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265e672179
# ignore-this-changeset --HG-- extra : amend_source : 4d301d3b0b8711c4692392aa76088ba7fd7d1022
92 lines
3.6 KiB
C++
92 lines
3.6 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsHtml5AtomTable_h
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#define nsHtml5AtomTable_h
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#include "nsHashKeys.h"
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#include "nsTHashtable.h"
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#include "nsAtom.h"
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#include "nsISerialEventTarget.h"
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#define RECENTLY_USED_PARSER_ATOMS_SIZE 31
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/**
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* nsHtml5AtomTable provides non-locking lookup and creation of atoms for
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* nsHtml5Parser or nsHtml5StreamParser.
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*
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* The hashtable holds dynamically allocated atoms that are private to an
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* instance of nsHtml5Parser or nsHtml5StreamParser. (Static atoms are used on
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* interned nsHtml5ElementNames and interned nsHtml5AttributeNames. Also, when
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* the doctype name is 'html', that identifier needs to be represented as a
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* static atom.)
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*
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* Each instance of nsHtml5Parser has a single instance of nsHtml5AtomTable,
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* and each instance of nsHtml5StreamParser has a single instance of
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* nsHtml5AtomTable. Dynamic atoms obtained from an nsHtml5AtomTable are valid
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* for == comparison with each other or with atoms declared in nsHtml5Atoms
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* within the nsHtml5Tokenizer and the nsHtml5TreeBuilder instances owned by
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* the same nsHtml5Parser/nsHtml5StreamParser instance that owns the
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* nsHtml5AtomTable instance.
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*
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* Dynamic atoms (atoms whose IsStatic() returns false) obtained from
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* nsHtml5AtomTable must be re-obtained from another atom table when there's a
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* need to migrate atoms from an nsHtml5Parser to its nsHtml5StreamParser
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* (re-obtain from the other nsHtml5AtomTable), from an nsHtml5Parser to its
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* owner nsHtml5Parser (re-obtain from the other nsHtml5AtomTable) or from the
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* parser to the DOM (re-obtain from the application-wide atom table). To
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* re-obtain an atom from another atom table, obtain a string from the atom
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* using ToString(nsAString&) and look up an atom in the other table using that
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* string.
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*
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* An instance of nsHtml5AtomTable that belongs to an nsHtml5Parser is only
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* accessed from the main thread. An instance of nsHtml5AtomTable that belongs
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* to an nsHtml5StreamParser is accessed both from the main thread and from the
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* thread that executes the runnables of the nsHtml5StreamParser instance.
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* However, the threads never access the nsHtml5AtomTable instance concurrently
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* in the nsHtml5StreamParser case.
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*
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* Methods on the atoms obtained from nsHtml5AtomTable may be called on any
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* thread, although they only need to be called on the main thread or on the
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* thread working for the nsHtml5StreamParser when nsHtml5AtomTable belongs to
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* an nsHtml5StreamParser.
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*
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* Dynamic atoms obtained from nsHtml5AtomTable are deleted when the
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* nsHtml5AtomTable itself is destructed, which happens when the owner
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* nsHtml5Parser or nsHtml5StreamParser is destructed.
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*/
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class nsHtml5AtomTable {
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public:
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nsHtml5AtomTable();
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~nsHtml5AtomTable();
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// NOTE: We rely on mRecentlyUsedParserAtoms keeping alive the returned atom,
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// but the caller is responsible to take a reference before calling GetAtom
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// again.
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nsAtom* GetAtom(const nsAString& aKey);
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/**
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* Empties the table.
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*/
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void Clear() {
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for (uint32_t i = 0; i < RECENTLY_USED_PARSER_ATOMS_SIZE; ++i) {
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mRecentlyUsedParserAtoms[i] = nullptr;
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}
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}
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#ifdef DEBUG
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void SetPermittedLookupEventTarget(nsISerialEventTarget* aEventTarget) {
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mPermittedLookupEventTarget = aEventTarget;
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}
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#endif
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private:
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RefPtr<nsAtom> mRecentlyUsedParserAtoms[RECENTLY_USED_PARSER_ATOMS_SIZE];
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#ifdef DEBUG
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nsCOMPtr<nsISerialEventTarget> mPermittedLookupEventTarget;
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#endif
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};
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#endif // nsHtml5AtomTable_h
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