SF.net SVN: fclient: [391] trunk/sandbox/fcp2/fcp_lib/node.py

[<jU...@us...>]

Revision: 391
          http://fclient.svn.sourceforge.net/fclient/?rev=391&view=rev
Author:   jUrner
Date:     2008-04-09 14:09:48 -0700 (Wed, 09 Apr 2008)

Log Message:
-----------
add node tree to deal with hirarchical message params

Added Paths:
-----------
    trunk/sandbox/fcp2/fcp_lib/node.py

Added: trunk/sandbox/fcp2/fcp_lib/node.py
===================================================================
--- trunk/sandbox/fcp2/fcp_lib/node.py	                        (rev 0)
+++ trunk/sandbox/fcp2/fcp_lib/node.py	2008-04-09 21:09:48 UTC (rev 391)
@@ -0,0 +1,174 @@
+"""Nodes and trees"""
+ 
+ 
+#***********************************************************************
+#
+#***********************************************************************
+class Node(object):
+	"""Simple node tree implementation
+	
+	@cvar ComponentSep: (str) separator to be used for keys
+		
+	@ivar children: (dict) name --> node of child nodes
+	@ivar key: (str) key of the node
+	@ivar name: (str) name of the node (take care that this is None for root nodes)
+	@ivar parent: (Node) parent node of the node (take care that this is None for root nodes)
+	@ivar value: (any) value contained by the node
+	
+	>>> node = Node()
+	
+	# for the root of the name and parent is always None
+	>>> node.name
+	
+	# to populate the tree with nodes, assign a value to the desired key. 
+	# All intermediate nodes will be created automatically
+	>>> node['foo/bar/baz'] = 1234
+	>>> node['foo/bar/baz'].value
+	1234
+	
+	>>> node['foo'].value
+	
+	"""
+	__slots__ = ('children', 'name', 'parent', 'value')
+		
+	ComponentSep = '/'
+		
+	def __init__(self):
+		"""Creates a new root node"""
+		
+		self.children = {}
+		self.name = None
+		self.parent = None
+		self.value = None
+
+	def _get_key(self):
+		out = []
+		node = self
+		while node.name is not None:
+			out.append(node.name)
+			node = node.parent
+		out.reverse()
+		return self.ComponentSep.join(out)
+	
+	key = property(_get_key, None, None)	
+		
+	
+	def __getitem__(self, key):
+		"""Returns the node located at key"""
+		L = key.split(self.ComponentSep)
+		node = self
+		while L:
+			nodeName = L.pop(0)
+			tmp_node = node.children.get(nodeName, None)
+			if tmp_node is None:
+				raise KeyError('No such node: %s' % key)
+			node = tmp_node
+		return node
+			
+		
+	def __setitem__(self, key, value):
+		"""Sets the value contained by a node at key key"""
+		L = key.split(self.ComponentSep)
+		node = self
+		while L:
+			nodeName = L.pop(0)
+			tmp_node = node.children.get(nodeName, None)
+			if tmp_node is None:
+				tmp_node = Node()
+				tmp_node.name = nodeName
+				tmp_node.parent = node
+				node.children[nodeName] = tmp_node		#<-- complete node init before querying default value!
+				tmp_node.value = self.getDefaultValue(tmp_node)
+			else:
+				node.children[nodeName] = tmp_node
+			node = tmp_node
+		node.value = value
+			
+	def get(self, key, default=None):
+		"""Returns the node associated to key or default if the node does not exist"""
+		try:
+			return self[key]
+		except KeyError:
+			return default
+	
+	def getDefaultValue(self, node):
+		"""Returns the default value of a node when a new node is about to be created
+		@paran node: the new node to query the default value for
+		@note: the default implementation returns None. Overwrite to customize
+		"""
+		return None
+		
+	def select(self, path):
+		"""Selects node according to a path pattern
+		@patram path: (str) path pattern
+		@return: (list) of matching nodes
+		@note: the pattern supported is pretty simplistic. It may contain wildcards
+		to select any node 'key.*.other' or a double wildcard to recursively select all
+		childnodes 'key.**'. That's it.
+		"""
+		components = path.split(self.ComponentSep)
+		tmp_components = components[:]
+		stack = [[self, ], ]
+		while tmp_components:
+			tmp_stack = []
+			component = tmp_components.pop(0)
+			for node in stack[-1]:
+				if component == '*':
+					for node in node.children.values():
+						tmp_stack.append(node)
+				elif component == '**':
+					if tmp_components:
+						raise ValueError('Component "**" must be last component')
+					enum = node.walk()
+					enum.next()
+					for node in enum:
+						tmp_stack.append(node)	
+				else:
+					node = node.children.get(component, None)
+					if node is not None:
+						tmp_stack.append(node)
+			if not tmp_stack:
+				break
+			stack.append(tmp_stack)
+		
+		if len(stack) == len(components) +1:
+			return stack[-1]
+		return []
+			
+	def walk(self, report=False):
+		"""Recursively iterates over the node and all its children
+		
+		@param report: if True, a tuple(levelup, node) is returned. Where levelup is set to 1
+		if a node containing child nodes is about to be traversed, -1 if traversal of such a node
+		is completed and 0 if the node does not contain child nodes. If report is False, the next
+		node in turn is returned.
+		"""
+		if report:
+			def walker(node):
+				if node.children:
+					yield 1, node
+				else:
+					yield 0, node
+				for node in node.children.values():
+					for x in walker(node):
+						yield x
+				if node.children:
+					yield -1, node
+		else:
+			def walker(node):
+				yield node
+				for node in node.children.values():
+					for x in walker(node):
+						yield x
+		return walker(self)
+		
+#***********************************************************************
+#
+#***********************************************************************		
+if __name__ == '__main__':
+	import doctest
+	print 'doctests failed: %s/%s' % doctest.testmod()
+
+	
+	
+	
\ No newline at end of file


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