#!/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_shaper_t``.
usage: ./gen-vowel-constraints.py ms-use/IndicShapingInvalidCluster.txt Scripts.txt
Input file:
* https://unicode.org/Public/UCD/latest/ucd/Scripts.txt
"""
import collections
def write (s):
sys.stdout.flush ()
sys.stdout.buffer.write (s.encode ('utf-8'))
import sys
if len (sys.argv) != 3:
sys.exit (__doc__)
with open (sys.argv[2], encoding='utf-8') as f:
scripts_header = [f.readline () for i in range (2)]
scripts = {}
script_order = {}
for line in f:
j = line.find ('#')
if j >= 0:
line = line[:j]
fields = [x.strip () for x in line.split (';')]
if len (fields) == 1:
continue
uu = fields[0].split ('..')
start = int (uu[0], 16)
if len (uu) == 1:
end = start
else:
end = int (uu[1], 16)
script = fields[1]
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).replace (' ', '\t')
def __str__ (self, index=0, depth=4):
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}u == buffer->cur ({}).codepoint;\n'.format (indent, next (iter (self._c)), index or ''))
else:
s.append ('{}if (0x{:04X}u == buffer->cur ({}).codepoint &&\n'.format (indent, self._c[0], index or ''))
if index:
s.append ('{}buffer->idx + {} < count &&\n'.format (self._indent (depth + 2), index + 1))
for i, cp in enumerate (self._c[1:], start=1):
s.append ('{}0x{:04X}u == buffer->cur ({}).codepoint{}\n'.format (
self._indent (depth + 2), cp, index + i, ')' if i == len (self._c) - 1 else ' &&'))
s.append ('{}{{\n'.format (indent))
for i in range (index):
s.append ('{}(void) buffer->next_glyph ();\n'.format (self._indent (depth + 1)))
s.append ('{}matched = true;\n'.format (self._indent (depth + 1)))
s.append ('{}}}\n'.format (indent))
else:
s.append ('{}switch (buffer->cur ({}).codepoint)\n'.format(indent, index or ''))
s.append ('{}{{\n'.format (indent))
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]):
for i, cp in enumerate (sorted (labels)):
if i % 4 == 0:
s.append (self._indent (depth + 1))
else:
s.append (' ')
s.append ('case 0x{:04X}u:{}'.format (cp, '\n' if i % 4 == 3 else ''))
if len (labels) % 4 != 0:
s.append ('\n')
s.append (body)
s.append ('{}break;\n'.format (self._indent (depth + 2)))
s.append ('{}}}\n'.format (indent))
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 ('/* == Start of generated functions == */')
print ('/*')
print (' * The following functions are generated by running:')
print (' *')
print (' * %s ms-use/IndicShapingInvalidCluster.txt Scripts.txt' % sys.argv[0])
print (' *')
print (' * on files with these headers:')
print (' *')
for line in constraints_header:
print (' * %s' % line.strip ())
print (' *')
for line in scripts_header:
print (' * %s' % line.strip ())
print (' */')
print ()
print ('#include "hb.hh"')
print ()
print ('#ifndef HB_NO_OT_SHAPE')
print ()
print ('#include "hb-ot-shaper-vowel-constraints.hh"')
print ()
print ('static void')
print ('_output_dotted_circle (hb_buffer_t *buffer)')
print ('{')
print (' (void) buffer->output_glyph (0x25CCu);')
print (' _hb_glyph_info_reset_continuation (&buffer->prev());')
print ('}')
print ()
print ('static void')
print ('_output_with_dotted_circle (hb_buffer_t *buffer)')
print ('{')
print (' _output_dotted_circle (buffer);')
print (' (void) buffer->next_glyph ();')
print ('}')
print ()
print ('void')
print ('_hb_preprocess_text_vowel_constraints (const hb_ot_shape_plan_t *plan HB_UNUSED,')
print ('\t\t\t\t hb_buffer_t *buffer,')
print ('\t\t\t\t hb_font_t *font HB_UNUSED)')
print ('{')
print ('#ifdef HB_NO_OT_SHAPER_VOWEL_CONSTRAINTS')
print (' return;')
print ('#endif')
print (' if (buffer->flags & HB_BUFFER_FLAG_DO_NOT_INSERT_DOTTED_CIRCLE)')
print (' return;')
print ()
print (' /* UGLY UGLY UGLY business of adding dotted-circle in the middle of')
print (' * vowel-sequences that look like another vowel. Data for each script')
print (' * collected from the USE script development spec.')
print (' *')
print (' * https://github.com/harfbuzz/harfbuzz/issues/1019')
print (' */')
print (' buffer->clear_output ();')
print (' unsigned int count = buffer->len;')
print (' switch ((unsigned) buffer->props.script)')
print (' {')
for script, constraints in sorted (constraints.items (), key=lambda s_c: script_order[s_c[0]]):
print (' case HB_SCRIPT_{}:'.format (script.upper ()))
print (' for (buffer->idx = 0; buffer->idx + 1 < count && buffer->successful;)')
print (' {')
print ('\tbool matched = false;')
write (str (constraints))
print ('\t(void) buffer->next_glyph ();')
print ('\tif (matched) _output_with_dotted_circle (buffer);')
print (' }')
print (' break;')
print ()
print (' default:')
print (' break;')
print (' }')
print (' buffer->sync ();')
print ('}')
print ()
print ()
print ('#endif')
print ('/* == End of generated functions == */')
