Package CedarBackup2 :: Module xmlutil
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Module CedarBackup2.xmlutil

Provides general XML-related functionality.

What I'm trying to do here is abstract much of the functionality that directly accesses the DOM tree. This is not so much to "protect" the other code from the DOM, but to standardize the way it's used. It will also help extension authors write code that easily looks more like the rest of Cedar Backup.

Author: Kenneth J. Pronovici <pronovic@ieee.org>

Classes
Serializer XML serializer class.

Function Summary
  createInputDom(xmlData, name)
Creates a DOM tree based on reading an XML string.
  createOutputDom(name)
Creates a DOM tree used for writing an XML document.
  serializeDom(xmlDom, indent)
Serializes a DOM tree and returns the result in a string.
  isElement(node)
Returns True or False depending on whether the XML node is an element node.
  readChildren(parent, name)
Returns a list of nodes with a given name immediately beneath the parent.
  readFirstChild(parent, name)
Returns the first child with a given name immediately beneath the parent.
  readStringList(parent, name)
Returns a list of the string contents associated with nodes with a given name immediately beneath the parent.
  readString(parent, name)
Returns string contents of the first child with a given name immediately beneath the parent.
  readInteger(parent, name)
Returns integer contents of the first child with a given name immediately beneath the parent.
  readBoolean(parent, name)
Returns boolean contents of the first child with a given name immediately beneath the parent.
  addContainerNode(xmlDom, parentNode, nodeName)
Adds a container node as the next child of a parent node.
  addStringNode(xmlDom, parentNode, nodeName, nodeValue)
Adds a text node as the next child of a parent, to contain a string.
  addIntegerNode(xmlDom, parentNode, nodeName, nodeValue)
Adds a text node as the next child of a parent, to contain an integer.
  addBooleanNode(xmlDom, parentNode, nodeName, nodeValue)
Adds a text node as the next child of a parent, to contain a boolean.
  _encodeText(text, encoding)
  _translateCDATA(characters, encoding, prev_chars, markupSafe)
  _translateCDATAAttr(characters)
Handles normalization and some intelligence about quoting.

Variable Summary
list TRUE_BOOLEAN_VALUES: List of boolean values in XML representing True.
list FALSE_BOOLEAN_VALUES: List of boolean values in XML representing False.
list VALID_BOOLEAN_VALUES: List of valid boolean values in XML.
Logger logger = <logging.Logger instance at 0x4054e50c>

Function Details

createInputDom(xmlData, name='cb_config')

Creates a DOM tree based on reading an XML string.
Parameters:
name - Assumed base name of the document (root node name).
Returns:
Tuple (xmlDom, parentNode) for the parsed document
Raises:
ValueError - If the document can't be parsed.

createOutputDom(name='cb_config')

Creates a DOM tree used for writing an XML document.
Parameters:
name - Base name of the document (root node name).
Returns:
Tuple (xmlDom, parentNode) for the new document

serializeDom(xmlDom, indent=3)

Serializes a DOM tree and returns the result in a string.
Parameters:
xmlDom - XML DOM tree to serialize
indent - Number of spaces to indent, as an integer
Returns:
String form of DOM tree, pretty-printed.

isElement(node)

Returns True or False depending on whether the XML node is an element node.

readChildren(parent, name)

Returns a list of nodes with a given name immediately beneath the parent.

By "immediately beneath" the parent, we mean from among nodes that are direct children of the passed-in parent node.

Underneath, we use the Python getElementsByTagName method, which is pretty cool, but which (surprisingly?) returns a list of all children with a given name below the parent, at any level. We just prune that list to include only children whose parentNode matches the passed-in parent.
Parameters:
parent - Parent node to search beneath.
name - Name of nodes to search for.
Returns:
List of child nodes with correct parent, or an empty list if no matching nodes are found.

readFirstChild(parent, name)

Returns the first child with a given name immediately beneath the parent.

By "immediately beneath" the parent, we mean from among nodes that are direct children of the passed-in parent node.
Parameters:
parent - Parent node to search beneath.
name - Name of node to search for.
Returns:
First properly-named child of parent, or None if no matching nodes are found.

readStringList(parent, name)

Returns a list of the string contents associated with nodes with a given name immediately beneath the parent.

By "immediately beneath" the parent, we mean from among nodes that are direct children of the passed-in parent node.

First, we find all of the nodes using readChildren, and then we retrieve the "string contents" of each of those nodes. The returned list has one entry per matching node. We assume that string contents of a given node belong to the first TEXT_NODE child of that node. Nodes which have no TEXT_NODE children are not represented in the returned list.
Parameters:
parent - Parent node to search beneath.
name - Name of node to search for.
Returns:
List of strings as described above, or None if no matching nodes are found.

readString(parent, name)

Returns string contents of the first child with a given name immediately beneath the parent.

By "immediately beneath" the parent, we mean from among nodes that are direct children of the passed-in parent node. We assume that string contents of a given node belong to the first TEXT_NODE child of that node.
Parameters:
parent - Parent node to search beneath.
name - Name of node to search for.
Returns:
String contents of node or None if no matching nodes are found.

readInteger(parent, name)

Returns integer contents of the first child with a given name immediately beneath the parent.

By "immediately beneath" the parent, we mean from among nodes that are direct children of the passed-in parent node.
Parameters:
parent - Parent node to search beneath.
name - Name of node to search for.
Returns:
Integer contents of node or None if no matching nodes are found.
Raises:
ValueError - If the string at the location can't be converted to an integer.

readBoolean(parent, name)

Returns boolean contents of the first child with a given name immediately beneath the parent.

By "immediately beneath" the parent, we mean from among nodes that are direct children of the passed-in parent node.

The string value of the node must be one of the values in VALID_BOOLEAN_VALUES.
Parameters:
parent - Parent node to search beneath.
name - Name of node to search for.
Returns:
Boolean contents of node or None if no matching nodes are found.
Raises:
ValueError - If the string at the location can't be converted to a boolean.

addContainerNode(xmlDom, parentNode, nodeName)

Adds a container node as the next child of a parent node.
Parameters:
xmlDom - DOM tree as from impl.createDocument().
parentNode - Parent node to create child for.
nodeName - Name of the new container node.
Returns:
Reference to the newly-created node.

addStringNode(xmlDom, parentNode, nodeName, nodeValue)

Adds a text node as the next child of a parent, to contain a string.

If the nodeValue is None, then the node will be created, but will be empty (i.e. will contain no text node child).
Parameters:
xmlDom - DOM tree as from impl.createDocument().
parentNode - Parent node to create child for.
nodeName - Name of the new container node.
nodeValue - The value to put into the node.
Returns:
Reference to the newly-created node.

addIntegerNode(xmlDom, parentNode, nodeName, nodeValue)

Adds a text node as the next child of a parent, to contain an integer.

If the nodeValue is None, then the node will be created, but will be empty (i.e. will contain no text node child).

The integer will be converted to a string using "%d". The result will be added to the document via addStringNode.
Parameters:
xmlDom - DOM tree as from impl.createDocument().
parentNode - Parent node to create child for.
nodeName - Name of the new container node.
nodeValue - The value to put into the node.
Returns:
Reference to the newly-created node.

addBooleanNode(xmlDom, parentNode, nodeName, nodeValue)

Adds a text node as the next child of a parent, to contain a boolean.

If the nodeValue is None, then the node will be created, but will be empty (i.e. will contain no text node child).

Boolean True, or anything else interpreted as True by Python, will be converted to a string "Y". Anything else will be converted to a string "N". The result is added to the document via addStringNode.
Parameters:
xmlDom - DOM tree as from impl.createDocument().
parentNode - Parent node to create child for.
nodeName - Name of the new container node.
nodeValue - The value to put into the node.
Returns:
Reference to the newly-created node.

_encodeText(text, encoding)

Copyright: This code, prior to customization, was part of the PyXML codebase, and before that was part of the 4DOM suite developed by Fourthought, Inc. It its original form, it was attributed to Martin v. Löwis and was Copyright (c) 2000 Fourthought Inc, USA; All Rights Reserved.

_translateCDATA(characters, encoding='UTF-8', prev_chars='', markupSafe=0)

Copyright: This code, prior to customization, was part of the PyXML codebase, and before that was part of the 4DOM suite developed by Fourthought, Inc. It its original form, it was Copyright (c) 2000 Fourthought Inc, USA; All Rights Reserved.

_translateCDATAAttr(characters)

Handles normalization and some intelligence about quoting.

Copyright: This code, prior to customization, was part of the PyXML codebase, and before that was part of the 4DOM suite developed by Fourthought, Inc. It its original form, it was Copyright (c) 2000 Fourthought Inc, USA; All Rights Reserved.


Variable Details

TRUE_BOOLEAN_VALUES

List of boolean values in XML representing True.
Type:
list
Value:
['Y', 'y']                                                             

FALSE_BOOLEAN_VALUES

List of boolean values in XML representing False.
Type:
list
Value:
['N', 'n']                                                             

VALID_BOOLEAN_VALUES

List of valid boolean values in XML.
Type:
list
Value:
['Y', 'y', 'N', 'n']                                                   

logger

Type:
Logger
Value:
<logging.Logger instance at 0x4054e50c>                                

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