#!/usr/bin/env python
#-*- coding: iso8859-15 -*-
##########################################################
#                       TAD v1.0                         #
##########################################################
# Autor: Juan Miguel Taboada Godoy                       #
# Fecha: Szczecin, 06 de Marzo de 2006                   #
# Descripción: Tipos abstractos de datos basicos         #
# Versión: 2007030600                                    #
#                                                        #
# Codigo fuente bajo licencia GNU/GPL                    #
# Centrologic (Computational Logistic Center)            #
# http://www.centrologic.com - info@centrologic.com      #
##########################################################

# Stack {{{1
## \internal
## Stack's definition
class Stack:
	# Constructor {{{2
	def __init__(self):
		self.lst = []
	# }}}2
	# Show the Stack {{{2
	def __repr__(self):
		# Inicialization
		first=True
		# Add the head
		str="<="
		# For all the list
		for element in self.lst:
			# Show coma
			if (first):
				first=False
			else:
				str="%s, " % (str)
			# Add element
			if (type(element)==type('abc')):
				str="%s'%s'" % (str,element)
			else:
				str="%s%s" % (str,element)
		# Add the tail
		str="%s%s" % (str,"=>")
		# Return the result
		return str
	# }}}2

	# Empty {{{2
	## Say if is empty the Stack
	## \param self -
	def empty(self):
		return len(self.lst) == 0
	# }}2
	# Pop {{{2
	## Pop an element
	## \param self -
	def pop(self):
		if (self.empty()):
			raise PopError,"Stack is already empty"
		else:
			result = self.lst[-1]
			del self.lst[-1]
			return result
	# }}}2
	# Push {{{2
	## Push an elemento to the stack
	## \param self -
	## \param element Element to push
	def push(self, element):
		self.lst.append(element)
	# }}}2
# }}}1

# ### EXCEPCIONES ### #################################
# EXCEPTION CLASSES {{{1
# Basic exceptions
# Except (General Exception) {{{2
class Except(Exception):
	def __init__(self,string):
		self.string=string
	def __str__(self):
		return self.string
#}}}2
# IOError (Input/Output error) {{{2
class IOError(Exception):
	def __init__(self,string):
		self.string=string
	def __str__(self):
		return self.string
# }}}2
# Exceptions in TADs
# PopError (Error doing pop in a Stack) {{{2
class PopError(Exception):
	def __init__(self,string):
		self.string=string
	def __str__(self):
		return self.string
# }}}2
# }}}1