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SVGAttrTearoffTable.h (2803B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #ifndef DOM_SVG_SVGATTRTEAROFFTABLE_H_
      8 #define DOM_SVG_SVGATTRTEAROFFTABLE_H_
      9 
     10 #include "mozilla/DebugOnly.h"
     11 #include "mozilla/StaticPtr.h"
     12 #include "nsDebug.h"
     13 #include "nsHashKeys.h"
     14 #include "nsTHashMap.h"
     15 
     16 namespace mozilla {
     17 
     18 /**
     19 * Global hashmap to associate internal SVG data types (e.g. SVGAnimatedLength)
     20 * with DOM tear-off objects (e.g. DOMSVGLength). This allows us to always
     21 * return the same object for subsequent requests for DOM objects.
     22 *
     23 * We don't keep an owning reference to the tear-off objects so they are
     24 * responsible for removing themselves from this table when they die.
     25 */
     26 template <class SimpleType, class TearoffType>
     27 class SVGAttrTearoffTable {
     28 public:
     29 #ifdef DEBUG
     30  ~SVGAttrTearoffTable() {
     31    NS_ASSERTION(!mTable, "Tear-off objects remain in hashtable at shutdown.");
     32  }
     33 #endif
     34 
     35  TearoffType* GetTearoff(SimpleType* aSimple);
     36 
     37  void AddTearoff(SimpleType* aSimple, TearoffType* aTearoff);
     38 
     39  void RemoveTearoff(SimpleType* aSimple);
     40 
     41 private:
     42  using SimpleTypePtrKey = nsPtrHashKey<SimpleType>;
     43  using TearoffTable = nsTHashMap<SimpleTypePtrKey, TearoffType*>;
     44 
     45  StaticAutoPtr<TearoffTable> mTable;
     46 };
     47 
     48 template <class SimpleType, class TearoffType>
     49 TearoffType* SVGAttrTearoffTable<SimpleType, TearoffType>::GetTearoff(
     50    SimpleType* aSimple) {
     51  if (!mTable) {
     52    return nullptr;
     53  }
     54 
     55  TearoffType* tearoff = nullptr;
     56 
     57  DebugOnly<bool> found = mTable->Get(aSimple, &tearoff);
     58  MOZ_ASSERT(!found || tearoff,
     59             "null pointer stored in attribute tear-off map");
     60 
     61  return tearoff;
     62 }
     63 
     64 template <class SimpleType, class TearoffType>
     65 void SVGAttrTearoffTable<SimpleType, TearoffType>::AddTearoff(
     66    SimpleType* aSimple, TearoffType* aTearoff) {
     67  if (!mTable) {
     68    mTable = new TearoffTable();
     69  }
     70 
     71  // We shouldn't be adding a tear-off if there already is one. If that happens,
     72  // something is wrong.
     73  if (mTable->Get(aSimple, nullptr)) {
     74    MOZ_ASSERT(false, "There is already a tear-off for this object.");
     75    return;
     76  }
     77 
     78  mTable->InsertOrUpdate(aSimple, aTearoff);
     79 }
     80 
     81 template <class SimpleType, class TearoffType>
     82 void SVGAttrTearoffTable<SimpleType, TearoffType>::RemoveTearoff(
     83    SimpleType* aSimple) {
     84  if (!mTable) {
     85    // Perhaps something happened in between creating the SimpleType object and
     86    // registering it
     87    return;
     88  }
     89 
     90  mTable->Remove(aSimple);
     91  if (mTable->Count() == 0) {
     92    mTable = nullptr;
     93  }
     94 }
     95 
     96 }  // namespace mozilla
     97 
     98 #endif  // DOM_SVG_SVGATTRTEAROFFTABLE_H_