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175 lines
4.3 KiB
175 lines
4.3 KiB
page "pyPEG – XML Backend", "counter-reset: chapter 3;" {
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h1 id=xmlbackend > XML Backend of ƒpyPEG
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h2 id=workhorses > etree functions
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p >>
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The ƒpyPEG XML Backend uses Python's «etree» semantic. This way it can
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easily be integrated into existing working code using XML. The usage of
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¬http://lxml.de/ lxml¬ is recommended. If the module «lxml» is
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installed, ƒpyPEG uses it automatically.
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>>
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h3 id=create_tree > Function create_tree()
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h4 > Synopsis
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p > «create_tree(thing, parent=None, object_names=False)»
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p > Create an XML etree from a thing.
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h4 > Arguments
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glossary {
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term "thing" > «thing» to interpret
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term "parent" > «etree.Element» to put subtree into; default: create a new «Element» tree
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term "object_names"
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>>
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experimental feature: if «True» tag names are object
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names instead of types
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>>
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}
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h4 > Returns
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p > «etree.Element» instance created
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p > Example:
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Code
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>>> from pypeg2.xmlast import create_tree
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>>> from pypeg2 import name, restline
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>>> class Key(str):
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... grammar = name(), "=", restline
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...
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>>> k = Key("world")
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>>> k.name = "hello"
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>>> t = ◊create_tree(k)◊
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>>> t.attrib["name"]
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'hello'
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>>> t.text
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'world'
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>>> type(t)
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<class 'lxml.etree._Element'>
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h3 id=create_thing > Function create_thing()
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h4 > Synopsis
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p > «create_thing(element, symbol_table)»
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p > Create thing from an XML element.
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h4 > Arguments
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glossary {
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term "element" > «etree.Element» instance to read
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term "symbol_table" > symbol table where the classes can be found; usually call «globals()»
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}
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h4 > Returns
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p > «thing» created
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p > Example:
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Code
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>>> from pypeg2.xmlast import create_thing, etree
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>>> from pypeg2 import name, restline
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>>> class Key(str):
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... grammar = name(), "=", restline
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...
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>>> e = etree.fromstring("<Key name='hello'>world</Key>")
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>>> k = ◊create_thing(e, globals())◊
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>>> k.name
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Symbol('hello')
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>>> k
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'world'
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>>> type(k)
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<class '__main__.Key'>
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h2 id=xmlconvenience > XML convenience functions
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h3 id=thing2xml > Function thing2xml()
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h4 > Synopsis
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p > «thing2xml(thing, pretty=False, object_names=False)»
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p > Create XML text from a thing.
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h4 > Arguments
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glossary {
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term "thing" > «thing» to interpret
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term "pretty"
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>>
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«True» if XML should be indented, «False» if XML should be plain
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(this feature requires ¬http://lxml.de lxml¬)
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>>
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term "object_names"
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>>
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experimental feature: if «True» tag names are object
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names instead of types
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>>
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}
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h4 > Returns
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p > «bytes» with encoded XML
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p > Example:
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Code
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>>> from pypeg2 import name, restline
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>>> from pypeg2.xmlast import thing2xml
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>>> class Key(str):
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... grammar = name(), "=", restline
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...
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>>> k = Key("world")
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>>> k.name = "hello"
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>>> ◊thing2xml(k)◊
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b'<Key name="hello">world</Key>'
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h3 id=xml2thing > Function xml2thing()
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h4 > Synopsis
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p > «xml2thing(xml, symbol_table)»
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p > Create «thing» from XML text.
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h4 > Arguments
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glossary {
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term "xml" > «bytes» with encoded XML
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term "symbol_table" > symbol table where the classes can be found; usually call «globals()»
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}
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h4 > Returns
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p > created «thing»
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p > Example:
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Code
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>>> from pypeg2 import name, restline
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>>> from pypeg2.xmlast import xml2thing
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>>> class Key(str):
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... grammar = name(), "=", restline
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...
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>>> k = ◊xml2thing(b"<Key name='hello'>world</Key>", globals())◊
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>>> k.name
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Symbol('hello')
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>>> k
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'world'
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div id="bottom" {
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"Want to download? Go to the "
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a "#top", "^Top^"; " and look to the right ;-)"
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}
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}
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