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#!/usr/bin/env python3
"""Generator of the function to prohibit certain vowel sequences.
It creates ``_hb_preprocess_text_vowel_constraints``, which inserts dotted
circles into sequences prohibited by the USE script development spec.
This function should be used as the ``preprocess_text`` of an
``hb_ot_complex_shaper_t``.
usage: ./gen-vowel-constraints.py ms-use/IndicShapingInvalidCluster.txt
"""
import collections
import youseedee
def write (s):
sys.stdout.flush ()
sys.stdout.buffer.write (s.encode ('utf-8'))
import sys
if len (sys.argv) != 2:
sys.exit (__doc__)
script_order = {}
scripts = {}
for start, end,script in youseedee.parse_file_ranges("Scripts.txt"):
for u in range (start, end + 1):
scripts[u] = script
if script not in script_order:
script_order[script] = start
class ConstraintSet (object):
"""A set of prohibited code point sequences.
Args:
constraint (List[int]): A prohibited code point sequence.
"""
def __init__ (self, constraint):
# Either a list or a dictionary. As a list of code points, it
# represents a prohibited code point sequence. As a dictionary,
# it represents a set of prohibited sequences, where each item
# represents the set of prohibited sequences starting with the
# key (a code point) concatenated with any of the values
# (ConstraintSets).
self._c = constraint
def add (self, constraint):
"""Add a constraint to this set."""
if not constraint:
return
first = constraint[0]
rest = constraint[1:]
if isinstance (self._c, list):
if constraint == self._c[:len (constraint)]:
self._c = constraint
elif self._c != constraint[:len (self._c)]:
self._c = {self._c[0]: ConstraintSet (self._c[1:])}
if isinstance (self._c, dict):
if first in self._c:
self._c[first].add (rest)
else:
self._c[first] = ConstraintSet (rest)
@staticmethod
def _indent (depth):
return (' ' * depth)
@staticmethod
def _cp_accessor(index):
if index:
return "buffer.items[i+{}].codepoint".format(index)
return "buffer.items[i].codepoint"
def __str__ (self, index=0, depth=2):
s = []
indent = self._indent (depth)
if isinstance (self._c, list):
if len (self._c) == 0:
assert index == 2, 'Cannot use `matched` for this constraint; the general case has not been implemented'
s.append ('{}matched = True\n'.format (indent))
elif len (self._c) == 1:
assert index == 1, 'Cannot use `matched` for this constraint; the general case has not been implemented'
s.append ('{}matched = 0x{:04X} == {}\n'.format (indent, next (iter (self._c)), self._cp_accessor(index)))
else:
s.append ('{}if (0x{:04X} == {} and\n'.format (indent, self._c[0], self._cp_accessor(index)))
if index:
s.append ('{}i + {} < len(buffer.items)-1 and\n'.format (self._indent (depth + 2), index + 1))
for i, cp in enumerate (self._c[1:], start=1):
s.append ('{}0x{:04X} == {}{}\n'.format (
self._indent (depth + 2), cp, self._cp_accessor(index + i), '):' if i == len (self._c) - 1 else 'and')
)
s.append ('{}matched = True\n'.format (self._indent (depth + 1)))
else:
cases = collections.defaultdict (set)
for first, rest in sorted (self._c.items ()):
cases[rest.__str__ (index + 1, depth + 2)].add (first)
for body, labels in sorted (cases.items (), key=lambda b_ls: sorted (b_ls[1])[0]):
if len(labels) == 1:
s.append (self._indent (depth + 1) + "if {} == 0x{:04X}:\n".format(self._cp_accessor(index), list(labels)[0]))
else:
points = ", ".join(['0x{:04X}'.format(cp) for cp in sorted(labels)])
s.append (self._indent (depth + 1) + "if {} in [{}]:\n".format(self._cp_accessor(index), points))
s.append (body)
return ''.join (s)
constraints = {}
with open (sys.argv[1], encoding='utf-8') as f:
constraints_header = []
while True:
line = f.readline ().strip ()
if line == '#':
break
constraints_header.append(line)
for line in f:
j = line.find ('#')
if j >= 0:
line = line[:j]
constraint = [int (cp, 16) for cp in line.split (';')[0].split ()]
if not constraint: continue
assert 2 <= len (constraint), 'Prohibited sequence is too short: {}'.format (constraint)
script = scripts[constraint[0]]
if script in constraints:
constraints[script].add (constraint)
else:
constraints[script] = ConstraintSet (constraint)
assert constraints, 'No constraints found'
print ('# The following functions are generated by running:')
print ('# %s ms-use/IndicShapingInvalidCluster.txt' % sys.argv[0])
print("""
from fontFeatures.shaperLib.Buffer import BufferItem
DOTTED_CIRCLE = 0x25CC
def _insert_dotted_circle(buf, index):
dotted_circle = BufferItem.new_unicode(DOTTED_CIRCLE)
buf.items.insert(index, dotted_circle)
""")
print ('def preprocess_text_vowel_constraints(buffer):')
for script, constraints in sorted (constraints.items (), key=lambda s_c: script_order[s_c[0]]):
print(f' if buffer.script == "{script}":')
print (' i = 0')
print (' while i < len(buffer.items)-1:')
print (' matched = False')
write (str (constraints))
print (' i = i + 1')
print (' if matched: _insert_dotted_circle(buffer, i)')
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