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# Copyright (C) 2009, 2010, 2011 Roman Zimbelmann <romanz@lavabit.com>
# This software is distributed under the terms of the GNU GPL version 3.
"""
Directions provide convenient methods for movement operations.
Direction objects are handled just like dicts but provide
methods like up() and down() which give you the correct value
for the vertical direction, even if only the "up" or "down" key
has been defined.
>>> d = Direction(down=5)
>>> d.down()
5
>>> d.up()
-5
>>> bool(d.horizontal())
False
"""
class Direction(dict):
def __init__(self, dictionary=None, **keywords):
if dictionary is not None:
dict.__init__(self, dictionary)
else:
dict.__init__(self, keywords)
if 'to' in self:
self['down'] = self['to']
self['absolute'] = True
def copy(self):
return Direction(**self)
def _get_bool(self, first, second, fallback=None):
try: return self[first]
except:
try: return not self[second]
except: return fallback
def _get_direction(self, first, second, fallback=0):
try: return self[first]
except:
try: return -self[second]
except: return fallback
def up(self):
return -Direction.down(self)
def down(self):
return Direction._get_direction(self, 'down', 'up')
def right(self):
return Direction._get_direction(self, 'right', 'left')
def absolute(self):
return Direction._get_bool(self, 'absolute', 'relative')
def left(self):
return -Direction.right(self)
def relative(self):
return not Direction.absolute(self)
def vertical_direction(self):
down = Direction.down(self)
return (down > 0) - (down < 0)
def horizontal_direction(self):
right = Direction.right(self)
return (right > 0) - (right < 0)
def vertical(self):
return set(self) & set(['up', 'down'])
def horizontal(self):
return set(self) & set(['left', 'right'])
def pages(self):
return 'pages' in self and self['pages']
def percentage(self):
return 'percentage' in self and self['percentage']
def multiply(self, n):
for key in ('up', 'right', 'down', 'left'):
try:
self[key] *= n
except:
pass
def set(self, n):
for key in ('up', 'right', 'down', 'left'):
if key in self:
self[key] = n
def move(self, direction, override=None, minimum=0, maximum=9999,
current=0, pagesize=1, offset=0):
"""
Calculates the new position in a given boundary.
Example:
>>> d = Direction(pages=True)
>>> d.move(direction=3)
3
>>> d.move(direction=3, current=2)
5
>>> d.move(direction=3, pagesize=5)
15
>>> # Note: we start to count at zero.
>>> d.move(direction=3, pagesize=5, maximum=10)
9
>>> d.move(direction=9, override=2)
18
"""
pos = direction
if override is not None:
if self.absolute():
pos = override
else:
pos *= override
if self.pages():
pos *= pagesize
elif self.percentage():
pos *= maximum / 100.0
if self.absolute():
if pos < minimum:
pos += maximum
else:
pos += current
return int(max(min(pos, maximum + offset - 1), minimum))
def select(self, lst, current, pagesize, override=None, offset=1):
dest = self.move(direction=self.down(), override=override,
current=current, pagesize=pagesize, minimum=0, maximum=len(lst))
selection = lst[min(current, dest):max(current, dest) + offset]
return dest + offset - 1, selection
if __name__ == '__main__':
import doctest
doctest.testmod()
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