forked from mirrors/gecko-dev
0d4a611a04
MozReview-Commit-ID: AXrQEjWzxvg --HG-- extra : rebase_source : bf972fbb22648af2edbb756eb899ebddf8444dbc
56 lines
1.6 KiB
C++
56 lines
1.6 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef RecurseGuard_h__
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#define RecurseGuard_h__
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#include "Utils.h"
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// This class acts as a tracker for avoiding infinite recursion when traversing
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// chains in CFGs etc.
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//
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// Constructing a RecurseGuard sets up a shared backing store which tracks the
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// currently observed objects. Whenever recursing, use RecurseGuard.recurse(T)
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// to construct another RecurseGuard with the same backing store.
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//
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// The RecurseGuard object will unregister its object when it is destroyed, and
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// has a method `isRepeat()` which will return `true` if the item was already
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// seen.
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template <typename T> class RecurseGuard {
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public:
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RecurseGuard(T Thing) : Thing(Thing), Set(new DenseSet<T>()), Repeat(false) {
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Set->insert(Thing);
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}
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RecurseGuard(T Thing, std::shared_ptr<DenseSet<T>> &Set)
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: Thing(Thing), Set(Set), Repeat(false) {
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Repeat = !Set->insert(Thing).second;
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}
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RecurseGuard(const RecurseGuard &) = delete;
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RecurseGuard(RecurseGuard &&Other)
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: Thing(Other.Thing), Set(Other.Set), Repeat(Other.Repeat) {
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Other.Repeat = true;
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}
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~RecurseGuard() {
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if (!Repeat) {
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Set->erase(Thing);
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}
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}
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bool isRepeat() { return Repeat; }
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T get() { return Thing; }
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operator T() { return Thing; }
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T operator->() { return Thing; }
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RecurseGuard recurse(T NewThing) { return RecurseGuard(NewThing, Set); }
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private:
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T Thing;
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std::shared_ptr<DenseSet<T>> Set;
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bool Repeat;
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};
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#endif // RecurseGuard_h__
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