parser/html/nsHtml5AtomTable.h

   1 /* ***** BEGIN LICENSE BLOCK *****
   2  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   3  *
   4  * The contents of this file are subject to the Mozilla Public License Version
   5  * 1.1 (the "License"); you may not use this file except in compliance with
   6  * the License. You may obtain a copy of the License at
   7  * http://www.mozilla.org/MPL/
   8  *
   9  * Software distributed under the License is distributed on an "AS IS" basis,
  10  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  11  * for the specific language governing rights and limitations under the
  12  * License.
  13  *
  14  * The Original Code is HTML Parser C++ Translator code.
  15  *
  16  * The Initial Developer of the Original Code is
  17  * Mozilla Foundation.
  18  * Portions created by the Initial Developer are Copyright (C) 2009
  19  * the Initial Developer. All Rights Reserved.
  20  *
  21  * Contributor(s):
  22  *   Henri Sivonen <hsivonen@iki.fi>
  23  *
  24  * Alternatively, the contents of this file may be used under the terms of
  25  * either the GNU General Public License Version 2 or later (the "GPL"), or
  26  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  27  * in which case the provisions of the GPL or the LGPL are applicable instead
  28  * of those above. If you wish to allow use of your version of this file only
  29  * under the terms of either the GPL or the LGPL, and not to allow others to
  30  * use your version of this file under the terms of the MPL, indicate your
  31  * decision by deleting the provisions above and replace them with the notice
  32  * and other provisions required by the GPL or the LGPL. If you do not delete
  33  * the provisions above, a recipient may use your version of this file under
  34  * the terms of any one of the MPL, the GPL or the LGPL.
  35  *
  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #ifndef nsHtml5AtomTable_h_
  39 #define nsHtml5AtomTable_h_
  40
  41 #include "nsHashKeys.h"
  42 #include "nsTHashtable.h"
  43 #include "nsAutoPtr.h"
  44 #include "nsIAtom.h"
  45 #include "nsIThread.h"
  46
  47 class nsHtml5Atom;
  48
  49 class nsHtml5AtomEntry : public nsStringHashKey
  50 {
  51   public:
  52     nsHtml5AtomEntry(KeyTypePointer aStr);
  53     nsHtml5AtomEntry(const nsHtml5AtomEntry& aOther);
  54     ~nsHtml5AtomEntry();
  55     inline nsHtml5Atom* GetAtom() {
  56       return mAtom;
  57     }
  58   private:
  59     nsAutoPtr<nsHtml5Atom> mAtom;
  60 };
  61
  62 /**
  63  * nsHtml5AtomTable provides non-locking lookup and creation of atoms for
  64  * nsHtml5Parser or nsHtml5StreamParser.
  65  *
  66  * The hashtable holds dynamically allocated atoms that are private to an
  67  * instance of nsHtml5Parser or nsHtml5StreamParser. (Static atoms are used on
  68  * interned nsHtml5ElementNames and interned nsHtml5AttributeNames. Also, when
  69  * the doctype name is 'html', that identifier needs to be represented as a
  70  * static atom.)
  71  *
  72  * Each instance of nsHtml5Parser has a single instance of nsHtml5AtomTable,
  73  * and each instance of nsHtml5StreamParser has a single instance of
  74  * nsHtml5AtomTable. Dynamic atoms obtained from an nsHtml5AtomTable are valid
  75  * for == comparison with each other or with atoms declared in nsHtml5Atoms
  76  * within the nsHtml5Tokenizer and the nsHtml5TreeBuilder instances owned by
  77  * the same nsHtml5Parser/nsHtml5StreamParser instance that owns the
  78  * nsHtml5AtomTable instance.
  79  *
  80  * Dynamic atoms (atoms whose IsStaticAtom() returns PR_FALSE) obtained from
  81  * nsHtml5AtomTable must be re-obtained from another atom table when there's a
  82  * need to migrate atoms from an nsHtml5Parser to its nsHtml5StreamParser
  83  * (re-obtain from the other nsHtml5AtomTable), from an nsHtml5Parser to its
  84  * owner nsHtml5Parser (re-obtain from the other nsHtml5AtomTable) or from the
  85  * parser to the DOM (re-obtain from the application-wide atom table). To
  86  * re-obtain an atom from another atom table, obtain a string from the atom
  87  * using ToString(nsAString&) and look up an atom in the other table using that
  88  * string.
  89  *
  90  * An instance of nsHtml5AtomTable that belongs to an nsHtml5Parser is only
  91  * accessed from the main thread. An instance of nsHtml5AtomTable that belongs
  92  * to an nsHtml5StreamParser is accessed both from the main thread and from the
  93  * thread that executes the runnables of the nsHtml5StreamParser instance.
  94  * However, the threads never access the nsHtml5AtomTable instance concurrently
  95  * in the nsHtml5StreamParser case.
  96  *
  97  * Methods on the atoms obtained from nsHtml5AtomTable may be called on any
  98  * thread, although they only need to be called on the main thread or on the
  99  * thread working for the nsHtml5StreamParser when nsHtml5AtomTable belongs to
 100  * an nsHtml5StreamParser.
 101  *
 102  * Dynamic atoms obtained from nsHtml5AtomTable are deleted when the
 103  * nsHtml5AtomTable itself is destructed, which happens when the owner
 104  * nsHtml5Parser or nsHtml5StreamParser is destructed.
 105  */
 106 class nsHtml5AtomTable
 107 {
 108   public:
 109     nsHtml5AtomTable();
 110     ~nsHtml5AtomTable();
 111
 112     /**
 113      * Must be called after the constructor before use. Returns PR_TRUE
 114      * when successful and PR_FALSE on OOM failure.
 115      */
 116     inline PRBool Init() {
 117       return mTable.Init();
 118     }
 119
 120     /**
 121      * Obtains the atom for the given string in the scope of this atom table.
 122      */
 123     nsIAtom* GetAtom(const nsAString& aKey);
 124
 125     /**
 126      * Empties the table.
 127      */
 128     void Clear() {
 129       mTable.Clear();
 130     }
 131
 132 #ifdef DEBUG
 133     void SetPermittedLookupThread(nsIThread* aThread) {
 134       mPermittedLookupThread = aThread;
 135     }
 136 #endif
 137
 138   private:
 139     nsTHashtable<nsHtml5AtomEntry> mTable;
 140 #ifdef DEBUG
 141     nsCOMPtr<nsIThread>            mPermittedLookupThread;
 142 #endif
 143 };
 144
 145 #endif // nsHtml5AtomTable_h_