libcruft-util/format.ipp

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/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Copyright 2015 Danny Robson <danny@nerdcruft.net>
*/
#if defined(__UTIL_FORMAT_IPP)
#error
#endif
#define __UTIL_FORMAT_IPP
#include "debug.hpp"
#include <algorithm>
#include <sstream>
#include <stdexcept>
#include <iterator>
#include <boost/filesystem/path.hpp>
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namespace util {
namespace detail { namespace format {
///////////////////////////////////////////////////////////////////////
template <typename T>
inline bool
is_valid_specifier (const char*)
{ return false; }
//---------------------------------------------------------------------
template <>
inline bool
is_valid_specifier<const char*> (const char *s)
{ return *s == 's'; }
//---------------------------------------------------------------------
template <>
inline bool
is_valid_specifier<char*> (const char *s)
{ return *s == 's'; }
//---------------------------------------------------------------------
template <>
inline bool
is_valid_specifier<std::string> (const char *s)
{ return *s == 's'; }
//---------------------------------------------------------------------
template <>
inline bool
is_valid_specifier<boost::filesystem::path> (const char *s)
{ return *s == 's'; }
//---------------------------------------------------------------------
template <>
inline bool
is_valid_specifier<size_t> (const char *s)
{ return *s == 'u'; }
///////////////////////////////////////////////////////////////////////
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template <typename InputIt>
void
render (InputIt first,
InputIt last,
std::ostringstream &dest)
{
static const char DELIMITER = '%';
if (std::find (first, last, DELIMITER) != last)
throw util::format::missing_error ("format specifier without value");
std::copy (first, last, std::ostream_iterator<char> (dest));
}
//---------------------------------------------------------------------
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template <typename InputIt,
typename ValueT,
typename ...Args>
void
render (InputIt first,
InputIt last,
std::ostringstream &dest,
const ValueT& val,
Args&& ...args)
{
CHECK (first <= last);
static const char DELIMITER = '%';
auto cursor = std::find (first, last, DELIMITER);
std::copy (first, cursor, std::ostream_iterator<char> (dest));
if (cursor == last)
return;
auto spec = cursor + 1;
if (spec == last)
throw util::format::format_error ("missing format specifier");
if (!is_valid_specifier<typename std::decay<ValueT>::type> (&*spec))
throw util::format::format_error ("invalid/unhandled format specifier");
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dest << val;
render (spec + 1, last, dest, std::forward<Args> (args)...);
}
} }
///////////////////////////////////////////////////////////////////////////
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namespace format {
template <typename ...Args>
std::string
render (const std::string &fmt, Args&&... args)
{
std::ostringstream out;
util::detail::format::render (
fmt.begin (),
fmt.end (),
out,
std::forward<Args> (args)...
);
return out.str ();
}
}
}