orga-comp/parser.cpp

#include "orga-comp.h"
#include <iostream>

struct token *
parser::parse_tokens() {
	// LR(k) parsing.
	// Pushea al stack hasta encontrar una cantidad de token suficiente
	// como para saber que hacer.
	// El parse a su vez arma un abstract syntax tree.
	if(pos < _tokens.size()) {
		_stack.push(_tokens[pos]);
		pos++;
		//_stack.push(tok);
		switch (_stack.top()->tok_type) {
			case token::TOK_ID:
				statement();
				break;
			case token::STM_COMPOUND:
				break;
			default:
				err();
				break;
		}
		return parse_tokens();
	}
	/*std::cout << "ESTADO FINAL DEL STACK:\n";
	for(int i = 0; i < _stack.size(); i++) {
		std::cout << str_token(pop()) << " ";
	}*/

	return _stack.top();
	//check if reduce is possible, if it is reduce.
}

parser::parser(std::vector<struct token*> tokens) {
	_tokens = tokens;
	pos = 0;
}

void
parser::reduce() {
	if(_stack.size() == 1) return;
	struct token *tok = pop();
	
//	std::cout << str_token(*tok) << " ";
	switch (tok->tok_type) {
		case token::TOK_NUM:
//			std::cout << "reduzco numero\n";
			reduce_num(tok);
//			reduce();
			break;
        case token::EXP_ID:
		case token::EXP_OPERATION:
		case token::EXP_NUMBER:
			// EL SIGUIENTE ES UN OP O UN ASSIGN
			reduce_exp(tok);
			break;
        case token::TOK_ID:
            reduce_id(tok);
            break;
		case token::TOK_SEMI:
//			reduce();
			break;
//		case token::TOK_ID:
			
		case token::STM_ASSIGN:
			reduce_stm(tok);
		default: break;
	}
	reduce();
}

void
parser::reduce_stm(struct token *stm) {
	struct token *tok = pop();
	struct token *tmp;
	switch (tok->tok_type) {
		case token::STM_ASSIGN:
		case token::STM_COMPOUND:
			tmp = new struct token;
			tmp->tok_type = token::STM_COMPOUND;
			tmp->rvalue = stm;
			tmp->lvalue = tok;
			push(tmp);
//			std::cout << "CHAD STM REDUCER " << str_token(*tmp);
			break;
		default: 
			err();
			break;
	}
}

void
parser::reduce_id(struct token *id) {
    struct token *tmp = new struct token;
	tmp->tok_type = token::EXP_ID;
	tmp->value = id->value;
	push(tmp);
}

void
parser::reduce_num(struct token *num) {
	struct token *tmp = new struct token;
	tmp->tok_type = token::EXP_NUMBER;
	tmp->value = num->value;
	push(tmp);
}

void
parser::reduce_exp(struct token *exp) {
//	std::cout << "reducing exp: " << str_token(*exp) << "\n";
	struct token *modifier = pop();
	struct token *tmp;
	struct token *stm;
	switch (modifier->tok_type) {
		case token::TOK_ASSIGN:
//			std::cout << "assign found\n";
			if(_stack.top()->tok_type != token::TOK_ID) err();
//			std::cout << str_token(*_stack.top()) << "\n";
			stm = new struct token;
			stm->tok_type = token::STM_ASSIGN;
			stm->rvalue = exp;
			stm->value = pop()->value;
			push(stm);
		break;
		case token::TOK_OP:
			if(_stack.top()->tok_type == token::TOK_NUM) {
				reduce_num(pop());
			}
			if(_stack.top()->tok_type == token::TOK_ID) {
				reduce_id(pop());
			}
			stm = new struct token;
			stm->tok_type = token::EXP_OPERATION;
            stm->value = modifier->value;
			stm->rvalue = exp;
			stm->lvalue = pop();
			push(stm);
			//reduce_exp(pop());
		break;
		default: err();
	}
}

struct token *
parser::pop() {
	struct token *tmp = _stack.top();
	_stack.pop();
	return tmp;
}

void
parser::push(struct token *tok) {
	_stack.push(tok);
}

void
parser::statement() {
	_stack.push(_tokens[pos]);
	pos++;
	assert(_stack.top()->tok_type == token::TOK_ASSIGN);
	expression();
}

void
parser::expression() {
	_stack.push(_tokens[pos]);
	pos++;
//	std::cout << "POS: " << pos << '\n';
	switch (_stack.top()->tok_type) {
//		case token::EXP_NUMBER:
//		case token::EXP_ID:
		case token::TOK_ID:
		case token::TOK_NUM:
			expression();
			break;
		case token::EXP_OPERATION:
//			std::cout << "Nested operations not supported\n";
			err();
			break;
		case token::TOK_OP:
			expression();
			break;
		case token::TOK_SEMI:
//			std::cout << "REDUCE\n";
			reduce();
			break;
		default: 
			err();
			break;;
	}
}

void
parser::err() {
	std::cout
	<< "unexpected symbol: "
	<< str_token(*_stack.top())
	<< '\n';
	exit(-1);
}

parser::~parser(){
	free_tree(pop());
//	while (_stack.size() > 0) {
//		delete pop();
//	}
}