The Tor Browser: js/src/jshashutil.h@a63d609f5ebe

     1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-

     2  * vim: set ts=8 sts=4 et sw=4 tw=99:

     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/. */

     7 #ifndef jshashutil_h

     8 #define jshashutil_h

    10 #include "jscntxt.h"

    12 namespace js {

    14 /*

    15  * Used to add entries to a js::HashMap or HashSet where the key depends on a GC

    16  * thing that may be moved by generational collection between the call to

    17  * lookupForAdd() and relookupOrAdd().

    18  */

    19 template <class T>

    20 struct DependentAddPtr

    21 {

    22     typedef typename T::AddPtr AddPtr;

    23     typedef typename T::Entry Entry;

    25     template <class Lookup>

    26     DependentAddPtr(const ExclusiveContext *cx, const T &table, const Lookup &lookup)

    27       : addPtr(table.lookupForAdd(lookup))

    28 #ifdef JSGC_GENERATIONAL

    29       , originalGcNumber(cx->zone()->gcNumber())

    30 #endif

    31         {}

    33     template <class KeyInput, class ValueInput>

    34     bool add(const ExclusiveContext *cx, T &table, const KeyInput &key, const ValueInput &value) {

    35 #ifdef JSGC_GENERATIONAL

    36         bool gcHappened = originalGcNumber != cx->zone()->gcNumber();

    37         if (gcHappened)

    38             addPtr = table.lookupForAdd(key);

    39 #endif

    40         return table.relookupOrAdd(addPtr, key, value);

    41     }

    43     typedef void (DependentAddPtr::* ConvertibleToBool)();

    44     void nonNull() {}

    46     bool found() const                 { return addPtr.found(); }

    47     operator ConvertibleToBool() const { return found() ? &DependentAddPtr::nonNull : 0; }

    48     const Entry &operator*() const     { return *addPtr; }

    49     const Entry *operator->() const    { return &*addPtr; }

    51   private:

    52     AddPtr addPtr ;

    53 #ifdef JSGC_GENERATIONAL

    54     const uint64_t originalGcNumber;

    55 #endif

    57     DependentAddPtr() MOZ_DELETE;

    58     DependentAddPtr(const DependentAddPtr&) MOZ_DELETE;

    59     DependentAddPtr& operator=(const DependentAddPtr&) MOZ_DELETE;

    60 };

    62 } // namespace js

    64 #endif

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