interpret.c

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    /* pop past local variables */
    StackP = FrameP;
    
    /* get stored return information */
    nArgs = (--StackP)->val.n;
    FrameP = (--StackP)->val.dataval;
    PC = (--StackP)->val.inst;
    
    /* pop past function arguments */
    StackP -= nArgs;
    
    /* push returned value, if requsted */
    if (PC == NULL) {
	if (valOnStack) {
    	    PUSH(retVal);
	} else {
	    PUSH(noValue);
	}
    } else if (*PC == fetchRetVal) {
	if (valOnStack) {
    	    PUSH(retVal);
	    PC++;
	} else {
	    return execError(
	    	"using return value of %s which does not return a value",
	    	((Symbol *)*(PC - 2))->name);
	}
    }
    
    /* NULL return PC indicates end of program */
    return PC == NULL ? STAT_DONE : STAT_OK;
}

/*
** Unconditional branch offset by immediate operand
**
** Before: Prog->  [branchDest], next, ..., (branchdest)next
** After:  Prog->  branchDest, next, ..., (branchdest)[next]
*/
static int branch(void)
{
    DISASM_RT(PC-1, 2);
    STACKDUMP(0, 3);

    PC += (int)*PC;
    return STAT_OK;
}

/*
** Conditional branches if stack value is True/False (non-zero/0) to address
** of immediate operand (pops stack)
**
** Before: Prog->  [branchDest], next, ..., (branchdest)next
** After:  either: Prog->  branchDest, [next], ...
** After:  or:     Prog->  branchDest, next, ..., (branchdest)[next]
*/
static int branchTrue(void)
{
    int value;
    Inst *addr;
    
    DISASM_RT(PC-1, 2);
    STACKDUMP(1, 3);

    POP_INT(value)
    addr = PC + (int)*PC;
    PC++;
    
    if (value)
    	PC = addr;
    return STAT_OK;
}
static int branchFalse(void)
{
    int value;
    Inst *addr;
    
    DISASM_RT(PC-1, 2);
    STACKDUMP(1, 3);

    POP_INT(value)
    addr = PC + (int)*PC;
    PC++;
    
    if (!value)
    	PC = addr;
    return STAT_OK;
}

/*
** Ignore the address following the instruction and continue.  Why? So
** some code that uses conditional branching doesn't have to figure out
** whether to store a branch address.
**
** Before: Prog->  [branchDest], next, ...
** After:  Prog->  branchDest, [next], ...
*/
static int branchNever(void)
{
    DISASM_RT(PC-1, 2);
    STACKDUMP(0, 3);

    PC++;
    return STAT_OK;
}

/*
** recursively copy(duplicate) the sparse array nodes of an array
** this does not duplicate the key/node data since they are never
** modified, only replaced
*/
int ArrayCopy(DataValue *dstArray, DataValue *srcArray)
{
    SparseArrayEntry *srcIter;
    
    dstArray->tag = ARRAY_TAG;
    dstArray->val.arrayPtr = ArrayNew();
    
    srcIter = arrayIterateFirst(srcArray);
    while (srcIter) {
        if (srcIter->value.tag == ARRAY_TAG) {
            int errNum;
            DataValue tmpArray;
            
            errNum = ArrayCopy(&tmpArray, &srcIter->value);
            if (errNum != STAT_OK) {
                return(errNum);
            }
            if (!ArrayInsert(dstArray, srcIter->key, &tmpArray)) {
                return(execError("array copy failed", NULL));
            }
        }
        else {
            if (!ArrayInsert(dstArray, srcIter->key, &srcIter->value)) {
                return(execError("array copy failed", NULL));
            }
        }
        srcIter = arrayIterateNext(srcIter);
    }
    return(STAT_OK);
}

/*
** creates an allocated string of a single key for all the sub-scripts
** using ARRAY_DIM_SEP as a separator
** this function uses the PEEK macros in order to remove most limits on
** the number of arguments to an array
** I really need to optimize the size approximation rather than assuming
** a worst case size for every integer argument
*/
static int makeArrayKeyFromArgs(int nArgs, char **keyString, int leaveParams)
{
    DataValue tmpVal;
    int maxIntDigits = (sizeof(tmpVal.val.n) * 3) + 1;
    int sepLen = strlen(ARRAY_DIM_SEP);
    int keyLength = 0;
    int i;

    keyLength = sepLen * (nArgs - 1);
    for (i = nArgs - 1; i >= 0; --i) {
        PEEK(tmpVal, i)
        if (tmpVal.tag == INT_TAG) {
            keyLength += maxIntDigits;
        }
        else if (tmpVal.tag == STRING_TAG) {
            keyLength += strlen(tmpVal.val.str);
        }
        else {
            return(execError("can only index array with string or int.", NULL));
        }
    }
    *keyString = AllocString(keyLength + 1);
    (*keyString)[0] = 0;
    for (i = nArgs - 1; i >= 0; --i) {
        if (i != nArgs - 1) {
            strcat(*keyString, ARRAY_DIM_SEP);
        }
        PEEK(tmpVal, i)
        if (tmpVal.tag == INT_TAG) {
            sprintf(&((*keyString)[strlen(*keyString)]), "%d", tmpVal.val.n);
        }
        else if (tmpVal.tag == STRING_TAG) {
            strcat(*keyString, tmpVal.val.str);
        }
        else {
            return(execError("can only index array with string or int.", NULL));
        }
    }
    if (!leaveParams) {
        for (i = nArgs - 1; i >= 0; --i) {
            POP(tmpVal)
        }
    }
    return(STAT_OK);
}

/*
** allocate an empty array node, this is used as the root node and never
** contains any data, only refernces to other nodes
*/
static rbTreeNode *arrayEmptyAllocator(void)
{
    SparseArrayEntry *newNode = allocateSparseArrayEntry();
    if (newNode) {
        newNode->key = NULL;
        newNode->value.tag = NO_TAG;
    }
    return((rbTreeNode *)newNode);
}

/*
** create and copy array node and copy contents, we merely copy pointers
** since they are never modified, only replaced
*/
static rbTreeNode *arrayAllocateNode(rbTreeNode *src)
{
    SparseArrayEntry *newNode = allocateSparseArrayEntry();
    if (newNode) {
        newNode->key = ((SparseArrayEntry *)src)->key;
        newNode->value = ((SparseArrayEntry *)src)->value;
    }
    return((rbTreeNode *)newNode);
}

/*
** copy array node data, we merely copy pointers since they are never
** modified, only replaced
*/
static int arrayEntryCopyToNode(rbTreeNode *dst, rbTreeNode *src)
{
    ((SparseArrayEntry *)dst)->key = ((SparseArrayEntry *)src)->key;
    ((SparseArrayEntry *)dst)->value = ((SparseArrayEntry *)src)->value;
    return(1);
}

/*
** compare two array nodes returning an integer value similar to strcmp()
*/
static int arrayEntryCompare(rbTreeNode *left, rbTreeNode *right)
{
    return(strcmp(((SparseArrayEntry *)left)->key, ((SparseArrayEntry *)right)->key));
}

/*
** dispose an array node, garbage collection handles this, so we mark it
** to allow iterators in macro language to determine they have been unlinked
*/
static void arrayDisposeNode(rbTreeNode *src)
{
    /* Let garbage collection handle this but mark it so iterators can tell */
    src->left = NULL;
    src->right = NULL;
    src->parent = NULL;
    src->color = -1;
}

struct SparseArrayEntry *ArrayNew(void)
{
	return((struct SparseArrayEntry *)rbTreeNew(arrayEmptyAllocator));
}

/*
** insert a DataValue into an array, allocate the array if needed
** keyStr must be a string that was allocated with AllocString()
*/
int ArrayInsert(DataValue *theArray, char *keyStr, DataValue *theValue)
{
    SparseArrayEntry tmpEntry;
    rbTreeNode *insertedNode;
    
    tmpEntry.key = keyStr;
    tmpEntry.value = *theValue;
    
    if (theArray->val.arrayPtr == NULL) {
        theArray->val.arrayPtr = ArrayNew();
    }
    if (theArray->val.arrayPtr != NULL) {
        insertedNode = rbTreeInsert((rbTreeNode *)(theArray->val.arrayPtr),
            (rbTreeNode *)&tmpEntry,
            arrayEntryCompare, arrayAllocateNode, arrayEntryCopyToNode);
        if (insertedNode) {
            return(1);
        }
        else {
            return(0);
        }
    }
    return(0);
}

/*
** remove a node from an array whose key matches keyStr
*/
void ArrayDelete(DataValue *theArray, char *keyStr)
{
    SparseArrayEntry searchEntry;

    if (theArray->val.arrayPtr) {
        searchEntry.key = keyStr;
        rbTreeDelete((rbTreeNode *)theArray->val.arrayPtr, (rbTreeNode *)&searchEntry,
                    arrayEntryCompare, arrayDisposeNode);
    }
}

/*
** remove all nodes from an array
*/
void ArrayDeleteAll(DataValue *theArray)
{
    
    if (theArray->val.arrayPtr) {
        rbTreeNode *iter = rbTreeBegin((rbTreeNode *)theArray->val.arrayPtr);
        while (iter) {
            rbTreeNode *nextIter = rbTreeNext(iter);
            rbTreeDeleteNode((rbTreeNode *)theArray->val.arrayPtr,
                        iter, arrayDisposeNode);

            iter = nextIter;
        }
    }
}

/*
** returns the number of elements (nodes containing values) of an array
*/
int ArraySize(DataValue *theArray)
{
    if (theArray->val.arrayPtr) {
        return(rbTreeSize((rbTreeNode *)theArray->val.arrayPtr));
    }
    else {
        return(0);
    }
}

/*
** retrieves an array node whose key matches
** returns 1 for success 0 for not found
*/
int ArrayGet(DataValue *theArray, char *keyStr, DataValue *theValue)
{
    SparseArrayEntry searchEntry;
    rbTreeNode *foundNode;

    if (theArray->val.arrayPtr) {
        searchEntry.key = keyStr;
        foundNode = rbTreeFind((rbTreeNode *)theArray->val.arrayPtr,
                (rbTreeNode *)&searchEntry, arrayEntryCompare);
        if (foundNode) {
            *theValue = ((SparseArrayEntry *)foundNode)->value;
            return(1);
        }
    }
    return(0);
}

/*
** get pointer to start iterating an array
*/
SparseArrayEntry *arrayIterateFirst(DataValue *theArray)
{
    SparseArrayEntry *startPos;
    if (theArray->val.arrayPtr) {
        startPos = (SparseArrayEntry *)rbTreeBegin((rbTreeNode *)theArray->val.arrayPtr);
    }
    else {
        startPos = NULL;
    }
    return(startPos);
}

/*
** move iterator to next entry in array
*/
SparseArrayEntry *arrayIterateNext(SparseArrayEntry *iterator)
{
    SparseArrayEntry *nextPos;
    if (iterator) {
        nextPos = (SparseArrayEntry *)rbTreeNext((rbTreeNode *)iterator);
    }
    else {
        nextPos = NULL;
    }
    return(nextPos);
}

/*
** evaluate an array element and push the result onto the stack
**
** Before: Prog->  [nDim], next, ...
**         Stack-> indnDim, ... ind1, ArraySym, next, ...
** After:  Prog->  nDim, [next], ...
**         Stack-> indexedArrayVal, next, ...
*/
static int arrayRef(void)
{
    int errNum;
    DataValue srcArray, valueItem;
    char *keyString = NULL;
    int nDim;
    
    nDim = (int)*PC;
    PC++;

    DISASM_RT(PC-2, 2);
    STACKDUMP(nDim, 3);

    if (nDim > 0) {
        errNum = makeArrayKeyFromArgs(nDim, &keyString, 0);
        if (errNum != STAT_OK) {
            return(errNum);
        }

        POP(srcArray)
        if (srcArray.tag == ARRAY_TAG) {
            if (!ArrayGet(&srcArray, keyString, &valueItem)) {
                return(execError("referenced array value not in array: %s", keyString));
            }
            PUSH(valueItem)
            return(STAT_OK);
        }
        else {
            return(execError("operator [] on non-array", NULL));
        }
    }
    else {
        POP(srcArray)
        if (srcArray.tag == ARRAY_TAG) {
            PUSH_INT(ArraySize(&srcArray))
            return(STAT_OK);
        }
        else {
            return(execError("operator [] on non-array", NULL));
        }
    }
}

/*
** assign to an array element of a referenced array on the stack
**
** Before: Prog->  [nDim], next, ...
**         Stack-> rhs, indnDim, ... ind1, ArraySym, next, ...
** After:  Prog->  nDim, [next], ...
**         Stack-> next, ...
*/
static int arrayAssign(void)
{
    char *keyString = NULL;
    DataValue srcValue, dstArray;
    int errNum;
    int nDim;
    
    nDim = (int)*PC;
    PC++;

    DISASM_RT(PC-2, 1);
    STACKDUMP(nDim, 3);

    if (nDim > 0) {