string_utils.cpp

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/*
    Copyright (C) 2005 - 2025
    by Philippe Plantier <ayin@anathas.org>
    Copyright (C) 2005 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.
*/
 
/**
 * @file
 * Various string-routines.
 */
 
#include "gettext.hpp"
#include "log.hpp"
#include "serialization/string_utils.hpp"
#include "serialization/unicode.hpp"
#include "utils/charconv.hpp"
#include "utils/general.hpp"
#include <array>
#include <limits>
#include "utils/optional_fwd.hpp"
#include <stdexcept>
 
#include <boost/algorithm/string.hpp>
 
static lg::log_domain log_engine("engine");
#define ERR_GENERAL LOG_STREAM(err, lg::general())
#define ERR_NG LOG_STREAM(err, log_engine)
 
namespace utils {
 
bool isnewline(const char c)
{
    return c == '\r' || c == '\n';
}
 
// Make sure that we can use Mac, DOS, or Unix style text files on any system
// and they will work, by making sure the definition of whitespace is consistent
bool portable_isspace(const char c)
{
    // returns true only on ASCII spaces
    if (static_cast<unsigned char>(c) >= 128)
        return false;
    return isnewline(c) || isspace(static_cast<unsigned char>(c));
}
 
// Make sure we regard '\r' and '\n' as a space, since Mac, Unix, and DOS
// all consider these differently.
bool notspace(const char c)
{
    return !portable_isspace(c);
}
 
void trim(std::string_view& s)
{
    s.remove_prefix(std::min(s.find_first_not_of(" \t\r\n"), s.size()));
    if(s.empty()) {
        return;
    }
    //find_last_not_of never returns npos because !s.empty()
    std::size_t first_to_trim = s.find_last_not_of(" \t\r\n") + 1;
    s = s.substr(0, first_to_trim);
}
 
/**
 * Splits a (comma-)separated string into a vector of pieces.
 * @param[in]  s      A (comma-)separated string.
 * @param[in]  sep    The separator character (usually a comma).
 * @param[in]  flags  Flags controlling how the split is done.
 *                    This is a bit field with two settings (both on by default):
 *                    REMOVE_EMPTY causes empty pieces to be skipped/removed.
 *                    STRIP_SPACES causes the leading and trailing spaces of each piece to be ignored/stripped.
 */
std::vector<std::string> split(std::string_view s, const char sep, const int flags)
{
    std::vector<std::string> res;
    split_foreach(s, sep, flags, [&](std::string_view item) {
        res.emplace_back(item);
    });
    return res;
}
 
std::set<std::string> split_set(std::string_view s, char sep, const int flags)
{
    std::set<std::string> res;
    split_foreach(s, sep, flags, [&](std::string_view item) {
        res.emplace(item);
    });
    return res;
}
 
std::vector<std::string_view> split_view(std::string_view s, const char sep, const int flags)
{
    std::vector<std::string_view> res;
    split_foreach(s, sep, flags, [&](std::string_view item) {
        res.push_back(item);
    });
    return res;
}
 
std::vector<std::string> square_parenthetical_split(const std::string& val,
        const char separator, const std::string& left,
        const std::string& right,const int flags)
{
    std::vector< std::string > res;
    std::vector<char> part;
    bool in_parenthesis = false;
    std::vector<std::string::const_iterator> square_left;
    std::vector<std::string::const_iterator> square_right;
    std::vector< std::string > square_expansion;
 
    std::string lp=left;
    std::string rp=right;
 
    std::string::const_iterator i1 = val.begin();
    std::string::const_iterator i2;
    std::string::const_iterator j1;
    if (flags & STRIP_SPACES) {
        while (i1 != val.end() && portable_isspace(*i1))
            ++i1;
    }
    i2=i1;
    j1=i1;
 
    if (i1 == val.end()) return res;
 
    if (!separator) {
        ERR_GENERAL << "Separator must be specified for square bracket split function.";
        return res;
    }
 
    if(left.size()!=right.size()){
        ERR_GENERAL << "Left and Right Parenthesis lists not same length";
        return res;
    }
 
    while (true) {
        if(i2 == val.end() || (!in_parenthesis && *i2 == separator)) {
            //push back square contents
            std::size_t size_square_exp = 0;
            for (std::size_t i=0; i < square_left.size(); i++) {
                std::string tmp_val(square_left[i]+1,square_right[i]);
                std::vector< std::string > tmp = split(tmp_val);
                for(const std::string& piece : tmp) {
                    std::size_t found_tilde = piece.find_first_of('~');
                    if (found_tilde == std::string::npos) {
                        std::size_t found_asterisk = piece.find_first_of('*');
                        if (found_asterisk == std::string::npos) {
                            std::string tmp2(piece);
                            boost::trim(tmp2);
                            square_expansion.push_back(tmp2);
                        }
                        else { //'*' multiple expansion
                            std::string s_begin = piece.substr(0,found_asterisk);
                            boost::trim(s_begin);
                            std::string s_end = piece.substr(found_asterisk+1);
                            boost::trim(s_end);
                            for (int ast=std::stoi(s_end); ast>0; --ast)
                                square_expansion.push_back(s_begin);
                        }
                    }
                    else { //expand number range
                        std::string s_begin = piece.substr(0,found_tilde);
                        boost::trim(s_begin);
                        int begin = std::stoi(s_begin);
                        std::size_t padding = 0, padding_end = 0;
                        while (padding<s_begin.size() && s_begin[padding]=='0') {
                            padding++;
                        }
                        std::string s_end = piece.substr(found_tilde+1);
                        boost::trim(s_end);
                        int end = std::stoi(s_end);
                        while (padding_end<s_end.size() && s_end[padding_end]=='0') {
                            padding_end++;
                        }
                        if (padding*padding_end > 0 && s_begin.size() != s_end.size()) {
                            ERR_GENERAL << "Square bracket padding sizes not matching: "
                                        << s_begin << " and " << s_end <<".";
                        }
                        if (padding_end > padding) padding = padding_end;
 
                        int increment = (end >= begin ? 1 : -1);
                        end+=increment; //include end in expansion
                        for (int k=begin; k!=end; k+=increment) {
                            std::string pb = std::to_string(k);
                            for (std::size_t p=pb.size(); p<=padding; p++)
                                pb = std::string("0") + pb;
                            square_expansion.push_back(pb);
                        }
                    }
                }
                if (i*square_expansion.size() != (i+1)*size_square_exp ) {
                    std::string tmp2(i1, i2);
                    ERR_GENERAL << "Square bracket lengths do not match up: " << tmp2;
                    return res;
                }
                size_square_exp = square_expansion.size();
            }
 
            //combine square contents and rest of string for comma zone block
            std::size_t j = 0;
            std::size_t j_max = 0;
            if (!square_left.empty())
                j_max = square_expansion.size() / square_left.size();
            do {
                j1 = i1;
                std::string new_val;
                for (std::size_t i=0; i < square_left.size(); i++) {
                    std::string tmp_val(j1, square_left[i]);
                    new_val.append(tmp_val);
                    std::size_t k = j+i*j_max;
                    if (k < square_expansion.size())
                        new_val.append(square_expansion[k]);
                    j1 = square_right[i]+1;
                }
                std::string tmp_val(j1, i2);
                new_val.append(tmp_val);
                if (flags & STRIP_SPACES)
                    boost::trim_right(new_val);
                if (!(flags & REMOVE_EMPTY) || !new_val.empty())
                    res.push_back(new_val);
                j++;
            } while (j<j_max);
 
            if (i2 == val.end()) //escape loop
                break;
            ++i2;
            if (flags & STRIP_SPACES) { //strip leading spaces
                while (i2 != val.end() && portable_isspace(*i2))
                    ++i2;
            }
            i1=i2;
            square_left.clear();
            square_right.clear();
            square_expansion.clear();
            continue;
        }
        if(!part.empty() && *i2 == part.back()) {
            part.pop_back();
            if (*i2 == ']') square_right.push_back(i2);
            if (part.empty())
                in_parenthesis = false;
            ++i2;
            continue;
        }
        bool found=false;
        for(std::size_t i=0; i < lp.size(); i++) {
            if (*i2 == lp[i]){
                if (*i2 == '[')
                    square_left.push_back(i2);
                ++i2;
                part.push_back(rp[i]);
                found=true;
                break;
            }
        }
        if(!found){
            ++i2;
        } else
            in_parenthesis = true;
    }
 
    if(!part.empty()){
            ERR_GENERAL << "Mismatched parenthesis:\n"<<val;
    }
 
    return res;
}
 
std::map<std::string, std::string> map_split(
          const std::string& val
        , char major
        , char minor
        , int flags
        , const std::string& default_value)
{
    //first split by major so that we get a vector with the key-value pairs
    std::vector< std::string > v = split(val, major, flags);
 
    //now split by minor to extract keys and values
    std::map< std::string, std::string > res;
 
    for( std::vector< std::string >::iterator i = v.begin(); i != v.end(); ++i) {
        std::size_t pos = i->find_first_of(minor);
        std::string key, value;
 
        if(pos == std::string::npos) {
            key = (*i);
            value = default_value;
        } else {
            key = i->substr(0, pos);
            value = i->substr(pos + 1);
        }
 
        res[key] = value;
    }
 
    return res;
}
 
std::vector<std::string> parenthetical_split(std::string_view val,
        const char separator, std::string_view left,
        std::string_view right,const int flags)
{
    std::vector< std::string > res;
    std::vector<char> part;
    bool in_parenthesis = false;
 
    std::string_view::const_iterator i1 = val.begin();
    std::string_view::const_iterator i2;
    if (flags & STRIP_SPACES) {
        while (i1 != val.end() && portable_isspace(*i1))
            ++i1;
    }
    i2=i1;
 
    if(left.size()!=right.size()){
        ERR_GENERAL << "Left and Right Parenthesis lists not same length";
        return res;
    }
 
    while (i2 != val.end()) {
        if(!in_parenthesis && separator && *i2 == separator){
            std::string new_val(i1, i2);
            if (flags & STRIP_SPACES)
                boost::trim_right(new_val);
            if (!(flags & REMOVE_EMPTY) || !new_val.empty())
                res.push_back(new_val);
            ++i2;
            if (flags & STRIP_SPACES) {
                while (i2 != val.end() && portable_isspace(*i2))
                    ++i2;
            }
            i1=i2;
            continue;
        }
        if(!part.empty() && *i2 == part.back()){
            part.pop_back();
            if(!separator && part.empty()){
                std::string new_val(i1, i2);
                if (flags & STRIP_SPACES)
                    boost::trim(new_val);
                res.push_back(new_val);
                ++i2;
                i1=i2;
            }else{
                if (part.empty())
                    in_parenthesis = false;
                ++i2;
            }
            continue;
        }
        bool found=false;
        for(std::size_t i=0; i < left.size(); i++){
            if (*i2 == left[i]){
                if (!separator && part.empty()){
                    std::string new_val(i1, i2);
                    if (flags & STRIP_SPACES)
                        boost::trim(new_val);
                    res.push_back(new_val);
                    ++i2;
                    i1=i2;
                }else{
                    ++i2;
                }
                part.push_back(right[i]);
                found=true;
                break;
            }
        }
        if(!found){
            ++i2;
        } else
            in_parenthesis = true;
    }
 
    std::string new_val(i1, i2);
    if (flags & STRIP_SPACES)
        boost::trim(new_val);
    if (!(flags & REMOVE_EMPTY) || !new_val.empty())
        res.push_back(std::move(new_val));
 
    if(!part.empty()){
            ERR_GENERAL << "Mismatched parenthesis:\n"<<val;
    }
 
    return res;
}
 
// Modify a number by string representing integer difference, or optionally %
int apply_modifier( const int number, const std::string &amount, const int minimum ) {
    // wassert( amount.empty() == false );
    int value = 0;
    try {
        value = std::stoi(amount);
    } catch(const std::invalid_argument&) {}
    if(amount[amount.size()-1] == '%') {
        value = div100rounded(number * value);
    }
    value += number;
    if (( minimum > 0 ) && ( value < minimum ))
        value = minimum;
    return value;
}
 
std::string escape(std::string_view str, const char *special_chars)
{
    std::string::size_type pos = str.find_first_of(special_chars);
    if (pos == std::string::npos) {
        // Fast path, possibly involving only reference counting.
        return std::string(str);
    }
    std::string res = std::string(str);
    do {
        res.insert(pos, 1, '\\');
        pos = res.find_first_of(special_chars, pos + 2);
    } while (pos != std::string::npos);
    return res;
}
 
std::string unescape(std::string_view str)
{
    std::string::size_type pos = str.find('\\');
    if (pos == std::string::npos) {
        // Fast path, possibly involving only reference counting.
        return std::string(str);
    }
    std::string res = std::string(str);
    do {
        res.erase(pos, 1);
        pos = res.find('\\', pos + 1);
    } while (pos != std::string::npos);
    return res;
}
 
std::string urlencode(std::string_view str)
{
    static const std::string nonresv_str =
        "-."
        "0123456789"
        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        "_"
        "abcdefghijklmnopqrstuvwxyz"
        "~";
    static const std::set<char> nonresv(nonresv_str.begin(), nonresv_str.end());
 
    std::ostringstream res;
    res << std::hex;
    res.fill('0');
 
    for(char c : str) {
        if(nonresv.count(c) != 0) {
            res << c;
            continue;
        }
 
        res << '%';
        res.width(2);
        res << static_cast<int>(c);
    }
 
    return res.str();
}
 
bool string_bool(const std::string& str, bool def) {
    if (str.empty()) return def;
 
    // yes/no is the standard, test it first
    if (str == "yes") return true;
    if (str == "no"|| str == "false" || str == "off" || str == "0" || str == "0.0")
        return false;
 
    // all other non-empty string are considered as true
    return true;
}
 
std::string bool_string(const bool value)
{
    std::ostringstream ss;
    ss << std::boolalpha << value;
 
    return ss.str();
}
 
std::string signed_value(int val)
{
    std::ostringstream oss;
    oss << (val >= 0 ? "+" : font::unicode_minus) << std::abs(val);
    return oss.str();
}
 
std::string half_signed_value(int val)
{
    std::ostringstream oss;
    if (val < 0)
        oss << font::unicode_minus;
    oss << std::abs(val);
    return oss.str();
}
 
static void si_string_impl_stream_write(std::stringstream &ss, double input) {
    std::streamsize oldprec = ss.precision();
#ifdef _MSC_VER
    // For MSVC, default mode misbehaves, so we use fixed instead.
    ss.precision(1);
    ss << std::fixed
       << input;
#else
    // In default mode, precision sets the number of significant figures.
 
    // 999.5 and above will render as 1000+, however, only numbers above 1000 will use 4 digits
    // Rounding everything from 100 up (at which point we stop using decimals anyway) avoids this.
    if (input >= 100) {
        input = std::round(input);
    }
 
    // When in binary mode, numbers of up to 1023.9999 can be passed
    // We should render those with 4 digits, instead of as 1e+3.
    // Input should be an integer number now, but doubles can do strange things, so check the halfway point instead.
    if (input >= 999.5) {
        ss.precision(4);
    } else {
        ss.precision(3);
    }
    ss << input;
#endif
    ss.precision(oldprec);
}
 
std::string si_string(double input, bool base2, const std::string& unit) {
    const double multiplier = base2 ? 1024 : 1000;
 
    typedef std::array<std::string, 9> strings9;
 
    if(input < 0){
        return font::unicode_minus + si_string(std::abs(input), base2, unit);
    }
 
    strings9 prefixes;
    strings9::const_iterator prefix;
    if (input == 0.0) {
        strings9 tmp { { "","","","","","","","","" } };
        prefixes = tmp;
        prefix = prefixes.begin();
    } else if (input < 1.0) {
        strings9 tmp { {
            "",
            _("prefix_milli^m"),
            _("prefix_micro^µ"),
            _("prefix_nano^n"),
            _("prefix_pico^p"),
            _("prefix_femto^f"),
            _("prefix_atto^a"),
            _("prefix_zepto^z"),
            _("prefix_yocto^y")
        } };
        prefixes = tmp;
        prefix = prefixes.begin();
        while (input < 1.0  && *prefix != prefixes.back()) {
            input *= multiplier;
            ++prefix;
        }
    } else {
        strings9 tmp { {
            "",
            (base2 ?
                // TRANSLATORS: Translate the K in KiB only
                _("prefix_kibi^K") :
                _("prefix_kilo^k")
            ),
            _("prefix_mega^M"),
            _("prefix_giga^G"),
            _("prefix_tera^T"),
            _("prefix_peta^P"),
            _("prefix_exa^E"),
            _("prefix_zetta^Z"),
            _("prefix_yotta^Y")
        } };
        prefixes = tmp;
        prefix = prefixes.begin();
        while (input > multiplier && *prefix != prefixes.back()) {
            input /= multiplier;
            ++prefix;
        }
    }
 
    std::stringstream ss;
    si_string_impl_stream_write(ss, input);
    ss << ' '
       << *prefix
       // TRANSLATORS: Translate the i in (for example) KiB only
       << (base2 && (!(*prefix).empty()) ? _("infix_binary^i") : "")
       << unit;
    return ss.str();
}
 
static bool is_username_char(char c) {
    return ((c == '_') || (c == '-'));
}
 
static bool is_wildcard_char(char c) {
    return ((c == '?') || (c == '*'));
}
 
bool isvalid_username(const std::string& username) {
    const std::size_t alnum = std::count_if(username.begin(), username.end(), isalnum);
    const std::size_t valid_char =
            std::count_if(username.begin(), username.end(), is_username_char);
    if ((alnum + valid_char != username.size())
            || valid_char == username.size() || username.empty() )
    {
        return false;
    }
    return true;
}
 
bool isvalid_wildcard(const std::string& username) {
    const std::size_t alnum = std::count_if(username.begin(), username.end(), isalnum);
    const std::size_t valid_char =
        std::count_if(username.begin(), username.end(), is_username_char);
    const std::size_t wild_char =
        std::count_if(username.begin(), username.end(), is_wildcard_char);
    if ((alnum + valid_char + wild_char != username.size())
        || valid_char == username.size() || username.empty() )
    {
        return false;
    }
    return true;
}
 
 
bool word_completion(std::string& text, std::vector<std::string>& wordlist) {
    std::vector<std::string> matches;
    const std::size_t last_space = text.rfind(" ");
    // If last character is a space return.
    if (last_space == text.size() -1) {
        wordlist = matches;
        return false;
    }
 
    bool text_start;
    std::string semiword;
    if (last_space == std::string::npos) {
        text_start = true;
        semiword = text;
    } else {
        text_start = false;
        semiword.assign(text, last_space + 1, text.size());
    }
 
    std::string best_match = semiword;
    for (std::vector<std::string>::const_iterator word = wordlist.begin();
            word != wordlist.end(); ++word)
    {
        if (word->size() < semiword.size()
        || !std::equal(semiword.begin(), semiword.end(), word->begin(),
            [](char a, char b) { return tolower(a) == tolower(b); })) // TODO: is this the right approach?
        {
            continue;
        }
        if (matches.empty()) {
            best_match = *word;
        } else {
            int j = 0;
            while (toupper(best_match[j]) == toupper((*word)[j])) j++;
            if (best_match.begin() + j < best_match.end()) {
                best_match.erase(best_match.begin() + j, best_match.end());
            }
        }
        matches.push_back(*word);
    }
    if(!matches.empty()) {
        text.replace(last_space + 1, best_match.size(), best_match);
    }
    wordlist = matches;
    return text_start;
}
 
static bool is_word_boundary(char c) {
    return (c == ' ' || c == ',' || c == ':' || c == '\'' || c == '"' || c == '-');
}
 
bool word_match(const std::string& message, const std::string& word) {
    std::size_t first = message.find(word);
    if (first == std::string::npos) return false;
    if (first == 0 || is_word_boundary(message[first - 1])) {
        std::size_t next = first + word.size();
        if (next == message.size() || is_word_boundary(message[next])) {
            return true;
        }
    }
    return false;
}
 
bool wildcard_string_match(const std::string& str, const std::string& match) {
    const bool wild_matching = (!match.empty() && (match[0] == '*' || match[0] == '+'));
    const std::string::size_type solid_begin = match.find_first_not_of("*+");
    const bool have_solids = (solid_begin != std::string::npos);
    // Check the simple cases first
    if(!have_solids) {
        const std::string::size_type plus_count = std::count(match.begin(), match.end(), '+');
        return match.empty() ? str.empty() : str.length() >= plus_count;
    } else if(str.empty()) {
        return false;
    }
 
    const std::string::size_type solid_end = match.find_first_of("*+", solid_begin);
    const std::string::size_type solid_len = (solid_end == std::string::npos)
        ? match.length() - solid_begin : solid_end - solid_begin;
    // Since + always consumes at least one character, increment current if the match
    // begins with one
    std::string::size_type current = match[0] == '+' ? 1 : 0;
    bool matches;
    do {
        matches = true;
        // Now try to place the str into the solid space
        const std::string::size_type test_len = str.length() - current;
        for(std::string::size_type i=0; i < solid_len && matches; ++i) {
            char solid_c = match[solid_begin + i];
            if(i > test_len || !(solid_c == '?' || solid_c == str[current+i])) {
                matches = false;
            }
        }
        if(matches) {
            // The solid space matched, now consume it and attempt to find more
            const std::string consumed_match = (solid_begin+solid_len < match.length())
                ? match.substr(solid_end) : "";
            const std::string consumed_str = (solid_len < test_len)
                ? str.substr(current+solid_len) : "";
            matches = wildcard_string_match(consumed_str, consumed_match);
        }
    } while(wild_matching && !matches && ++current < str.length());
    return matches;
}
 
void to_sql_wildcards(std::string& str, bool underscores)
{
    std::replace(str.begin(), str.end(), '*', '%');
    if(underscores)
    {
        std::size_t n = 0;
        while((n = str.find("_", n)) != std::string::npos)
        {
            str.replace(n, 1, "\\_");
            n += 2;
        }
    }
}
 
std::string indent(const std::string& string, std::size_t indent_size)
{
    if(indent_size == 0) {
        return string;
    }
 
    std::string indent(indent_size, ' ');
 
    if(string.empty()) {
        return indent;
    }
 
    const std::vector<std::string>& lines = split(string, '\x0A', 0);
    std::string res;
 
    for(std::size_t lno = 0; lno < lines.size();) {
        const std::string& line = lines[lno];
 
        // Lines containing only a carriage return count as empty.
        if(!line.empty() && line != "\x0D") {
            res += indent;
        }
 
        res += line;
 
        if(++lno < lines.size()) {
            res += '\x0A';
        }
    }
 
    return res;
}
 
std::vector<std::string> quoted_split(const std::string& val, char c, int flags, char quote)
{
    std::vector<std::string> res;
 
    std::string::const_iterator i1 = val.begin();
    std::string::const_iterator i2 = val.begin();
 
    while (i2 != val.end()) {
        if (*i2 == quote) {
            // Ignore quoted character
            ++i2;
            if (i2 != val.end()) ++i2;
        } else if (*i2 == c) {
            std::string new_val(i1, i2);
            if (flags & STRIP_SPACES)
                boost::trim(new_val);
            if (!(flags & REMOVE_EMPTY) || !new_val.empty())
                res.push_back(std::move(new_val));
            ++i2;
            if (flags & STRIP_SPACES) {
                while(i2 != val.end() && *i2 == ' ')
                    ++i2;
            }
 
            i1 = i2;
        } else {
            ++i2;
        }
    }
 
    std::string new_val(i1, i2);
    if (flags & STRIP_SPACES)
        boost::trim(new_val);
    if (!(flags & REMOVE_EMPTY) || !new_val.empty())
        res.push_back(new_val);
 
    return res;
}
 
namespace
{
/**
 * Internal common code for parse_range and parse_range_real.
 *
 * If str contains two elements and a separator such as "a-b", returns a and b.
 * Otherwise, returns the original string and utils::nullopt.
 */
std::pair<std::string_view, utils::optional<std::string_view>> parse_range_internal_separator(std::string_view str)
{
    // If turning this into a list with additional options, ensure that "-" (if present) is last. Otherwise a
    // range such as "-2..-1" might be incorrectly split as "-2..", "1".
    static const auto separator = std::string{"-"};
 
    // Starting from the second character means that it won't interpret the minus
    // sign on a negative number as the separator.
    // No need to check the string length first, as str.find() already does that.
    auto pos = str.find(separator, 1);
    auto length = separator.size();
 
    if(pos != std::string::npos && pos + length < str.size()) {
        return {str.substr(0, pos), str.substr(pos + length)};
    }
 
    return {str, utils::nullopt};
}
} // namespace
 
std::pair<int, int> parse_range(std::string_view str)
{
    auto [a, b] = parse_range_internal_separator(str);
    std::pair<int, int> res{0, 0};
    try {
        if(a == "-infinity" && b) {
            // The "&& b" is so that we treat parse_range("-infinity") the same as parse_range("infinity"),
            // both of those will report an invalid range.
            res.first = std::numeric_limits<int>::min();
        } else {
            res.first = utils::stoi(a);
        }
 
        if(!b) {
            res.second = res.first;
        } else if(*b == "infinity") {
            res.second = std::numeric_limits<int>::max();
        } else {
            res.second = utils::stoi(*b);
            if(res.second < res.first) {
                res.second = res.first;
            }
        }
    } catch(const std::invalid_argument&) {
        ERR_GENERAL << "Invalid range: " << str;
    }
 
    return res;
}
 
std::pair<double, double> parse_range_real(std::string_view str)
{
    auto [a, b] = parse_range_internal_separator(str);
    std::pair<double, double> res{0, 0};
    try {
        if(a == "-infinity" && b) {
            // There's already a static-assert for is_iec559 in random.cpp, so this isn't limiting the architectures
            // that Wesnoth can run on.
            static_assert(std::numeric_limits<double>::is_iec559,
                "Don't know how negative infinity is treated on this architecture");
            res.first = -std::numeric_limits<double>::infinity();
        } else {
            res.first = utils::stod(a);
        }
 
        if(!b) {
            res.second = res.first;
        } else if(*b == "infinity") {
            res.second = std::numeric_limits<double>::infinity();
        } else {
            res.second = utils::stod(*b);
            if(res.second < res.first) {
                res.second = res.first;
            }
        }
    } catch(const std::invalid_argument&) {
        ERR_GENERAL << "Invalid range: " << str;
    }
 
    return res;
}
 
std::vector<std::pair<int, int>> parse_ranges_unsigned(const std::string& str)
{
    auto to_return = parse_ranges_int(str);
    if(std::any_of(to_return.begin(), to_return.end(), [](const std::pair<int, int>& r) { return r.first < 0; })) {
        ERR_GENERAL << "Invalid range (expected values to be zero or positive): " << str;
        return {};
    }
 
    return to_return;
}
 
std::vector<std::pair<double, double>> parse_ranges_real(const std::string& str)
{
    std::vector<std::pair<double, double>> to_return;
    for(const std::string& r : utils::split(str)) {
        to_return.push_back(parse_range_real(r));
    }
 
    return to_return;
}
 
std::vector<std::pair<int, int>> parse_ranges_int(const std::string& str)
{
    std::vector<std::pair<int, int>> to_return;
    for(const std::string& r : utils::split(str)) {
        to_return.push_back(parse_range(r));
    }
 
    return to_return;
}
 
void ellipsis_truncate(std::string& str, const std::size_t size)
{
    const std::size_t prev_size = str.length();
 
    utf8::truncate(str, size);
 
    if(str.length() != prev_size) {
        str += font::ellipsis;
    }
}
 
} // end namespace utils