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correct_syntax_check.h
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correct_syntax_check.h
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// Copyright 2021 Oganyan Robert
#ifndef OGANYAN_LAMBDA_CALC_CORRECT_SYNTAX_CHECK_H
#define OGANYAN_LAMBDA_CALC_CORRECT_SYNTAX_CHECK_H
#include <iostream>
#include <string>
#include <vector>
#include <cctype>
#include "terms_lib.h"
using std::cout;
using std::string;
using std::vector;
using std::to_string;
// Check if term is correctly written. If not, returns false and prints the mistake.
bool IsSyntaxCorrect(const string &term) {
// Check for correct brackets
int brackets_count = 0;
for (const char &elem : term) {
if (elem == '(') {
brackets_count++;
} else if (elem == ')') {
brackets_count--;
}
if (brackets_count < 0) {
cout << "Invalid syntax: some ending brackets dont belong to opening brackets" << "\n";
return false;
}
}
if (brackets_count < 0) {
cout << "Invalid syntax: invalid syntax: too much of ending brackets" << "\n";
return false;
}
if (brackets_count > 0) {
cout << "Invalid syntax: invalid syntax: too much of opening brackets" << "\n";
return false;
}
// Check for existing lambdas
bool exist_lib_fun = false;
for (char num : term) {
if ((num >= 'A' && num <= 'Z')) {
exist_lib_fun = true;
break;
}
}
if (!exist_lib_fun) {
for (size_t num = 0; num < term.size(); ++num) {
if (term[num] == '\\') {
break;
} else {
if (num == term.size() - 1) {
cout << "There are no lambdas: nothing to reduce" << "\n";
return false;
}
}
}
}
// Check for correct lambda-usages
for (size_t num = 0; num < term.size() - 1; ++num) {
if (term[num] == '\\' && !isalpha(term[num + 1])) {
cout << "Invalid syntax: there is no variable after lambda" << "\n";
return false;
}
}
if (term[term.size() - 1] == '\\') {
cout << "Invalid syntax: there is no variable after lambda" << "\n";
return false;
}
return true;
}
bool IsSyntaxCorrect(const vector<string> &term_vec) {
for (size_t elem = 0; elem < term_vec.size() - 1; ++elem) {
if (term_vec[elem][0] == '\\') {
bool is_correct = false;
for (size_t j = elem + 1; j < term_vec.size(); ++j) {
if (term_vec[j] != ")") {
is_correct = true;
}
}
if (!is_correct) {
cout << "Invalid syntax: there is no variable after lambda" << "\n";
return false;
}
}
}
return true;
}
// Basically just transforms string to vector
vector<string> ParseToVec(string term) {
vector<string> term_vector;
LibFuncs library;
for (size_t num = 0; num < term.size(); ++num) {
if (term[num] == ' ') {
continue;
}
if ((term[num] == ')') || (term[num] == '(')) {
string element;
element += term[num];
term_vector.push_back(element);
continue;
}
string element;
element.push_back(term[num]);
while ((num + 1 < term.size()) &&
term[num + 1] != ' ' &&
term[num + 1] != '(' &&
term[num + 1] != ')') {
element.push_back(term[num + 1]);
++num;
}
if ((element[0] >= 'A') && ((element[0] <= 'Z'))) {
if (!library.exist("There is no such library function!"));
}
term_vector.push_back(element);
}
return term_vector;
}
// Finds library functions in term (such as True, False, etc) and decompose them
bool ChangeLibFuncsToTerms(vector<string> &term_vec) {
LibFuncs library;
while (true) {
bool need_to_parse = false;
string new_term;
for (size_t elem = 0; elem < term_vec.size(); elem++) {
bool found_capital = false;
string cur_term = term_vec[elem];
for (char letter : cur_term) {
if ((letter >= 'A') && (letter <= 'Z')) {
found_capital = true;
break;
}
}
if (!found_capital) {
new_term += cur_term;
if (elem != term_vec.size() - 1) {
new_term += " ";
}
continue;
}
if (cur_term[0] == '\\') {
if (!library.exist(cur_term.substr(1))) {
cout << "Invalid syntax: capital characters can be only used for library functions" << "\n";
return false;
}
} else {
if (!library.exist(cur_term)) {
cout << "Invalid syntax: capital characters can be only used for library functions" << "\n";
return false;
}
}
new_term += library[cur_term];
if (elem != term_vec.size() - 1) {
new_term += " ";
}
need_to_parse = true;
}
term_vec = ParseToVec(new_term);
if (!need_to_parse) break;
}
return true;
}
#endif //OGANYAN_LAMBDA_CALC_CORRECT_SYNTAX_CHECK_H