# Source code for fontTools.varLib.featureVars

    """Module to build FeatureVariation tables:
    https://docs.microsoft.com/en-us/typography/opentype/spec/chapter2#featurevariations-table

    NOTE: The API is experimental and subject to change.
    """

    from fontTools.misc.dictTools import hashdict
    from fontTools.misc.intTools import bit_count
    from fontTools.ttLib import newTable
    from fontTools.ttLib.tables import otTables as ot
    from fontTools.ttLib.ttVisitor import TTVisitor
    from fontTools.otlLib.builder import buildLookup, buildSingleSubstSubtable
    from collections import OrderedDict

    from .errors import VarLibError, VarLibValidationError

    def addFeatureVariations(font, conditionalSubstitutions, featureTag="rvrn"):
        """Add conditional substitutions to a Variable Font.

        The `conditionalSubstitutions` argument is a list of (Region, Substitutions)
        tuples.

        A Region is a list of Boxes. A Box is a dict mapping axisTags to
        (minValue, maxValue) tuples. Irrelevant axes may be omitted and they are
        interpretted as extending to end of axis in each direction.  A Box represents
        an orthogonal 'rectangular' subset of an N-dimensional design space.
        A Region represents a more complex subset of an N-dimensional design space,
        ie. the union of all the Boxes in the Region.
        For efficiency, Boxes within a Region should ideally not overlap, but
        functionality is not compromised if they do.

        The minimum and maximum values are expressed in normalized coordinates.

        A Substitution is a dict mapping source glyph names to substitute glyph names.

        Example:

        # >>> f = TTFont(srcPath)
        # >>> condSubst = [
        # ...     # A list of (Region, Substitution) tuples.
        # ...     ([{"wdth": (0.5, 1.0)}], {"cent": "cent.rvrn"}),
        # ...     ([{"wght": (0.5, 1.0)}], {"dollar": "dollar.rvrn"}),
        # ... ]
        # >>> addFeatureVariations(f, condSubst)
        # >>> f.save(dstPath)

        The `featureTag` parameter takes either a str or a iterable of str (the single str
        is kept for backwards compatibility), and defines which feature(s) will be
        associated with the feature variations.
        Note, if this is "rvrn", then the substitution lookup will be inserted at the
        beginning of the lookup list so that it is processed before others, otherwise
        for any other feature tags it will be appended last.
        """

        # process first when "rvrn" is the only listed tag
        featureTags = [featureTag] if isinstance(featureTag, str) else sorted(featureTag)
        processLast = "rvrn" not in featureTags or len(featureTags) > 1

        _checkSubstitutionGlyphsExist(
            glyphNames=set(font.getGlyphOrder()),
            substitutions=conditionalSubstitutions,
        )

        substitutions = overlayFeatureVariations(conditionalSubstitutions)

        # turn substitution dicts into tuples of tuples, so they are hashable
        conditionalSubstitutions, allSubstitutions = makeSubstitutionsHashable(
            substitutions
        )
        if "GSUB" not in font:
            font["GSUB"] = buildGSUB()
        else:
            existingTags = _existingVariableFeatures(font["GSUB"].table).intersection(
                featureTags
            )
            if existingTags:
                raise VarLibError(
                    f"FeatureVariations already exist for feature tag(s): {existingTags}"
                )

        # setup lookups
        lookupMap = buildSubstitutionLookups(
            font["GSUB"].table, allSubstitutions, processLast
        )

        # addFeatureVariationsRaw takes a list of
        #  ( {condition}, [ lookup indices ] )
        # so rearrange our lookups to match
        conditionsAndLookups = []
        for conditionSet, substitutions in conditionalSubstitutions:
            conditionsAndLookups.append(
                (conditionSet, [lookupMap[s] for s in substitutions])
            )

        addFeatureVariationsRaw(font, font["GSUB"].table, conditionsAndLookups, featureTags)

        # Update OS/2.usMaxContext in case the font didn't have features before, but
        # does now, if the OS/2 table exists. The table may be required, but
        # fontTools needs to be able to deal with non-standard fonts. Since feature
        # variations are always 1:1 mappings, we can set the value to at least 1
        # instead of recomputing it with `otlLib.maxContextCalc.maxCtxFont()`.
        if (os2 := font.get("OS/2")) is not None:
            os2.usMaxContext = max(1, os2.usMaxContext)

    def _existingVariableFeatures(table):
        existingFeatureVarsTags = set()
        if hasattr(table, "FeatureVariations") and table.FeatureVariations is not None:
            features = table.FeatureList.FeatureRecord
            for fvr in table.FeatureVariations.FeatureVariationRecord:
                for ftsr in fvr.FeatureTableSubstitution.SubstitutionRecord:
                    existingFeatureVarsTags.add(features[ftsr.FeatureIndex].FeatureTag)
        return existingFeatureVarsTags

    def _checkSubstitutionGlyphsExist(glyphNames, substitutions):
        referencedGlyphNames = set()
        for _, substitution in substitutions:
            referencedGlyphNames |= substitution.keys()
            referencedGlyphNames |= set(substitution.values())
        missing = referencedGlyphNames - glyphNames
        if missing:
            raise VarLibValidationError(
                "Missing glyphs are referenced in conditional substitution rules:"
                f" {', '.join(missing)}"
            )

    def overlayFeatureVariations(conditionalSubstitutions):
        """Compute overlaps between all conditional substitutions.

        The `conditionalSubstitutions` argument is a list of (Region, Substitutions)
        tuples.

        A Region is a list of Boxes. A Box is a dict mapping axisTags to
        (minValue, maxValue) tuples. Irrelevant axes may be omitted and they are
        interpretted as extending to end of axis in each direction.  A Box represents
        an orthogonal 'rectangular' subset of an N-dimensional design space.
        A Region represents a more complex subset of an N-dimensional design space,
        ie. the union of all the Boxes in the Region.
        For efficiency, Boxes within a Region should ideally not overlap, but
        functionality is not compromised if they do.

        The minimum and maximum values are expressed in normalized coordinates.

        A Substitution is a dict mapping source glyph names to substitute glyph names.

        Returns data is in similar but different format.  Overlaps of distinct
        substitution Boxes (*not* Regions) are explicitly listed as distinct rules,
        and rules with the same Box merged.  The more specific rules appear earlier
        in the resulting list.  Moreover, instead of just a dictionary of substitutions,
        a list of dictionaries is returned for substitutions corresponding to each
        unique space, with each dictionary being identical to one of the input
        substitution dictionaries.  These dictionaries are not merged to allow data
        sharing when they are converted into font tables.

        Example::

            >>> condSubst = [
            ...     # A list of (Region, Substitution) tuples.
            ...     ([{"wght": (0.5, 1.0)}], {"dollar": "dollar.rvrn"}),
            ...     ([{"wght": (0.5, 1.0)}], {"dollar": "dollar.rvrn"}),
            ...     ([{"wdth": (0.5, 1.0)}], {"cent": "cent.rvrn"}),
            ...     ([{"wght": (0.5, 1.0), "wdth": (-1, 1.0)}], {"dollar": "dollar.rvrn"}),
            ... ]
            >>> from pprint import pprint
            >>> pprint(overlayFeatureVariations(condSubst))
            [({'wdth': (0.5, 1.0), 'wght': (0.5, 1.0)},
              [{'dollar': 'dollar.rvrn'}, {'cent': 'cent.rvrn'}]),
             ({'wdth': (0.5, 1.0)}, [{'cent': 'cent.rvrn'}]),
             ({'wght': (0.5, 1.0)}, [{'dollar': 'dollar.rvrn'}])]

        """

        # Merge same-substitutions rules, as this creates fewer number oflookups.
        merged = OrderedDict()
        for value, key in conditionalSubstitutions:
            key = hashdict(key)
            if key in merged:
                merged[key].extend(value)
            else:
                merged[key] = value
        conditionalSubstitutions = [(v, dict(k)) for k, v in merged.items()]
        del merged

        # Merge same-region rules, as this is cheaper.
        # Also convert boxes to hashdict()
        #
        # Reversing is such that earlier entries win in case of conflicting substitution
        # rules for the same region.
        merged = OrderedDict()
        for key, value in reversed(conditionalSubstitutions):
            key = tuple(
                sorted(
                    (hashdict(cleanupBox(k)) for k in key),
                    key=lambda d: tuple(sorted(d.items())),
                )
            )
            if key in merged:
                merged[key].update(value)
            else:
                merged[key] = dict(value)
        conditionalSubstitutions = list(reversed(merged.items()))
        del merged

        # Overlay
        #
        # Rank is the bit-set of the index of all contributing layers.
        initMapInit = ((hashdict(), 0),)  # Initializer representing the entire space
        boxMap = OrderedDict(initMapInit)  # Map from Box to Rank
        for i, (currRegion, _) in enumerate(conditionalSubstitutions):
            newMap = OrderedDict(initMapInit)
            currRank = 1 << i
            for box, rank in boxMap.items():
                for currBox in currRegion:
                    intersection, remainder = overlayBox(currBox, box)
                    if intersection is not None:
                        intersection = hashdict(intersection)
                        newMap[intersection] = newMap.get(intersection, 0) | rank | currRank
                    if remainder is not None:
                        remainder = hashdict(remainder)
                        newMap[remainder] = newMap.get(remainder, 0) | rank
            boxMap = newMap

        # Generate output
        items = []
        for box, rank in sorted(
            boxMap.items(), key=(lambda BoxAndRank: -bit_count(BoxAndRank[1]))
        ):
            # Skip any box that doesn't have any substitution.
            if rank == 0:
                continue
            substsList = []
            i = 0
            while rank:
                if rank & 1:
                    substsList.append(conditionalSubstitutions[i][1])
                rank >>= 1
                i += 1
            items.append((dict(box), substsList))
        return items

    #
    # Terminology:
    #
    # A 'Box' is a dict representing an orthogonal "rectangular" bit of N-dimensional space.
    # The keys in the dict are axis tags, the values are (minValue, maxValue) tuples.
    # Missing dimensions (keys) are substituted by the default min and max values
    # from the corresponding axes.
    #

    def overlayBox(top, bot):
        """Overlays ``top`` box on top of ``bot`` box.

        Returns two items:

        * Box for intersection of ``top`` and ``bot``, or None if they don't intersect.
        * Box for remainder of ``bot``.  Remainder box might not be exact (since the
          remainder might not be a simple box), but is inclusive of the exact
          remainder.
        """

        # Intersection
        intersection = {}
        intersection.update(top)
        intersection.update(bot)
        for axisTag in set(top) & set(bot):
            min1, max1 = top[axisTag]
            min2, max2 = bot[axisTag]
            minimum = max(min1, min2)
            maximum = min(max1, max2)
            if not minimum < maximum:
                return None, bot  # Do not intersect
            intersection[axisTag] = minimum, maximum

        # Remainder
        #
        # Remainder is empty if bot's each axis range lies within that of intersection.
        #
        # Remainder is shrank if bot's each, except for exactly one, axis range lies
        # within that of intersection, and that one axis, it extrudes out of the
        # intersection only on one side.
        #
        # Bot is returned in full as remainder otherwise, as true remainder is not
        # representable as a single box.

        remainder = dict(bot)
        extruding = False
        fullyInside = True
        for axisTag in top:
            if axisTag in bot:
                continue
            extruding = True
            fullyInside = False
            break
        for axisTag in bot:
            if axisTag not in top:
                continue  # Axis range lies fully within
            min1, max1 = intersection[axisTag]
            min2, max2 = bot[axisTag]
            if min1 <= min2 and max2 <= max1:
                continue  # Axis range lies fully within

            # Bot's range doesn't fully lie within that of top's for this axis.
            # We know they intersect, so it cannot lie fully without either; so they
            # overlap.

            # If we have had an overlapping axis before, remainder is not
            # representable as a box, so return full bottom and go home.
            if extruding:
                return intersection, bot
            extruding = True
            fullyInside = False

            # Otherwise, cut remainder on this axis and continue.
            if min1 <= min2:
                # Right side survives.
                minimum = max(max1, min2)
                maximum = max2
            elif max2 <= max1:
                # Left side survives.
                minimum = min2
                maximum = min(min1, max2)
            else:
                # Remainder leaks out from both sides.  Can't cut either.
                return intersection, bot

            remainder[axisTag] = minimum, maximum

        if fullyInside:
            # bot is fully within intersection.  Remainder is empty.
            return intersection, None

        return intersection, remainder

    def cleanupBox(box):
        """Return a sparse copy of `box`, without redundant (default) values.

        >>> cleanupBox({})
        {}
        >>> cleanupBox({'wdth': (0.0, 1.0)})
        {'wdth': (0.0, 1.0)}
        >>> cleanupBox({'wdth': (-1.0, 1.0)})
        {}

        """
        return {tag: limit for tag, limit in box.items() if limit != (-1.0, 1.0)}

    #
    # Low level implementation
    #

    def addFeatureVariationsRaw(font, table, conditionalSubstitutions, featureTag="rvrn"):
        """Low level implementation of addFeatureVariations that directly
        models the possibilities of the FeatureVariations table."""

        featureTags = [featureTag] if isinstance(featureTag, str) else sorted(featureTag)
        processLast = "rvrn" not in featureTags or len(featureTags) > 1

        #
        # if a <featureTag> feature is not present:
        #     make empty <featureTag> feature
        #     sort features, get <featureTag> feature index
        #     add <featureTag> feature to all scripts
        # if a <featureTag> feature is present:
        #     reuse <featureTag> feature index
        # make lookups
        # add feature variations
        #
        if table.Version < 0x00010001:
            table.Version = 0x00010001  # allow table.FeatureVariations

        varFeatureIndices = set()

        existingTags = {
            feature.FeatureTag
            for feature in table.FeatureList.FeatureRecord
            if feature.FeatureTag in featureTags
        }

        newTags = set(featureTags) - existingTags
        if newTags:
            varFeatures = []
            for featureTag in sorted(newTags):
                varFeature = buildFeatureRecord(featureTag, [])
                table.FeatureList.FeatureRecord.append(varFeature)
                varFeatures.append(varFeature)
            table.FeatureList.FeatureCount = len(table.FeatureList.FeatureRecord)

            sortFeatureList(table)

            for varFeature in varFeatures:
                varFeatureIndex = table.FeatureList.FeatureRecord.index(varFeature)

                for scriptRecord in table.ScriptList.ScriptRecord:
                    if scriptRecord.Script.DefaultLangSys is None:
                        # We need to have a default LangSys to attach variations to.
                        langSys = ot.LangSys()
                        langSys.LookupOrder = None
                        langSys.ReqFeatureIndex = 0xFFFF
                        langSys.FeatureIndex = []
                        langSys.FeatureCount = 0
                        scriptRecord.Script.DefaultLangSys = langSys
                    langSystems = [lsr.LangSys for lsr in scriptRecord.Script.LangSysRecord]
                    for langSys in [scriptRecord.Script.DefaultLangSys] + langSystems:
                        langSys.FeatureIndex.append(varFeatureIndex)
                        langSys.FeatureCount = len(langSys.FeatureIndex)
                varFeatureIndices.add(varFeatureIndex)

        if existingTags:
            # indices may have changed if we inserted new features and sorted feature list
            # so we must do this after the above
            varFeatureIndices.update(
                index
                for index, feature in enumerate(table.FeatureList.FeatureRecord)
                if feature.FeatureTag in existingTags
            )

        axisIndices = {
            axis.axisTag: axisIndex for axisIndex, axis in enumerate(font["fvar"].axes)
        }

        hasFeatureVariations = (
            hasattr(table, "FeatureVariations") and table.FeatureVariations is not None
        )

        featureVariationRecords = []
        for conditionSet, lookupIndices in conditionalSubstitutions:
            conditionTable = []
            for axisTag, (minValue, maxValue) in sorted(conditionSet.items()):
                if minValue > maxValue:
                    raise VarLibValidationError(
                        "A condition set has a minimum value above the maximum value."
                    )
                ct = buildConditionTable(axisIndices[axisTag], minValue, maxValue)
                conditionTable.append(ct)
            records = []
            for varFeatureIndex in sorted(varFeatureIndices):
                existingLookupIndices = table.FeatureList.FeatureRecord[
                    varFeatureIndex
                ].Feature.LookupListIndex
                combinedLookupIndices = (
                    existingLookupIndices + lookupIndices
                    if processLast
                    else lookupIndices + existingLookupIndices
                )

                records.append(
                    buildFeatureTableSubstitutionRecord(
                        varFeatureIndex, combinedLookupIndices
                    )
                )
            if hasFeatureVariations and (
                fvr := findFeatureVariationRecord(table.FeatureVariations, conditionTable)
            ):
                fvr.FeatureTableSubstitution.SubstitutionRecord.extend(records)
                fvr.FeatureTableSubstitution.SubstitutionCount = len(
                    fvr.FeatureTableSubstitution.SubstitutionRecord
                )
            else:
                featureVariationRecords.append(
                    buildFeatureVariationRecord(conditionTable, records)
                )

        if hasFeatureVariations:
            if table.FeatureVariations.Version != 0x00010000:
                raise VarLibError(
                    "Unsupported FeatureVariations table version: "
                    f"0x{table.FeatureVariations.Version:08x} (expected 0x00010000)."
                )
            table.FeatureVariations.FeatureVariationRecord.extend(featureVariationRecords)
            table.FeatureVariations.FeatureVariationCount = len(
                table.FeatureVariations.FeatureVariationRecord
            )
        else:
            table.FeatureVariations = buildFeatureVariations(featureVariationRecords)

    #
    # Building GSUB/FeatureVariations internals
    #

    def buildGSUB():
        """Build a GSUB table from scratch."""
        fontTable = newTable("GSUB")
        gsub = fontTable.table = ot.GSUB()
        gsub.Version = 0x00010001  # allow gsub.FeatureVariations

        gsub.ScriptList = ot.ScriptList()
        gsub.ScriptList.ScriptRecord = []
        gsub.FeatureList = ot.FeatureList()
        gsub.FeatureList.FeatureRecord = []
        gsub.LookupList = ot.LookupList()
        gsub.LookupList.Lookup = []

        srec = ot.ScriptRecord()
        srec.ScriptTag = "DFLT"
        srec.Script = ot.Script()
        srec.Script.DefaultLangSys = None
        srec.Script.LangSysRecord = []
        srec.Script.LangSysCount = 0

        langrec = ot.LangSysRecord()
        langrec.LangSys = ot.LangSys()
        langrec.LangSys.ReqFeatureIndex = 0xFFFF
        langrec.LangSys.FeatureIndex = []
        srec.Script.DefaultLangSys = langrec.LangSys

        gsub.ScriptList.ScriptRecord.append(srec)
        gsub.ScriptList.ScriptCount = 1
        gsub.FeatureVariations = None

        return fontTable

    def makeSubstitutionsHashable(conditionalSubstitutions):
        """Turn all the substitution dictionaries in sorted tuples of tuples so
        they are hashable, to detect duplicates so we don't write out redundant
        data."""
        allSubstitutions = set()
        condSubst = []
        for conditionSet, substitutionMaps in conditionalSubstitutions:
            substitutions = []
            for substitutionMap in substitutionMaps:
                subst = tuple(sorted(substitutionMap.items()))
                substitutions.append(subst)
                allSubstitutions.add(subst)
            condSubst.append((conditionSet, substitutions))
        return condSubst, sorted(allSubstitutions)

    class ShifterVisitor(TTVisitor):
        def __init__(self, shift):
            self.shift = shift

    @ShifterVisitor.register_attr(ot.Feature, "LookupListIndex")  # GSUB/GPOS
    def visit(visitor, obj, attr, value):
        shift = visitor.shift
        value = [l + shift for l in value]
        setattr(obj, attr, value)

    @ShifterVisitor.register_attr(
        (ot.SubstLookupRecord, ot.PosLookupRecord), "LookupListIndex"
    )
    def visit(visitor, obj, attr, value):
        setattr(obj, attr, visitor.shift + value)

    def buildSubstitutionLookups(gsub, allSubstitutions, processLast=False):
        """Build the lookups for the glyph substitutions, return a dict mapping
        the substitution to lookup indices."""

        # Insert lookups at the beginning of the lookup vector
        # https://github.com/googlefonts/fontmake/issues/950

        firstIndex = len(gsub.LookupList.Lookup) if processLast else 0
        lookupMap = {}
        for i, substitutionMap in enumerate(allSubstitutions):
            lookupMap[substitutionMap] = firstIndex + i

        if not processLast:
            # Shift all lookup indices in gsub by len(allSubstitutions)
            shift = len(allSubstitutions)
            visitor = ShifterVisitor(shift)
            visitor.visit(gsub.FeatureList.FeatureRecord)
            visitor.visit(gsub.LookupList.Lookup)

        for i, subst in enumerate(allSubstitutions):
            substMap = dict(subst)
            lookup = buildLookup([buildSingleSubstSubtable(substMap)])
            if processLast:
                gsub.LookupList.Lookup.append(lookup)
            else:
                gsub.LookupList.Lookup.insert(i, lookup)
            assert gsub.LookupList.Lookup[lookupMap[subst]] is lookup
        gsub.LookupList.LookupCount = len(gsub.LookupList.Lookup)
        return lookupMap

    def buildFeatureVariations(featureVariationRecords):
        """Build the FeatureVariations subtable."""
        fv = ot.FeatureVariations()
        fv.Version = 0x00010000
        fv.FeatureVariationRecord = featureVariationRecords
        fv.FeatureVariationCount = len(featureVariationRecords)
        return fv

    def buildFeatureRecord(featureTag, lookupListIndices):
        """Build a FeatureRecord."""
        fr = ot.FeatureRecord()
        fr.FeatureTag = featureTag
        fr.Feature = ot.Feature()
        fr.Feature.LookupListIndex = lookupListIndices
        fr.Feature.populateDefaults()
        return fr

    def buildFeatureVariationRecord(conditionTable, substitutionRecords):
        """Build a FeatureVariationRecord."""
        fvr = ot.FeatureVariationRecord()
        if len(conditionTable) != 0:
            fvr.ConditionSet = ot.ConditionSet()
            fvr.ConditionSet.ConditionTable = conditionTable
            fvr.ConditionSet.ConditionCount = len(conditionTable)
        else:
            fvr.ConditionSet = None
        fvr.FeatureTableSubstitution = ot.FeatureTableSubstitution()
        fvr.FeatureTableSubstitution.Version = 0x00010000
        fvr.FeatureTableSubstitution.SubstitutionRecord = substitutionRecords
        fvr.FeatureTableSubstitution.SubstitutionCount = len(substitutionRecords)
        return fvr

    def buildFeatureTableSubstitutionRecord(featureIndex, lookupListIndices):
        """Build a FeatureTableSubstitutionRecord."""
        ftsr = ot.FeatureTableSubstitutionRecord()
        ftsr.FeatureIndex = featureIndex
        ftsr.Feature = ot.Feature()
        ftsr.Feature.LookupListIndex = lookupListIndices
        ftsr.Feature.LookupCount = len(lookupListIndices)
        return ftsr

    def buildConditionTable(axisIndex, filterRangeMinValue, filterRangeMaxValue):
        """Build a ConditionTable."""
        ct = ot.ConditionTable()
        ct.Format = 1
        ct.AxisIndex = axisIndex
        ct.FilterRangeMinValue = filterRangeMinValue
        ct.FilterRangeMaxValue = filterRangeMaxValue
        return ct

    def findFeatureVariationRecord(featureVariations, conditionTable):
        """Find a FeatureVariationRecord that has the same conditionTable."""
        if featureVariations.Version != 0x00010000:
            raise VarLibError(
                "Unsupported FeatureVariations table version: "
                f"0x{featureVariations.Version:08x} (expected 0x00010000)."
            )

        for fvr in featureVariations.FeatureVariationRecord:
            if conditionTable == fvr.ConditionSet.ConditionTable:
                return fvr

        return None

    def sortFeatureList(table):
        """Sort the feature list by feature tag, and remap the feature indices
        elsewhere. This is needed after the feature list has been modified.
        """
        # decorate, sort, undecorate, because we need to make an index remapping table
        tagIndexFea = [
            (fea.FeatureTag, index, fea)
            for index, fea in enumerate(table.FeatureList.FeatureRecord)
        ]
        tagIndexFea.sort()
        table.FeatureList.FeatureRecord = [fea for tag, index, fea in tagIndexFea]
        featureRemap = dict(
            zip([index for tag, index, fea in tagIndexFea], range(len(tagIndexFea)))
        )

        # Remap the feature indices
        remapFeatures(table, featureRemap)

    def remapFeatures(table, featureRemap):
        """Go through the scripts list, and remap feature indices."""
        for scriptIndex, script in enumerate(table.ScriptList.ScriptRecord):
            defaultLangSys = script.Script.DefaultLangSys
            if defaultLangSys is not None:
                _remapLangSys(defaultLangSys, featureRemap)
            for langSysRecordIndex, langSysRec in enumerate(script.Script.LangSysRecord):
                langSys = langSysRec.LangSys
                _remapLangSys(langSys, featureRemap)

        if hasattr(table, "FeatureVariations") and table.FeatureVariations is not None:
            for fvr in table.FeatureVariations.FeatureVariationRecord:
                for ftsr in fvr.FeatureTableSubstitution.SubstitutionRecord:
                    ftsr.FeatureIndex = featureRemap[ftsr.FeatureIndex]

    def _remapLangSys(langSys, featureRemap):
        if langSys.ReqFeatureIndex != 0xFFFF:
            langSys.ReqFeatureIndex = featureRemap[langSys.ReqFeatureIndex]
        langSys.FeatureIndex = [featureRemap[index] for index in langSys.FeatureIndex]

    if __name__ == "__main__":
        import doctest, sys

        sys.exit(doctest.testmod().failed)