+)
 		JUMP(OP_JUMP_IF_FALSE,+)
 		JUMP(OP_JUMP_IF_TRUE,+)

test/testUnpackIter.krk

@@ -0,0 +1,31 @@
+for k,v in [(1,2),(3,4),(5,6)]:
+    print(k,v)
+# 1 2
+# 3 4
+# 5 6
+
+try:
+    for k,v,z in [(1,2,7),(3,4,8),(5,6)]:
+        print(k,v,z)
+except:
+    print(exception.__class__.__name__)
+# 1 2 7
+# 3 4 8
+# ValueError
+
+try:
+    for k,v in [1,2,3]:
+        print("type error")
+except:
+    print(exception.__class__.__name__)
+# TypeError
+
+for k, v in {'a': 1, 2: 'b'}.items():
+    print(k,v)
+# a 1
+# 2 b
+
+for i in {'a': 1, 2: 'b'}.items():
+    print(i)
+# ('a', 1)
+# (2, 'b')

test/testUnpackIter.krk.expect

@@ -0,0 +1,11 @@
+1 2
+3 4
+5 6
+1 2 7
+3 4 8
+ValueError
+TypeError
+a 1
+2 b
+('a', 1)
+(2, 'b')

vm.c

@@ -3559,6 +3559,24 @@ static KrkValue run() {
 				}
 				break;
 			}
+			case OP_UNPACK_TUPLE_LONG:
+			case OP_UNPACK_TUPLE: {
+				size_t count = readBytes(frame, operandWidth);
+				KrkValue tuple = krk_peek(0);
+				if (!IS_TUPLE(tuple)) {
+					krk_runtimeError(vm.exceptions.typeError, "Can not unpack non-tuple '%s'", krk_typeName(tuple));
+					goto _finishException;
+				} else if (AS_TUPLE(tuple)->values.count != count) {
+					krk_runtimeError(vm.exceptions.valueError, "Wrong number of values to unpack (wanted %d, got %d)", (int)count, (int)AS_TUPLE(tuple)->values.count);
+					goto _finishException;
+				}
+				/* Unpack from 1 to end, then unpack 0 into bottom slot */
+				for (size_t i = 1; i < AS_TUPLE(tuple)->values.count; ++i) {
+					krk_push(AS_TUPLE(tuple)->values.values[i]);
+				}
+				vm.stackTop[-count] = AS_TUPLE(tuple)->values.values[0];
+				break;
+			}
 		}
 		if (!(vm.flags & KRK_HAS_EXCEPTION)) continue;
 _finishException: