# Source code for fontTools.ttLib.tables.F__e_a_t

    from fontTools.misc import sstruct
    from fontTools.misc.fixedTools import floatToFixedToStr
    from fontTools.misc.textTools import safeEval
    from . import DefaultTable
    from . import grUtils
    import struct

    Feat_hdr_format='''
        >
        version:    16.16F
    '''

    class table_F__e_a_t(DefaultTable.DefaultTable):
        """The ``Feat`` table is used exclusively by the Graphite shaping engine
        to store features and possible settings specified in GDL. Graphite features
        determine what rules are applied to transform a glyph stream.

        Not to be confused with ``feat``, or the OpenType Layout tables
        ``GSUB``/``GPOS``."""

        def __init__(self, tag=None):
            DefaultTable.DefaultTable.__init__(self, tag)
            self.features = {}

        def decompile(self, data, ttFont):
            (_, data) = sstruct.unpack2(Feat_hdr_format, data, self)
            self.version = float(floatToFixedToStr(self.version, precisionBits=16))
            numFeats, = struct.unpack('>H', data[:2])
            data = data[8:]
            allfeats = []
            maxsetting = 0
            for i in range(numFeats):
                if self.version >= 2.0:
                    (fid, nums, _, offset, flags, lid) = struct.unpack(">LHHLHH",
                                                                data[16*i:16*(i+1)])
                    offset = int((offset - 12 - 16 * numFeats) / 4)
                else:
                    (fid, nums, offset, flags, lid) = struct.unpack(">HHLHH",
                                                                data[12*i:12*(i+1)])
                    offset = int((offset - 12 - 12 * numFeats) / 4)
                allfeats.append((fid, nums, offset, flags, lid))
                maxsetting = max(maxsetting, offset + nums)
            data = data[16*numFeats:]
            allsettings = []
            for i in range(maxsetting):
                if len(data) >= 4 * (i + 1):
                    (val, lid) = struct.unpack(">HH", data[4*i:4*(i+1)])
                    allsettings.append((val, lid))
            for i,f in enumerate(allfeats):
                (fid, nums, offset, flags, lid) = f
                fobj = Feature()
                fobj.flags = flags
                fobj.label = lid
                self.features[grUtils.num2tag(fid)] = fobj
                fobj.settings = {}
                fobj.default = None
                fobj.index = i
                for i in range(offset, offset + nums):
                    if i >= len(allsettings): continue
                    (vid, vlid) = allsettings[i]
                    fobj.settings[vid] = vlid
                    if fobj.default is None:
                        fobj.default = vid

        def compile(self, ttFont):
            fdat = b""
            vdat = b""
            offset = 0
            for f, v in sorted(self.features.items(), key=lambda x:x[1].index):
                fnum = grUtils.tag2num(f)
                if self.version >= 2.0:
                    fdat += struct.pack(">LHHLHH", grUtils.tag2num(f), len(v.settings),
                        0, offset * 4 + 12 + 16 * len(self.features), v.flags, v.label)
                elif fnum > 65535:      # self healing for alphabetic ids
                    self.version = 2.0
                    return self.compile(ttFont)
                else:
                    fdat += struct.pack(">HHLHH", grUtils.tag2num(f), len(v.settings),
                        offset * 4 + 12 + 12 * len(self.features), v.flags, v.label)
                for s, l in sorted(v.settings.items(), key=lambda x:(-1, x[1]) if x[0] == v.default else x):
                    vdat += struct.pack(">HH", s, l)
                offset += len(v.settings)
            hdr = sstruct.pack(Feat_hdr_format, self)
            return hdr + struct.pack('>HHL', len(self.features), 0, 0) + fdat + vdat

        def toXML(self, writer, ttFont):
            writer.simpletag('version', version=self.version)
            writer.newline()
            for f, v in sorted(self.features.items(), key=lambda x:x[1].index):
                writer.begintag('feature', fid=f, label=v.label, flags=v.flags,
                                default=(v.default if v.default else 0))
                writer.newline()
                for s, l in sorted(v.settings.items()):
                    writer.simpletag('setting', value=s, label=l)
                    writer.newline()
                writer.endtag('feature')
                writer.newline()

        def fromXML(self, name, attrs, content, ttFont):
            if name == 'version':
                self.version = float(safeEval(attrs['version']))
            elif name == 'feature':
                fid = attrs['fid']
                fobj = Feature()
                fobj.flags = int(safeEval(attrs['flags']))
                fobj.label = int(safeEval(attrs['label']))
                fobj.default = int(safeEval(attrs.get('default','0')))
                fobj.index = len(self.features)
                self.features[fid] = fobj
                fobj.settings = {}
                for element in content:
                    if not isinstance(element, tuple): continue
                    tag, a, c = element
                    if tag == 'setting':
                        fobj.settings[int(safeEval(a['value']))] = int(safeEval(a['label']))

    class Feature(object):
        pass