Opening files by UTF-8 path on every platform. More...

#include <concepts>
#include <cstdio>
#include <filesystem>
#include <string>
#include <type_traits>

Include dependency graph for FileIO.hpp:

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Namespaces
namespace	openswmm

namespace	openswmm::io

Functions
std::filesystem::path	openswmm::io::utf8_path (const std::string &utf8)
	Convert borrowed path bytes into an owned native filesystem path.

template<class P> requires std::same_as<std::remove_cvref_t<P>, std::filesystem::path>
std::filesystem::path	openswmm::io::utf8_path (P &&)=delete
	Passing an `fs::path` to `utf8_path()` is always a mistake — refuse it at compile time, on EVERY platform.

std::string	openswmm::io::path_utf8 (const std::filesystem::path &p, bool generic=false)
	Copy a native path into the engine byte-string representation.

template<class S> requires (!std::same_as<std::remove_cvref_t<S>, std::filesystem::path>)
std::string	openswmm::io::path_utf8 (S &&, bool=false)=delete
	The mirror guard: `path_utf8()` takes a path, never a string.

std::FILE *	openswmm::io::fopen_path (const std::filesystem::path &p, const char *mode)
	Open a borrowed native path using platform C stdio.

std::FILE *	openswmm::io::fopen_utf8 (const std::string &utf8, const char *mode)
	Convert engine path bytes and open a C stdio stream.

Detailed Description

Opening files by UTF-8 path on every platform.

Paths reach the engine as UTF-8 std::string — that is what the GUI hands over (QString::toUtf8), what the C API documents, and what a UTF-8 .inp carries in [FILES].

On POSIX a path is an opaque byte string, so UTF-8 bytes go straight through. On Windows they do not: the narrow char* file APIs — std::fopen, and the const char* fstream constructors — interpret their argument in the process's ACTIVE ANSI CODE PAGE (CP936/GBK on a Chinese system, CP1252 on a Western one), never as UTF-8. A path such as

C:/…/模拟情景8/模拟情景[8].inp

is therefore mangled before it reaches the filesystem and the open fails with a plain "no such file" — issue #7.

std::filesystem::path is the fix because on Windows it stores wchar_t natively and the standard fstream/fopen-equivalent overloads that take a path use the wide APIs. The trap is that path(const std::string&) assumes the NATIVE NARROW encoding, so simply switching to fs::path fixes nothing; the input has to be declared as UTF-8, which is what utf8_path() below does.

Author: Caleb Buahin caleb.nosp@m..bua.nosp@m.hin@g.nosp@m.mail.nosp@m..com

License: Apache-2.0

Namespaces

Functions

Detailed Description