#!/usr/bin/env python
#
# $Id: MapStack.py,v 1.2 2006/12/05 13:10:45 doughellmann Exp $
#
# Copyright 2003 Doug Hellmann.
#
#
# All Rights Reserved
#
# Permission to use, copy, modify, and distribute this software and
# its documentation for any purpose and without fee is hereby
# granted, provided that the above copyright notice appear in all
# copies and that both that copyright notice and this permission
# notice appear in supporting documentation, and that the name of Doug
# Hellmann not be used in advertising or publicity pertaining to
# distribution of the software without specific, written prior
# permission.
#
# DOUG HELLMANN DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
# INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
# NO EVENT SHALL DOUG HELLMANN BE LIABLE FOR ANY SPECIAL, INDIRECT OR
# CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
# OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
# CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
"""Implements a dictionary-like class to provide namespace and context stacking.
Based on the MultiMapping extension class found in Zope.
"""
__rcs_info__ = {
#
# Creation Information
#
'module_name' : '$RCSfile: MapStack.py,v $',
'rcs_id' : '$Id: MapStack.py,v 1.2 2006/12/05 13:10:45 doughellmann Exp $',
'creator' : 'Doug Hellmann',
'project' : 'HappyDoc',
'created' : 'Sun, 19-Jan-2003 07:45:43 EST',
#
# Current Information
#
'author' : '$Author: doughellmann $',
'version' : '$Revision: 1.2 $',
'date' : '$Date: 2006/12/05 13:10:45 $',
}
try:
__version__ = __rcs_info__['version'].split(' ')[1]
except:
__version__ = '0.0'
#
# Import system modules
#
import unittest
#
# Import Local modules
#
#
# Module
#
class MapStack:
"""Implements a dictionary-like class to provide namespace and context stacking.
Based on the MultiMapping extension class found in Zope.
"""
def __init__(self, *dicts):
"""Construct a new MapStack.
Pass some existing mappings to be pushed onto the stack.
"""
#print 'MapStack', dicts
self.stack = []
for d in dicts:
self.push(d)
return
def push(self, newDict):
"""Add a new context to the stack.
"""
self.stack.insert(0, newDict)
return
_push = push
def pop(self):
"""Remove and return the top context.
"""
if self.stack:
top = self.stack[0]
else:
top = None
self.stack = self.stack[1:]
return top
_pop = pop
def __getitem__(self, key):
for map in self.stack:
if map.has_key(key):
return map[key]
raise KeyError(key)
def dump(self):
for map in self.stack:
print map.keys()
return
def __setitem__(self, name, value):
#print 'MapStack.setitem(%s, %s)' % (name, value)
if not self.stack:
raise ValueError('Stack empty')
top = self.stack[0]
top[name] = value
return
def has_get(self, key):
try:
val = self[key]
except KeyError:
has = 0
val = None
else:
has = 1
#print 'has_get(%s) -> (%s, %s)' % (key, has, val)
#if not has:
# self.dump()
return (has, val)
class MapStackTest(unittest.TestCase):
def testEmpty(self):
ms = MapStack()
try:
anything = ms['anything']
except KeyError:
pass
else:
self.fail('Should have raised KeyError. Got: %s' % anything)
return
def testOneLevel(self):
ms = MapStack()
ms.push({'one':1, 'two':2})
try:
one = ms['one']
except KeyError:
self.fail('Should have found one')
try:
two = ms['two']
except KeyError:
self.fail('Should have found two')
return
def testTwoLevels(self):
ms = MapStack()
ms.push({'one':1})
ms.push({'two':2})
try:
one = ms['one']
except KeyError:
self.fail('Should have found one')
try:
two = ms['two']
except KeyError:
self.fail('Should have found two')
return
def testTwoLevelsWithOverride(self):
ms = MapStack()
ms.push({'one':1})
ms.push({'one':3, 'two':2})
try:
one = ms['one']
except KeyError:
self.fail('Should have found one')
else:
self.failUnlessEqual(one, 3)
try:
two = ms['two']
except KeyError:
self.fail('Should have found two')
return
def testTwoLevelsWithPop(self):
ms = MapStack()
ms.push({'one':1})
try:
one = ms['one']
except KeyError:
self.fail('Should have found one')
else:
self.failUnlessEqual(one, 1)
ms.push({'one':3, 'two':2})
try:
one = ms['one']
except KeyError:
self.fail('Should have found one')
else:
self.failUnlessEqual(one, 3)
try:
two = ms['two']
except KeyError:
self.fail('Should have found two')
removed = ms.pop()
try:
one = ms['one']
except KeyError:
self.fail('Should have found one')
else:
self.failUnlessEqual(one, 1)
try:
two = ms['two']
except KeyError:
pass
else:
self.fail('Should have gotten a KeyError')
return
if __name__ == '__main__':
unittest.main()
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