@@ -2,45 +2,52 @@
# Released under the New BSD license.
"""
This module contains a base type which provides list-style mutations
-This is akin to UserList, but without specific data storage methods.
-Possible candidate for a more general position in the source tree,
-perhaps django.utils
+without specific data storage methods.
+
+See also http://www.aryehleib.com/MutableLists.html
Author: Aryeh Leib Taurog.
"""
class ListMixin (object ):
"""
- A base class which provides complete list interface
- derived classes should implement the following:
+ A base class which provides complete list interface.
+ Derived classes must call ListMixin's __init__() function
+ and implement the following:
- function _getitem_external(self, i):
- Return single item with index i for general use
+ function _get_single_external(self, i):
+ Return single item with index i for general use.
+ The index i will always satisfy 0 <= i < len(self).
- function _getitem_internal (self, i):
+ function _get_single_internal (self, i):
Same as above, but for use within the class [Optional]
+ Note that if _get_single_internal and _get_single_internal return
+ different types of objects, _set_list must distinguish
+ between the two and handle each appropriately.
+
+ function _set_list(self, length, items):
+ Recreate the entire object.
- function _set_collection(self, length, items):
- Recreate the entire object
+ NOTE : items may be a generator which calls _get_single_internal.
+ Therefore, it is necessary to cache the values in a temporary:
+ temp = list(items)
+ before clobbering the original storage.
function _set_single(self, i, value):
Set the single item at index i to value [Optional]
If left undefined, all mutations will result in rebuilding
- the object using _set_collection .
+ the object using _set_list .
function __len__(self):
Return the length
- function __iter__(self):
- Return an iterator for the object
-
int _minlength:
The minimum legal length [Optional]
int _maxlength:
The maximum legal length [Optional]
- iterable _allowed:
- A list of allowed item types [Optional]
+ type or tuple _allowed:
+ A type or tuple of allowed item types [Optional]
class _IndexError:
The type of exception to be raise on invalid index [Optional]
@@ -50,11 +57,11 @@ class _IndexError:
_maxlength = None
_IndexError = IndexError
- # ## Python initialization and list interface methods ###
+ # ## Python initialization and special list interface methods ###
def __init__ (self * args , ** kwargs ):
- if not hasattr (self , ' _getitem_internal '
- self ._getitem_internal = self ._getitem_external
+ if not hasattr (self , ' _get_single_internal '
+ self ._get_single_internal = self ._get_single_external
if not hasattr (self , ' _set_single'
self ._set_single = self ._set_single_rebuild
@@ -63,15 +70,15 @@ def __init__(self, *args, **kwargs):
super (ListMixin, self ).__init__ (* args, ** kwargs)
def __getitem__ (self index ):
- " Gets the coordinates of the point (s) at the specified index/slice."
+ " Get the item (s) at the specified index/slice."
if isinstance (index, slice ):
- return [self ._getitem_external (i) for i in xrange (* index.indices(len (self )))]
+ return [self ._get_single_external (i) for i in xrange (* index.indices(len (self )))]
else :
index = self ._checkindex(index)
- return self ._getitem_external (index)
+ return self ._get_single_external (index)
def __delitem__ (self index ):
- " Delete the point (s) at the specified index/slice."
+ " Delete the item (s) at the specified index/slice."
if not isinstance (index, (int , long , slice )):
raise TypeError (" %s is not a legal index" % index)
@@ -84,22 +91,89 @@ def __delitem__(self, index):
indexRange = range (* index.indices(origLen))
newLen = origLen - len (indexRange)
- newItems = ( self ._getitem_internal (i)
+ newItems = ( self ._get_single_internal (i)
for i in xrange (origLen)
if i not in indexRange )
self ._rebuild(newLen, newItems)
def __setitem__ (self index , val ):
- " Sets the Geometry at the specified index."
+ " Set the item(s) at the specified index/slice ."
if isinstance (index, slice ):
self ._set_slice(index, val)
else :
index = self ._checkindex(index)
self ._check_allowed((val,))
self ._set_single(index, val)
+ def __iter__ (self
+ " Iterate over the items in the list"
+ for i in xrange (len (self )):
+ yield self [i]
+
+ # ## Special methods for arithmetic operations ###
+ def __add__ (self other ):
+ ' add another list-like object'
+ return self .__class__ (list (self ) + list (other))
+
+ def __radd__ (self other ):
+ ' add to another list-like object'
+ return other.__class__ (list (other) + list (self ))
+
+ def __iadd__ (self other ):
+ ' add another list-like object to self'
+ self .extend(list (other))
+ return self
+
+ def __mul__ (self n ):
+ ' multiply'
+ return self .__class__ (list (self ) * n)
+
+ def __rmul__ (self n ):
+ ' multiply'
+ return self .__class__ (list (self ) * n)
+
+ def __imul__ (self n ):
+ ' multiply'
+ if n <= 0 :
+ del self [:]
+ else :
+ cache = list (self )
+ for i in range (n- 1 ):
+ self .extend(cache)
+ return self
+
+ def __cmp__ (self other ):
+ ' cmp'
+ slen = len (self )
+ for i in range (slen):
+ try :
+ c = cmp (self [i], other[i])
+ except IndexError :
+ # must be other is shorter
+ return 1
+ else :
+ # elements not equal
+ if c: return c
+
+ return cmp (slen, len (other))
+
# ## Public list interface Methods ###
+ # # Non-mutating ##
+ def count (self val ):
+ " Standard list count method"
+ count = 0
+ for i in self :
+ if val == i: count += 1
+ return count
+
+ def index (self val ):
+ " Standard list index method"
+ for i in xrange (0 , len (self )):
+ if self [i] == val: return i
+ raise ValueError (' %s not found in object' % str (val))
+
+ # # Mutating ##
def append (self val ):
" Standard list append method"
self [len (self ):] = [val]
@@ -120,32 +194,33 @@ def pop(self, index=-1):
del self [index]
return result
- def index (self val ):
- " Standard list index method"
- for i in xrange (0 , len (self )):
- if self [i] == val: return i
- raise ValueError (' %s not found in object' % str (val))
-
def remove (self val ):
" Standard list remove method"
del self [self .index(val)]
- def count (self val ):
- " Standard list count method"
- count = 0
- for i in self :
- if val == i: count += 1
- return count
+ def reverse (self
+ " Standard list reverse method"
+ self [:] = self [- 1 ::- 1 ]
- # ## Private API routines unique to ListMixin ###
+ def sort (self cmp = cmp , key = None , reverse = False ):
+ " Standard list sort method"
+ if key:
+ temp = [(key(v),v) for v in self ]
+ temp.sort(cmp = cmp , key = lambda x : x[0 ], reverse = reverse)
+ self [:] = [v[1 ] for v in temp]
+ else :
+ temp = list (self )
+ temp.sort(cmp = cmp , reverse = reverse)
+ self [:] = temp
+ # ## Private routines ###
def _rebuild (self newLen , newItems ):
if newLen < self ._minlength:
raise ValueError (' Must have at least %d items' % self ._minlength)
if self ._maxlength is not None and newLen > self ._maxlength:
raise ValueError (' Cannot have more than %d items' % self ._maxlength)
- self ._set_collection (newLen, newItems)
+ self ._set_list (newLen, newItems)
def _set_single_rebuild (self index , value ):
self ._set_slice(slice (index, index + 1 , 1 ), [value])
@@ -200,7 +275,7 @@ def newItems():
if i in newVals:
yield newVals[i]
else :
- yield self ._getitem_internal (i)
+ yield self ._get_single_internal (i)
self ._rebuild(newLen, newItems())
@@ -229,6 +304,6 @@ def newItems():
if i < origLen:
if i < start or i >= stop:
- yield self ._getitem_internal (i)
+ yield self ._get_single_internal (i)
self ._rebuild(newLen, newItems())
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