[feaLib] Build ScriptList subtable

Also, fixed a bug that caused language tags to be sometimes stripped.
Added an assertion to verify that language tags are always 4 chars.

Lib/fontTools/feaLib/ast.py

@@ -76,6 +76,7 @@ class AnchorDefinition(Statement):
 class LanguageStatement(Statement):
     def __init__(self, location, language, include_default, required):
         Statement.__init__(self, location)
+        assert(len(language) == 4)
         self.language = language
         self.include_default = include_default
         self.required = required

Lib/fontTools/feaLib/builder.py

@@ -85,6 +85,7 @@ class Builder(object):
         # Build a table for mapping (tag, lookup_indices) to feature_index.
         # For example, ('liga', (2,3,7)) --> 23.
         feature_indices = {}
+        scripts = {}  # 'cyrl' --> {'DEU': [23, 24]} for feature #23,24
         for key, lookups in sorted(self.features_.items()):
             script, lang, feature_tag = key
             # l.lookup_index will be None when a lookup is not needed
@@ -94,6 +95,7 @@ class Builder(object):
                                     if l.lookup_index is not None])
             if len(lookup_indices) == 0:
                 continue
+
             feature_key = (feature_tag, lookup_indices)
             feature_index = feature_indices.get(feature_key)
             if feature_index is None:
@@ -106,8 +108,29 @@ class Builder(object):
                 frec.Feature.LookupCount = len(lookup_indices)
                 table.FeatureList.FeatureRecord.append(frec)
                 feature_indices[feature_key] = feature_index
+            scripts.setdefault(script, {}).setdefault(lang, []).append(
+                feature_index)
+
+        # Build ScriptList.
+        for script, lang_features in sorted(scripts.items()):
+            srec = otTables.ScriptRecord()
+            srec.ScriptTag = script
+            srec.Script = otTables.Script()
+            srec.Script.DefaultLangSys = None
+            srec.Script.LangSysRecord = []
+            for lang, feature_indices in sorted(lang_features.items()):
+                langsys = otTables.LangSys()
+                langsys.LookupOrder = None
+                langsys.ReqFeatureIndex = 0xFFFF
+                langsys.FeatureCount = len(feature_indices)
+                langsys.FeatureIndex = feature_indices
+                if lang == "dflt":
+                    srec.Script.DefaultLangSys = langsys
+                else:
+                    srec.Script.LangSysRecord.append(langsys)
+            srec.Script.LangSysCount = len(srec.Script.LangSysRecord)
+            table.ScriptList.ScriptRecord.append(srec)
 
-        # TODO(sascha): Build table.ScriptList.
         table.ScriptList.ScriptCount = len(table.ScriptList.ScriptRecord)
         table.FeatureList.FeatureCount = len(table.FeatureList.FeatureRecord)
         table.LookupList.LookupCount = len(table.LookupList.Lookup)
@@ -158,6 +181,7 @@ class Builder(object):
         self.cur_lookup_ = None
 
     def set_language(self, location, language, include_default):
+        assert(len(language) == 4)
         if self.cur_lookup_name_:
             raise FeatureLibError(
                 "Within a named lookup block, it is not allowed "

Lib/fontTools/feaLib/builder_test.py

@@ -142,16 +142,16 @@ class BuilderTest(unittest.TestCase):
 
     def test_language(self):
         builder = Builder(None, TTFont())
-        builder.add_language_system(None, 'latn', 'FRA')
+        builder.add_language_system(None, 'latn', 'FRA ')
         builder.start_feature(location=None, name='test')
         builder.set_script(location=None, script='cyrl')
-        builder.set_language(location=None, language='RUS',
+        builder.set_language(location=None, language='RUS ',
                              include_default=False)
-        self.assertEqual(builder.language_systems, {('cyrl', 'RUS')})
-        builder.set_language(location=None, language='BGR',
+        self.assertEqual(builder.language_systems, {('cyrl', 'RUS ')})
+        builder.set_language(location=None, language='BGR ',
                              include_default=True)
         self.assertEqual(builder.language_systems,
-                         {('latn', 'FRA'), ('cyrl', 'BGR')})
+                         {('latn', 'FRA '), ('cyrl', 'BGR ')})
 
     def test_language_in_lookup_block(self):
         self.assertRaisesRegex(

Lib/fontTools/feaLib/parser.py

@@ -174,7 +174,7 @@ class Parser(object):
             self.expect_keyword_("required")
             required = True
         self.expect_symbol_(";")
-        return ast.LanguageStatement(location, language.strip(),
+        return ast.LanguageStatement(location, language,
                                      include_default, required)
 
     def parse_lookup_(self, vertical):

Lib/fontTools/feaLib/testdata/GSUB_3.ttx

@@ -5,7 +5,19 @@
     <GSUB>
       <Version value="1.0"/>
       <ScriptList>
-        <!-- ScriptCount=0 -->
+        <!-- ScriptCount=1 -->
+        <ScriptRecord index="0">
+          <ScriptTag value="DFLT"/>
+          <Script>
+            <DefaultLangSys>
+              <ReqFeatureIndex value="65535"/>
+              <!-- FeatureCount=2 -->
+              <FeatureIndex index="0" value="0"/>
+              <FeatureIndex index="1" value="1"/>
+            </DefaultLangSys>
+            <!-- LangSysCount=0 -->
+          </Script>
+        </ScriptRecord>
       </ScriptList>
       <FeatureList>
         <!-- FeatureCount=2 -->

Lib/fontTools/feaLib/testdata/spec4h1.ttx

@@ -5,10 +5,53 @@
     <GSUB>
       <Version value="1.0"/>
       <ScriptList>
-        <!-- ScriptCount=0 -->
+        <!-- ScriptCount=3 -->
+        <ScriptRecord index="0">
+          <ScriptTag value="DFLT"/>
+          <Script>
+            <DefaultLangSys>
+              <ReqFeatureIndex value="65535"/>
+              <!-- FeatureCount=1 -->
+              <FeatureIndex index="0" value="0"/>
+            </DefaultLangSys>
+            <!-- LangSysCount=0 -->
+          </Script>
+        </ScriptRecord>
+        <ScriptRecord index="1">
+          <ScriptTag value="cyrl"/>
+          <Script>
+            <DefaultLangSys>
+              <ReqFeatureIndex value="65535"/>
+              <!-- FeatureCount=1 -->
+              <FeatureIndex index="0" value="0"/>
+            </DefaultLangSys>
+            <!-- LangSysCount=0 -->
+          </Script>
+        </ScriptRecord>
+        <ScriptRecord index="2">
+          <ScriptTag value="latn"/>
+          <Script>
+            <DefaultLangSys>
+              <ReqFeatureIndex value="65535"/>
+              <!-- FeatureCount=1 -->
+              <FeatureIndex index="0" value="0"/>
+            </DefaultLangSys>
+            <!-- LangSysCount=2 -->
+            <LangSysRecord index="0">
+              <ReqFeatureIndex value="65535"/>
+              <!-- FeatureCount=1 -->
+              <FeatureIndex index="0" value="0"/>
+            </LangSysRecord>
+            <LangSysRecord index="1">
+              <ReqFeatureIndex value="65535"/>
+              <!-- FeatureCount=1 -->
+              <FeatureIndex index="0" value="0"/>
+            </LangSysRecord>
+          </Script>
+        </ScriptRecord>
       </ScriptList>
       <FeatureList>
-        <!-- FeatureCount=2 -->
+        <!-- FeatureCount=1 -->
         <FeatureRecord index="0">
           <FeatureTag value="liga"/>
           <Feature>
@@ -18,13 +61,6 @@
             <LookupListIndex index="2" value="2"/>
           </Feature>
         </FeatureRecord>
-        <FeatureRecord index="1">
-          <FeatureTag value="liga"/>
-          <Feature>
-            <!-- LookupCount=1 -->
-            <LookupListIndex index="0" value="2"/>
-          </Feature>
-        </FeatureRecord>
       </FeatureList>
       <LookupList>
         <!-- LookupCount=3 -->

Lib/fontTools/feaLib/testdata/spec5d1.ttx

@@ -5,7 +5,19 @@
     <GSUB>
       <Version value="1.0"/>
       <ScriptList>
-        <!-- ScriptCount=0 -->
+        <!-- ScriptCount=1 -->
+        <ScriptRecord index="0">
+          <ScriptTag value="DFLT"/>
+          <Script>
+            <DefaultLangSys>
+              <ReqFeatureIndex value="65535"/>
+              <!-- FeatureCount=2 -->
+              <FeatureIndex index="0" value="0"/>
+              <FeatureIndex index="1" value="1"/>
+            </DefaultLangSys>
+            <!-- LangSysCount=0 -->
+          </Script>
+        </ScriptRecord>
       </ScriptList>
       <FeatureList>
         <!-- FeatureCount=2 -->

Lib/fontTools/feaLib/testdata/spec5d2.ttx

@@ -5,7 +5,19 @@
     <GSUB>
       <Version value="1.0"/>
       <ScriptList>
-        <!-- ScriptCount=0 -->
+        <!-- ScriptCount=1 -->
+        <ScriptRecord index="0">
+          <ScriptTag value="DFLT"/>
+          <Script>
+            <DefaultLangSys>
+              <ReqFeatureIndex value="65535"/>
+              <!-- FeatureCount=2 -->
+              <FeatureIndex index="0" value="0"/>
+              <FeatureIndex index="1" value="1"/>
+            </DefaultLangSys>
+            <!-- LangSysCount=0 -->
+          </Script>
+        </ScriptRecord>
       </ScriptList>
       <FeatureList>
         <!-- FeatureCount=2 -->