string_utils.hpp

Go to the documentation of this file.

/*
    Copyright (C) 2005 - 2022
    by Guillaume Melquiond <guillaume.melquiond@gmail.com>
    Copyright (C) 2003 by David White <dave@whitevine.net>
    Part of the Battle for Wesnoth Project https://www.wesnoth.org/

    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.

    See the COPYING file for more details.
*/

#pragma once

// Need this to get the default GETTEXT_DOMAIN for VGETTEXT/VNGETTEXT
#include "gettext.hpp"

#include "serialization/string_utils.hpp"

#include <ctime>

class variable_set;

namespace utils {

    namespace detail {
        extern std::string(* evaluate_formula)(const std::string& formula);
    }

/**
 * Determines if a string might contain variables to interpolate.
 * This can allow one to skip future interpolations (plural -- if there is only
 * one interpolation, the savings are not worth this check). In this spirit,
 * precision is sacrificed in the name of efficiency; the check is quick and
 * allows false positives, but there are no false negatives. (A false negative
 * would lead to incorrect behavior, whereas a false positive leads to merely
 * inefficient behavior.) In practice, false positives should be uncommon enough
 * to not worry about.
 */
inline bool might_contain_variables(const std::string &str)
{ return str.find('$') != std::string::npos; }

/**
 * Function which will interpolate variables, starting with '$' in the string
 * 'str' with the equivalent symbols in the given symbol table. If 'symbols'
 * is nullptr, then game event variables will be used instead.
 */
std::string interpolate_variables_into_string(const std::string &str, const std::map<std::string, t_string> * const symbols);
std::string interpolate_variables_into_string(const std::string &str, const std::map<std::string,std::string> * const symbols);
std::string interpolate_variables_into_string(const std::string &str, const variable_set& variables);

/**
 * Function that does the same as the above, for t_stringS.
 * If a change was made, then the t_string's translation is done in this
 * function, rather than at use. This limitation is due to the use of
 * create-time interpolation, rather than use-time.
 */
t_string interpolate_variables_into_tstring(const t_string &str, const variable_set& variables);

/**
 * Format a conjunctive list.
 * @param empty The string to return for an empty list
 * @param elems The list of entries in the list
 * @return The elements of the list joined by "and".
 */
std::string format_conjunct_list(const t_string& empty, const std::vector<t_string>& elems);

/**
 * Format a disjunctive list.
 * @param empty The string to return for an empty list
 * @param elems The list of entries in the list
 * @return The elements of the list joined or "and".
 */
std::string format_disjunct_list(const t_string& empty, const std::vector<t_string>& elems);

/**
 * Formats a timespan into human-readable text for player authentication functions.
 *
 * This is intentionally not a very thorough representation of time intervals.
 * See <https://github.com/wesnoth/wesnoth/issues/6036> for more information.
 *
 * @param time     The timespan in seconds.
 * @param detailed Whether to display more specific values such as "3 months, 2 days,
 *                 30 minutes, and 1 second". If not specified or set to @a false, the
 *                 return value will ONLY include most significant time unit (e.g. "3
 *                 months").
 * @return         A human-readable timespan description.
 *
 * @note The implementation is not very precise because not all months in the Gregorian
 *       calendar have 30 days. Furthermore, it doesn't take into account leap years or
 *       leap seconds. If you need to account for those, you are better off importing
 *       a new library and providing it with more specific information about the start and
 *       end times of the interval; otherwise your next best option is to hire a fortune
 *       teller to manually service your requests every time instead of this function.
 */
std::string format_timespan(std::time_t time, bool detailed = false);
}

/**
 * Implementation functions for the VGETTEXT and VNGETTEXT macros.
 *
 * DO NOT USE DIRECTLY unless you really know what you're doing.
 * See https://github.com/wesnoth/wesnoth/issues/2716 for more info.
 */

std::string vgettext_impl(const char* domain, const char* msgid, const utils::string_map& symbols);

std::string vngettext_impl(const char* domain,
        const char* singular,
        const char* plural,
        int count,
        const utils::string_map& symbols);

/**
 * Handy wrappers around interpolate_variables_into_string and gettext.
 *
 * These should cover most usecases. If you're not sure whether you want
 * these macros or their implementation functions, use these. The only time
 * you should need to use the implementation functions directly is to pass a
 * different textdomain than the current value of GETTEXT_DOMAIN.
 */

#define VGETTEXT(msgid, ...) \
    vgettext_impl(GETTEXT_DOMAIN, msgid, __VA_ARGS__)

#define VNGETTEXT(msgid, msgid_plural, count, ...) \
    vngettext_impl(GETTEXT_DOMAIN, msgid, msgid_plural, count, __VA_ARGS__)

/**
 * Approximately calculates the distance between two strings
 *
 * Inspired in the Levenshtein distance, but made simpler
 * to avoid using recursion and wasting resources.
 *
 * The consequence is that the function gets "lost"
 * after two consecutive differences.
 *
 * @param str_1 First string to compare
 * @param str_2 Second string to compare
 */

int edit_distance_approx(const std::string &str_1, const std::string &str_2);