cookie_guard.H File Reference

RAII guards for graph node/arc cookies. More...

#include <vector>
#include <utility>
#include <tpl_graph.H>

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Classes
class	Aleph::Cookie_Guard< GT >
	RAII guard that clears graph cookies on destruction. More...
class	Aleph::Cookie_Saver< GT >
	RAII guard that saves and restores graph cookies. More...
class	Aleph::Scope_Guard< GT, Cleanup >
	Generic RAII scope guard for cleanup operations on graphs. More...

Namespaces
namespace	Aleph
	Main namespace for Aleph-w library functions.

Functions
template<class GT , class Func >
auto	Aleph::with_clean_cookies (GT &g, Func &&func) -> decltype(func())
	Convenience function to run an algorithm with automatic cookie cleanup.
template<class GT , class Func >
auto	Aleph::with_saved_cookies (GT &g, Func &&func) -> decltype(func())
	Convenience function to run an algorithm preserving existing cookies.
template<class GT , class Cleanup >
	Aleph::Scope_Guard (const GT &, Cleanup) -> Scope_Guard< GT, Cleanup >
	Deduction guide for Scope_Guard.

Detailed Description

RAII guards for graph node/arc cookies.

This file provides RAII-style guards for managing cookies in graph algorithms. Cookies are temporary void* fields in nodes and arcs used by algorithms to store intermediate data.

Two main utilities are provided:

• Cookie_Guard: Automatically clears all cookies when the guard goes out of scope. Useful for exception safety - ensures cookies are cleaned even if an exception is thrown.
• Cookie_Saver: Saves current cookie values and restores them when the guard goes out of scope. Useful when an algorithm needs to temporarily use cookies without destroying data from a previous algorithm.

Example - Cookie_Guard (cleanup on exit)

template <class GT>
void my_algorithm(GT & g)
{
  Cookie_Guard<GT> guard(g);  // will clear cookies on exit
  
  // Use cookies for algorithm...
  for_each_node(g, [](auto * p) {
    NODE_COOKIE(p) = new MyData();
  });
  
  // ... algorithm logic that might throw ...
  
} // guard destructor clears all cookies (and optionally deletes)

Example - Cookie_Saver (preserve and restore)

template <class GT>
void nested_algorithm(GT & g)
{
  // Another algorithm already stored data in cookies
  Cookie_Saver<GT> saver(g);  // saves current cookies
  
  // Now we can use cookies freely
  for_each_node(g, [](auto * p) {
    NODE_COOKIE(p) = new TempData();
  });
  
  // ... do work ...
  
  // Clean up our temporary data
  for_each_node(g, [](auto * p) {
    delete static_cast<TempData*>(NODE_COOKIE(p));
  });
  
} // saver destructor restores original cookies

Author

Leandro Rabindranath León

Definition in file cookie_guard.H.