void Parser:: Statement() {
switch(lookahead) {
int tempVal;
case T_M:
match(T_M);
match(T_OPENBRACKET);
Expression();
if( evaluate == true) {
tempVal= value;
}
match(T_CLOSEBRACKET);
match(T_EQUALS);
Expression();
if( evaluate == true) {
if( (tempVal<0) || (tempVal>99) ) indexError(scanner.lineNumber(), tempVal);
m[tempVal] = value;
}
break;
case T_PRINT:
match(T_PRINT);
Expression();
if( evaluate == true ) {
std::cout << value << std::endl;
}
break;
default:
parseError(scanner.lineNumber(), lookahead);
break;
}
}
// Factor_Tail-> "*" power Factor_Tail | "/"" power Factor_Tail | Epsolon
void Parser::Factor_Tail()
{
switch (scanner.nextToken()) {
case T_MULTIPLY: // *
{
scanner.eatToken(T_MULTIPLY);
Power();
if (scanner.nextToken() == T_MULTIPLY || scanner.nextToken() == T_DIVIDE)
Factor_Tail();
break;
}
case T_DIVIDE: // /
{
scanner.eatToken(T_DIVIDE);
Power();
if (scanner.nextToken() == T_MULTIPLY || scanner.nextToken() == T_DIVIDE)
Factor_Tail();
break;
}
case T_EOF:
break;
default:
{
parseError(scanner.lineNumber(), scanner.nextToken());
break;
}
}
}
//Exp_Tail -> "+" Factor Exp_Tail | "-" Factor Exp_Tail | EPSOLON
void Parser::Exp_Tail()
{
switch (scanner.nextToken())
{
case T_PLUS: // +
{
scanner.eatToken(T_PLUS);
Factor();
if (scanner.nextToken() == T_PLUS || scanner.nextToken() == T_MINUS)
Exp_Tail();
break;
}
case T_MINUS: // -
{
scanner.eatToken(T_MINUS);
Factor();
if (scanner.nextToken() == T_PLUS || scanner.nextToken() == T_MINUS)
Exp_Tail();
break;
}
case T_EOF:
break;
default:
{
parseError(scanner.lineNumber(), scanner.nextToken());
break;
}
}
}
// final -> Num | "(" Expression ")" | m [ Expression ]
void Parser:: Final()
{
switch (scanner.nextToken())
{
case T_OPENPAREN: // (
{
scanner.eatToken(T_OPENPAREN);
switch(scanner.nextToken())
{
case T_M:
case T_NUMBER:
case T_OPENPAREN:
Expression();
case T_EOF:
break;
}
scanner.eatToken(T_CLOSEPAREN);
break;
}
case T_M: // m
{
scanner.eatToken(T_M);
scanner.eatToken(T_OPENBRACKET);
switch(scanner.nextToken())
{
case T_M:
case T_NUMBER:
case T_OPENPAREN:
Expression();
case T_EOF:
break;
}
scanner.eatToken(T_CLOSEBRACKET);
break;
}
case T_NUMBER: // num
{
scanner.eatToken(T_NUMBER);
num_parser = scanner.getNumberValue();
break;
}
case T_EOF:
break;
default:
{
parseError(scanner.lineNumber(), scanner.nextToken());
break;
}
}
}
void Parser::match(token current_token) {
if(current_token == lookahead) {
scanner.eatToken(current_token);
lookahead = scanner.nextToken();
}
else {
mismatchError(scanner.lineNumber(),current_token , lookahead);
}
}
void Parser::MultDiv_1() {
switch(lookahead) {
int tempVal;
case T_MULTIPLY:
match(T_MULTIPLY);
if( evaluate == true) {
tempVal = value;
}
Exp();
if( evaluate == true) {
value = tempVal * value;
}
MultDiv_1();
break;
case T_DIVIDE:
match(T_DIVIDE);
if( evaluate == true) {
tempVal = value;
}
Exp();
if( evaluate == true) {
if (value == 0 ) divideError(scanner.lineNumber());
value = tempVal / value;
}
MultDiv_1();
break;
case T_SEMICOLON:
case T_EOF:
case T_PLUS:
case T_MINUS:
case T_CLOSEPAREN:
case T_CLOSEBRACKET:
//epsilon
break;
default:
parseError(scanner.lineNumber(), lookahead);
break;
}
}
// power_Tail -> "**" final power_Tail | Epsilon
void Parser::Power_Tail()
{
switch (scanner.nextToken()) {
case T_POWER: // **
{
scanner.eatToken(T_POWER);
Final();
if (scanner.nextToken() == T_POWER)
Power_Tail();
break;
}
case T_EOF:
break;
default:
{
parseError(scanner.lineNumber(), scanner.nextToken());
break;
}
}
}
void Parser::SubAdd_1() {
switch(lookahead) {
int tempVal;
int tempVal_2;
case T_PLUS:
match(T_PLUS);
if( evaluate == true) {
tempVal = value;
}
MultDiv();
if( evaluate == true) {
value = tempVal + value;
}
SubAdd_1();
break;
case T_MINUS:
match(T_MINUS);
if( evaluate == true) {
tempVal_2 = value;
}
MultDiv();
if( evaluate == true) {
value = tempVal_2 - value;
}
SubAdd_1();
break;
case T_SEMICOLON:
case T_EOF:
case T_CLOSEPAREN:
case T_CLOSEBRACKET:
//epsilon
break;
default:
parseError(scanner.lineNumber(), lookahead);
break;
}
}
void Parser::Exp_1(int *p) {
int tempVal;
int q;
int base;
if(lookahead == T_POWER) {
match(T_POWER);
Paren();
if (evaluate == true) {
base = value;
}
Exp_1(&q);
if(evaluate == true) {
*p = pow(base,q);
}
}
else {
//do nothing
switch(lookahead) {
case T_SEMICOLON:
case T_EOF:
case T_PLUS:
case T_MINUS:
case T_MULTIPLY:
case T_DIVIDE:
case T_CLOSEPAREN:
case T_CLOSEBRACKET:
//epsilon
break;
default:
parseError(scanner.lineNumber(), lookahead);
break;
}
if(evaluate == true) {
*p = 1; //default power is set to 1
}
}
}
// Term -> ; Statement Term | Epsolon
void Parser::Term()
{
//cout<< tokenToString(scanner.nextToken()) <<endl;
switch (scanner.nextToken()) {
case T_SEMICOLON: //;
{
scanner.eatToken(T_SEMICOLON);
Statement();
if (scanner.nextToken() == T_SEMICOLON)
Term();
//Term();
break;
}
case T_EOF:
break;
default:
{
parseError(scanner.lineNumber(), scanner.nextToken());
break;
}
}
}
// Statement -> "m" "[" Expression "]" "=" Expression | print Expression
void Parser::Statement()
{
switch(scanner.nextToken())
{
case T_M:
{
scanner.eatToken(T_M);
scanner.eatToken(T_OPENBRACKET);
switch(scanner.nextToken())
{
case T_M:
case T_NUMBER:
case T_OPENPAREN:
Expression();
case T_EOF:
break;
}
scanner.eatToken(T_CLOSEBRACKET);
scanner.eatToken(T_EQUALS);
switch(scanner.nextToken())
{
case T_M:
case T_NUMBER:
case T_OPENPAREN:
Expression();
case T_EOF:
break;
}
break;
}
case T_PRINT:
{
scanner.eatToken(T_PRINT);
switch(scanner.nextToken())
{
case T_M:
case T_NUMBER:
case T_OPENPAREN:
Expression();
case T_EOF:
break;
}
break;
}
case T_EOF:
break;
default:
{
parseError(scanner.lineNumber(), scanner.nextToken());
break;
}
}
}
