qt-creator/src/libs/utils/algorithm.h

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt Creator.
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
****************************************************************************/

#ifndef ALGORITHM_H
#define ALGORITHM_H

#include <qcompilerdetection.h> // for Q_REQUIRED_RESULT

#include <algorithm>
#include <functional>
#include <tuple>

#include <QStringList>

namespace Utils
{
//////////////////
// anyOf
/////////////////

// anyOf taking a member function pointer
template<typename T, typename R, typename S>
bool anyOf(const T &container, R (S::*predicate)() const)
{
    return std::any_of(container.begin(), container.end(), std::mem_fn(predicate));
}

template<typename T, typename F>
bool anyOf(const T &container, F predicate)
{
    return std::any_of(container.begin(), container.end(), predicate);
}

template<typename T, typename F>
int count(const T &container, F predicate)
{
    return std::count_if(container.begin(), container.end(), predicate);
}

//////////////////
// allOf
/////////////////
template<typename T, typename F>
bool allOf(const T &container, F predicate)
{
    return std::all_of(container.begin(), container.end(), predicate);
}

//////////////////
// erase
/////////////////
template<typename T, typename F>
void erase(QList<T> &container, F predicate)
{
    container.erase(std::remove_if(container.begin(), container.end(), predicate),
                    container.end());
}

//////////////////
// contains
/////////////////
template<typename T, typename F>
bool contains(const T &container, F function)
{
    typename T::const_iterator end = container.end();
    typename T::const_iterator begin = container.begin();

    typename T::const_iterator it = std::find_if(begin, end, function);
    return it != end;
}

//////////////////
// findOr
/////////////////
template<typename T, typename F>
typename T::value_type findOr(const T &container, typename T::value_type other, F function)
{
    typename T::const_iterator end = container.end();
    typename T::const_iterator begin = container.begin();

    typename T::const_iterator it = std::find_if(begin, end, function);
    if (it == end)
        return other;
    return *it;
}

template<typename T, typename R, typename S>
typename T::value_type findOr(const T &container, typename T::value_type other, R (S::*function)() const)
{
    return findOr(container, other, std::mem_fn(function));
}


template<typename T, typename F>
int indexOf(const T &container, F function)
{
    typename T::const_iterator end = container.end();
    typename T::const_iterator begin = container.begin();

    typename T::const_iterator it = std::find_if(begin, end, function);
    if (it == end)
        return -1;
    return it - begin;
}

template<typename T, typename F>
typename T::value_type findOrDefault(const T &container, F function)
{
    return findOr(container, typename T::value_type(), function);
}

template<typename T, typename R, typename S>
typename T::value_type findOrDefault(const T &container, R (S::*function)() const)
{
    return findOr(container, typename T::value_type(), function);
}

//////////////////
// find helpers
//////////////////
template<typename R, typename S, typename T>
auto equal(R (S::*function)() const, T value)
    -> decltype(std::bind<bool>(std::equal_to<T>(), value, std::bind(function, std::placeholders::_1)))
{
    // This should use std::equal_to<> instead of std::eqaul_to<T>,
    // but that's not supported everywhere yet, since it is C++14
    return std::bind<bool>(std::equal_to<T>(), value, std::bind(function, std::placeholders::_1));
}

template<typename R, typename S, typename T>
auto equal(R S::*member, T value)
    -> decltype(std::bind<bool>(std::equal_to<T>(), value, std::bind(member, std::placeholders::_1)))
{
    return std::bind<bool>(std::equal_to<T>(), value, std::bind(member, std::placeholders::_1));
}


//////////////////
// transform
/////////////////

namespace {
/////////////////
// helper code for transform to use back_inserter and thus push_back for everything
// and insert for QSet<>
//

// QSetInsertIterator, straight from the standard for insert_iterator
// just without the additional parameter to insert
template <class Container>
  class QSetInsertIterator :
    public std::iterator<std::output_iterator_tag,void,void,void,void>
{
protected:
  Container *container;

public:
  typedef Container container_type;
  explicit QSetInsertIterator (Container &x)
    : container(&x) {}
  QSetInsertIterator<Container> &operator=(const typename Container::value_type &value)
    { container->insert(value); return *this; }
  QSetInsertIterator<Container> &operator= (typename Container::value_type &&value)
    { container->insert(std::move(value)); return *this; }
  QSetInsertIterator<Container >&operator*()
    { return *this; }
  QSetInsertIterator<Container> &operator++()
    { return *this; }
  QSetInsertIterator<Container> operator++(int)
    { return *this; }
};

// inserter helper function, returns a std::back_inserter for most containers
// and is overloaded for QSet<> to return a QSetInsertIterator
template<typename C>
inline std::back_insert_iterator<C>
inserter(C &container)
{
    return std::back_inserter(container);
}

template<typename X>
inline QSetInsertIterator<QSet<X>>
inserter(QSet<X> &container)
{
    return QSetInsertIterator<QSet<X>>(container);
}

// decay_t is C++14, so provide it here, remove once we require C++14
template<typename T>
using decay_t = typename std::decay<T>::type;

// abstraction to treat Container<T> and QStringList similarly
template<typename T>
struct ContainerType
{

};

// specialization for qt container T_Container<T_Type>
template<template<typename> class T_Container, typename T_Type>
struct ContainerType<T_Container<T_Type>> {
    typedef T_Type ElementType;

    template<class NewElementType>
    struct WithElementType
    {
        typedef T_Container<NewElementType> type;
    };

    template<class F, template<typename> class C = T_Container>
    struct ResultOfTransform
    {
        typedef C<decay_t<typename std::result_of<F (ElementType)>::type>> type;
    };

    template<class R>
    struct ResultOfTransformPMF
    {
        typedef typename WithElementType<decay_t<R>>::type type;
    };
};

// specialization for QStringList
template<>
struct ContainerType<QStringList> : ContainerType<QList<QString>>
{
};

}

// actual implementation of transform
template<typename C, // result container type
         typename SC> // input container type
struct TransformImpl {
    template <typename F>
    Q_REQUIRED_RESULT
    static C call(const SC &container, F function)
    {
        C result;
        std::transform(container.begin(), container.end(),
                       inserter(result),
                       function);
        return result;
    }

    template <typename R, typename S>
    Q_REQUIRED_RESULT
    static C call(const SC &container, R (S::*p)() const)
    {
        return call(container, std::mem_fn(p));
    }

};

// same container type for input and output, e.g. transforming a QList<QString> into QList<int>
// or QStringList -> QList<>
template<typename C, // container
         typename F>
Q_REQUIRED_RESULT
auto transform(const C &container, F function)
-> typename ContainerType<C>::template ResultOfTransform<F>::type
{
    return TransformImpl<
                typename ContainerType<C>::template ResultOfTransform<F>::type,
                C
            >::call(container, function);
}

// same container type for member function pointer
template<typename C,
        typename R,
        typename S>
Q_REQUIRED_RESULT
auto transform(const C &container, R (S::*p)() const)
    ->typename ContainerType<C>::template ResultOfTransformPMF<R>::type
{
    return TransformImpl<
                typename ContainerType<C>::template ResultOfTransformPMF<R>::type,
                C
            >::call(container, p);
}

// different container types for input and output, e.g. transforming a QList into a QSet
template<template<typename> class C, // result container type
         typename SC, // input container type
         typename F> // function type
Q_REQUIRED_RESULT
auto transform(const SC &container, F function)
     -> typename ContainerType<SC>::template ResultOfTransform<F, C>::type
{
    return TransformImpl<
                typename ContainerType<SC>::template ResultOfTransform<F, C>::type,
                SC
            >::call(container, function);
}

// different container types for input and output, e.g. transforming a QList into a QSet
// for member function pointers
template<template<typename> class C, // result container type
         typename SC, // input container type
         typename R,
         typename S>
Q_REQUIRED_RESULT
auto transform(const SC &container, R (S::*p)() const)
     -> C<decay_t<R>>
{
    return TransformImpl<
                C<decay_t<R>>,
                SC
            >::call(container, p);
}

//////////////////
// filtered
/////////////////
template<typename C, typename F>
Q_REQUIRED_RESULT
C filtered(const C &container, F predicate)
{
    C out;
    std::copy_if(container.begin(), container.end(),
                 inserter(out), predicate);
    return out;
}

template<typename C, typename R, typename S>
Q_REQUIRED_RESULT
C filtered(const C &container, R (S::*predicate)() const)
{
    C out;
    std::copy_if(container.begin(), container.end(),
                 inserter(out), std::mem_fn(predicate));
    return out;
}

//////////////////
// partition
/////////////////

// Recommended usage:
// C hit;
// C miss;
// std::tie(hit, miss) = Utils::partition(container, predicate);

template<typename C, typename F>
Q_REQUIRED_RESULT
std::tuple<C, C> partition(const C &container, F predicate)
{
    C hit;
    C miss;
    auto hitIns = inserter(hit);
    auto missIns = inserter(miss);
    foreach (auto i, container) {
        if (predicate(i))
            hitIns = i;
        else
            missIns = i;
    }
    return std::make_tuple(hit, miss);
}

template<typename C, typename R, typename S>
Q_REQUIRED_RESULT
std::tuple<C, C> partition(const C &container, R (S::*predicate)() const)
{
    return partition(container, std::mem_fn(predicate));
}

//////////////////
// filteredUnique
/////////////////

template<typename C>
Q_REQUIRED_RESULT
C filteredUnique(const C &container)
{
    C result;
    auto ins = inserter(result);

    QSet<typename C::value_type> seen;
    int setSize = 0;

    auto endIt = container.end();
    for (auto it = container.begin(); it != endIt; ++it) {
        seen.insert(*it);
        if (setSize == seen.size()) // unchanged size => was already seen
            continue;
        ++setSize;
        ins = *it;
    }
    return result;
}

//////////////////
// sort
/////////////////
template <typename Container>
inline void sort(Container &c)
{
    std::sort(c.begin(), c.end());
}

template <typename Container, typename Predicate>
inline void sort(Container &c, Predicate p)
{
    std::sort(c.begin(), c.end(), p);
}

}

#endif // ALGORITHM_H