20.11. "xml.sax.saxutils" --- SAX Utilities
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**Source code:** Lib/xml/sax/saxutils.py

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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 版新加入: 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.
