The Tor Browser: parser/html/nsHtml5AtomTable.h@8bccb770b82d

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 #ifndef nsHtml5AtomTable_h

     6 #define nsHtml5AtomTable_h

     8 #include "nsHashKeys.h"

     9 #include "nsTHashtable.h"

    10 #include "nsAutoPtr.h"

    11 #include "nsIAtom.h"

    12 #include "nsIThread.h"

    14 class nsHtml5Atom;

    16 class nsHtml5AtomEntry : public nsStringHashKey

    17 {

    18   public:

    19     nsHtml5AtomEntry(KeyTypePointer aStr);

    20     nsHtml5AtomEntry(const nsHtml5AtomEntry& aOther);

    21     ~nsHtml5AtomEntry();

    22     inline nsHtml5Atom* GetAtom()

    23     {

    24       return mAtom;

    25     }

    26   private:

    27     nsAutoPtr<nsHtml5Atom> mAtom;

    28 };

    30 /**

    31  * nsHtml5AtomTable provides non-locking lookup and creation of atoms for

    32  * nsHtml5Parser or nsHtml5StreamParser.

    33  *

    34  * The hashtable holds dynamically allocated atoms that are private to an

    35  * instance of nsHtml5Parser or nsHtml5StreamParser. (Static atoms are used on

    36  * interned nsHtml5ElementNames and interned nsHtml5AttributeNames. Also, when

    37  * the doctype name is 'html', that identifier needs to be represented as a

    38  * static atom.)

    39  *

    40  * Each instance of nsHtml5Parser has a single instance of nsHtml5AtomTable,

    41  * and each instance of nsHtml5StreamParser has a single instance of

    42  * nsHtml5AtomTable. Dynamic atoms obtained from an nsHtml5AtomTable are valid

    43  * for == comparison with each other or with atoms declared in nsHtml5Atoms

    44  * within the nsHtml5Tokenizer and the nsHtml5TreeBuilder instances owned by

    45  * the same nsHtml5Parser/nsHtml5StreamParser instance that owns the

    46  * nsHtml5AtomTable instance.

    47  *

    48  * Dynamic atoms (atoms whose IsStaticAtom() returns false) obtained from

    49  * nsHtml5AtomTable must be re-obtained from another atom table when there's a

    50  * need to migrate atoms from an nsHtml5Parser to its nsHtml5StreamParser

    51  * (re-obtain from the other nsHtml5AtomTable), from an nsHtml5Parser to its

    52  * owner nsHtml5Parser (re-obtain from the other nsHtml5AtomTable) or from the

    53  * parser to the DOM (re-obtain from the application-wide atom table). To

    54  * re-obtain an atom from another atom table, obtain a string from the atom

    55  * using ToString(nsAString&) and look up an atom in the other table using that

    56  * string.

    57  *

    58  * An instance of nsHtml5AtomTable that belongs to an nsHtml5Parser is only

    59  * accessed from the main thread. An instance of nsHtml5AtomTable that belongs

    60  * to an nsHtml5StreamParser is accessed both from the main thread and from the

    61  * thread that executes the runnables of the nsHtml5StreamParser instance.

    62  * However, the threads never access the nsHtml5AtomTable instance concurrently

    63  * in the nsHtml5StreamParser case.

    64  *

    65  * Methods on the atoms obtained from nsHtml5AtomTable may be called on any

    66  * thread, although they only need to be called on the main thread or on the

    67  * thread working for the nsHtml5StreamParser when nsHtml5AtomTable belongs to

    68  * an nsHtml5StreamParser.

    69  *

    70  * Dynamic atoms obtained from nsHtml5AtomTable are deleted when the

    71  * nsHtml5AtomTable itself is destructed, which happens when the owner

    72  * nsHtml5Parser or nsHtml5StreamParser is destructed.

    73  */

    74 class nsHtml5AtomTable

    75 {

    76   public:

    77     nsHtml5AtomTable();

    78     ~nsHtml5AtomTable();

    80     /**

    81      * Obtains the atom for the given string in the scope of this atom table.

    82      */

    83     nsIAtom* GetAtom(const nsAString& aKey);

    85     /**

    86      * Empties the table.

    87      */

    88     void Clear()

    89     {

    90       mTable.Clear();

    91     }

    93 #ifdef DEBUG

    94     void SetPermittedLookupThread(nsIThread* aThread)

    95     {

    96       mPermittedLookupThread = aThread;

    97     }

    98 #endif

   100   private:

   101     nsTHashtable<nsHtml5AtomEntry> mTable;

   102 #ifdef DEBUG

   103     nsCOMPtr<nsIThread>            mPermittedLookupThread;

   104 #endif

   105 };

   107 #endif // nsHtml5AtomTable_h

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