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#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
metadata.py
~~~~~~~~~~~
metadata generation
:copyright: (c) 2013 by Jauhien Piatlicki
:license: GPL-2, see LICENSE for more details.
"""
from .exceptions import XMLGeneratorError
import xml.etree.ElementTree as ET
import xml.dom.minidom as minidom
def prettify(tree):
"""
Convert XML tree to a string.
Args:
tree: xml.etree.ElementTree.Element instance
Returns:
A string with XML source.
"""
rough_str = ET.tostring(tree, "utf-8").decode("utf-8")
reparsed = minidom.parseString(rough_str)
return reparsed.toprettyxml(encoding="utf-8").decode("utf-8")
class XMLGenerator(object):
"""
XML generator. Generates an XML tree according a given
schema using a dict as a source of data.
Schema format.
~~~~~~~~~~~~~~
Schema is a list of entries. Each entry describes one XML tag.
Entry is a dict. dict keys are:
name: Name of a tag
multiple: Defines if a given tag can be used more
then one time. It is a tuple. First element
of a tuple is boolean. If it is set a tag can be
repeated. Second element is a string. If it is not
empty, it defines a name for an attribute
that will distinguish different entries of a tag.
required: Boolean that defines if a given tag is required.
subtags: List of subtags.
Data dictinonary format.
~~~~~~~~~~~~~~~~~~~~~~~~
Keys correspond to tags from a schema with the same name.
If a tag is not multiple without subkeys value is just a
string with text for the tag.
If tag is multiple value is a list with entries
corresponding to a single tag.
If tag has subtags value is a dictionary with entries
corresponding to subkeys and 'text' entry corresponding
to text for the tag.
If tag should have attributes value is a tuple or list with
0 element containing an attribute and 1 element containing
a value for the tag as described previously.
"""
def __init__(self, external, schema):
"""
Args:
external: Name of an outermost tag.
schema: XML schema.
"""
self.external = external
self.schema = schema
def generate(self, values):
"""
Generate an XML tree filled with values from
a given dictionary.
Args:
values: Data dictionary.
Returns:
XML tree being an istance of
xml.etree.ElementTree.Element
"""
root = ET.Element(self.external)
for tag in self.schema:
self.add_tag(root, tag, values)
return root
def add_tag(self, root, tag, values):
"""
Add a tag.
Args:
root: A parent tag.
tag: Tag from schema to be added.
values: Data dictionary.
"""
name = tag['name']
if not name in values:
if tag['required']:
raise XMLGeneratorError('Required tag not found: ' + name)
return
value = values[name]
multiple, attr = tag['multiple']
if multiple:
for val in value:
self.add_single_tag(root, name, tag, val, attr)
else:
self.add_single_tag(root, name, tag, value)
def add_single_tag(self, root, name, tag, value, attr=None):
"""
Add a single tag.
Args:
root: A parent tag.
name: Name of tag to be added.
tag: Tag from schema to be added.
value: Entry of a data dictionary
corresponding to the tag.
attr: An attribute of the tag.
"""
child = ET.SubElement(root, name)
if attr:
child.set(attr, value[0])
value = value[1]
subtags = tag['subtags']
if subtags:
if 'text' in value:
child.text = value['text']
for child_tag in subtags:
self.add_tag(child, child_tag, value)
else:
child.text = value
# A default schema describing metadata.xml
# See http://devmanual.gentoo.org/ebuild-writing/misc-files/metadata/
default_schema = [{'name' : 'herd',
'multiple' : (True, ""),
'required' : False,
'subtags' : []},
{'name' : 'maintainer',
'multiple' : (True, ""),
'required' : False,
'subtags' : [{'name' : 'email',
'multiple' : (False, ""),
'required' : True,
'subtags' : []},
{'name' : 'name',
'multiple' : (False, ""),
'required' : False,
'subtags' : []},
{'name' : 'description',
'multiple' : (False, ""),
'required' : False,
'subtags' : []},
]
},
{'name' : 'longdescription',
'multiple' : (False, ""),
'required' : False,
'subtags' : []},
{'name' : 'use',
'multiple' : (False, ""),
'required' : False,
'subtags' : [{'name' : 'flag',
'multiple' : (True, "name"),
'required' : True,
'subtags' : []}]
},
{'name' : 'upstream',
'multiple' : (False, ""),
'required' : False,
'subtags' : [{'name' : 'maintainer',
'multiple' : (True, ""),
'required' : False,
'subtags' : [{'name' : 'name',
'multiple' : (False, ""),
'required' : True,
'subtags' : []},
{'name' : 'email',
'multiple' : (False, ""),
'required' : False,
'subtags' : []}]},
{'name' : 'changelog',
'multiple' : (False, ""),
'required' : False,
'subtags' : []},
{'name' : 'doc',
'multiple' : (False, ""),
'required' : False,
'subtags' : []},
{'name' : 'bugs-to',
'multiple' : (False, ""),
'required' : False,
'subtags' : []},
{'name' : 'remote-id',
'multiple' : (False, ""),
'required' : False,
'subtags' : []},
]
},
]
class MetadataGenerator(object):
"""
Metada generator. Generates metadata for a given package.
"""
def __init__(self, package_db, schema = None):
"""
Args:
package_db: Package database.
schema: Schema of an XML tree.
"""
if not schema:
schema = default_schema
self.package_db = package_db
self.xmlg = XMLGenerator('pkgmetadata', schema)
def generate(self, package):
"""
Generate metadata for a package.
Args:
package: package_db.Package instance.
Returns:
Metadata source as a list of strings.
"""
description = self.package_db.get_package_description(package)
metadata = self.process(package, description)
metadata = self.postprocess(package, description, metadata)
metadata = prettify(metadata)
metadata = metadata.split('\n')
if metadata[-1] == '':
metadata = metadata[:-1]
dtp = '<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">'
metadata.insert(1, dtp)
return metadata
def process(self, package, description):
"""
Generate metadata using values from a description.
Args:
package: package_db.Package instance.
description: Package description (see package_db module).
Returns:
Metadata source as a list of strings.
DOCTYPE missing.
"""
metadata = self.xmlg.generate(description)
return metadata
def postprocess(self, package, description, metadata):
"""
Postprocess generated metadata. Can be overrided.
Args:
package: package_db.Package instance.
description: Package description (see package_db module).
metadata: xml.etree.ElementTree.Element instance
Returns:
Metadata source as a list of strings.
DOCTYPE missing.
"""
return metadata
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