20.11. xml.sax.saxutils --- SAX Utilities

Source code: Lib/xml/sax/saxutils.py

The module xml.sax.saxutils contains a number of classes and functions that are commonly useful when creating SAX applications, either in direct use, or as base classes.

xml.sax.saxutils.escape(data, entities={})

Escape '&', '<', and '>' in a string of data.

You can escape other strings of data by passing a dictionary as the optional entities parameter. The keys and values must all be strings; each key will be replaced with its corresponding value. The characters '&', '<' and '>' are always escaped, even if entities is provided.

xml.sax.saxutils.unescape(data, entities={})

Unescape '&amp;', '&lt;', and '&gt;' in a string of data.

You can unescape other strings of data by passing a dictionary as the optional entities parameter. The keys and values must all be strings; each key will be replaced with its corresponding value. '&amp', '&lt;', and '&gt;' are always unescaped, even if entities is provided.

xml.sax.saxutils.quoteattr(data, entities={})

Similar to escape(), but also prepares data to be used as an attribute value. The return value is a quoted version of data with any additional required replacements. quoteattr() will select a quote character based on the content of data, attempting to avoid encoding any quote characters in the string. If both single- and double-quote characters are already in data, the double-quote characters will be encoded and data will be wrapped in double-quotes. The resulting string can be used directly as an attribute value:

>>> print("<element attr=%s>" % quoteattr("ab ' cd \" ef"))
<element attr="ab ' cd &quot; ef">

This function is useful when generating attribute values for HTML or any SGML using the reference concrete syntax.

class xml.sax.saxutils.XMLGenerator(out=None, encoding='iso-8859-1', short_empty_elements=False)

This class implements the ContentHandler interface by writing SAX events back into an XML document. In other words, using an XMLGenerator as the content handler will reproduce the original document being parsed. out should be a file-like object which will default to sys.stdout. encoding is the encoding of the output stream which defaults to 'iso-8859-1'. short_empty_elements controls the formatting of elements that contain no content: if False (the default) they are emitted as a pair of start/end tags, if set to True they are emitted as a single self-closed tag.

3.2 新版功能: The short_empty_elements parameter.

class xml.sax.saxutils.XMLFilterBase(base)

This class is designed to sit between an XMLReader and the client application's event handlers. By default, it does nothing but pass requests up to the reader and events on to the handlers unmodified, but subclasses can override specific methods to modify the event stream or the configuration requests as they pass through.

xml.sax.saxutils.prepare_input_source(source, base='')

This function takes an input source and an optional base URL and returns a fully resolved InputSource object ready for reading. The input source can be given as a string, a file-like object, or an InputSource object; parsers will use this function to implement the polymorphic source argument to their parse() method.