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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef RecurseGuard_h__
#define RecurseGuard_h__
#include "Utils.h"
// This class acts as a tracker for avoiding infinite recursion when traversing
// chains in CFGs etc.
// Constructing a RecurseGuard sets up a shared backing store which tracks the
// currently observed objects. Whenever recursing, use RecurseGuard.recurse(T)
// to construct another RecurseGuard with the same backing store.
// The RecurseGuard object will unregister its object when it is destroyed, and
// has a method `isRepeat()` which will return `true` if the item was already
// seen.
template <typename T> class RecurseGuard {
RecurseGuard(T Thing) : Thing(Thing), Set(new DenseSet<T>()), Repeat(false) {
RecurseGuard(T Thing, std::shared_ptr<DenseSet<T>> &Set)
: Thing(Thing), Set(Set), Repeat(false) {
Repeat = !Set->insert(Thing).second;
RecurseGuard(const RecurseGuard &) = delete;
RecurseGuard(RecurseGuard &&Other)
: Thing(Other.Thing), Set(Other.Set), Repeat(Other.Repeat) {
Other.Repeat = true;
~RecurseGuard() {
if (!Repeat) {
bool isRepeat() { return Repeat; }
T get() { return Thing; }
operator T() { return Thing; }
T operator->() { return Thing; }
RecurseGuard recurse(T NewThing) { return RecurseGuard(NewThing, Set); }
T Thing;
std::shared_ptr<DenseSet<T>> Set;
bool Repeat;
#endif // RecurseGuard_h__