Merge pull request #2052 from simoncozens/fealib-debug

feaLib source debugging

Lib/fontTools/feaLib/__main__.py

@@ -38,6 +38,12 @@ def main(args=None):
         nargs="+",
         help="Specify the table(s) to be built.",
     )
+    parser.add_argument(
+        "-d",
+        "--debug",
+        action="store_true",
+        help="Add source-level debugging information to font.",
+    )
     parser.add_argument(
         "-v",
         "--verbose",
@@ -58,7 +64,9 @@ def main(args=None):
 
     font = TTFont(options.input_font)
     try:
-        addOpenTypeFeatures(font, options.input_fea, tables=options.tables)
+        addOpenTypeFeatures(
+            font, options.input_fea, tables=options.tables, debug=options.debug
+        )
     except FeatureLibError as e:
         if options.traceback:
             raise

Lib/fontTools/feaLib/builder.py

@@ -2,6 +2,7 @@ from fontTools.misc.py23 import *
 from fontTools.misc import sstruct
 from fontTools.misc.textTools import binary2num, safeEval
 from fontTools.feaLib.error import FeatureLibError
+from fontTools.feaLib.lookupDebugInfo import LookupDebugInfo, LOOKUP_DEBUG_INFO_KEY
 from fontTools.feaLib.parser import Parser
 from fontTools.feaLib.ast import FeatureFile
 from fontTools.otlLib import builder as otl
@@ -34,7 +35,7 @@ import logging
 log = logging.getLogger(__name__)
 
 
-def addOpenTypeFeatures(font, featurefile, tables=None):
+def addOpenTypeFeatures(font, featurefile, tables=None, debug=False):
     """Add features from a file to a font. Note that this replaces any features
     currently present.
 
@@ -44,13 +45,17 @@ def addOpenTypeFeatures(font, featurefile, tables=None):
             parse it into an AST), or a pre-parsed AST instance.
         tables: If passed, restrict the set of affected tables to those in the
             list.
+        debug: Whether to add source debugging information to the font in the
+            ``Debg`` table
 
     """
     builder = Builder(font, featurefile)
-    builder.build(tables=tables)
+    builder.build(tables=tables, debug=debug)
 
 
-def addOpenTypeFeaturesFromString(font, features, filename=None, tables=None):
+def addOpenTypeFeaturesFromString(
+    font, features, filename=None, tables=None, debug=False
+):
     """Add features from a string to a font. Note that this replaces any
     features currently present.
 
@@ -62,13 +67,15 @@ def addOpenTypeFeaturesFromString(font, features, filename=None, tables=None):
             directory is assumed.
         tables: If passed, restrict the set of affected tables to those in the
             list.
+        debug: Whether to add source debugging information to the font in the
+            ``Debg`` table
 
     """
 
     featurefile = UnicodeIO(tounicode(features))
     if filename:
         featurefile.name = filename
-    addOpenTypeFeatures(font, featurefile, tables=tables)
+    addOpenTypeFeatures(font, featurefile, tables=tables, debug=debug)
 
 
 class Builder(object):
@@ -108,6 +115,7 @@ class Builder(object):
         self.cur_lookup_name_ = None
         self.cur_feature_name_ = None
         self.lookups_ = []
+        self.lookup_locations = {"GSUB": {}, "GPOS": {}}
         self.features_ = {}  # ('latn', 'DEU ', 'smcp') --> [LookupBuilder*]
         self.required_features_ = {}  # ('latn', 'DEU ') --> 'scmp'
         # for feature 'aalt'
@@ -146,7 +154,7 @@ class Builder(object):
         # for table 'vhea'
         self.vhea_ = {}
 
-    def build(self, tables=None):
+    def build(self, tables=None, debug=False):
         if self.parseTree is None:
             self.parseTree = Parser(self.file, self.glyphMap).parse()
         self.parseTree.build(self)
@@ -201,6 +209,8 @@ class Builder(object):
                 self.font["BASE"] = base
             elif "BASE" in self.font:
                 del self.font["BASE"]
+        if debug:
+            self.buildDebg()
 
     def get_chained_lookup_(self, location, builder_class):
         result = builder_class(self.font, location)
@@ -638,6 +648,12 @@ class Builder(object):
             sets.append(glyphs)
         return otl.buildMarkGlyphSetsDef(sets, self.glyphMap)
 
+    def buildDebg(self):
+        if "Debg" not in self.font:
+            self.font["Debg"] = newTable("Debg")
+            self.font["Debg"].data = {}
+        self.font["Debg"].data[LOOKUP_DEBUG_INFO_KEY] = self.lookup_locations
+
     def buildLookups_(self, tag):
         assert tag in ("GPOS", "GSUB"), tag
         for lookup in self.lookups_:
@@ -647,6 +663,11 @@ class Builder(object):
             if lookup.table != tag:
                 continue
             lookup.lookup_index = len(lookups)
+            self.lookup_locations[tag][str(lookup.lookup_index)] = LookupDebugInfo(
+                location=str(lookup.location),
+                name=self.get_lookup_name_(lookup),
+                feature=None,
+            )
             lookups.append(lookup)
         try:
             otLookups = [l.build() for l in lookups]
@@ -685,6 +706,11 @@ class Builder(object):
             if len(lookup_indices) == 0 and not size_feature:
                 continue
 
+            for ix in lookup_indices:
+                self.lookup_locations[tag][str(ix)] = self.lookup_locations[tag][
+                    str(ix)
+                ]._replace(feature=key)
+
             feature_key = (feature_tag, lookup_indices)
             feature_index = feature_indices.get(feature_key)
             if feature_index is None:
@@ -737,6 +763,12 @@ class Builder(object):
         table.LookupList.LookupCount = len(table.LookupList.Lookup)
         return table
 
+    def get_lookup_name_(self, lookup):
+        rev = {v: k for k, v in self.named_lookups_.items()}
+        if lookup in rev:
+            return rev[lookup]
+        return None
+
     def add_language_system(self, location, script, language):
         # OpenType Feature File Specification, section 4.b.i
         if script == "DFLT" and language == "dflt" and self.default_language_systems_:

Lib/fontTools/feaLib/lookupDebugInfo.py

@@ -0,0 +1,10 @@
+from typing import NamedTuple
+
+LOOKUP_DEBUG_INFO_KEY = "com.github.fonttools.feaLib"
+
+class LookupDebugInfo(NamedTuple):
+    """Information about where a lookup came from, to be embedded in a font"""
+
+    location: str
+    name: str
+    feature: list

Lib/fontTools/ttLib/tables/D__e_b_g.py

@@ -0,0 +1,17 @@
+import json
+
+from . import DefaultTable
+
+
+class table_D__e_b_g(DefaultTable.DefaultTable):
+    def decompile(self, data, ttFont):
+        self.data = json.loads(data)
+
+    def compile(self, ttFont):
+        return json.dumps(self.data).encode("utf-8")
+
+    def toXML(self, writer, ttFont):
+        writer.writecdata(json.dumps(self.data))
+
+    def fromXML(self, name, attrs, content, ttFont):
+        self.data = json.loads(content)

Lib/fontTools/ttLib/tables/otTables.py

@@ -12,6 +12,7 @@ from fontTools.misc.py23 import *
 from fontTools.misc.fixedTools import otRound
 from fontTools.misc.textTools import pad, safeEval
 from .otBase import BaseTable, FormatSwitchingBaseTable, ValueRecord, CountReference
+from fontTools.feaLib.lookupDebugInfo import LookupDebugInfo, LOOKUP_DEBUG_INFO_KEY
 import logging
 import struct
 
@@ -1187,6 +1188,44 @@ class COLR(BaseTable):
 		}
 
 
+class LookupList(BaseTable):
+	@property
+	def table(self):
+		for l in self.Lookup:
+			for st in l.SubTable:
+				if type(st).__name__.endswith("Subst"):
+					return "GSUB"
+				if type(st).__name__.endswith("Pos"):
+					return "GPOS"
+		raise ValueError
+
+	def toXML2(self, xmlWriter, font):
+		if not font or "Debg" not in font or LOOKUP_DEBUG_INFO_KEY not in font["Debg"].data:
+			return super().toXML2(xmlWriter, font)
+		debugData = font["Debg"].data[LOOKUP_DEBUG_INFO_KEY][self.table]
+		for conv in self.getConverters():
+			if conv.repeat:
+				value = getattr(self, conv.name, [])
+				for lookupIndex, item in enumerate(value):
+					if str(lookupIndex) in debugData:
+						info = LookupDebugInfo(*debugData[str(lookupIndex)])
+						tag = info.location
+						if info.name:
+							tag = f'{info.name}: {tag}'
+						if info.feature:
+							script,language,feature = info.feature
+							tag = f'{tag} in {feature} ({script}/{language})'
+						xmlWriter.comment(tag)
+						xmlWriter.newline()
+
+					conv.xmlWrite(xmlWriter, font, item, conv.name,
+							[("index", lookupIndex)])
+			else:
+				if conv.aux and not eval(conv.aux, None, vars(self)):
+					continue
+				value = getattr(self, conv.name, None) # TODO Handle defaults instead of defaulting to None!
+				conv.xmlWrite(xmlWriter, font, value, conv.name, [])
+
 class BaseGlyphRecordArray(BaseTable):
 
 	def preWrite(self, font):

Tests/feaLib/builder_test.py

@@ -114,12 +114,16 @@ class BuilderTest(unittest.TestCase):
                     lines.append(line.rstrip() + os.linesep)
         return lines
 
-    def expect_ttx(self, font, expected_ttx):
+    def expect_ttx(self, font, expected_ttx, replace=None):
         path = self.temp_path(suffix=".ttx")
         font.saveXML(path, tables=['head', 'name', 'BASE', 'GDEF', 'GSUB',
                                    'GPOS', 'OS/2', 'hhea', 'vhea'])
         actual = self.read_ttx(path)
         expected = self.read_ttx(expected_ttx)
+        if replace:
+            for i in range(len(expected)):
+                for k, v in replace.items():
+                    expected[i] = expected[i].replace(k, v)
         if actual != expected:
             for line in difflib.unified_diff(
                     expected, actual, fromfile=expected_ttx, tofile=path):
@@ -133,12 +137,17 @@ class BuilderTest(unittest.TestCase):
 
     def check_feature_file(self, name):
         font = makeTTFont()
-        addOpenTypeFeatures(font, self.getpath("%s.fea" % name))
+        feapath = self.getpath("%s.fea" % name)
+        addOpenTypeFeatures(font, feapath)
         self.expect_ttx(font, self.getpath("%s.ttx" % name))
         # Make sure we can produce binary OpenType tables, not just XML.
         for tag in ('GDEF', 'GSUB', 'GPOS'):
             if tag in font:
                 font[tag].compile(font)
+        debugttx = self.getpath("%s-debug.ttx" % name)
+        if os.path.exists(debugttx):
+            addOpenTypeFeatures(font, feapath, debug=True)
+            self.expect_ttx(font, debugttx, replace = {"__PATH__": feapath})
 
     def check_fea2fea_file(self, name, base=None, parser=Parser):
         font = makeTTFont()

Tests/feaLib/data/lookup-debug.ttx

@@ -0,0 +1,80 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ttFont>
+
+  <GSUB>
+    <Version value="0x00010000"/>
+    <ScriptList>
+      <!-- ScriptCount=1 -->
+      <ScriptRecord index="0">
+        <ScriptTag value="DFLT"/>
+        <Script>
+          <DefaultLangSys>
+            <ReqFeatureIndex value="65535"/>
+            <!-- FeatureCount=4 -->
+            <FeatureIndex index="0" value="0"/>
+            <FeatureIndex index="1" value="1"/>
+            <FeatureIndex index="2" value="2"/>
+            <FeatureIndex index="3" value="3"/>
+          </DefaultLangSys>
+          <!-- LangSysCount=0 -->
+        </Script>
+      </ScriptRecord>
+    </ScriptList>
+    <FeatureList>
+      <!-- FeatureCount=4 -->
+      <FeatureRecord index="0">
+        <FeatureTag value="tst1"/>
+        <Feature>
+          <!-- LookupCount=1 -->
+          <LookupListIndex index="0" value="0"/>
+        </Feature>
+      </FeatureRecord>
+      <FeatureRecord index="1">
+        <FeatureTag value="tst2"/>
+        <Feature>
+          <!-- LookupCount=1 -->
+          <LookupListIndex index="0" value="0"/>
+        </Feature>
+      </FeatureRecord>
+      <FeatureRecord index="2">
+        <FeatureTag value="tst3"/>
+        <Feature>
+          <!-- LookupCount=1 -->
+          <LookupListIndex index="0" value="1"/>
+        </Feature>
+      </FeatureRecord>
+      <FeatureRecord index="3">
+        <FeatureTag value="tst4"/>
+        <Feature>
+          <!-- LookupCount=1 -->
+          <LookupListIndex index="0" value="1"/>
+        </Feature>
+      </FeatureRecord>
+    </FeatureList>
+    <LookupList>
+      <!-- LookupCount=2 -->
+      <!-- SomeLookup: __PATH__:4:5 in tst2 (DFLT/dflt) -->
+      <Lookup index="0">
+        <LookupType value="4"/>
+        <LookupFlag value="0"/>
+        <!-- SubTableCount=1 -->
+        <LigatureSubst index="0">
+          <LigatureSet glyph="f">
+            <Ligature components="f,i" glyph="f_f_i"/>
+            <Ligature components="i" glyph="f_i"/>
+          </LigatureSet>
+        </LigatureSubst>
+      </Lookup>
+      <!-- EmbeddedLookup: __PATH__:18:9 in tst4 (DFLT/dflt) -->
+      <Lookup index="1">
+        <LookupType value="1"/>
+        <LookupFlag value="0"/>
+        <!-- SubTableCount=1 -->
+        <SingleSubst index="0">
+          <Substitution in="A" out="A.sc"/>
+        </SingleSubst>
+      </Lookup>
+    </LookupList>
+  </GSUB>
+
+</ttFont>