fprint.hpp

// The MIT License (MIT)

// Copyright (c) 2012-2014 Danny Y., Rapptz

// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#ifndef GEARS_IO_FPRINT_HPP
#define GEARS_IO_FPRINT_HPP

#include "detail/index_printer.hpp"
#include "../string/classification.hpp"
#include <string>

namespace gears {
namespace io {

template<class Elem, class Traits, typename... Args>
inline void fprint(std::basic_ostream<Elem, Traits>& out, const std::basic_string<Elem, Traits>& str, Args&&... arguments) {
    if(sizeof...(arguments) < 1) {
        out << str;
        return;
    }

    auto args = std::make_tuple(std::forward<Args>(arguments)...);

    string::is_digit cmp;
    auto&& length = str.size();
    auto&& original_width = out.width();
    std::ios_base::fmtflags original_format = out.flags();
    auto&& original_precision = out.precision();

    for(decltype(str.size()) i = 0; i < length; ++i) {
        auto&& c = str[i];
        // doesn't start with { so just print it and continue
        if(c != out.widen('{')) {
            out << c;
            continue;
        }

        // at this point, the character c points to {
        // check if we're done printing
        if(i + 1 > length) {
            out << c;
            break;
        }

        // check the next characters
        auto j = i + 1;
        unsigned index = 0;
        decltype(out.width()) width = 0;
        decltype(out.precision()) precision = 0;
        auto format = original_format;

        // escaped character
        if(str[j] == out.widen('{')) {
            out << str[i];
            i = j;
            continue;
        }

        // now we're at a sane point where we can work with the format string
        // check if the next character is a digit
        if(cmp(str[j])) {
            do {
                // since it is, multiply the index
                index = (index * 10) + (str[j++] - out.widen('0'));
            }
            while(j < length && cmp(str[j]));
        }
        else {
            // since it isn't a digit, it doesn't match our format string
            throw std::runtime_error("invalid format string specified");
        }

        // check if alignment argument exists
        if(str[j] == out.widen(',')) {
            // check if the next character is valid
            if(j + 1 < length) {
                // check if the alignment is left or right
                if(str[j + 1] == out.widen('-')) {
                    format |= out.left;
                    // increment by two to get to the numerical section
                    j += 2;
                }
                else {
                    format |= out.right;
                    ++j;
                }
                // check if the next character is a digit
                if(j < length && cmp(str[j])) {
                    do {
                        // since it is, multiply the width
                        width = (width * 10) + (str[j++] - out.widen('0'));
                    }
                    while(j < length && cmp(str[j]));
                }
                else {
                    // invalid format string found
                    throw std::runtime_error("invalid format string specified");
                }

            }
        }

        // check if format specifier exists
        if(str[j] == out.widen(':')) {
            // check if the character is valid
            if(j + 1 < length) {
                auto&& specifier = str[j + 1];
                switch(specifier) {
                case 'F':
                    format |= out.fixed;
                    break;
                case 'O':
                    format = (format & ~out.basefield) | out.oct;
                    break;
                case 'x':
                    format = (format & ~out.basefield) | out.hex;
                    break;
                case 'X':
                    format = (format & ~out.basefield) | out.hex | out.uppercase;
                    break;
                case 'E':
                    format |= out.scientific | out.uppercase;
                    break;
                case 'e':
                    format |= out.scientific;
                    break;
                case 'B':
                    format |= out.boolalpha;
                    break;
                case 'S':
                    format |= out.showpos;
                    break;
                default:
                    throw std::runtime_error("no such format specifier found");
                    break;
                }
                j += 2;

                // handle precision specifier
                if(j < length && cmp(str[j])) {
                    do {
                        precision = (precision * 10) + (str[j++] - out.widen('0'));
                    }
                    while(j < length && cmp(str[j]));
                }
            }
        }

        // now that we're done processing, handle the results
        if(str[j] == out.widen('}')) {
            out.flags(format);
            out.width(width);
            out.precision(precision);
            detail::index_printer(out, index, args);
            out.width(original_width);
            out.flags(original_format);
            out.precision(original_precision);
            i = j;
        }
    }
}
} // io
} // gears

#endif // GEARS_IO_FPRINT_HPP