Erythro/src/Pointers.c

/*************/
/*GEMWIRE    */
/*    ERYTHRO*/
/*************/

#include <Defs.h>
#include <Data.h>

int PointerTo(int Type) {
    //Type = Type + 1;
    printf("\t\tPointerising a %s\n", TypeNames[Type]);
    // As it stands, the conversion between
    // RET and PTR is +4.
    // TODO: if we add types, increase this number
    // TODO: Make this a proper translation table
    // TODO: More checks! This can go wrong easily!
    if(Type >= RET_CHAR && Type <= RET_VOID) {
        return Type + (PTR_CHAR - RET_CHAR);
    } else {
        DieDecimal("Unable to create a pointer to the desired type", Type);
    }

    return -1;
}

int ValueAt(int Type) {

    printf("\t\tDereferencing a %s\n", TypeNames[Type]);
    //TODO: this is still bullshittery!
    if(Type >= PTR_CHAR && Type <= PTR_VOID) {
        printf("\t\t\tDereference of %s is %s.\r\n", TypeNames[Type], TypeNames[Type - 4]);
        return Type - 4;
    } else {
        DieDecimal("Unable to dereference type", Type);
    }
    return -1;
}

int ParseOptionalPointer() {

    int Type;
    // TODO: THIS IS WRONG AND SHOULD NOT EXIST

    if(CurrentToken.type >= TY_CHAR && CurrentToken.type <= TY_VOID) {
        Type = CurrentToken.type - (TY_CHAR - RET_CHAR);
        printf("\t\tConverting a %s token to a %s type.\n", TokenNames[CurrentToken.type], TypeNames[Type]);
    } else {
        DieDecimal("Illegal type for pointerisation", CurrentToken.type);
    }
    // Recursively scan more *s
    // This makes things like:
    // x = **y;
    // possible.
    while(1) {
        Tokenise(&CurrentToken);
        printf("\t\t\tType on parsing is %d\n", CurrentToken.type);
        if(CurrentToken.type != AR_STAR)
            break;
        
        Type = PointerTo(Type);
    }

    return Type;
}

struct ASTNode* AccessArray() {
    struct ASTNode* LeftNode, *RightNode;
    int ID;

    printf("\tAccessing array %s as requested\r\n", CurrentIdentifier);
    if ((ID = FindSymbol(CurrentIdentifier)) == -1 || Symbols[ID].Structure != ST_ARR)
        DieMessage("Accessing undeclared array", CurrentIdentifier);
    
    LeftNode = ConstructASTLeaf(OP_ADDRESS, Symbols[ID].Type, ID);
    //printf("\t\tCurrent token: %s\r\n", TokenNames[CurrentToken.type]);
    Tokenise(&CurrentToken);
    //printf("\t\tCurrent token: %s\r\n", TokenNames[CurrentToken.type]);

    RightNode = ParsePrecedenceASTNode(0);

    VerifyToken(LI_RBRAS, "]");

    if(!TypeIsInt(RightNode->ExprType))
        Die("Array index is not integer");
    
    printf("\t\tPreparing types - RightNode of type %s must be mutated to LeftNode type %s\r\n", TypeNames[RightNode->ExprType], TypeNames[LeftNode->ExprType]);
    RightNode = MutateType(RightNode, LeftNode->ExprType, OP_ADD);

    LeftNode = ConstructASTNode(OP_ADD, Symbols[ID].Type, LeftNode, NULL, RightNode, 0);
    printf("\tAccessArray: Preparing LeftNode for dereference.\r\n");
    LeftNode = ConstructASTBranch(OP_DEREF, ValueAt(LeftNode->ExprType), LeftNode, 0);
    printf("\tArray Access constructed\r\n");
    return LeftNode;
}