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11cc728e75
This presents value semantics for a stack of constant values. Internally it shares ownership to avoid copies. Previously this was implemented by `cmListFileBacktrace` explicitly, but the approach can be re-used for other kinds of stacks.
40 lines
1.1 KiB
C++
40 lines
1.1 KiB
C++
/* Distributed under the OSI-approved BSD 3-Clause License. See accompanying
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file Copyright.txt or https://cmake.org/licensing for details. */
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#pragma once
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#include "cmConfigure.h" // IWYU pragma: keep
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#include <memory>
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/** Base class template for CRTP to represent a stack of constant values.
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Provide value semantics, but use efficient reference-counting underneath
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to avoid copies. */
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template <typename T, typename Stack>
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class cmConstStack
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{
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struct Entry;
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std::shared_ptr<Entry const> TopEntry;
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public:
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/** Default-construct an empty stack. */
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cmConstStack();
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/** Get a stack with the given call context added to the top. */
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Stack Push(T value) const;
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/** Get a stack with the top level removed.
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May not be called until after a matching Push. */
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Stack Pop() const;
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/** Get the value at the top of the stack.
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This may be called only if Empty() would return false. */
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T const& Top() const;
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/** Return true if this stack is empty. */
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bool Empty() const;
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protected:
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cmConstStack(std::shared_ptr<Entry const> parent, T value);
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cmConstStack(std::shared_ptr<Entry const> top);
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};
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