translation.cpp

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/*
    Copyright (C) 2006 - 2025
    by Mark de Wever <koraq@xs4all.nl>
    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
 *  Routines for terrain-conversion.
 */
 
#define GETTEXT_DOMAIN "wesnoth-lib"
 
#include "gettext.hpp"
#include "lexical_cast.hpp"
#include "log.hpp"
#include "terrain/translation.hpp"
#include "serialization/string_utils.hpp"
#include "utils/iterable_pair.hpp" //equal_range returns a std:pair instead of sometihng iterable for some reason.
 
#define ERR_G LOG_STREAM(err, lg::general())
#define WRN_G LOG_STREAM(warn, lg::general())
 
namespace t_translation {
 
    int max_map_size() {
        return 1000; //TODO make this overridable by the user without having to rebuild
    }
 
/***************************************************************************************/
// forward declaration of internal functions
 
    // The low level convertors,
    // These function are the ones which know about the internal format.
    // All other functions are unaware of the internal format.
 
    /**
     * Get the mask for a single layer.
     *
     * @param terrain   1 layer of a terrain, might have a wildcard.
     *
     * @return          Mask for that layer.
     */
    static ter_layer get_layer_mask_(ter_layer terrain); //inlined
 
    /**
     * Gets a mask for a terrain, this mask is used for wildcard matching.
     *
     * @param terrain   The terrain which might have a wildcard.
     *
     * @return          The mask for this terrain.
     */
    static terrain_code get_mask_(const terrain_code& terrain);
 
    static ter_layer string_to_layer_(std::string_view str);
 
    /**
     * Converts a string to a layer.
     *
     * @param str       The terrain string to convert, but needs to be
     *                  sanitized so no spaces and only the terrain to convert.
     *
     * @return          The converted layer.
     */
    static ter_layer string_to_layer_(const std::string& str)
    {
        return string_to_layer_(std::string_view(str));
    }
 
    /**
     * Converts a terrain string to a number.
     * @param str               The terrain string with an optional number.
     * @param start_positions   Returns the start_positions, the caller should
     *                          set it on -1 and it's only changed it there is
     *                          a starting position found.
     * @param filler            If no overlay is specified this value will be used.
     *
     * @return                  The terrain code found in the string if no
     *                          valid terrain is found VOID will be returned.
     */
    static terrain_code string_to_number_(std::string_view str, std::vector<std::string>& start_positions, const ter_layer filler);
    static terrain_code string_to_number_(std::string_view str, const ter_layer filler = NO_LAYER);
 
    /**
     * Converts a terrain number to a string
     *
     * @param terrain               The terrain number to convert.
     * @param start_position        The starting position, if smaller than 0
     *                              it's ignored else it's written.
     *
     * @return                      The converted string, if no starting
     *                              position given it's padded to 4 chars else
     *                              padded to 7 chars.
     */
    static std::string number_to_string_(terrain_code terrain, const std::vector<std::string>& start_position = std::vector<std::string>());
 
    /**
     * Converts a terrain string to a number for the builder.
     * The translation rules differ from the normal conversion rules
     *
     * @param str   The terrain string.
     *
     * @return      Number for the builder map.
     */
    static terrain_code string_to_builder_number_(std::string str);
 
/***************************************************************************************/
 
const terrain_code OFF_MAP_USER = string_to_number_("_off^_usr");
 
/**
 * VOID_TERRAIN is used for shrouded hexes. It's also used by terrain_type's
 * default constructor, but that's only used as the sentinel value for when
 * terrain_type_data::get_terrain_info() is asked for an unknown terrain code.
 */
const terrain_code VOID_TERRAIN = string_to_number_("_s");
const terrain_code FOGGED = string_to_number_("_f");
 
const terrain_code HUMAN_CASTLE = string_to_number_("Ch");
const terrain_code HUMAN_KEEP = string_to_number_("Kh");
const terrain_code SHALLOW_WATER = string_to_number_("Ww");
const terrain_code DEEP_WATER = string_to_number_("Wo");
const terrain_code GRASS_LAND = string_to_number_("Gg");
const terrain_code FOREST = string_to_number_("Gg^Ff");
const terrain_code MOUNTAIN = string_to_number_("Mm");
const terrain_code HILL = string_to_number_("Hh");
 
const terrain_code CAVE_WALL = string_to_number_("Xu");
const terrain_code CAVE = string_to_number_("Uu");
const terrain_code UNDERGROUND_VILLAGE = string_to_number_("Uu^Vu");
const terrain_code DWARVEN_CASTLE = string_to_number_("Cud");
const terrain_code DWARVEN_KEEP = string_to_number_("Kud");
 
const terrain_code PLUS = string_to_number_("+");
const terrain_code MINUS = string_to_number_("-");
const terrain_code NOT = string_to_number_("!");
const terrain_code STAR = string_to_number_("*");
const terrain_code BASE = string_to_number_("_bas");
 
const ter_match ALL_OFF_MAP("_off^_usr,*^_fme");
const ter_match ALL_FORESTS("F*,*^F*");
const ter_match ALL_HILLS("!,*^V*,!,H*");
const ter_match ALL_MOUNTAINS("!,*^V*,!,M*"); //excluding impassable mountains
const ter_match ALL_SWAMPS("!,*^V*,*^B*,!,S*"); //excluding swamp villages and bridges
 
/***************************************************************************************/
 
terrain_code::terrain_code(const std::string& b, ter_layer o) :
    base(string_to_layer_(b)), overlay(o)
{}
 
terrain_code::terrain_code(const std::string& b, const std::string& o) :
    base(string_to_layer_(b)), overlay(string_to_layer_(o))
{}
 
ter_match::ter_match() :
    terrain(),
    mask(),
    masked_terrain(),
    has_wildcard(false),
    is_empty(true)
{}
 
ter_match::ter_match(std::string_view str, const ter_layer filler) :
    terrain(t_translation::read_list(str, filler)),
    mask(),
    masked_terrain(),
    has_wildcard(t_translation::has_wildcard(terrain)),
    is_empty(terrain.empty())
 
{
    mask.resize(terrain.size());
    masked_terrain.resize(terrain.size());
 
    for(std::size_t i = 0; i < terrain.size(); i++) {
        mask[i] = t_translation::get_mask_(terrain[i]);
        masked_terrain[i] = mask[i] & terrain[i];
    }
}
 
ter_match::ter_match(const terrain_code& tcode):
    terrain(ter_list(1, tcode)),
    mask(),
    masked_terrain(),
    has_wildcard(t_translation::has_wildcard(terrain)),
    is_empty(terrain.empty())
{
    mask.resize(terrain.size());
    masked_terrain.resize(terrain.size());
 
    for(std::size_t i = 0; i < terrain.size(); i++) {
        mask[i] = t_translation::get_mask_(terrain[i]);
        masked_terrain[i] = mask[i] & terrain[i];
    }
}
 
terrain_code read_terrain_code(std::string_view str, const ter_layer filler)
{
    return string_to_number_(str, filler);
}
 
std::string write_terrain_code(const terrain_code& tcode)
{
    return number_to_string_(tcode);
}
 
ter_list read_list(std::string_view str, const ter_layer filler)
{
    // Handle an empty string
    ter_list result;
 
    if(str.empty()) {
        return result;
    }
 
    std::size_t offset = 0;
    while(offset < str.length()) {
 
        // Get a terrain chunk
        const std::string separators = ",";
        const size_t pos_separator = str.find_first_of(separators, offset);
        std::string_view terrain = str.substr(offset, pos_separator - offset);
 
        // Process the chunk
        const terrain_code tile = string_to_number_(terrain, filler);
 
        // Add the resulting terrain number
        result.push_back(tile);
 
        // Evaluate the separator
        if(pos_separator == std::string_view::npos) {
            offset =  str.length();
        } else {
            offset = pos_separator + 1;
        }
    }
 
    return result;
}
 
std::string write_list(const ter_list& list)
{
    std::stringstream result;
 
    ter_list::const_iterator itor = list.begin();
    for( ; itor != list.end(); ++itor) {
        if(itor == list.begin()) {
            result << number_to_string_(*itor);
        } else {
            result << ", " << number_to_string_(*itor);
        }
    }
 
    return result.str();
}
 
static std::pair<int, int> get_map_size(const char* begin, const char* end)
{
    int w = 1;
    int h = 0;
    for (const char* it = begin; it != end;) {
        int cur_w = 1;
        ++h;
 
 
        for (;it != end && (*it != '\n' && *it != '\r'); ++it) {
            if (*it == ',') {
                ++cur_w;
            }
        }
        w = std::max(w, cur_w);
 
        while (it != end && (*it == '\n' || *it == '\r')) {
            ++it;
        }
 
    }
    return{ w, h };
}
 
ter_map read_game_map(std::string_view str, starting_positions& starting_positions, coordinate border_offset)
{
    std::size_t offset = 0;
    int x = 0, y = 0, width = 0;
 
    // Skip the leading newlines
    while(!str.empty() && utils::isnewline(str.front())) {
        str.remove_prefix(1);
    }
 
    // Did we get an empty map?
    if(str.length() <= 1) {
        return ter_map();
    }
 
    auto map_size = get_map_size(&str[0], &str[0] + str.size());
    ter_map result(map_size.first, map_size.second);
 
    while(offset < str.length()) {
 
        // Get a terrain chunk
        const std::string separators = ",\n\r";
        const std::size_t pos_separator = str.find_first_of(separators, offset);
        std::string_view terrain = str.substr(offset, pos_separator - offset);
 
        // Process the chunk
        std::vector<std::string> sp;
        // The gamemap never has a wildcard
        const terrain_code tile = string_to_number_(terrain, sp, NO_LAYER);
 
        // Add to the resulting starting position
        for(const auto& starting_position : sp) {
            if (starting_positions.left.find(starting_position) != starting_positions.left.end()) {
                WRN_G << "Starting position " << starting_position << " is redefined.";
            }
            starting_positions.insert(starting_positions::value_type(starting_position, coordinate(x - border_offset.x, y - border_offset.y)));
        }
 
        if(result.w <= x || result.h <= y) {
            throw error("Map not a rectangle.");
        }
 
        // Add the resulting terrain number
        result.get(x, y) = tile;
 
        // Evaluate the separator
        if(pos_separator == std::string::npos || utils::isnewline(str[pos_separator])) {
            // the first line we set the with the other lines we check the width
            if(y == 0) {
                // x contains the offset in the map
                width = x + 1;
            } else {
                if((x + 1) != width ) {
                    ERR_G << "Map not a rectangle error occurred at line offset " << y << " position offset " << x;
                    throw error("Map not a rectangle.");
                }
                if (y > max_map_size()) {
                    ERR_G << "Map size exceeds limit (y > " << max_map_size() << ")";
                    throw error("Map height limit exceeded.");
                }
            }
 
            // Prepare next iteration
            ++y;
            x = 0;
 
            // Avoid in infinite loop if the last line ends without an EOL
            if(pos_separator == std::string::npos) {
                offset = str.length();
 
            } else {
 
                offset = pos_separator + 1;
                // Skip the following newlines
                while(offset < str.length() && utils::isnewline(str[offset])) {
                    ++offset;
                }
            }
 
        } else {
            ++x;
            offset = pos_separator + 1;
            if (x > max_map_size()) {
                ERR_G << "Map size exceeds limit (x > " << max_map_size() << ")";
                throw error("Map width limit exceeded.");
            }
        }
 
    }
 
    if(x != 0 && (x + 1) != width) {
        ERR_G << "Map not a rectangle error occurred at the end";
        throw error("Map not a rectangle.");
    }
 
    return result;
}
 
std::string write_game_map(const ter_map& map, const starting_positions& starting_positions, coordinate border_offset)
{
    std::stringstream str;
 
    for(int y = 0; y < map.h; ++y) {
        for(int x = 0; x < map.w; ++x) {
 
            // If the current location is a starting position,
            // it needs to be added to the terrain.
            // After it's found it can't be found again,
            // so the location is removed from the map.
            std::vector<std::string> sp;
 
            for(const auto& pair : starting_positions.right.equal_range(coordinate(x - border_offset.x, y - border_offset.y))) {
                sp.push_back(pair.second);
            }
            // Add the separator
            if(x != 0) {
                str << ", ";
            }
            str << number_to_string_(map[x][y], sp);
        }
 
        if (y < map.h -1)
            str << "\n";
    }
 
    return str.str();
}
 
bool terrain_matches(const terrain_code& src, const terrain_code& dest)
{
    return terrain_matches(src, ter_list(1, dest));
}
 
bool terrain_matches(const terrain_code& src, const ter_list& dest)
{
    // NOTE we impose some code duplication.
    // It could have been rewritten to get a match structure
    // and then call the version with the match structure.
    // IMO that's some extra overhead to this function
    // which is not required. Hence the two versions
    if(dest.empty()) {
        return false;
    }
 
#if 0
    PLAIN_LOG << std::hex << "src = " << src.base << "^" << src.overlay << "\t"
        << src_mask.base << "^" << src_mask.overlay << "\t"
        << masked_src.base << "^" << masked_src.overlay << "\t"
        << src_has_wildcard << "\n";
#endif
 
    bool result = true;
    ter_list::const_iterator itor = dest.begin();
 
    // Try to match the terrains if matched jump out of the loop.
    for(; itor != dest.end(); ++itor) {
 
        // Match wildcard
        if(*itor == STAR) {
            return result;
        }
 
        // Match inverse symbol
        if(itor->base == NOT.base) {
            result = !result;
            continue;
        }
 
        // Full match
        if(src == *itor) {
            return result;
        }
 
        // Does the destination wildcard match
        const terrain_code dest_mask = get_mask_(*itor);
        const terrain_code masked_dest = (*itor & dest_mask);
        const bool dest_has_wildcard = has_wildcard(*itor);
#if 0
        PLAIN_LOG << std::hex << "dest= "
            << itor->base << "^" << itor->overlay  << "\t"
            << dest_mask.base << "^" << dest_mask.overlay << "\t"
            << masked_dest.base << "^" << masked_dest.overlay << "\t"
            << dest_has_wildcard << "\n";
#endif
        if(dest_has_wildcard &&
                (src.base & dest_mask.base) == masked_dest.base &&
                (src.overlay & dest_mask.overlay) == masked_dest.overlay) {
            return result;
        }
 
/* Test code */ /*
        if(src_has_wildcard && dest_has_wildcard && (
                (
                    get_layer_mask_(itor->base) != NO_LAYER &&
                    get_layer_mask_(src.overlay) != NO_LAYER &&
                    (src.base & dest_mask.base) == masked_dest.base &&
                    (itor->overlay & src_mask.overlay) == masked_src.overlay
                ) || (
                    get_layer_mask_(itor->overlay) != NO_LAYER &&
                    get_layer_mask_(src.base) != NO_LAYER &&
                    (src.overlay & dest_mask.overlay) == masked_dest.overlay &&
                    (itor->base & src_mask.base) == masked_src.base
                ))) {
 
            return result;
        }
*/
    }
 
    // No match, return the inverse of the result
    return !result;
}
 
// This routine is used for the terrain building,
// so it's one of the delays while loading a map.
// This routine is optimized a bit at the loss of readability.
bool terrain_matches(const terrain_code& src, const ter_match& dest)
{
    if(dest.is_empty) {
        return false;
    }
 
    bool result = true;
 
    // Try to match the terrains if matched jump out of the loop.
    // We loop on the dest.terrain since the iterator is faster than operator[].
    // The i holds the value for operator[].
    // Since dest.mask and dest.masked_terrain need to be in sync,
    // they are less often looked up, so no iterator for them.
    std::size_t i = 0;
    ter_list::const_iterator end = dest.terrain.end();
    for(ter_list::const_iterator terrain_itor = dest.terrain.begin();
            terrain_itor != end;
            ++i, ++terrain_itor) {
 
        // Match wildcard
        if(*terrain_itor == STAR) {
            return result;
        }
 
        // Match inverse symbol
        if(terrain_itor->base == NOT.base) {
            result = !result;
            continue;
        }
 
        // Full match
        if(*terrain_itor == src) {
            return result;
        }
 
        // Does the destination wildcard match
        if(dest.has_wildcard &&
                (src.base & dest.mask[i].base) == dest.masked_terrain[i].base &&
                (src.overlay & dest.mask[i].overlay) == dest.masked_terrain[i].overlay) {
            return result;
        }
 
/* Test code */ /*
        if(src_has_wildcard && has_wildcard(*terrain_itor) && (
                (
                    get_layer_mask_(terrain_itor->base) != NO_LAYER &&
                    get_layer_mask_(src.overlay) != NO_LAYER &&
                    (src.base & dest.mask[i].base) == dest.masked_terrain[i].base &&
                    (terrain_itor->overlay & src_mask.overlay) == masked_src.overlay
                ) || (
                    get_layer_mask_(terrain_itor->overlay) != NO_LAYER &&
                    get_layer_mask_(src.base) != NO_LAYER &&
                    (src.overlay & dest.mask[i].overlay) == dest.masked_terrain[i].overlay &&
                    (terrain_itor->base & src_mask.base) == masked_src.base
                ))) {
 
            return result;
        }
*/
    }
 
    // No match, return the inverse of the result
    return !result;
}
 
bool has_wildcard(const terrain_code& tcode)
{
    if(tcode.overlay == NO_LAYER) {
        return get_layer_mask_(tcode.base) != NO_LAYER;
    } else {
        return get_layer_mask_(tcode.base) != NO_LAYER || get_layer_mask_(tcode.overlay) != NO_LAYER;
    }
}
 
bool has_wildcard(const ter_list& list)
{
    if(list.empty()) {
        return false;
    }
 
    // Test all items for a wildcard
    ter_list::const_iterator itor = list.begin();
    for(; itor != list.end(); ++itor) {
        if(has_wildcard(*itor)) {
            return true;
        }
    }
 
    // No wildcard found
    return false;
}
 
ter_map read_builder_map(const std::string& str)
{
    std::size_t offset = 0;
    // Skip the leading newlines
    while(offset < str.length() && utils::isnewline(str[offset])) {
        ++offset;
    }
    // Did we get an empty map?
    if((offset + 1) >= str.length()) {
        return ter_map();
    }
 
    auto map_size = get_map_size(&str[offset], str.c_str() + str.size());
    ter_map result(map_size.second, map_size.first, terrain_code(t_translation::TB_DOT, ter_layer()));
 
    int x = 0, y = 0;
    while(offset < str.length()) {
 
        // Get a terrain chunk
        const std::string separators = ",\n\r";
        const std::size_t pos_separator = str.find_first_of(separators, offset);
        std::string terrain = "";
        // Make sure we didn't hit an empty chunk
        // which is allowed
        if(pos_separator != offset) {
            terrain = str.substr(offset, pos_separator - offset);
        }
 
        // Process the chunk
        const terrain_code tile = string_to_builder_number_(terrain);
 
        // Make space for the new item
        if (result.h <= x || result.w <= y) {
            throw error("Map not a rectangle.");
        }
 
        // Add the resulting terrain number,
        result.get(y, x) = tile;
 
        // evaluate the separator
        if(pos_separator == std::string::npos) {
            // Probably not required to change the value,
            // but be sure the case should be handled at least.
            // I'm not sure how it is defined in the standard,
            // but here it's defined at max u32 which with +1 gives 0
            // and make a nice infinite loop.
            offset = str.length();
        } else if(utils::isnewline(str[pos_separator])) {
            // Prepare next iteration
            ++y;
            x = 0;
 
            offset =  pos_separator + 1;
            // Skip the following newlines
            while(offset < str.length() && utils::isnewline(str[offset])) {
                ++offset;
            }
 
        } else {
            ++x;
            offset = pos_separator + 1;
        }
 
    }
 
    return result;
}
 
/***************************************************************************************/
// Internal
 
inline ter_layer get_layer_mask_(ter_layer terrain)
{
    // Test for the star 0x2A in every position
    // and return the appropriate mask
/*
 *  This is what the code intents to do, but in order to gain some more
 *  speed it's changed to the code below, which does the same but faster.
 *  This routine is used often in the builder and the speedup is noticeable. */
    if((terrain & 0xFF000000) == 0x2A000000) return 0x00000000;
    if((terrain & 0x00FF0000) == 0x002A0000) return 0xFF000000;
    if((terrain & 0x0000FF00) == 0x00002A00) return 0xFFFF0000;
    if((terrain & 0x000000FF) == 0x0000002A) return 0xFFFFFF00;
 
/*
    uint8_t *ptr = (uint8_t *) &terrain;
 
    if(ptr[3] == 0x2A) return 0x00000000;
    if(ptr[2] == 0x2A) return 0xFF000000;
    if(ptr[1] == 0x2A) return 0xFFFF0000;
    if(ptr[0] == 0x2A) return 0xFFFFFF00;
*/
    // no star found return the default
    return 0xFFFFFFFF;
}
 
static terrain_code get_mask_(const terrain_code& terrain)
{
    if(terrain.overlay == NO_LAYER) {
        return terrain_code(get_layer_mask_(terrain.base), 0xFFFFFFFF);
    } else {
        return terrain_code(get_layer_mask_(terrain.base), get_layer_mask_(terrain.overlay));
    }
}
 
static ter_layer string_to_layer_(std::string_view str)
{
    if(str.empty()) {
        return NO_LAYER;
    }
 
    if(str.size() > 4) {
        throw error("A terrain with a string with more "
            "than 4 characters has been found, the affected terrain is: " + std::string(str));
    }
 
    ter_layer result = 0;
    // The conversion to int puts the first char
    // in the highest part of the number.
    // This will make the wildcard matching
    // later on a bit easier.
    for(std::size_t i = 0; i < 4; ++i) {
        const unsigned char c = (i < str.size()) ? str[i] : 0;
 
        // Clearing the lower area is a nop on i == 0
        // so no need for if statement
        result <<= 8;
 
        // Add the result
        result += c;
    }
 
    return result;
}
 
static terrain_code string_to_number_(std::string_view str, const ter_layer filler) {
    std::vector<std::string> dummy;
    return string_to_number_(str, dummy, filler);
}
 
static terrain_code string_to_number_(std::string_view str, std::vector<std::string>& start_positions, const ter_layer filler)
{
    terrain_code result;
 
    // Strip the spaces around us
    // unlike the old implementation this also trims newlines.
    utils::trim(str);
    if(str.empty()) {
        return result;
    }
 
    // Split if we have spaces inside
    std::size_t offset = str.find(' ', 0);
    while(offset != std::string::npos) {
        start_positions.push_back(std::string(str.substr(0, offset)));
        str.remove_prefix(offset + 1);
        offset = str.find(' ', 0);
    }
 
    offset = str.find('^', 0);
    if(offset !=  std::string::npos) {
        result = terrain_code { string_to_layer_(str.substr(0, offset)), string_to_layer_(str.substr(offset + 1)) };
    } else {
        result = terrain_code { string_to_layer_(str), filler };
    }
 
    return result;
}
 
static std::string number_to_string_(terrain_code terrain, const std::vector<std::string>& start_positions)
{
    std::string result = "";
 
    // Insert the start position
    for (const std::string& str : start_positions) {
        result = str + " " + result;
    }
 
    /*
     * The initialization of tcode is done to make gcc-4.7 happy. Otherwise it
     * some uninitialized fields might be used. Its analysis are wrong, but
     * Initialize to keep it happy.
     */
    unsigned char tcode[9] {0};
    // Insert the terrain tcode
    tcode[0] = ((terrain.base & 0xFF000000) >> 24);
    tcode[1] = ((terrain.base & 0x00FF0000) >> 16);
    tcode[2] = ((terrain.base & 0x0000FF00) >> 8);
    tcode[3] =  (terrain.base & 0x000000FF);
 
    if(terrain.overlay != NO_LAYER) {
        tcode[4] = '^'; //the layer separator
        tcode[5] = ((terrain.overlay & 0xFF000000) >> 24);
        tcode[6] = ((terrain.overlay & 0x00FF0000) >> 16);
        tcode[7] = ((terrain.overlay & 0x0000FF00) >> 8);
        tcode[8] =  (terrain.overlay & 0x000000FF);
    } else {
        // If no second layer, the second layer won't be written,
        // so no need to initialize that part of the array
        tcode[4] = 0;
    }
 
    for(int i = 0; i < 9; ++i) {
        if(tcode[i] != 0 && tcode[i] != 0xFF) {
            result += tcode[i];
        }
        if(i == 4 && tcode[i] == 0) {
            // no layer, stop
            break;
        }
    }
 
    return result;
}
 
static terrain_code string_to_builder_number_(std::string str)
{
    // Strip the spaces around us
    const std::string& whitespace = " \t";
    str.erase(0, str.find_first_not_of(whitespace));
    if(! str.empty()) {
        str.erase(str.find_last_not_of(whitespace) + 1);
    }
 
    // Empty string is allowed here, so handle it
    if(str.empty()) {
        return terrain_code();
    }
 
    const int number = lexical_cast_default(str, -1);
    if(number == -1) {
        // At this point we have a single char
        // which should be interpreted by the
        // map builder, so return this number
        return terrain_code(str[0] << 24, 0);
    } else {
        return terrain_code(0, number);
    }
}
 
} // end namespace t_translation
 
#if 0
// small helper rule to test the matching rules
// building rule
// make terrain_translation.o &&  g++ terrain_translation.o libwesnoth-core.a -lSDL -o terrain_translation
int main(int argc, char** argv)
{
    if(argc > 1) {
 
        if(std::string(argv[1]) == "match" && argc == 4) {
            t_translation::terrain_code src = t_translation::read_terrain_code(std::string(argv[2]));
 
            t_translation::ter_list dest = t_translation::read_list(std::string(argv[3]));
 
            if(t_translation::terrain_matches(src, dest)) {
                std::cout << "Match\n" ;
            } else {
                std::cout << "No match\n";
            }
        }
    }
}
 
#endif