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Support specifying complete result type in Utils::transform

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Can come in handy when the function or member does not directly return
the right value type for the result list, but is implicitly convertable
to it. For example from pointer to class to pointer to superclass, or
from int to double.

const auto result
    = Utils::transform<QVector<double>>(v, &ValueType::intMember)

Change-Id: I0e1914d70bb2580b91098dd37e85a31ca14b0ae6
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>
Reviewed-by: Marco Bubke <marco.bubke@qt.io>
This commit is contained in:
Eike Ziller
2017-12-11 20:35:39 +01:00
parent b054e1b1f5
commit 6b48beeeb0
2 changed files with 105 additions and 15 deletions
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54
src/libs/utils/algorithm.h
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@@ -332,7 +332,21 @@ inserter(QSet<X> &container)
// different container types for input and output, e.g. transforming a QList into a QSet
// function:
// function without result type deduction:
template<typename ResultContainer, // complete result container type
template<typename...> class SC, // input container type
typename F, // function type
typename... SCArgs> // Arguments to SC
Q_REQUIRED_RESULT
decltype(auto) transform(const SC<SCArgs...> &container, F function)
{
ResultContainer result;
result.reserve(container.size());
std::transform(std::begin(container), std::end(container), inserter(result), function);
return result;
}
// function with result type deduction:
template<template<typename> class C, // result container type
template<typename...> class SC, // input container type
typename F, // function type
@@ -342,10 +356,7 @@ template<template<typename> class C, // result container type
Q_REQUIRED_RESULT
decltype(auto) transform(const SC<SCArgs...> &container, F function)
{
ResultContainer result;
result.reserve(container.size());
std::transform(std::begin(container), std::end(container), inserter(result), function);
return result;
return transform<ResultContainer>(container, function);
}
template<template<typename, typename> class C, // result container type
@@ -358,13 +369,10 @@ template<template<typename, typename> class C, // result container type
Q_REQUIRED_RESULT
decltype(auto) transform(const SC<SCArgs...> &container, F function)
{
ResultContainer result;
result.reserve(container.size());
std::transform(std::begin(container), std::end(container), inserter(result), function);
return result;
return transform<ResultContainer>(container, function);
}
// member function:
// member function without result type deduction:
template<template<typename...> class C, // result container type
template<typename...> class SC, // input container type
typename R,
@@ -376,7 +384,31 @@ decltype(auto) transform(const SC<SCArgs...> &container, R (S::*p)() const)
return transform<C, SC>(container, std::mem_fn(p));
}
// members:
// member function with result type deduction:
template<typename ResultContainer, // complete 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<SCArgs...> &container, R (S::*p)() const)
{
return transform<ResultContainer, SC>(container, std::mem_fn(p));
}
// member without result type deduction:
template<typename ResultContainer, // complete result container type
template<typename...> class SC, // input container
typename R,
typename S,
typename... SCArgs> // Arguments to SC
Q_REQUIRED_RESULT
decltype(auto) transform(const SC<SCArgs...> &container, R S::*p)
{
return transform<ResultContainer, SC>(container, std::mem_fn(p));
}
// member with result type deduction:
template<template<typename...> class C, // result container
template<typename...> class SC, // input container
typename R,