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Simplify transform and add support for more input container types

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Change-Id: Ib75cfcc7741be686c0117fbb27df869e14db4f69
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>
This commit is contained in:
Eike Ziller
2017-12-06 16:42:06 +01:00
parent d81c6c7403
commit fb4f7e7420
2 changed files with 44 additions and 62 deletions
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93
src/libs/utils/algorithm.h
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@@ -324,18 +324,6 @@ inserter(QSet<X> &container)
return QSetInsertIterator<QSet<X>>(container);
}
// Result type of transform operation
template<template<typename, typename...> class Container, typename IT, typename Function>
using ResultContainer = Container<std::decay_t<std::result_of_t<Function(IT)>>>;
template<typename C, typename SC, typename F>
void transform_impl(const SC &container, C &result, F function)
{
result.reserve(container.size());
std::transform(std::begin(container), std::end(container), inserter(result), function);
}
} // anonymous
// --------------------------------------------------------------------
@@ -346,125 +334,106 @@ void transform_impl(const SC &container, C &result, F function)
// function:
template<template<typename, typename...> class C, // result container type
template<typename, typename...> class SC, // input container type
template<typename...> class SC, // input container type
typename F, // function type
typename T, // input value type
typename... SCArgs> // Arguments to SC
typename... SCArgs, // Arguments to SC
typename Value = typename SC<SCArgs...>::value_type,
typename ResultContainer = C<std::decay_t<std::result_of_t<F(Value)>>>>
Q_REQUIRED_RESULT
decltype(auto) transform(const SC<T, SCArgs...> &container, F function)
decltype(auto) transform(const SC<SCArgs...> &container, F function)
{
ResultContainer<C, T, F> result;
transform_impl(container, result, function);
ResultContainer result;
result.reserve(container.size());
std::transform(std::begin(container), std::end(container), inserter(result), function);
return result;
}
// member function:
template<template<typename, typename...> class C, // result container type
template<typename, typename...> class SC, // input container type
typename T, // input value type
template<template<typename...> class C, // result container type
template<typename...> class SC, // input container type
typename R,
typename S,
typename... SCArgs> // Arguments to SC
Q_REQUIRED_RESULT
decltype(auto) transform(const SC<T, SCArgs...> &container, R (S::*p)() const)
decltype(auto) transform(const SC<SCArgs...> &container, R (S::*p)() const)
{
ResultContainer<C, T, decltype(std::mem_fn(p))> result;
transform_impl(container, result, std::mem_fn(p));
return result;
return transform<C, SC>(container, std::mem_fn(p));
}
// members:
template<template<typename, typename...> class C, // result container
template<typename, typename...> class SC, // input container
typename T, // container value type
template<template<typename...> class C, // result container
template<typename...> class SC, // input container
typename R,
typename S,
typename... SCArgs> // Arguments to SC
Q_REQUIRED_RESULT
decltype(auto) transform(const SC<T, SCArgs...> &container, R S::*p)
decltype(auto) transform(const SC<SCArgs...> &container, R S::*p)
{
ResultContainer<C, T, decltype(std::mem_fn(p))> result;
transform_impl(container, result, std::mem_fn(p));
return result;
return transform<C, SC>(container, std::mem_fn(p));
}
// different container types for input and output, e.g. transforming a QList into a QSet
// function:
template<template<typename, typename...> class C, // container type
template<template<typename...> class C, // container type
typename F, // function type
typename T, // input value type
typename... CArgs> // Arguments to SC
Q_REQUIRED_RESULT
decltype(auto) transform(const C<T, CArgs...> &container, F function)
decltype(auto) transform(const C<CArgs...> &container, F function)
{
ResultContainer<C, T, F> result;
transform_impl(container, result, function);
return result;
return transform<C, C>(container, function);
}
// member function:
template<template<typename, typename...> class C, // container type
typename T, // input value type
template<template<typename...> class C, // container type
typename R,
typename S,
typename... CArgs> // Arguments to SC
Q_REQUIRED_RESULT
decltype(auto) transform(const C<T, CArgs...> &container, R (S::*p)() const)
decltype(auto) transform(const C<CArgs...> &container, R (S::*p)() const)
{
ResultContainer<C, T, decltype(std::mem_fn(p))> result;
transform_impl(container, result, std::mem_fn(p));
return result;
return transform<C, C>(container, std::mem_fn(p));
}
// members:
template<template<typename, typename...> class C, // container
typename T, // container value type
template<template<typename...> class C, // container
typename R,
typename S,
typename... CArgs> // Arguments to SC
Q_REQUIRED_RESULT
decltype(auto) transform(const C<T, CArgs...> &container, R S::*p)
decltype(auto) transform(const C<CArgs...> &container, R S::*p)
{
ResultContainer<C, T, decltype(std::mem_fn(p))> result;
transform_impl(container, result, std::mem_fn(p));
return result;
return transform<C, C>(container, std::mem_fn(p));
}
// Specialization for QStringList:
template<template<typename, typename...> class C = QList, // result container
template<template<typename...> class C = QList, // result container
typename F> // Arguments to C
Q_REQUIRED_RESULT
decltype(auto) transform(const QStringList &container, F function)
{
ResultContainer<C, QString, F> result;
transform_impl(static_cast<QList<QString>>(container), result, function);
return result;
return transform<C, QList>(static_cast<QList<QString>>(container), function);
}
// member function:
template<template<typename, typename...> class C = QList, // result container type
template<template<typename...> class C = QList, // result container type
typename R,
typename S>
Q_REQUIRED_RESULT
decltype(auto) transform(const QStringList &container, R (S::*p)() const)
{
ResultContainer<C, QString, decltype(std::mem_fn(p))> result;
transform_impl(container, result, std::mem_fn(p));
return result;
return transform<C, QList>(static_cast<QList<QString>>(container), std::mem_fn(p));
}
// members:
template<template<typename, typename...> class C = QList, // result container
template<template<typename...> class C = QList, // result container
typename R,
typename S>
Q_REQUIRED_RESULT
decltype(auto) transform(const QStringList &container, R S::*p)
{
ResultContainer<C, QString, decltype(std::mem_fn(p))> result;
transform_impl(container, result, std::mem_fn(p));
return result;
return transform<C, QList>(static_cast<QList<QString>>(container), std::mem_fn(p));
}
//////////////////

13
tests/auto/algorithm/tst_algorithm.cpp
View File

@@ -28,6 +28,7 @@
#include <array>
#include <deque>
#include <memory>
#include <unordered_map>
#include <valarray>
// must get included after the containers above or gcc4.9 will have a problem using
@@ -235,6 +236,18 @@ void tst_Algorithm::transform()
const std::vector<int> trans = Utils::transform(v, &Struct::member);
QCOMPARE(trans, std::vector<int>({1, 2, 3, 4}));
}
{
// std::unordered_map -> QList
std::unordered_map<int, double> m;
m.emplace(1, 1.5);
m.emplace(3, 2.5);
m.emplace(5, 3.5);
QList<double> trans = Utils::transform<QList>(m, [](const std::pair<int, double> &in) {
return in.first * in.second;
});
Utils::sort(trans);
QCOMPARE(trans, QList<double>({1.5, 7.5, 17.5}));
}
}
void tst_Algorithm::sort()