# -*- coding: ISO-8859-1 -*-
#
#
# Copyright (C) 2003-2004 Jrg Lehmann <joergl@users.sourceforge.net>
# Copyright (C) 2003-2004 Michael Schindler <m-schindler@users.sourceforge.net>
# Copyright (C) 2003-2004 Andr Wobst <wobsta@users.sourceforge.net>
#
# This file is part of PyX (http://pyx.sourceforge.net/).
#
# PyX 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.
#
# PyX 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 PyX; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
# check for an isinstance which accepts both a class and a sequence of classes
# as second argument and emulate this behaviour if necessary
try:
isinstance(1, (int, float))
except TypeError:
# workaround for Python 2.1
_isinstance = isinstance
def isinstance(instance, clsarg):
import types
if _isinstance(clsarg, types.ClassType):
return _isinstance(instance, clsarg)
for cls in clsarg:
if _isinstance(instance, cls):
return 1
return 0
#
# some helper functions for the attribute handling
#
def mergeattrs(attrs):
"""perform merging of the attribute list attrs as defined by the
merge methods of the attributes"""
newattrs = []
for a in attrs:
# XXX Do we really need this test?
if isinstance(a, attr):
newattrs = a.merge(newattrs)
else:
raise TypeError("only instances of class attr.attr are allowed")
return newattrs
def getattrs(attrs, getclasses):
"""return all attributes in the attribute list attrs, which are
instances of one of the classes in getclasses"""
return [attr for attr in attrs if isinstance(attr, tuple(getclasses))]
def checkattrs(attrs, allowedclasses):
"""check whether only attributes which are instances of classes in
allowedclasses are present in the attribute list attrs; if not it
raises a TypeError"""
if len(attrs) != len(getattrs(attrs, allowedclasses)):
for attr1, attr2 in zip(attrs, getattrs(attrs, allowedclasses)):
if attr1 is not attr2:
raise TypeError("instance %r not allowed" % attr1)
else:
raise TypeError("instance %r not allowed" % attrs[len(getattrs(attrs, allowedclasses))])
#
# attr class and simple descendants
#
class attr:
""" attr is the base class of all attributes, i.e., colors, decorators,
styles, text attributes and trafos"""
def merge(self, attrs):
"""merge self into list of attrs
self may either be appended to attrs or inserted at a proper position
immediately before a dependent attribute. Attributes of the same type
should be removed, if redundant. Note that it is safe to modify
attrs."""
attrs.append(self)
return attrs
class exclusiveattr(attr):
"""an attribute which swallows all but the last of the same type (specified
by the exlusiveclass argument to the constructor) in an attribute list"""
def __init__(self, exclusiveclass):
self.exclusiveclass = exclusiveclass
def merge(self, attrs):
attrs = [attr for attr in attrs if not isinstance(attr, self.exclusiveclass)]
attrs.append(self)
return attrs
class sortbeforeattr(attr):
"""an attribute which places itself previous to all attributes given
in the beforetheclasses argument to the constructor"""
def __init__(self, beforetheclasses):
self.beforetheclasses = tuple(beforetheclasses)
def merge(self, attrs):
first = 1
result = []
for attr in attrs:
if first and isinstance(attr, self.beforetheclasses):
result.append(self)
first = 0
result.append(attr)
if first:
result.append(self)
return result
class sortbeforeexclusiveattr(attr):
"""an attribute which swallows all but the last of the same type (specified
by the exlusiveclass argument to the constructor) in an attribute list and
places itself previous to all attributes given in the beforetheclasses
argument to the constructor"""
def __init__(self, exclusiveclass, beforetheclasses):
self.exclusiveclass = exclusiveclass
self.beforetheclasses = tuple(beforetheclasses)
def merge(self, attrs):
first = 1
result = []
for attr in attrs:
if first and isinstance(attr, self.beforetheclasses):
result.append(self)
first = 0
if not isinstance(attr, self.exclusiveclass):
result.append(attr)
if first:
result.append(self)
return result
class clearclass(attr):
"""a special attribute which allows to remove all predecessing attributes of
the same type in an attribute list"""
def __init__(self, clearclass):
self.clearclass = clearclass
def merge(self, attrs):
return [attr for attr in attrs if not isinstance(attr, self.clearclass)]
class _clear(attr):
"""a special attribute which removes all predecessing attributes
in an attribute list"""
def merge(self, attrs):
return []
# we define the attribute "clear", an instance of "_clear",
# which can be used to remove all predecessing attributes
# in an attribute list
clear = _clear()
#
# changeable attrs
#
def selectattrs(attrs, index, total):
"""performs select calls for all changeable attributes and
returns the resulting attribute list
- attrs should be a list containing attributes and changeable
attributes
- index should be an unsigned integer
- total should be a positive number
- valid sections fullfill 0<=index<total
- returns None, when attrs is None
- returns None, when a changeable attribute returns None"""
if attrs is None:
return None
result = []
for a in attrs:
if isinstance(a, changeattr):
select = a.select(index, total)
if select is None:
return None
result.append(select)
else:
result.append(a)
return result
def selectattr(attr, index, total):
"""as select, but for a single attribute"""
if isinstance(attr, changeattr):
select = attr.select(index, total)
if select is None:
return None
return select
else:
return attr
class changeattr:
"""changeattr is the base class of all changeable attributes"""
def select(self, index, total):
"""returns an attribute for a given index out of a total number
if attributes to be provided
- index should be an unsigned integer
- total should be a positive number
- valid selections fullfill 0 <= index < total
- the select method may raise a ValueError, when the
changeable attribute does not allow for a requested
selection"""
raise RuntimeError("not implemented")
class changelist(changeattr):
"""a changeable attribute over a list of attribute choises"""
def __init__(self, attrs, cyclic=1):
"""initializes the instance
- attrs is a list of attributes to cycle
- If cyclic is set, we restart from the beginning after
the end of the list has been reached; otherwise
selecting beyond the end of the list returns None"""
self.attrs = attrs
self.cyclic = cyclic
def select(self, index, total):
if self.cyclic:
return self.attrs[index % len(self.attrs)]
elif index < len(self.attrs):
return self.attrs[index]
else:
return None
class multichangeattr(changeattr):
"""a changeable attr, which selects a changeable attr from
a given dict (or list) of changeable attrs depending on the
value of total in the select call"""
def __init__(self, changeattrs):
self.changeattrs = changeattrs
def select(self, index, total):
return self.changeattrs[total].select(index, total)
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