Added iterable objects

__iter and __next are now reserved IStrings, OP_NEXT and OP_ITER have also been added. A new token (TOKEN_IN) has been added to the lexer. The parser now supports the for each loop (for i, ... in <object> do ... end).
savedPushed has been removed from the CCompilerState struct.

examples/iterator.cosmo

@@ -0,0 +1,22 @@
+proto Range
+    function __init(self, x)
+        self.max = x
+    end
+
+    function __iter(self)
+        self.i = 0
+        return self
+    end
+
+    function __next(self)
+        if self.i >= self.max then
+            return nil // exit iterator loop
+        end
+
+        return self.i++, self.i
+    end
+end
+
+for i, x in Range(10) do
+    print("was " .. i .. ", now " .. x)
+end

src/cdebug.c

@@ -132,6 +132,10 @@ int disasmInstr(CChunk *chunk, int offset, int indent) {
             return simpleInstruction("OP_SETOBJECT", offset);
         case OP_INVOKE:
             return u8u8OperandInstruction("OP_INVOKE", chunk, offset);
+        case OP_ITER:
+            return simpleInstruction("OP_ITER", offset);
+        case OP_NEXT:
+            return u8u16OperandInstruction("OP_NEXT", chunk, offset);
         case OP_ADD:
             return simpleInstruction("OP_ADD", offset);
         case OP_SUB:

src/clex.c

@@ -13,6 +13,7 @@ CReservedWord reservedWords[] = {
     {TOKEN_FOR, "for", 3},
     {TOKEN_FUNCTION, "function", 8},
     {TOKEN_IF, "if", 2},
+    {TOKEN_IN, "in", 2},
     {TOKEN_LOCAL, "local", 5},
     {TOKEN_NIL, "nil", 3},
     {TOKEN_NOT, "not", 3},

src/clex.h

@@ -52,6 +52,7 @@ typedef enum {
     TOKEN_FUNCTION,
     TOKEN_PROTO,
     TOKEN_IF,
+    TOKEN_IN,
     TOKEN_LOCAL,
     TOKEN_NOT,
     TOKEN_OR,

src/coperators.h

@@ -36,6 +36,8 @@ typedef enum {
     OP_SETOBJECT,
     OP_GETOBJECT,
     OP_INVOKE,
+    OP_ITER, // if stack[top] is an object, __iter is expected and called, else if stack[top] is a dictionary a dummy iterator object is made (SEE: cosmoV_makeIter())
+    OP_NEXT, // if stack[top] is an object, __next is expected and called, expecting uint8_t return values. if stack[top] after calling is nil, jump uint16_t
 
     // ARITHMETIC
     OP_ADD,

src/cparse.c

@@ -35,7 +35,6 @@ typedef struct CCompilerState {
     int localCount;
     int scopeDepth;
     int pushedValues;
-    int savedPushed;
     int expectedValues; 
     struct CCompilerState* enclosing;
 } CCompilerState;
@@ -94,7 +93,6 @@ static void initCompilerState(CParseState* pstate, CCompilerState *ccstate, Func
     ccstate->localCount = 0;
     ccstate->scopeDepth = 0;
     ccstate->pushedValues = 0;
-    ccstate->savedPushed = 0;
     ccstate->expectedValues = 0;
     ccstate->type = type;
     ccstate->function = cosmoO_newFunction(pstate->state);
@@ -362,6 +360,7 @@ static void alignStack(CParseState *pstate, int alignment) {
         writePop(pstate, pstate->compiler->pushedValues - alignment);
     } else if (pstate->compiler->pushedValues < alignment) {
         error(pstate, "Missing expression!");
+        printf("%d < %d\n", pstate->compiler->pushedValues, alignment);
     }
 
     pstate->compiler->pushedValues = alignment;
@@ -746,6 +745,7 @@ ParseRule ruleTable[] = {
     [TOKEN_FUNCTION]        = {anonFunction, NULL, PREC_NONE},
     [TOKEN_PROTO]           = {NULL, NULL, PREC_NONE},
     [TOKEN_IF]              = {NULL, NULL, PREC_NONE},
+    [TOKEN_IN]              = {NULL, NULL, PREC_NONE},
     [TOKEN_LOCAL]           = {NULL, NULL, PREC_NONE},
     [TOKEN_NOT]             = {NULL, NULL, PREC_NONE},
     [TOKEN_OR]              = {NULL, or_,  PREC_OR},
@@ -1091,7 +1091,75 @@ static void localFunction(CParseState *pstate) {
     defineVariable(pstate, var, true);
 }
 
+static void forEachLoop(CParseState *pstate) {
+    beginScope(pstate);
+
+    // mark a slot on the stack as reserved, we do this by declaring a local with no identifer
+    Local *local = &pstate->compiler->locals[pstate->compiler->localCount++];
+    local->depth = pstate->compiler->scopeDepth;
+    local->isCaptured = false;
+    local->name.start = "";
+    local->name.length = 0;
+
+    // how many values does it expect the iterator to return?
+    beginScope(pstate);
+    int values = 0;
+    do {
+        uint16_t funcIdent = parseVariable(pstate, "Expected identifier!", true);
+        defineVariable(pstate, funcIdent, true);
+        values++;
+    } while (match(pstate, TOKEN_COMMA));
+
+    if (values > UINT8_MAX) {
+        error(pstate, "Too many values expected!");
+        return;
+    }
+
+    // after we consume the values, get the dictionary/object/whatever on the stack
+    consume(pstate, TOKEN_IN, "Expected 'in' before iterator!");
+    expression(pstate, 1, true);
+
+    consume(pstate, TOKEN_DO, "Expected 'do' before loop block!");
+
+    writeu8(pstate, OP_ITER); // checks if stack[top] is iterable and makes an iterable object wrapper for CObjs like CObjDict
+
+    int loopStart = getChunk(pstate)->count;
+
+    // OP_NEXT expected a uint8_t after the opcode for how many values __next is expected to return
+    writeu8(pstate, OP_NEXT); 
+    writeu8(pstate, values);
+
+    // after the u8, is a u16 with how far to jump if __next returns nil
+    int jmpPatch = getChunk(pstate)->count;
+    writeu16(pstate, 0xFFFF); // placeholder, we'll patch this later
+
+    // OP_NEXT pushes the values needed
+    valuePushed(pstate, values);
+
+    // compile loop block
+    beginScope(pstate);
+    block(pstate);
+    endScope(pstate);
+
+    // pop all of the values, OP_NEXT will repopulate them
+    endScope(pstate);
+
+    // write jmp back to the start of the loop
+    writeJmpBack(pstate, loopStart);
+    patchJmp(pstate, jmpPatch); // and finally, patch our OP_NEXT
+
+    // remove reserved local
+    endScope(pstate);
+    valuePopped(pstate, 1);
+}
+
 static void forLoop(CParseState *pstate) {
+    // first, check if the next token is an identifier. if it is, this is a for loop for an iterator
+    if (check(pstate, TOKEN_IDENTIFIER)) {
+        forEachLoop(pstate);
+        return;
+    }
+
     beginScope(pstate);
 
     consume(pstate, TOKEN_LEFT_PAREN, "Expected '(' after 'for'");
@@ -1173,7 +1241,7 @@ static int expression(CParseState *pstate, int needed, bool forceNeeded) {
 }
 
 static void expressionStatement(CParseState *pstate) {
-    pstate->compiler->savedPushed = pstate->compiler->pushedValues;
+    int savedPushed = pstate->compiler->pushedValues;
 
     if (match(pstate, TOKEN_VAR)) {
         varDeclaration(pstate, false, 0);
@@ -1205,7 +1273,7 @@ static void expressionStatement(CParseState *pstate) {
     }
 
     // realign the stack
-    alignStack(pstate, pstate->compiler->savedPushed);
+    alignStack(pstate, savedPushed);
 }
 
 static void statement(CParseState *pstate) {

src/cstate.c

@@ -49,6 +49,10 @@ CState *cosmoV_newState() {
     state->iStrings[ISTRING_GETTER] = cosmoO_copyString(state, "__getter", 8);
     state->iStrings[ISTRING_SETTER] = cosmoO_copyString(state, "__setter", 8);
 
+    // for iterators
+    state->iStrings[ISTRING_ITER] = cosmoO_copyString(state, "__iter", 6);
+    state->iStrings[ISTRING_NEXT] = cosmoO_copyString(state, "__next", 6);
+
     // set the IString flags
     for (int i = 0; i < ISTRING_MAX; i++)
         state->iStrings[i]->isIString = true;

src/cstate.h

@@ -18,6 +18,8 @@ typedef enum IStringEnum {
     ISTRING_NEWINDEX,   // __newindex
     ISTRING_GETTER,     // __getter
     ISTRING_SETTER,     // __setter
+    ISTRING_ITER,       // __iter
+    ISTRING_NEXT,       // __next
     ISTRING_MAX
 } IStringEnum;
 

src/cvm.c

@@ -43,6 +43,8 @@ void cosmoV_error(CState *state, const char *format, ...) {
     
     // TODO: push error onto the stack :P
     state->panic = true;
+
+    cosmoV_printStack(state);
 }
 
 CObjUpval *captureUpvalue(CState *state, CValue *local) {
@@ -552,6 +554,72 @@ int cosmoV_execute(CState *state) {
                 invokeMethod(state, object, val, args, nres, 0);
                 break;
             }
+            case OP_ITER: {
+                StkPtr temp = cosmoV_getTop(state, 0); // should be the object/dictionary
+
+                if (!IS_OBJ(*temp)) {
+                    cosmoV_error(state, "Couldn't iterate over non-iterator type %s!", cosmoV_typeStr(*temp));
+                    break;
+                }
+
+                switch (cosmoV_readObj(*temp)->type) {
+                    case COBJ_DICT: {
+                        //CObjDict *dict = (CObjDict*)cosmoV_readObj(*temp);
+
+                        // TODO: add cosmoV_makeIter, which will make a dummy iterable object for dictionaries
+                        cosmoV_error(state, "unimpl. mass ping cpunch!!!!");
+                        break;
+                    }
+                    case COBJ_OBJECT: {
+                        CObjObject *obj = (CObjObject*)cosmoV_readObj(*temp);
+                        CValue val;
+
+                        // grab __iter & call it
+                        if (cosmoO_getIString(state, obj, ISTRING_ITER, &val)) {
+                            cosmoV_pop(state); // pop the object from the stack
+                            cosmoV_pushValue(state, val);
+                            cosmoV_pushValue(state, cosmoV_newObj(obj));
+                            cosmoV_call(state, 1, 1); // we expect 1 return value on the stack, the iterable object
+                        } else {
+                            cosmoV_error(state, "Expected iterable object! '__iter' not defined!");
+                        }
+
+                        break;
+                    }
+                    default: {
+                        cosmoV_error(state, "Couldn't iterate over non-iterator type %s!", cosmoV_typeStr(*temp));
+                        break;
+                    }
+                }
+                break;
+            }
+            case OP_NEXT: {
+                uint8_t nresults = READBYTE();
+                uint16_t jump = READUINT();
+                StkPtr temp = cosmoV_getTop(state, 0); // we don't actually pop this off the stack
+
+                if (!IS_OBJECT(*temp)) {
+                    cosmoV_error(state, "Couldn't iterate over non-iterator type %s!", cosmoV_typeStr(*temp));
+                    break;
+                }
+
+                CObjObject *obj = (CObjObject*)cosmoV_readObj(*temp);
+                CValue val;
+
+                if (cosmoO_getIString(state, obj, ISTRING_NEXT, &val)) {
+                    cosmoV_pushValue(state, val);
+                    cosmoV_pushValue(state, *temp);
+                    cosmoV_call(state, 1, nresults);
+
+                    if (IS_NIL(*(cosmoV_getTop(state, 0)))) { // __next returned a nil, which means to exit the loop
+                        cosmoV_setTop(state, nresults); // pop the return values
+                        frame->pc += jump;
+                    }
+                } else {
+                    cosmoV_error(state, "Expected iterable object! '__next' not defined!");
+                }
+                break;
+            }
             case OP_ADD: { // pop 2 values off the stack & try to add them together
                 NUMBEROP(cosmoV_newNumber, +);
                 break;