"""
Copyright 2008, 2009 Free Software Foundation, Inc.
This file is part of GNU Radio

GNU Radio Companion is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

GNU Radio Companion is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
"""

class Element(object):

	def __init__(self, parent=None):
		self._parent = parent

	##################################################
	# Element Validation API
	##################################################
	def validate(self):
		"""
		Validate this element and call validate on all children.
		Call this base method before adding error messages in the subclass.
		"""
		self._error_messages = list()
		for child in self.get_children(): child.validate()

	def is_valid(self):
		"""
		Is this element valid?
		@return true when the element is enabled and has no error messages
		"""
		return not self.get_error_messages() or not self.get_enabled()

	def add_error_message(self, msg):
		"""
		Add an error message to the list of errors.
		@param msg the error message string
		"""
		self._error_messages.append(msg)

	def get_error_messages(self):
		"""
		Get the list of error messages from this element and all of its children.
		Cleverly indent the children error messages for printing purposes.
		@return a list of error message strings
		"""
		error_messages = list(self._error_messages) #make a copy
		for child in self.get_children():
			for msg in child.get_error_messages():
				error_messages.append("%s:\n\t%s"%(child, msg.replace("\n", "\n\t")))
		return error_messages

	def rewrite(self):
		"""
		Rewrite this element and call rewrite on all children.
		Call this base method before rewriting the element.
		"""
		for child in self.get_children(): child.rewrite()

	def get_enabled(self): return True

	##############################################
	## Tree-like API
	##############################################
	def get_parent(self): return self._parent
	def get_children(self): return list()

	##############################################
	## Type testing methods
	##############################################
	def is_element(self): return True
	def is_platform(self): return False
	def is_flow_graph(self): return False
	def is_connection(self): return False
	def is_block(self): return False
	def is_source(self): return False
	def is_sink(self): return False
	def is_port(self): return False
	def is_param(self): return False