Source/cmConstStack.h

   1 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
   2    file Copyright.txt or https://cmake.org/licensing for details.  */
   3 #pragma once
   4
   5 #include "cmConfigure.h" // IWYU pragma: keep
   6
   7 #include <memory>
   8
   9 /** Base class template for CRTP to represent a stack of constant values.
  10     Provide value semantics, but use efficient reference-counting underneath
  11     to avoid copies.  */
  12 template <typename T, typename Stack>
  13 class cmConstStack
  14 {
  15   struct Entry;
  16   std::shared_ptr<Entry const> TopEntry;
  17
  18 public:
  19   /** Default-construct an empty stack.  */
  20   cmConstStack();
  21
  22   /** Get a stack with the given call context added to the top.  */
  23   Stack Push(T value) const;
  24
  25   /** Get a stack with the top level removed.
  26       May not be called until after a matching Push.  */
  27   Stack Pop() const;
  28
  29   /** Get the value at the top of the stack.
  30       This may be called only if Empty() would return false.  */
  31   T const& Top() const;
  32
  33   /** Return true if this stack is empty.  */
  34   bool Empty() const;
  35
  36 protected:
  37   cmConstStack(std::shared_ptr<Entry const> parent, T value);
  38   cmConstStack(std::shared_ptr<Entry const> top);
  39 };