formula_string_utils.cpp

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/* $Id: formula_string_utils.cpp 52533 2012-01-07 02:35:17Z shadowmaster $ */
/*
   Copyright (C) 2003 by David White <dave@whitevine.net>
   Copyright (C) 2005 - 2012 by Guillaume Melquiond <guillaume.melquiond@gmail.com>
   Part of the Battle for Wesnoth Project http://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.
*/

#include "formula_string_utils.hpp"

#include "config.hpp"
#include "log.hpp"
#include "formula.hpp"
#include "gettext.hpp"

static lg::log_domain log_engine("engine");
#define ERR_NG LOG_STREAM(err, log_engine)

static bool two_dots(char a, char b) { return a == '.' && b == '.'; }

namespace utils {

class string_map_variable_set : public variable_set
{
public:
    string_map_variable_set(const string_map& map) : map_(map) {};

    virtual config::attribute_value get_variable_const(const std::string &key) const
    {
        config::attribute_value val;
        const string_map::const_iterator itor = map_.find(key);
        if (itor != map_.end())
            val = itor->second;
        return val;
    }
private:
    const string_map& map_;

};
}

static std::string do_interpolation(const std::string &str, const variable_set& set)
{
    std::string res = str;
    // This needs to be able to store negative numbers to check for the while's condition
    // (which is only false when the previous '$' was at index 0)
    int rfind_dollars_sign_from = res.size();
    while(rfind_dollars_sign_from >= 0) {
        // Going in a backwards order allows nested variable-retrieval, e.g. in arrays.
        // For example, "I am $creatures[$i].user_description!"
        const std::string::size_type var_begin_loc = res.rfind('$', rfind_dollars_sign_from);

        // If there are no '$' left then we're done.
        if(var_begin_loc == std::string::npos) {
            break;
        }

        // For the next iteration of the loop, search for more '$'
        // (not from the same place because sometimes the '$' is not replaced)
        rfind_dollars_sign_from = int(var_begin_loc) - 1;


        const std::string::iterator var_begin = res.begin() + var_begin_loc;

        // The '$' is not part of the variable name.
        const std::string::iterator var_name_begin = var_begin + 1;
        std::string::iterator var_end = var_name_begin;

        if(var_name_begin == res.end()) {
            // Any '$' at the end of a string is just a '$'
            continue;
        } else if(*var_name_begin == '(') {
            // The $( ... ) syntax invokes a formula
            int paren_nesting_level = 0;
            bool in_string = false,
                in_comment = false;
            do {
                switch(*var_end) {
                case '(':
                    if(!in_string && !in_comment) {
                        ++paren_nesting_level;
                    }
                    break;
                case ')':
                    if(!in_string && !in_comment) {
                        --paren_nesting_level;
                    }
                    break;
                case '#':
                    if(!in_string) {
                        in_comment = !in_comment;
                    }
                    break;
                case '\'':
                    if(!in_comment) {
                        in_string = !in_string;
                    }
                    break;
                // TODO: support escape sequences when/if they are allowed in FormulaAI strings
                }
            } while(++var_end != res.end() && paren_nesting_level > 0);
            if(paren_nesting_level > 0) {
                ERR_NG << "Formula in WML string cannot be evaluated due to "
                    << "a missing closing parenthesis:\n\t--> \""
                    << std::string(var_begin, var_end) << "\"\n";
                res.replace(var_begin, var_end, "");
                continue;
            }
            try {
                const game_logic::formula form(std::string(var_begin+2, var_end-1));
                res.replace(var_begin, var_end, form.evaluate().string_cast());
            } catch(game_logic::formula_error& e) {
                ERR_NG << "Formula in WML string cannot be evaluated due to "
                    << e.type << "\n\t--> \""
                    << e.formula << "\"\n";
                res.replace(var_begin, var_end, "");
            }
            continue;
        }

        // Find the maximum extent of the variable name (it may be shortened later).
        for(int bracket_nesting_level = 0; var_end != res.end(); ++var_end) {
            const char c = *var_end;
            if(c == '[') {
                ++bracket_nesting_level;
            }
            else if(c == ']') {
                if(--bracket_nesting_level < 0) {
                    break;
                }
            }
            // isascii() breaks on mingw with -std=c++0x
            else if (!(((c) & ~0x7f) == 0)/*isascii(c)*/ || (!isalnum(c) && c != '.' && c != '_')) {
                break;
            }
        }

        // Two dots in a row cannot be part of a valid variable name.
        // That matters for random=, e.g. $x..$y
        var_end = std::adjacent_find(var_name_begin, var_end, two_dots);

        // If the last character is '.', then it can't be a sub-variable.
        // It's probably meant to be a period instead. Don't include it.
        // Would need to do it repetitively if there are multiple '.'s at the end,
        // but don't actually need to do so because the previous check for adjacent '.'s would catch that.
        // For example, "My score is $score." or "My score is $score..."
        if(*(var_end-1) == '.'
        // However, "$array[$i]" by itself does not name a variable,
        // so if "$array[$i]." is encountered, then best to include the '.',
        // so that it more closely follows the syntax of a variable (if only to get rid of all of it).
        // (If it's the script writer's error, they'll have to fix it in either case.)
        // For example in "$array[$i].$field_name", if field_name does not exist as a variable,
        // then the result of the expansion should be "", not "." (which it would be if this exception did not exist).
        && *(var_end-2) != ']') {
            --var_end;
        }

        const std::string var_name(var_name_begin, var_end);

        if(var_end != res.end() && *var_end == '|') {
            // It's been used to end this variable name; now it has no more effect.
            // This can allow use of things like "$$composite_var_name|.x"
            // (Yes, that's a WML 'pointer' of sorts. They are sometimes useful.)
            // If there should still be a '|' there afterwards to affect other variable names (unlikely),
            // just put another '|' there, one matching each '$', e.g. "$$var_containing_var_name||blah"
            ++var_end;
        }


        if (var_name == "") {
            // Allow for a way to have $s in a string.
            // $| will be replaced by $.
            res.replace(var_begin, var_end, "$");
        }
        else {
            // The variable is replaced with its value.
            res.replace(var_begin, var_end,
                set.get_variable_const(var_name));
        }
    }

    return res;
}

namespace utils {

std::string interpolate_variables_into_string(const std::string &str, const string_map * const symbols)
{
    string_map_variable_set set(*symbols);
    return do_interpolation(str, set);
}

std::string interpolate_variables_into_string(const std::string &str, const variable_set& variables)
{
    return do_interpolation(str, variables);
}

t_string interpolate_variables_into_tstring(const t_string &tstr, const variable_set& variables)
{
    if(!tstr.str().empty()) {
        std::string interp = utils::interpolate_variables_into_string(tstr.str(), variables);
        if(tstr.str() != interp) {
            return t_string(interp);
        }
    }
    return tstr;
}

}

std::string vgettext(const char *msgid, const utils::string_map& symbols)
{
    const std::string orig(_(msgid));
    const std::string msg = utils::interpolate_variables_into_string(orig, &symbols);
    return msg;
}

std::string vgettext(const char *domain
        , const char *msgid
        , const utils::string_map& symbols)
{
    const std::string orig(dgettext(domain, msgid));
    const std::string msg = utils::interpolate_variables_into_string(orig, &symbols);
    return msg;
}
std::string vngettext(const char* sing, const char* plur, int n, const utils::string_map& symbols)
{
    const std::string orig(_n(sing, plur, n));
    const std::string msg = utils::interpolate_variables_into_string(orig, &symbols);
    return msg;
}