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/******************************************************************************
* ____ _ _____ *
* / ___| / \ | ___| C++ *
* | | / _ \ | |_ Actor *
* | |___ / ___ \| _| Framework *
* \____/_/ \_|_| *
* *
* Copyright 2011-2019 Dominik Charousset *
* *
* Distributed under the terms and conditions of the BSD 3-Clause License or *
* (at your option) under the terms and conditions of the Boost Software *
* License 1.0. See accompanying files LICENSE and LICENSE_ALTERNATIVE. *
* *
* If you did not receive a copy of the license files, see *
* http://opensource.org/licenses/BSD-3-Clause and *
* http://www.boost.org/LICENSE_1_0.txt. *
******************************************************************************/
#pragma once
#include <cctype>
#include <cstdint>
#include "caf/fwd.hpp"
#include "caf/pec.hpp"
#include "caf/string_view.hpp"
namespace caf {
/// Stores all informations necessary for implementing an FSM-based parser.
template <class Iterator, class Sentinel>
struct parser_state {
/// Current position of the parser.
Iterator i;
/// End-of-input marker.
Sentinel e;
/// Current state of the parser.
pec code;
/// Current line in the input.
int32_t line;
/// Position in the current line.
int32_t column;
parser_state() noexcept : i(), e(), code(pec::success), line(1), column(1) {
// nop
}
explicit parser_state(Iterator first) noexcept : parser_state() {
i = first;
}
parser_state(Iterator first, Sentinel last) noexcept : parser_state() {
i = first;
e = last;
}
/// Returns the null terminator when reaching the end of the string,
/// otherwise the next character.
char next() noexcept {
++i;
++column;
if (i != e) {
auto c = *i;
if (c == '\n') {
++line;
column = 1;
}
return c;
}
return '\0';
}
/// Returns the null terminator if `i == e`, otherwise the current character.
char current() const noexcept {
return i != e ? *i : '\0';
}
/// Checks whether `i == e`.
bool at_end() const noexcept {
return i == e;
}
/// Skips any whitespaces characters in the input.
void skip_whitespaces() noexcept {
auto c = current();
while (isspace(c))
c = next();
}
/// Tries to read `x` as the next character, automatically skipping leading
/// whitespaces.
bool consume(char x) noexcept {
skip_whitespaces();
if (current() == x) {
next();
return true;
}
return false;
}
/// Consumes the next character if it satisfies given predicate, automatically
/// skipping leading whitespaces.
template <class Predicate>
bool consume_if(Predicate predicate) noexcept {
skip_whitespaces();
if (predicate(current())) {
next();
return true;
}
return false;
}
/// Tries to read `x` as the next character without automatically skipping
/// leading whitespaces.
bool consume_strict(char x) noexcept {
if (current() == x) {
next();
return true;
}
return false;
}
/// Consumes the next character if it satisfies given predicate without
/// automatically skipping leading whitespaces.
template <class Predicate>
bool consume_strict_if(Predicate predicate) noexcept {
if (predicate(current())) {
next();
return true;
}
return false;
}
};
/// Returns an error object from the current code in `ps` as well as its
/// current position.
template <class Iterator, class Sentinel>
auto make_error(const parser_state<Iterator, Sentinel>& ps)
-> decltype(make_error(ps.code, ps.line, ps.column)) {
return make_error(ps.code, ps.line, ps.column);
}
/// Specialization for parsers operating on string views.
using string_parser_state = parser_state<string_view::iterator>;
} // namespace caf
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