[feaLib] Support compact syntax for chaining to ligature substitutions
https://github.com/behdad/fonttools/issues/445
This commit is contained in:
Sascha Brawer
parent
b19c6b3dec
commit
931bbc50c1
@ -250,19 +250,17 @@ class IgnoreSubstitutionRule(Statement):
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class LigatureSubstStatement(Statement):
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def __init__(self, location, glyphs, replacement):
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def __init__(self, location, prefix, glyphs, suffix, replacement):
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Statement.__init__(self, location)
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self.glyphs, self.replacement = (glyphs, replacement)
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self.prefix, self.glyphs, self.suffix = (prefix, glyphs, suffix)
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self.replacement = replacement
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def build(self, builder):
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# OpenType feature file syntax, section 5.d, "Ligature substitution":
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# "Since the OpenType specification does not allow ligature
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# substitutions to be specified on target sequences that contain
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# glyph classes, the implementation software will enumerate
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# all specific glyph sequences if glyph classes are detected"
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g = [g.glyphSet() for g in self.glyphs]
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for glyphs in sorted(itertools.product(*g)):
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builder.add_ligature_subst(self.location, glyphs, self.replacement)
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prefix = [p.glyphSet() for p in self.prefix]
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glyphs = [g.glyphSet() for g in self.glyphs]
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suffix = [s.glyphSet() for s in self.suffix]
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builder.add_ligature_subst(
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self.location, prefix, glyphs, suffix, self.replacement)
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class LookupFlagStatement(Statement):
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@ -4,6 +4,7 @@ from fontTools.feaLib.error import FeatureLibError
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from fontTools.feaLib.parser import Parser
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from fontTools.ttLib import getTableClass
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from fontTools.ttLib.tables import otBase, otTables
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import itertools
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import warnings
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@ -410,9 +411,22 @@ class Builder(object):
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location)
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lookup.alternates[glyph] = from_class
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def add_ligature_subst(self, location, glyphs, replacement):
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lookup = self.get_lookup_(location, LigatureSubstBuilder)
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lookup.ligatures[glyphs] = replacement
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def add_ligature_subst(self, location,
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prefix, glyphs, suffix, replacement):
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if prefix or suffix:
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lookup = self.get_chained_lookup_(location, LigatureSubstBuilder)
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chain = self.get_lookup_(location, ChainContextSubstBuilder)
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chain.substitutions.append((prefix, glyphs, suffix, [lookup]))
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else:
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lookup = self.get_lookup_(location, LigatureSubstBuilder)
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# OpenType feature file syntax, section 5.d, "Ligature substitution":
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# "Since the OpenType specification does not allow ligature
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# substitutions to be specified on target sequences that contain
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# glyph classes, the implementation software will enumerate
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# all specific glyph sequences if glyph classes are detected"
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for g in sorted(itertools.product(*glyphs)):
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lookup.ligatures[g] = replacement
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def add_multiple_subst(self, location,
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prefix, glyph, suffix, replacements):
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@ -16,7 +16,7 @@ import unittest
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def makeTTFont():
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glyphs = (
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".notdef space slash fraction semicolon period comma "
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".notdef space slash fraction semicolon period comma ampersand "
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"zero one two three four five six seven eight nine "
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"zero.oldstyle one.oldstyle two.oldstyle three.oldstyle "
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"four.oldstyle five.oldstyle six.oldstyle seven.oldstyle "
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@ -26,7 +26,7 @@ def makeTTFont():
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"A.sc B.sc C.sc D.sc E.sc F.sc G.sc H.sc I.sc J.sc K.sc L.sc M.sc "
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"N.sc O.sc P.sc Q.sc R.sc S.sc T.sc U.sc V.sc W.sc X.sc Y.sc Z.sc "
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"A.alt1 A.alt2 A.alt3 B.alt1 B.alt2 B.alt3 C.alt1 C.alt2 C.alt3 "
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"d.alt n.end s.end "
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"d.alt e.begin n.end s.end "
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"f_l c_h c_k c_s c_t f_f f_f_i f_f_l f_i o_f_f_i s_t "
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"ydieresis yacute "
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"grave acute dieresis macron circumflex cedilla umlaut ogonek caron "
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@ -165,7 +165,7 @@ class BuilderTest(unittest.TestCase):
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self.expect_ttx(font, self.getpath("GSUB_%s.ttx" % name))
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def test_spec(self):
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for name in "4h1 5d1 5d2 5fi1 5fi2 5h1 6d2 6e 6f 6h_ii".split():
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for name in "4h1 5d1 5d2 5fi1 5fi2 5fi4 5h1 6d2 6e 6f 6h_ii".split():
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font = makeTTFont()
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addOpenTypeFeatures(self.getpath("spec%s.fea" % name), font)
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self.expect_ttx(font, self.getpath("spec%s.ttx" % name))
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@ -510,12 +510,13 @@ class Parser(object):
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# GSUB lookup type 4: Ligature substitution.
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# Format: "substitute f f i by f_f_i;"
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if (not reverse and len(old_prefix) == 0 and len(old_suffix) == 0 and
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if (not reverse and
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len(old) > 1 and len(new) == 1 and
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len(new[0].glyphSet()) == 1 and
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num_lookups == 0):
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return ast.LigatureSubstStatement(
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location, old, list(new[0].glyphSet())[0])
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location, old_prefix, old, old_suffix,
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list(new[0].glyphSet())[0])
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# GSUB lookup type 8: Reverse chaining substitution.
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if reverse:
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@ -807,7 +807,7 @@ class ParserTest(unittest.TestCase):
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self.assertEqual(sub.glyph, "f_f_i")
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self.assertEqual(sub.replacement, ("f", "f", "i"))
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def test_substitute_multiple_chained(self): # GSUB LookupType 2
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def test_substitute_multiple_chained(self): # chain to GSUB LookupType 2
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doc = self.parse("lookup L {sub [A-C] f_f_i' [X-Z] by f f i;} L;")
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sub = doc.statements[0].statements[0]
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self.assertIsInstance(sub, ast.MultipleSubstStatement)
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@ -836,9 +836,20 @@ class ParserTest(unittest.TestCase):
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def test_substitute_ligature(self): # GSUB LookupType 4
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doc = self.parse("feature liga {substitute f f i by f_f_i;} liga;")
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sub = doc.statements[0].statements[0]
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self.assertEqual(type(sub), ast.LigatureSubstStatement)
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self.assertIsInstance(sub, ast.LigatureSubstStatement)
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self.assertEqual(glyphstr(sub.glyphs), "f f i")
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self.assertEqual(sub.replacement, "f_f_i")
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self.assertEqual(glyphstr(sub.prefix), "")
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self.assertEqual(glyphstr(sub.suffix), "")
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def test_substitute_ligature_chained(self): # chain to GSUB LookupType 4
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doc = self.parse("feature F {substitute A B f' i' Z by f_i;} F;")
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sub = doc.statements[0].statements[0]
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self.assertIsInstance(sub, ast.LigatureSubstStatement)
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self.assertEqual(glyphstr(sub.glyphs), "f i")
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self.assertEqual(sub.replacement, "f_i")
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self.assertEqual(glyphstr(sub.prefix), "A B")
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self.assertEqual(glyphstr(sub.suffix), "Z")
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def test_substitute_lookups(self): # GSUB LookupType 6
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doc = Parser(self.getpath("spec5fi1.fea")).parse()
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5
Lib/fontTools/feaLib/testdata/GSUB_6.fea
vendored
5
Lib/fontTools/feaLib/testdata/GSUB_6.fea
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@ -7,7 +7,12 @@ lookup ChainedMultipleSubst {
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substitute [A-C a-c] [D d] E c_t' V [W w] [X-Z x-z] by c t;
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} ChainedMultipleSubst;
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lookup ChainedLigatureSubst {
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substitute A [C c]' [T t]' Z by c_t;
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} ChainedLigatureSubst;
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feature test {
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lookup ChainedSingleSubst;
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lookup ChainedMultipleSubst;
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lookup ChainedLigatureSubst;
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} test;
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49
Lib/fontTools/feaLib/testdata/GSUB_6.ttx
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49
Lib/fontTools/feaLib/testdata/GSUB_6.ttx
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@ -22,14 +22,15 @@
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<FeatureRecord index="0">
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<FeatureTag value="test"/>
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<Feature>
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<!-- LookupCount=2 -->
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<!-- LookupCount=3 -->
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<LookupListIndex index="0" value="1"/>
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<LookupListIndex index="1" value="4"/>
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<LookupListIndex index="2" value="6"/>
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</Feature>
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</FeatureRecord>
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</FeatureList>
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<LookupList>
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<!-- LookupCount=5 -->
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<!-- LookupCount=7 -->
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<Lookup index="0">
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<!-- LookupType=1 -->
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<LookupFlag value="0"/>
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@ -151,6 +152,50 @@
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</SubstLookupRecord>
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</ChainContextSubst>
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</Lookup>
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<Lookup index="5">
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<!-- LookupType=4 -->
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<LookupFlag value="0"/>
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<!-- SubTableCount=1 -->
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<LigatureSubst index="0" Format="1">
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<LigatureSet glyph="C">
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<Ligature components="T" glyph="c_t"/>
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<Ligature components="t" glyph="c_t"/>
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</LigatureSet>
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<LigatureSet glyph="c">
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<Ligature components="T" glyph="c_t"/>
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<Ligature components="t" glyph="c_t"/>
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</LigatureSet>
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</LigatureSubst>
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</Lookup>
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<Lookup index="6">
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<!-- LookupType=6 -->
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<LookupFlag value="0"/>
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<!-- SubTableCount=1 -->
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<ChainContextSubst index="0" Format="3">
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<!-- BacktrackGlyphCount=1 -->
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<BacktrackCoverage index="0">
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<Glyph value="A"/>
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</BacktrackCoverage>
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<!-- InputGlyphCount=2 -->
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<InputCoverage index="0">
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<Glyph value="C"/>
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<Glyph value="c"/>
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</InputCoverage>
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<InputCoverage index="1">
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<Glyph value="T"/>
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<Glyph value="t"/>
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</InputCoverage>
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<!-- LookAheadGlyphCount=1 -->
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<LookAheadCoverage index="0">
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<Glyph value="Z"/>
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</LookAheadCoverage>
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<!-- SubstCount=1 -->
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<SubstLookupRecord index="0">
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<SequenceIndex value="0"/>
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<LookupListIndex value="5"/>
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</SubstLookupRecord>
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</ChainContextSubst>
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</Lookup>
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</LookupList>
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</GSUB>
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9
Lib/fontTools/feaLib/testdata/spec5fi4.fea
vendored
Normal file
9
Lib/fontTools/feaLib/testdata/spec5fi4.fea
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@ -0,0 +1,9 @@
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# OpenType Feature File specification, section 5.f.i, example 4
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# "Specifying a Chain Sub rule and marking sub-runs"
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# http://www.adobe.com/devnet/opentype/afdko/topic_feature_file_syntax.html
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languagesystem latn dflt;
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feature test {
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substitute [e e.begin]' t' c by ampersand;
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} test;
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73
Lib/fontTools/feaLib/testdata/spec5fi4.ttx
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73
Lib/fontTools/feaLib/testdata/spec5fi4.ttx
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@ -0,0 +1,73 @@
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<?xml version="1.0" encoding="UTF-8"?>
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<ttFont>
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<GSUB>
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<Version value="1.0"/>
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<ScriptList>
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<!-- ScriptCount=1 -->
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<ScriptRecord index="0">
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<ScriptTag value="latn"/>
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<Script>
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<DefaultLangSys>
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<ReqFeatureIndex value="65535"/>
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<!-- FeatureCount=1 -->
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<FeatureIndex index="0" value="0"/>
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</DefaultLangSys>
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<!-- LangSysCount=0 -->
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</Script>
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</ScriptRecord>
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</ScriptList>
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<FeatureList>
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<!-- FeatureCount=1 -->
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<FeatureRecord index="0">
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<FeatureTag value="test"/>
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<Feature>
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<!-- LookupCount=1 -->
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<LookupListIndex index="0" value="1"/>
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</Feature>
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</FeatureRecord>
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</FeatureList>
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<LookupList>
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<!-- LookupCount=2 -->
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<Lookup index="0">
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<!-- LookupType=4 -->
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<LookupFlag value="0"/>
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<!-- SubTableCount=1 -->
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<LigatureSubst index="0" Format="1">
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<LigatureSet glyph="e">
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<Ligature components="t" glyph="ampersand"/>
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</LigatureSet>
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<LigatureSet glyph="e.begin">
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<Ligature components="t" glyph="ampersand"/>
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</LigatureSet>
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</LigatureSubst>
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</Lookup>
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<Lookup index="1">
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<!-- LookupType=6 -->
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<LookupFlag value="0"/>
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<!-- SubTableCount=1 -->
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<ChainContextSubst index="0" Format="3">
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<!-- BacktrackGlyphCount=0 -->
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<!-- InputGlyphCount=2 -->
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<InputCoverage index="0">
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<Glyph value="e"/>
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<Glyph value="e.begin"/>
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</InputCoverage>
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<InputCoverage index="1">
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<Glyph value="t"/>
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</InputCoverage>
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<!-- LookAheadGlyphCount=1 -->
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<LookAheadCoverage index="0">
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<Glyph value="c"/>
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</LookAheadCoverage>
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<!-- SubstCount=1 -->
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<SubstLookupRecord index="0">
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<SequenceIndex value="0"/>
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<LookupListIndex value="0"/>
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</SubstLookupRecord>
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</ChainContextSubst>
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</Lookup>
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</LookupList>
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</GSUB>
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</ttFont>
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