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# The Parser Model |
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The parser model here follows the model in section |
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[](http://www.w3.org/TR/2012/CR-html5-20121217/syntax.html#parsing8.2.1](http://www.w3.org/TR/2012/CR-html5-20121217/syntax.html#parsing](http://www.w3.org/TR/2012/CR-html5-20121217/syntax.html#parsing) |
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of the HTML5 specification, though we do not assume a networking layer. |
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[ InputStream ] // Generic support for reading input. |
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[ Scanner ] // Breaks down the stream into characters. |
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[ Tokenizer ] // Groups characters into syntactic |
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[ Tree Builder ] // Organizes units into a tree of objects |
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[ DOM Document ] // The final state of the parsed document. |
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## InputStream |
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This is an interface with at least two concrete implementations: |
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- StringInputStream: Reads an HTML5 string. |
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- FileInputStream: Reads an HTML5 file. |
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## Scanner |
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This is a mechanical piece of the parser. |
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## Tokenizer |
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This follows section 8.4 of the HTML5 spec. It is (roughly) a recursive |
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descent parser. (Though there are plenty of optimizations that are less |
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than purely functional. |
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## EventHandler and DOMTree |
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EventHandler is the interface for tree builders. Since not all |
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implementations will necessarily build trees, we've chosen a more |
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generic name. |
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The event handler emits tokens during tokenization. |
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The DOMTree is an event handler that builds a DOM tree. The output of |
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the DOMTree builder is a DOMDocument. |
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## DOMDocument |
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PHP has a DOMDocument class built-in (technically, it's part of libxml.) |
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We use that, thus rendering the output of this process compatible with |
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SimpleXML, QueryPath, and many other XML/HTML processing tools. |
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For cases where the HTML5 is a fragment of a HTML5 document a |
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DOMDocumentFragment is returned instead. This is another built-in class. |
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