forked from KolibriOS/kolibrios
72 lines
2.2 KiB
Plaintext
72 lines
2.2 KiB
Plaintext
Hubbub parser architecture
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==========================
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Introduction
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------------
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Hubbub is a flexible HTML parser. It offers two interfaces:
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* a SAX-style event interface
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* a DOM-style tree-based interface
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Overview
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--------
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Hubbub is comprised of two parts:
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* a tokeniser
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* a tree builder
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Tokeniser
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---------
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The tokeniser divides the data held in the document buffer into chunks.
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It sends SAX-style events for each chunk.
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Tree builder
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------------
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The tree builder constructs a DOM-like tree from the SAX events emitted by
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the tokeniser. The exact representation of the tree is up to the client,
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which must provide a number of tree building handler functions.
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Memory usage and ownership
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--------------------------
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Memory usage within the library is well defined, as is ownership of allocated
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memory.
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Raw input data provided by the library client is owned by the client.
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SAX events which refer to document segments contain direct references to
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internal data. Token objects are transient and data within them are no
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longer valid once the event handler has returned control to the tokeniser.
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All data returned by a SAX event is owned by the library.
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The tree builder will use client callbacks to create the objects used
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within the tree. Tree objects may be reference counted (the client may
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do nothing in the ref/unref callbacks and use garbage collection instead).
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The resultant tree is owned by the client.
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Parse errors
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------------
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Notification of parse errors is made through a dedicated event. This event
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contains the line/column offset of the error location, along with a message
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detailing the error.
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Exceptional circumstances
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-------------------------
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Exceptional circumstances (such as memory exhaustion) are reported
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immediately.
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The parser's state in such situations is undefined. There is no recovery
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mechanism.
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Therefore, if the client is able to recover from the exceptional
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circumstance (e.g. by making more free memory available) the only valid
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way to proceed is to create a new parser instance and start parsing from
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scratch. The client should ensure that they destroy the old parser instance
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and any DOM tree produced by it, to avoid resource leaks.
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