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Refactor read_file and read_wfile: switch to daw::string_view, … #579

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Merged
beached merged 1 commit into from
Oct 3, 2026
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Refactor read_file and read_wfile: switch to daw::string_view, … #579

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70 changes: 39 additions & 31 deletions include/daw/daw_read_file.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,9 +8,10 @@

#pragma once

#include "ciso646.h"
#include "daw_attributes.h"
#include "daw_traits.h"
#include "daw/ciso646.h"
#include "daw/daw_attributes.h"
#include "daw/daw_string_view.h"
#include "daw/daw_traits.h"

#include <cstddef>
#include <cstdio>
Expand All @@ -19,95 +20,102 @@
#include <iostream>
#include <optional>
#include <string>
#include <string_view>
#include <utility>

namespace daw {
template<typename CharT = char>
DAW_ATTRIB_NOINLINE std::optional<std::basic_string<CharT>>
read_file( std::string const &path ) {
read_file( daw::string_view path ) {
auto ec = std::error_code{ };
auto const fsize = std::filesystem::file_size( path, ec );
auto const fsize =
std::filesystem::file_size( std::string_view( path ), ec );
if( ec ) {
return std::nullopt;
}
if( fsize == 0 ) {
return std::basic_string<CharT>{ };
if( fsize % sizeof( CharT ) != 0 ) {
return std::nullopt;
}
auto const element_count = fsize / sizeof( CharT );
if( static_cast<std::uintmax_t>( std::basic_string<CharT>{ }.max_size( ) ) <
fsize ) {
element_count ) {
// File is too big to fit into string(WIN32)
return std::nullopt;
}
auto result =
std::basic_string<CharT>( static_cast<std::size_t>( fsize ), CharT{ } );
auto result = std::basic_string<CharT>(
static_cast<std::size_t>( element_count ), CharT{ } );
#if defined( _MSC_VER )
FILE *f = nullptr;
auto err = fopen_s( &f, path.c_str( ), "rb" );
if( err ) {
auto err = fopen_s( &f, path.get_c_str( ).c_str( ), "rb" );
if( err or not f ) {
return std::nullopt;
}
#else
auto *f = fopen( path.c_str( ), "rb" );
auto *f = fopen( path.get_c_str( ).c_str( ), "rb" );
if( not f ) {
return std::nullopt;
}
#endif
auto num_read = fread( result.data( ), sizeof( CharT ), result.size( ), f );
if( num_read != ( result.size( ) / sizeof( CharT ) ) ) {
fclose( f );
auto const num_read =
fread( result.data( ), sizeof( CharT ), result.size( ), f );
auto const close_result = fclose( f );
if( num_read != result.size( ) or close_result != 0 ) {
return std::nullopt;
}
fclose( f );
return result;
}

struct terminate_on_read_file_error_t {};
inline constexpr auto terminate_on_read_file_error =
terminate_on_read_file_error_t{ };

inline std::string read_file( std::string const &path,
inline std::string read_file( daw::string_view path,
terminate_on_read_file_error_t ) {
auto result = read_file( path );
if( not result ) {
std::cerr << "Error: could not open file '" << path << "'\n";
std::terminate( );
}
return *result;
return std::move( *result );
}

#if defined( _MSC_VER )
DAW_ATTRIB_NOINLINE inline std::optional<std::wstring>
read_wfile( std::wstring path ) {
read_wfile( daw::wstring_view path ) {
using CharT = wchar_t;
auto ec = std::error_code{ };
auto const fsize = std::filesystem::file_size( path, ec );
auto const fsize =
std::filesystem::file_size( std::wstring_view( path ), ec );
if( ec ) {
return std::nullopt;
}
if( fsize == 0 ) {
return std::basic_string<CharT>{ };
if( fsize % sizeof( CharT ) != 0 ) {
return std::nullopt;
}
auto const element_count = fsize / sizeof( CharT );
if( static_cast<std::uintmax_t>( std::basic_string<CharT>{ }.max_size( ) ) <
fsize ) {
element_count ) {
// File is too big to fit into string(WIN32)
return std::nullopt;
}
auto result =
std::basic_string<CharT>( static_cast<std::size_t>( fsize ), CharT{ } );
auto result = std::basic_string<CharT>(
static_cast<std::size_t>( element_count ), CharT{ } );
FILE *f = nullptr;
auto err = _wfopen_s( &f, path.c_str( ), L"rb" );
if( err ) {
auto err = _wfopen_s( &f, path.get_c_str( ).c_str( ), L"rb" );
if( err or not f ) {
return std::nullopt;
}
auto num_read = fread( result.data( ), sizeof( CharT ), result.size( ), f );
if( num_read != ( result.size( ) / sizeof( CharT ) ) ) {
auto const num_read =
fread( result.data( ), sizeof( CharT ), result.size( ), f );
auto const close_result = fclose( f );
if( num_read != result.size( ) or close_result != 0 ) {
return std::nullopt;
}
return result;
}

DAW_ATTRIB_NOINLINE inline std::wstring
read_wfile( std::wstring const &path, terminate_on_read_file_error_t ) {
read_wfile( daw::wstring_view path, terminate_on_read_file_error_t ) {
auto result = read_wfile( path );
if( not result ) {
std::wcerr << L"Error: could not open file '" << path << L'\n';
Expand Down
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