Ichthyostega
806db414dd
* Lumiera source code always was copyrighted by individual contributors * there is no entity "Lumiera.org" which holds any copyrights * Lumiera source code is provided under the GPL Version 2+ == Explanations == Lumiera as a whole is distributed under Copyleft, GNU General Public License Version 2 or above. For this to become legally effective, the ''File COPYING in the root directory is sufficient.'' The licensing header in each file is not strictly necessary, yet considered good practice; attaching a licence notice increases the likeliness that this information is retained in case someone extracts individual code files. However, it is not by the presence of some text, that legally binding licensing terms become effective; rather the fact matters that a given piece of code was provably copyrighted and published under a license. Even reformatting the code, renaming some variables or deleting parts of the code will not alter this legal situation, but rather creates a derivative work, which is likewise covered by the GPL! The most relevant information in the file header is the notice regarding the time of the first individual copyright claim. By virtue of this initial copyright, the first author is entitled to choose the terms of licensing. All further modifications are permitted and covered by the License. The specific wording or format of the copyright header is not legally relevant, as long as the intention to publish under the GPL remains clear. The extended wording was based on a recommendation by the FSF. It can be shortened, because the full terms of the license are provided alongside the distribution, in the file COPYING.
233 lines
6.5 KiB
C++
233 lines
6.5 KiB
C++
/*
|
||
UTIL-FOREACH.hpp - helpers for doing something for each element
|
||
|
||
Copyright (C)
|
||
2009, Hermann Vosseler <Ichthyostega@web.de>
|
||
|
||
**Lumiera** 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. See the file COPYING for further details.
|
||
|
||
*/
|
||
|
||
|
||
/** @file util-foreach.hpp
|
||
** Perform operations "for each element" of a collection.
|
||
** This header defines various flavours of these active iteration functions,
|
||
** which all take a functor and invoke it in some way over the collection's elements.
|
||
** - basic constructs
|
||
** - for_each
|
||
** - and_all (all quantisation)
|
||
** - has_any (existence quantisation)
|
||
** - kinds of collection
|
||
** - STL collections and anything which has an iterator, \c begin() and \c end()
|
||
** - "Lumiera Forward Iterator" instance to yield all the elements of the collection
|
||
** - support for on-the-fly binding up to 4 arguments of the functor
|
||
**
|
||
** @warning in the standard case (STL container) the collection to operate on is
|
||
** taken by \c const& -- but the <b>const is stripped</b> silently.
|
||
**
|
||
** Thus, within the iteration, the function passed in can \em modify the original collection.
|
||
** If you pass in a ref to a temporary, the compiler won't complain. Moreover, several kinds
|
||
** of wrappers are also <b>stripped silently</b>, including reference_wrapper, shared_ptr and
|
||
** lumiera::P. The rationale for this non-standard behaviour is to allow convenient writing
|
||
** of in-line iteration, where even the collection to iterate is yielded by function call.
|
||
**
|
||
** @see util-foreach-test.cpp
|
||
**
|
||
*/
|
||
|
||
|
||
#ifndef UTIL_FOREACH_H
|
||
#define UTIL_FOREACH_H
|
||
|
||
#include "lib/util.hpp"
|
||
#include "lib/meta/trait.hpp"
|
||
|
||
#include <functional>
|
||
#include <algorithm>
|
||
|
||
|
||
|
||
namespace util {
|
||
|
||
using lib::meta::enable_if;
|
||
using lib::meta::disable_if;
|
||
|
||
using lib::meta::can_STL_ForEach;
|
||
using lib::meta::can_IterForEach;
|
||
|
||
|
||
|
||
/** All quantification: check if all elements of a collection
|
||
* satisfy the given predicate. Actually a short-circuit
|
||
* evaluation is performed.
|
||
*/
|
||
template <typename IT, typename FUN>
|
||
inline bool
|
||
and_all (IT i, IT end, FUN predicate)
|
||
{
|
||
for ( ; i!=end; ++i )
|
||
if (!predicate(*i))
|
||
return false;
|
||
|
||
return true;
|
||
}
|
||
|
||
|
||
/** Existential quantification: check if any element
|
||
* of a collection satisfies the given predicate.
|
||
* Actually, a short-circuit evaluation is performed.
|
||
*/
|
||
template <typename IT, typename FUN>
|
||
inline bool
|
||
has_any (IT i, IT end, FUN predicate)
|
||
{
|
||
for ( ; i!=end; ++i )
|
||
if (predicate(*i))
|
||
return true;
|
||
|
||
return false;
|
||
}
|
||
|
||
|
||
/* === specialisations for STL containers and Lumiera Forward Iterators === */
|
||
|
||
/** operate on all elements of a STL container.
|
||
* @note the container is taken by \c const& and
|
||
* the \c const is \em stripped before iteration.
|
||
* @todo reconsider if using rvalue references covers
|
||
* the "inline iteration" use case sufficiently,
|
||
* so that we can get rid of the unwrapping and
|
||
* thus get back to strict const correctness.
|
||
* @note this case is the default and kicks in
|
||
* \em unless we detect a Lumiera iterator.
|
||
* The handling is different for \c and_all
|
||
*/
|
||
template <typename Container
|
||
,typename FUN
|
||
>
|
||
inline disable_if< can_IterForEach<Container>,
|
||
FUN >
|
||
for_each (Container const& coll, FUN doIt)
|
||
{
|
||
using lib::meta::unwrap;
|
||
|
||
return std::for_each (unwrap(coll).begin()
|
||
,unwrap(coll).end()
|
||
, doIt);
|
||
}
|
||
|
||
|
||
/** operate on a Lumiera Forward Iterator until exhaustion. */
|
||
template <typename IT
|
||
,typename FUN
|
||
>
|
||
inline enable_if< can_IterForEach<IT>,
|
||
FUN >
|
||
for_each (IT const& ii, FUN doIt)
|
||
{
|
||
return std::for_each (ii, IT(), doIt);
|
||
}
|
||
|
||
|
||
|
||
|
||
template <typename Container
|
||
,typename FUN
|
||
>
|
||
inline enable_if< can_STL_ForEach<Container>,
|
||
bool >
|
||
and_all (Container const& coll, FUN predicate)
|
||
{
|
||
using lib::meta::unwrap;
|
||
|
||
return and_all (unwrap(coll).begin()
|
||
,unwrap(coll).end()
|
||
, predicate);
|
||
}
|
||
|
||
|
||
template <typename IT
|
||
,typename FUN
|
||
>
|
||
inline enable_if< can_IterForEach<IT>,
|
||
bool >
|
||
and_all (IT const& ii, FUN predicate)
|
||
{
|
||
return and_all (ii, IT(), predicate);
|
||
}
|
||
|
||
|
||
|
||
template <typename Container
|
||
,typename FUN
|
||
>
|
||
inline enable_if< can_STL_ForEach<Container>,
|
||
bool >
|
||
has_any (Container const& coll, FUN predicate)
|
||
{
|
||
using lib::meta::unwrap;
|
||
|
||
return has_any (unwrap(coll).begin()
|
||
,unwrap(coll).end()
|
||
, predicate);
|
||
}
|
||
|
||
|
||
template <typename IT
|
||
,typename FUN
|
||
>
|
||
inline enable_if< can_IterForEach<IT>,
|
||
bool >
|
||
has_any (IT const& ii, FUN predicate)
|
||
{
|
||
return has_any (ii, IT(), predicate);
|
||
}
|
||
|
||
|
||
|
||
|
||
/* === allow creating argument binders on-the-fly === */
|
||
|
||
|
||
/** Accept binding for arbitrary function arguments
|
||
* @note obviously one of those arguments must be a placeholder */
|
||
template <typename CON, typename FUN, typename P1, typename...ARGS>
|
||
inline void
|
||
for_each (CON const& elements, FUN function, P1&& bind1, ARGS&& ...args)
|
||
{
|
||
for_each (elements, std::bind (function, std::forward<P1>(bind1), std::forward<ARGS> (args)...));
|
||
}
|
||
|
||
|
||
|
||
|
||
|
||
/** Accept binding for arbitrary function arguments
|
||
* @note obviously one of those arguments must be a placeholder */
|
||
template <typename CON, typename FUN, typename P1, typename...ARGS>
|
||
inline bool
|
||
and_all (CON const& elements, FUN function, P1&& bind1, ARGS&& ...args)
|
||
{
|
||
return and_all (elements, std::bind<bool> (function, std::forward<P1>(bind1), std::forward<ARGS> (args)...));
|
||
}
|
||
|
||
|
||
|
||
|
||
|
||
/** Accept binding for arbitrary function arguments
|
||
* @note obviously one of those arguments must be a placeholder */
|
||
template <typename CON, typename FUN, typename P1, typename...ARGS>
|
||
inline bool
|
||
has_any (CON const& elements, FUN function, P1&& bind1, ARGS&& ...args)
|
||
{
|
||
return has_any (elements, std::bind<bool> (function, std::forward<P1>(bind1), std::forward<ARGS> (args)...));
|
||
}
|
||
|
||
|
||
|
||
} // namespace util
|
||
#endif /*UTIL_FOREACH_H*/
|