Improve feature parsing, sub rules specifically

1 files changed, 32 insertions, 20 deletions

diff --git a/scripts/lib/fontbuild/features.py b/scripts/lib/fontbuild/features.py
index 1519034..681d6ed 100755
--- a/scripts/lib/fontbuild/features.py
+++ b/scripts/lib/fontbuild/features.py
@@ -16,8 +16,14 @@ _classVal = re.compile(
 _classDef = re.compile(

     r"(%s)\s*=\s*%s\s*;" % (_className.pattern, _classVal.pattern))

 _featureDef = re.compile(

-    r"(feature\s+(?P<tag>[A-Za-z]{4})\s+\{.*?\}\s+(?P=tag)\s*;\s*?\n)",

+    r"(feature\s+(?P<tag>[A-Za-z]{4})\s+\{.*?\}\s+(?P=tag)\s*;)",

     re.DOTALL)

+_subRuleToken = r"(?:%s|%s)'?" % (_glyphName, _className.pattern)

+_subRuleTokenList =  (

+    r"\[?\s*(%s(?:\s+%s)*)\s*\]?" % (_subRuleToken, _subRuleToken))

+_subRule = re.compile(

+    r"(\s*)sub(?:stitute)?\s+%s\s+by\s+%s\s*;" %

+    (_subRuleTokenList, _subRuleTokenList))

 _systemDef = re.compile(r"languagesystem\s+([A-Za-z]+)\s+([A-Za-z]+)\s*;")

 _comment = re.compile(r"\s*#.*")

 

@@ -28,20 +34,28 @@ def readFeatureFile(font, text):
     readGlyphClasses(font, text)

     text = "\n".join([l for l in text.splitlines() if not _comment.match(l)])

 

-    errorMsg = "feature definition %s (definition removed)"

+    # filter out substitution rules with invalid references

+    errorMsg = "feature definition %s (substitution rule removed)"

     if not hasattr(font.features, "tags"):

         font.features.tags = []

         font.features.values = {}

     for value, tag in _featureDef.findall(text):

-        valid = True

-        for reference in _className.findall(value):

-            valid = valid and _isValidReference(errorMsg % tag, reference, font)

-        for referenceList in _classVal.findall(value):

-            for ref in referenceList.split():

-                valid = valid and _isValidReference(errorMsg % tag, ref, font)

-        if valid:

-            font.features.tags.append(tag)

-            font.features.values[tag] = value

+        lines = value.splitlines()

+        for i in range(len(lines)):

+            if _subRule.match(lines[i]):

+                indentation, subbed, sub = _subRule.match(lines[i]).groups()

+                refs = subbed.split() + sub.split()

+                invalid = None

+                for ref in refs:

+                    if ref[-1] == "'":

+                        ref = ref[:-1]

+                    if not invalid and not _isValidRef(errorMsg % tag, ref, font):

+                        invalid = ref

+                if invalid:

+                    lines[i] = ("%s; # substitution rule removed for invalid "

+                                "reference %s" % (indentation, invalid))

+        font.features.tags.append(tag)

+        font.features.values[tag] = "\n".join(lines)

 

 

 def readGlyphClasses(font, text, update=True):

@@ -49,6 +63,7 @@ def readGlyphClasses(font, text, update=True):
 

     text = "\n".join([l for l in text.splitlines() if not _comment.match(l)])

 

+    # filter out invalid references from glyph class definitions

     errorMsg = "glyph class definition %s (reference removed)"

     if not hasattr(font, "classNames"):

         font.classNames = []

@@ -58,13 +73,10 @@ def readGlyphClasses(font, text, update=True):
             if not update:

                 continue

             font.classNames.remove(name)

-        validRefs = []

-        for reference in value.split():

-            if _isValidReference(errorMsg % name, reference, font):

-                validRefs.append(reference)

-        value = " ".join(validRefs)

+        refs = value.split()

+        refs = [r for r in refs if _isValidRef(errorMsg % name, r, font)]

         font.classNames.append(name)

-        font.classVals[name] = value

+        font.classVals[name] = " ".join(refs)

 

     if not hasattr(font, "languageSystems"):

         font.languageSystems = []

@@ -73,7 +85,7 @@ def readGlyphClasses(font, text, update=True):
             font.languageSystems.append(system)

 

 

-def _isValidReference(referencer, ref, font):

+def _isValidRef(referencer, ref, font):

     """Check if a reference is valid for a font."""

 

     if ref.startswith("@"):

@@ -95,8 +107,8 @@ def generateFeatureFile(font):
         ["%s = [%s];" % (n, font.classVals[n]) for n in font.classNames])

     systems = "\n".join(

         ["languagesystem %s %s;" % (s[0], s[1]) for s in font.languageSystems])

-    features = "\n".join([font.features.values[t] for t in font.features.tags])

-    font.features.text = "\n\n".join([classes, systems, features])

+    fea = "\n\n".join([font.features.values[t] for t in font.features.tags])

+    font.features.text = "\n\n".join([classes, systems, fea])

 

 

 def writeFeatureFile(font, path):