dosbox-staging/include/string_utils.h

/*
 *  SPDX-License-Identifier: GPL-2.0-or-later
 *
 *  Copyright (C) 2020-2022  The DOSBox Staging Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#ifndef DOSBOX_STRING_UTILS_H
#define DOSBOX_STRING_UTILS_H

#include "dosbox.h"

#include <cassert>
#include <cstdarg>
#include <cstring>
#include <string>
#include <vector>

template <size_t N>
int safe_sprintf(char (&dst)[N], const char *fmt, ...)
        GCC_ATTRIBUTE(format(printf, 2, 3));

template <size_t N>
int safe_sprintf(char (&dst)[N], const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	const int ret = vsnprintf(dst, N, fmt, args);
	va_end(args);
	return ret;
}

/* Copy a string into C array
 *
 * This function copies string pointed by src to a fixed-size buffer dst.
 * At most N bytes from src are copied, where N is size of dst. If exactly
 * N bytes are copied, then terminating null byte is put into dst, thus
 * buffer overrun is prevented.
 *
 * Function returns pointer to buffer to be compatible with strcpy.
 *
 * This is a safer drop-in replacement for strcpy function (when used to fill
 * buffers, whose size is known at compilation time), however some caveats
 * still apply:
 *
 * - src cannot be null, otherwise the behaviour is undefined
 * - dst and src strings must not overlap, otherwise the behaviour is undefined
 * - src string must be null-terminated, otherwise the behaviour is undefined
 *
 * Usage:
 *
 *     char buffer[2];
 *     safe_strcpy(buffer, "abc");
 *     // buffer is filled with "a"
 */
template <size_t N>
char *safe_strcpy(char (&dst)[N], const char *src) noexcept
{
	assert(src != nullptr);
	assert(src < &dst[0] || src > &dst[N - 1]);
	const auto rcode = safe_sprintf(dst, "%s", src);
	return (rcode >= 0) ? &dst[0] : nullptr;
}

template <size_t N>
char *safe_strcat(char (&dst)[N], const char *src) noexcept
{
	strncat(dst, src, N - strnlen(dst, N) - 1);
	return &dst[0];
}

template <size_t N>
size_t safe_strlen(char (&str)[N]) noexcept
{
	static_assert(N != 0, "zero-length arrays are not supported");
	return strnlen(str, N - 1);
}

template <size_t N>
bool starts_with(const char (&pfx)[N], const char *str) noexcept
{
	return (strncmp(pfx, str, N - 1) == 0);
}

template <size_t N>
bool starts_with(const char (&pfx)[N], const std::string &str) noexcept
{
	return (strncmp(pfx, str.c_str(), N - 1) == 0);
}

bool ends_with(const std::string &str, const std::string &suffix) noexcept;

bool find_in_case_insensitive(const std::string &needle, const std::string &haystack);

// Safely terminate a C string at the given offset
//
// Convert code like: stuff[n] = 0;
//  - "is stuff an integer array?"
//  - "are we setting a counter back to 0?"
//  - "is stuff a valid array?"
//
// To: terminate_str_at(stuff, n);
// which is self-documenting about the type (stuff is a string),
// intent (terminating), and where it's being applied (n);
//
template <typename T, typename INDEX_T>
void terminate_str_at(T *str, INDEX_T i) noexcept
{
	// Check that we're only operating on bona-fide C strings
	static_assert(std::is_same_v<T, char> || std::is_same_v<T, wchar_t>,
	              "Can only reset a *char or *wchar_t with the string-terminator");

	// Check that we don't underflow with a negative index
	assert(std::is_unsigned_v<INDEX_T> || i >= 0);

	// Check that we don't dereferrence a null pointer
	assert(str != nullptr);
	str[i] = '\0';
}

// reset a C string with the string-terminator character
template <typename T>
void reset_str(T *str) noexcept
{
	terminate_str_at(str, 0);
}

bool is_hex_digits(const std::string_view s) noexcept;

bool is_digits(const std::string_view s) noexcept;

void strreplace(char *str, char o, char n);
char *ltrim(char *str);
char *rtrim(char *str);
char *trim(char *str);
char *upcase(char *str);
char *lowcase(char *str);

inline bool is_empty(const char *str) noexcept
{
	return str[0] == '\0';
}

char *strip_word(char *&cmd);

std::string replace(const std::string &str, char old_char, char new_char) noexcept;
void trim(std::string &str, const char trim_chars[] = " \r\t\f\n");
void upcase(std::string &str);
void lowcase(std::string &str);
void strip_punctuation(std::string &str);

// Split a string on an arbitrary character delimiter. Absent string content on
// either side of a delimiter is treated as an empty string. For example:
//   split("abc:", ':') returns {"abc", ""}
//   split(":def", ':') returns {"", "def"}
//   split(":", ':') returns {"", ""}
//   split("::", ':') returns {"", "", ""}
std::vector<std::string> split(const std::string &seq, const char delim);

// Split a string on whitespace, where whitespace can be any of the following:
// ' '    (0x20)  space (SPC)
// '\t'   (0x09)  horizontal tab (TAB)
// '\n'   (0x0a)  newline (LF)
// '\v'   (0x0b)  vertical tab (VT)
// '\f'   (0x0c)  feed (FF)
// '\r'   (0x0d)  carriage return (CR)
// Absent string content on either side of a delimiter is omitted. For example:
//   split("abc") returns {"abc"}
//   split("  a   b   c  ") returns {"a", "b", "c"}
//   split("\t \n abc \r \v def \f \v ") returns {"abc", "def"}
//   split("a\tb\nc\vd e\rf") returns {"a", "b", "c", "d", "e", "f"}
//   split("  ") returns {}
//   split(" ") returns {}
std::vector<std::string> split(const std::string &seq);


// Clear the language if it's set to the POSIX default
void clear_language_if_default(std::string &language);


// UTF-8 support

// Get recommended DOS code page to render the UTF-8 strings to. This
// might not be the code page set using KEYB command, for example due
// to emulated hardware limitations, or duplicated code page numbers
uint16_t UTF8_GetCodePage();

// Convert the UTF-8 string (NFC normalized, otherwise some national
// characters might remain unrecognized) to a format intended for
// display inside emulated environment. 
// Code page '0' means a pure 7-bit ASCII.
void UTF8_RenderForDos(const std::string &str_in, std::string &str_out,
                       const uint16_t code_page = 0);

#endif