# This file is part of python-ly, https://pypi.python.org/pypi/python-ly
#
# Copyright (c) 2011 - 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.
"""
Convert absolute music to relative music.
"""
from __future__ import unicode_literals
import itertools
import ly.lex.lilypond
[docs]
def abs2rel(cursor, language="nederlands", startpitch=True, first_pitch_absolute=False):
"""Converts pitches from absolute to relative.
language: language to start reading pitch names in
startpitch: if True, write a starting pitch before the opening bracket of
a relative expression.
first_pitch_absolute: this option only makes sense when startpitch is False.
If first_pitch_absolute is True, the first pitch of a \\relative
expression is written as absolute. This mimics the behaviour of
LilyPond >= 2.18. (In fact, the starting pitch is then assumed to be f.)
If False, the first pitch is written as relative to c'
(LilyPond < 2.18 behaviour).
Existing \\relative expressions are not changed.
"""
start = cursor.start
cursor.start = 0
source = ly.document.Source(cursor, True, tokens_with_position=True)
pitches = ly.pitch.PitchIterator(source, language)
psource = pitches.pitches()
if start > 0:
# consume tokens before the selection, following the language
t = source.consume(pitches.tokens(), start)
if t:
psource = itertools.chain((t,), psource)
# this class dispatches the tokens. we can't use a generator function
# as that doesn't like to be called again while there is already a body
# running.
class gen(object):
def __iter__(self):
return self
def __next__(self):
t = next(psource)
while isinstance(t, (ly.lex.Space, ly.lex.Comment)):
t = next(psource)
if t == '\\relative' and isinstance(t, ly.lex.lilypond.Command):
relative()
t = next(psource)
elif isinstance(t, ly.lex.lilypond.ChordMode):
consume() # do not change chords
t = next(psource)
elif isinstance(t, ly.lex.lilypond.MarkupScore):
consume()
t = next(psource)
return t
next = __next__
tsource = gen()
def getpitches(iterable):
"""Consumes iterable but only yields Pitch instances."""
for p in iterable:
if isinstance(p, ly.pitch.Pitch):
yield p
def context():
"""Consume tokens till the level drops (we exit a construct)."""
depth = source.state.depth()
for t in tsource:
yield t
if source.state.depth() < depth:
return
def consume():
"""Consume tokens from context() returning the last token, if any."""
t = None
for t in context():
pass
return t
def relative():
r"""Consume the whole \relative expression without doing anything. """
# skip pitch argument
t = next(tsource)
if isinstance(t, ly.pitch.Pitch):
t = next(tsource)
while True:
# eat stuff like \new Staff == "bla" \new Voice \notes etc.
if isinstance(source.state.parser(), ly.lex.lilypond.ParseTranslator):
t = consume()
elif isinstance(t, ly.lex.lilypond.NoteMode):
t = next(tsource)
else:
break
if t in ('{', '<<', '<'):
consume()
# Do it!
with cursor.document as document:
for t in tsource:
if t in ('{', '<<'):
# Ok, parse current expression.
pos = t.pos # where to insert the \relative command
lastPitch = None
chord = None
for t in context():
# skip commands with pitches that do not count
if isinstance(t, ly.lex.lilypond.PitchCommand):
consume()
elif isinstance(t, ly.lex.lilypond.ChordStart):
# Handle chord
chord = []
elif isinstance(t, ly.lex.lilypond.ChordEnd):
if chord:
lastPitch = chord[0]
chord = None
elif isinstance(t, ly.pitch.Pitch):
# Handle pitch
if lastPitch is None:
if startpitch:
lastPitch = ly.pitch.Pitch.c1()
lastPitch.octave = t.octave
if t.note > 3:
lastPitch.octave += 1
document[pos:pos] = "\\relative {0} ".format(
lastPitch.output(pitches.language))
else:
if first_pitch_absolute:
lastPitch = ly.pitch.Pitch.f0()
else:
lastPitch = ly.pitch.Pitch.c1()
document[pos:pos] = "\\relative "
p = t.copy()
t.makeRelative(lastPitch)
pitches.write(t)
lastPitch = p
# remember the first pitch of a chord
if chord == []:
chord.append(p)