# This file is part of python-ly, https://pypi.python.org/pypi/python-ly
#
# Copyright (c) 2008 - 2015 by Wilbert Berendsen
#
# This program 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.
#
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
# See http://www.gnu.org/licenses/ for more information.
"""
LilyPond information and logic concerning durations
"""
from __future__ import unicode_literals
from fractions import Fraction
durations = [
'\\maxima', '\\longa', '\\breve',
'1', '2', '4', '8', '16', '32', '64', '128', '256', '512', '1024', '2048'
]
[docs]def tostring(dur, dots=0, factor=1):
r"""Returns the LilyPond string representation of a given logarithmic duration.
Supports values from -3 up to and including 11.
-2 = '\longa', 0 = '1' (whole note), etc.
Adds the number of dots (defaults to 0) and the fraction factor if given.
"""
s = durations[dur + 3] + '.' * dots
if factor != 1:
s += '*{0}'.format(factor)
return s
[docs]def base_scaling(tokens):
"""Return (base, scaling) as two Fractions for the list of tokens."""
base = Fraction(8, 1 << durations.index(tokens[0]))
scaling = Fraction(1)
half = base
for t in tokens[1:]:
if t == '.':
half /= 2
base += half
elif t.startswith('*'):
scaling *= Fraction(t[1:])
return base, scaling
[docs]def base_scaling_string(duration):
"""Return (base, scaling) as two Fractions for the specified string."""
items = duration.split('*')
dots = items[0].split('.')
base = Fraction(8, 1 << durations.index(dots[0].strip()))
scaling = Fraction(1)
half = base
for dot in dots[1:]:
half /= 2
base += half
for f in items[1:]:
scaling *= Fraction(f.strip())
return base, scaling
[docs]def fraction(tokens):
"""Return the duration of the Duration tokens as a Fraction."""
base, scaling = base_scaling(tokens)
return base * scaling
[docs]def fraction_string(duration):
"""Return the duration of the specified string as a Fraction."""
base, scaling = base_scaling_string(duration)
return base * scaling