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/* Distributed under the OSI-approved BSD 3-Clause License. See accompanying
file LICENSE.rst or https://cmake.org/licensing for details. */
#pragma once
#include "cmConfigure.h" // IWYU pragma: keep
#include <memory>
#include <type_traits>
enum class cmStackType
{
Const,
Mutable,
};
template <typename T, cmStackType Mutable>
struct cmStackEntry;
/** Base class template for CRTP to represent a stack of values.
Copies of the stack <i>share data</i>; mutating data on one copy will
change the data on <i>all</i> copies. */
template <typename T, typename Stack,
cmStackType Mutable = cmStackType::Mutable>
class cmStack
{
using Entry = cmStackEntry<T, Mutable>;
std::shared_ptr<Entry const> TopEntry;
public:
/** Default-construct an empty stack. */
cmStack();
/** Get a stack with the given call context added to the top. */
Stack Push(T value) const;
/** Get a stack with the top level removed.
May not be called until after a matching Push. */
Stack Pop() const;
/** Get the value at the top of the stack.
This may be called only if Empty() would return false. */
T const& Top() const;
template <bool E = (Mutable == cmStackType::Mutable)>
typename std::enable_if<E, T>::type& Top();
/** Return true if this stack is empty. */
bool Empty() const;
protected:
using Base = cmStack<T, Stack, Mutable>;
cmStack(std::shared_ptr<Entry const> parent, T value);
cmStack(std::shared_ptr<Entry const> top);
};
/** Specialization of cmStack for CRTP to represent a stack of constant values.
Provide value semantics, but use efficient reference-counting underneath
to avoid copies. */
template <typename T, typename Stack>
using cmConstStack = cmStack<T const, Stack, cmStackType::Const>;
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