#include "AST.h"
#include "interp.h"

static void printFunc(AST *args);

int executeExpr(AST *p)
{
    if(p == NULL) return 0;
    switch(p->op){
    case NUM:
	return p->val;
    case SYM:
	return getValue(getSymbol(p));
    case EQ_OP:
	return setValue(getSymbol(p->left),executeExpr(p->right));
    case PLUS_OP:
	return executeExpr(p->left) + executeExpr(p->right);
    case MINUS_OP:
	return executeExpr(p->left) - executeExpr(p->right);
    case MUL_OP:
	return executeExpr(p->left) * executeExpr(p->right);
    case LT_OP:
	return executeExpr(p->left) < executeExpr(p->right);
    case GT_OP:
	return executeExpr(p->left) > executeExpr(p->right);
    case GET_ARRAY_OP:
	return getArray(executeExpr(p->left),executeExpr(p->right));
    case SET_ARRAY_OP:
	return setArray(executeExpr(getNth(p->left,0)),
			executeExpr(getNth(p->left,1)),
			executeExpr(p->right));
    case CALL_OP:
	return executeCallFunc(getSymbol(p->left),p->right);
    case PRINTLN_OP:
	printFunc(p->left);
	return 0;
    default:
	error("unknown operater/statement");
    }
}

static void printFunc(AST *args)
{
    printf((char *)executeExpr(getNth(args,0)),
	   executeExpr(getNth(args,1)));
    printf("\n");
}

/*
 * global variable
 */
void declareVariable(Symbol *vsym,AST *init_value)
{
    if(init_value != NULL){
	vsym->val = executeExpr(init_value);
    }
}

/* 
 * Array
 */
void declareArray(Symbol *a, AST *size)
{
    a->val = (int)malloc(sizeof(int)*executeExpr(size));
}

int getArray(int a, int index)
{
    int *ap;
    ap = (int *)a;
    return ap[index];
}

int setArray(int a,int index,int value)
{
    int *ap;
    ap = (int *)a;
    ap[index] = value;
    return value;
}