From 236d42dda5160b88e6d0437cccc13d0853a9001a Mon Sep 17 00:00:00 2001
From: James Godfrey-Kittle <jamesgk@google.com>
Date: Fri, 27 Mar 2015 12:29:51 -0700
Subject: Handle new contextual feature rules.

This depends on our own version of feaTools, which is a bit hacky. Ideally we should use something more robust that feaTools (e.g. a full feature syntax compiler). This also adds a message about the feaTools dependency to the readme, which I forgot about before.
---
 scripts/lib/fontbuild/features.py | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

(limited to 'scripts')

diff --git a/scripts/lib/fontbuild/features.py b/scripts/lib/fontbuild/features.py
index 898aa56..1f59801 100755
--- a/scripts/lib/fontbuild/features.py
+++ b/scripts/lib/fontbuild/features.py
@@ -26,7 +26,7 @@ parser.classContentRE = re.compile(
 parser.sequenceInlineClassRE = re.compile(
         "\["                   # [
         "([\w\d\s_.@']+)"      # content
-        "\]"                   # ]
+        "\]'?"                 # ], optional contextual marking
         )
 
 # allow apostrophes in the target and replacement of a substitution
@@ -76,8 +76,19 @@ class FilterFeatureWriter(FDKSyntaxFeatureWriter):
         """Use this class for nested expressions e.g. in feature definitions."""
         return FilterFeatureWriter(self.refs, name, isFeature)
 
+    def _flattenRefs(self, refs):
+        """Flatten a list of references."""
+        flatRefs = []
+        for ref in refs:
+            if type(ref) == list:
+                flatRefs.extend(self._flattenRefs(ref))
+            elif ref != "'":  # ignore contextual class markings
+                flatRefs.append(ref)
+        return flatRefs
+
     def _checkRefs(self, refs, errorMsg):
         """Check a list of references found in a sub or pos rule."""
+        refs = self._flattenRefs(refs)
         for ref in refs:
             # trailing apostrophes should be ignored
             if ref[-1] == "'":
@@ -105,14 +116,12 @@ class FilterFeatureWriter(FDKSyntaxFeatureWriter):
 
     def gsubType1(self, target, replacement):
         """Check a sub rule with one-to-one replacement."""
-        if type(target) == str:
-            target, replacement = [target], [replacement]
-        if self._checkRefs(target + replacement, self.subErr):
+        if self._checkRefs([target, replacement], self.subErr):
             super(FilterFeatureWriter, self).gsubType1(target, replacement)
 
     def gsubType4(self, target, replacement):
         """Check a sub rule with many-to-one replacement."""
-        if self._checkRefs(target + [replacement], self.subErr):
+        if self._checkRefs([target, replacement], self.subErr):
             super(FilterFeatureWriter, self).gsubType4(target, replacement)
 
     def gposType1(self, target, value):
-- 
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