"xml.sax.saxutils" --- SAX 工具集
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**源代码:** Lib/xml/sax/saxutils.py

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"xml.sax.saxutils" 模块包含一些在创建 SAX 应用程序时十分有用的类和函数
，它们可以被直接使用，或者是作为基类使用。

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

   对数据字符串中的 "'&'", "'<'" 和 "'>'" 进行转义。

   你可以通过传入一个字典作为可选的 *entities* 形参来对其他字符串数据
   进行转义。 字典的键和值必须为字符串；每个键将被替换为其所对应的值。
   字符 "'&'", "'<'" 和 "'>'" 总是会被转义，即使提供了 *entities*。

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

   对字符串数据中的 "'&amp;'", "'&lt;'" 和 "'&gt;'" 进行反转义。

   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.
