void tryEvaluatePrefixOperatorOnStackThenPush(Operator *newToken,Stack *numberStack,Stack *operatorStack)
{
Operator *previousToken=(Operator*)stackPop(operatorStack);
if(previousToken == NULL){
stackPush(newToken,operatorStack);
}
else{
while(previousToken!=NULL)
{
if(((Operator*)newToken)->info->id ==CLOSING_BRACKET_OP){
if(((Operator*)previousToken)->info == NULL){
Throw(ERR_EXPECTING_OPENING_BRACKET);
}else if(((Operator*)previousToken)->info->id == OPENING_BRACKET_OP){
operatorPrefixEvaluate(numberStack ,previousToken);
free(newToken);
if(((Operator*)previousToken)->info->id == OPENING_BRACKET_OP){
previousToken=(Operator*)stackPop(operatorStack);
break;
}
}else {
operatorEvaluate(numberStack,previousToken);
}
}else if(newToken->info->precedence >= previousToken->info->precedence || ((Operator*)newToken)->info->id==OPENING_BRACKET_OP ){
break;
}
else{
operatorEvaluate(numberStack,previousToken);
}
previousToken=(Operator*)stackPop(operatorStack);
}
if(previousToken!=NULL ){
stackPush(previousToken,operatorStack);
}
if(newToken->info->affix == PREFIX){
stackPush(newToken,operatorStack);
}
}
}
/*******************************************************************************************
* This function is to evaluate the expression which contains numbers and operators and
* return the results in number form.
* This function is a prototype function which use as reference to
* improve in the evaluateExpression(char*expression) function.
* Thus, this function could not evaluate expression like -2,*2,(((2))), +-+-2... *
* input : expression
* output : none
* return : ((Number*)token)->value
*
********************************************************************************************/
int evaluate(char *expression){
Token *token;
Number *result;
Stack *numberStack=createStack();
Stack *operatorStack=createStack();
if(expression ==NULL){
Throw(ERR_NO_ARGUMENT);
}
Text *newText=textNew(expression);
String *tokenizer = stringNew(newText);
while((token=getToken(tokenizer))!=NULL ){
if(isNumber(token)){
stackPush(token,numberStack);
} else if(isOperator(token)) {
if(((Operator*)token)->info->id==OPENING_BRACKET_OP || ((Operator*)token)->info->id==CLOSING_BRACKET_OP) {
tryEvaluatePrefixOperatorOnStackThenPush((Operator*)token,numberStack,operatorStack);
} else{
tryEvaluateOperatorOnStackThenPush((Operator*)token,numberStack,operatorStack);
}
}
}
if(operatorStack == NULL){
operatorPrefixEvaluate(numberStack ,(Operator*)token);
}else{
evaluateAllOperatorOnStack(numberStack,operatorStack);
}
result=(Number*)stackPop(numberStack);
destroyStack(numberStack);
if(operatorStack !=NULL){
destroyStack(operatorStack);
}
return result->value;
}
