/usr/share/pyshared/paste/util/looper.py is in python-paste 1.7.5.1-4.1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 | """
Helper for looping over sequences, particular in templates.
Often in a loop in a template it's handy to know what's next up,
previously up, if this is the first or last item in the sequence, etc.
These can be awkward to manage in a normal Python loop, but using the
looper you can get a better sense of the context. Use like::
>>> for loop, item in looper(['a', 'b', 'c']):
... print loop.number, item
... if not loop.last:
... print '---'
1 a
---
2 b
---
3 c
"""
__all__ = ['looper']
class looper(object):
"""
Helper for looping (particularly in templates)
Use this like::
for loop, item in looper(seq):
if loop.first:
...
"""
def __init__(self, seq):
self.seq = seq
def __iter__(self):
return looper_iter(self.seq)
def __repr__(self):
return '<%s for %r>' % (
self.__class__.__name__, self.seq)
class looper_iter(object):
def __init__(self, seq):
self.seq = list(seq)
self.pos = 0
def __iter__(self):
return self
def next(self):
if self.pos >= len(self.seq):
raise StopIteration
result = loop_pos(self.seq, self.pos), self.seq[self.pos]
self.pos += 1
return result
class loop_pos(object):
def __init__(self, seq, pos):
self.seq = seq
self.pos = pos
def __repr__(self):
return '<loop pos=%r at %r>' % (
self.seq[pos], pos)
def index(self):
return self.pos
index = property(index)
def number(self):
return self.pos + 1
number = property(number)
def item(self):
return self.seq[self.pos]
item = property(item)
def next(self):
try:
return self.seq[self.pos+1]
except IndexError:
return None
next = property(next)
def previous(self):
if self.pos == 0:
return None
return self.seq[self.pos-1]
previous = property(previous)
def odd(self):
return not self.pos % 2
odd = property(odd)
def even(self):
return self.pos % 2
even = property(even)
def first(self):
return self.pos == 0
first = property(first)
def last(self):
return self.pos == len(self.seq)-1
last = property(last)
def length(self):
return len(self.seq)
length = property(length)
def first_group(self, getter=None):
"""
Returns true if this item is the start of a new group,
where groups mean that some attribute has changed. The getter
can be None (the item itself changes), an attribute name like
``'.attr'``, a function, or a dict key or list index.
"""
if self.first:
return True
return self._compare_group(self.item, self.previous, getter)
def last_group(self, getter=None):
"""
Returns true if this item is the end of a new group,
where groups mean that some attribute has changed. The getter
can be None (the item itself changes), an attribute name like
``'.attr'``, a function, or a dict key or list index.
"""
if self.last:
return True
return self._compare_group(self.item, self.next, getter)
def _compare_group(self, item, other, getter):
if getter is None:
return item != other
elif (isinstance(getter, basestring)
and getter.startswith('.')):
getter = getter[1:]
if getter.endswith('()'):
getter = getter[:-2]
return getattr(item, getter)() != getattr(other, getter)()
else:
return getattr(item, getter) != getattr(other, getter)
elif callable(getter):
return getter(item) != getter(other)
else:
return item[getter] != other[getter]
|