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96 lines
2.8 KiB
C++
96 lines
2.8 KiB
C++
/*
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* This file is part of RGBDS.
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*
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* Copyright (c) 2022, Eldred Habert and RGBDS contributors.
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*
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* SPDX-License-Identifier: MIT
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*/
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#ifndef RGBDS_FILE_HPP
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#define RGBDS_FILE_HPP
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#include <array>
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#include <assert.h>
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#include <cassert>
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#include <fcntl.h>
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#include <filesystem>
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#include <fstream>
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#include <ios>
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#include <iostream>
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#include <streambuf>
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#include <string>
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#include <string.h>
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#include <string_view>
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#include <variant>
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#include "helpers.h"
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#include "platform.h"
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#include "gfx/main.hpp"
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// Convenience feature for visiting the below.
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template<typename... Ts>
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struct Visitor : Ts... {
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using Ts::operator()...;
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};
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template<typename... Ts>
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Visitor(Ts...) -> Visitor<Ts...>;
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class File {
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// Construct a `std::streambuf *` by default, since it's probably lighter than a `filebuf`.
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std::variant<std::streambuf *, std::filebuf> _file;
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public:
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File() {}
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~File() { close(); }
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/**
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* This should only be called once, and before doing any `->` operations.
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* Returns `nullptr` on error, and a non-null pointer otherwise.
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*/
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File *open(std::filesystem::path const &path, std::ios_base::openmode mode) {
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if (path != "-") {
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return _file.emplace<std::filebuf>().open(path, mode) ? this : nullptr;
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} else if (mode & std::ios_base::in) {
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assert(!(mode & std::ios_base::out));
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_file.emplace<std::streambuf *>(std::cin.rdbuf());
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if (setmode(STDIN_FILENO, mode & std::ios_base::binary ? O_BINARY : O_TEXT) == -1) {
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fatal("Failed to set stdin to %s mode: %s",
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mode & std::ios_base::binary ? "binary" : "text", strerror(errno));
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}
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} else {
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assert(mode & std::ios_base::out);
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_file.emplace<std::streambuf *>(std::cout.rdbuf());
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}
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return this;
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}
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std::streambuf &operator*() {
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return std::visit(Visitor{[](std::filebuf &file) -> std::streambuf & { return file; },
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[](std::streambuf *buf) -> std::streambuf & { return *buf; }},
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_file);
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}
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std::streambuf const &operator*() const {
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// The non-`const` version does not perform any modifications, so it's okay.
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return **const_cast<File *>(this);
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}
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std::streambuf *operator->() { return &**this; }
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std::streambuf const *operator->() const {
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// See the `operator*` equivalent.
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return const_cast<File *>(this)->operator->();
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}
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File *close() {
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return std::visit(Visitor{[this](std::filebuf &file) {
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// This is called by the destructor, and an explicit `close`
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// shouldn't close twice.
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_file.emplace<std::streambuf *>(nullptr);
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return file.close() != nullptr;
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},
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[](std::streambuf *buf) { return buf != nullptr; }},
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_file)
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? this
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: nullptr;
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}
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};
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#endif // RGBDS_FILE_HPP
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