michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef nsHtml5AtomTable_h
michael@0: #define nsHtml5AtomTable_h
michael@0: 
michael@0: #include "nsHashKeys.h"
michael@0: #include "nsTHashtable.h"
michael@0: #include "nsAutoPtr.h"
michael@0: #include "nsIAtom.h"
michael@0: #include "nsIThread.h"
michael@0: 
michael@0: class nsHtml5Atom;
michael@0: 
michael@0: class nsHtml5AtomEntry : public nsStringHashKey
michael@0: {
michael@0:   public:
michael@0:     nsHtml5AtomEntry(KeyTypePointer aStr);
michael@0:     nsHtml5AtomEntry(const nsHtml5AtomEntry& aOther);
michael@0:     ~nsHtml5AtomEntry();
michael@0:     inline nsHtml5Atom* GetAtom()
michael@0:     {
michael@0:       return mAtom;
michael@0:     }
michael@0:   private:
michael@0:     nsAutoPtr<nsHtml5Atom> mAtom;
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * nsHtml5AtomTable provides non-locking lookup and creation of atoms for 
michael@0:  * nsHtml5Parser or nsHtml5StreamParser.
michael@0:  *
michael@0:  * The hashtable holds dynamically allocated atoms that are private to an 
michael@0:  * instance of nsHtml5Parser or nsHtml5StreamParser. (Static atoms are used on 
michael@0:  * interned nsHtml5ElementNames and interned nsHtml5AttributeNames. Also, when 
michael@0:  * the doctype name is 'html', that identifier needs to be represented as a 
michael@0:  * static atom.)
michael@0:  *
michael@0:  * Each instance of nsHtml5Parser has a single instance of nsHtml5AtomTable, 
michael@0:  * and each instance of nsHtml5StreamParser has a single instance of 
michael@0:  * nsHtml5AtomTable. Dynamic atoms obtained from an nsHtml5AtomTable are valid 
michael@0:  * for == comparison with each other or with atoms declared in nsHtml5Atoms 
michael@0:  * within the nsHtml5Tokenizer and the nsHtml5TreeBuilder instances owned by 
michael@0:  * the same nsHtml5Parser/nsHtml5StreamParser instance that owns the 
michael@0:  * nsHtml5AtomTable instance.
michael@0:  * 
michael@0:  * Dynamic atoms (atoms whose IsStaticAtom() returns false) obtained from 
michael@0:  * nsHtml5AtomTable must be re-obtained from another atom table when there's a 
michael@0:  * need to migrate atoms from an nsHtml5Parser to its nsHtml5StreamParser 
michael@0:  * (re-obtain from the other nsHtml5AtomTable), from an nsHtml5Parser to its 
michael@0:  * owner nsHtml5Parser (re-obtain from the other nsHtml5AtomTable) or from the 
michael@0:  * parser to the DOM (re-obtain from the application-wide atom table). To 
michael@0:  * re-obtain an atom from another atom table, obtain a string from the atom 
michael@0:  * using ToString(nsAString&) and look up an atom in the other table using that 
michael@0:  * string.
michael@0:  *
michael@0:  * An instance of nsHtml5AtomTable that belongs to an nsHtml5Parser is only 
michael@0:  * accessed from the main thread. An instance of nsHtml5AtomTable that belongs 
michael@0:  * to an nsHtml5StreamParser is accessed both from the main thread and from the 
michael@0:  * thread that executes the runnables of the nsHtml5StreamParser instance. 
michael@0:  * However, the threads never access the nsHtml5AtomTable instance concurrently 
michael@0:  * in the nsHtml5StreamParser case.
michael@0:  *
michael@0:  * Methods on the atoms obtained from nsHtml5AtomTable may be called on any 
michael@0:  * thread, although they only need to be called on the main thread or on the 
michael@0:  * thread working for the nsHtml5StreamParser when nsHtml5AtomTable belongs to 
michael@0:  * an nsHtml5StreamParser.
michael@0:  *
michael@0:  * Dynamic atoms obtained from nsHtml5AtomTable are deleted when the 
michael@0:  * nsHtml5AtomTable itself is destructed, which happens when the owner 
michael@0:  * nsHtml5Parser or nsHtml5StreamParser is destructed.
michael@0:  */
michael@0: class nsHtml5AtomTable
michael@0: {
michael@0:   public:
michael@0:     nsHtml5AtomTable();
michael@0:     ~nsHtml5AtomTable();
michael@0:     
michael@0:     /**
michael@0:      * Obtains the atom for the given string in the scope of this atom table.
michael@0:      */
michael@0:     nsIAtom* GetAtom(const nsAString& aKey);
michael@0:     
michael@0:     /**
michael@0:      * Empties the table.
michael@0:      */
michael@0:     void Clear()
michael@0:     {
michael@0:       mTable.Clear();
michael@0:     }
michael@0:     
michael@0: #ifdef DEBUG
michael@0:     void SetPermittedLookupThread(nsIThread* aThread)
michael@0:     {
michael@0:       mPermittedLookupThread = aThread;
michael@0:     }
michael@0: #endif  
michael@0:   
michael@0:   private:
michael@0:     nsTHashtable<nsHtml5AtomEntry> mTable;
michael@0: #ifdef DEBUG
michael@0:     nsCOMPtr<nsIThread>            mPermittedLookupThread;
michael@0: #endif
michael@0: };
michael@0: 
michael@0: #endif // nsHtml5AtomTable_h