Python lxml library study note 4

Parser object: lxml. etree uses the standard parser with the default configuration by default. to configure the parser, you can create your own instance.

>>> Parser = etree. XMLParser (remove_blk_text = True) # lxml. etree only!

In this example, a parser is created to remove null text between tags, which can reduce the size of the tree and avoid tail, if you know that the blank content does not make any sense to you.

>>> Root = etree. XML ("<root> <a/> <B> </root>", parser)
>>> Etree. tostring (root)
B '<root> <a/> <B> </root>'
>>> For element in root. iter ("*"):
... If element. text is not None and not element. text. strip ():
... Element. text = None
>>> Etree. tostring (root)
B '<root> <a/> <B/> </root>'

Incremental Resolution:

Lxml. etree provides two methods for incremental parsing. One method is through a class object, which repeatedly calls the read () method.
>>> Class DataSource:
... Data = [B "<roo", B "t> <", B "a/", B "> <", B "/root>"]
... Def read (self, requested_size ):
... Try:
... Return self. data. pop (0)
... Handle T IndexError:
... Return B''
>>> Tree = etree. parse (DataSource ())
>>> Etree. tostring (tree)
B '<root> <a/> </root>'

The second method is provided by the feed (data) and close () methods through the feed parser interface.

>>> Parser = etree. XMLParser ()
>>> Parser. feed ("<roo ")
>>> Parser. feed ("t> <")
>>> Parser. feed ("/")
>>> Parser. feed ("> <")
>>> Parser. feed ("/root> ")

>>> Root = parser. close ()
>>> Etree. tostring (root)
'<Root> <a/> </root>'

When calling the close () method (or when an exception occurs), you can call the feed () method to re-use parser:
>>> Parser. feed ("<root/> ")
>>> Root = parser. close ()
>>> Etree. tostring (root)
B '<root/>'