# Source code for fontTools.ttLib.tables._c_v_t

    from fontTools.misc.textTools import safeEval
    from . import DefaultTable
    import sys
    import array

    class table__c_v_t(DefaultTable.DefaultTable):
        """Control Value Table

        The Control Value Table holds a list of values that can be referenced
        by TrueType font instructions.

        See also https://learn.microsoft.com/en-us/typography/opentype/spec/cvt
        """

        def decompile(self, data, ttFont):
            values = array.array("h")
            values.frombytes(data)
            if sys.byteorder != "big":
                values.byteswap()
            self.values = values

        def compile(self, ttFont):
            if not hasattr(self, "values"):
                return b""
            values = self.values[:]
            if sys.byteorder != "big":
                values.byteswap()
            return values.tobytes()

        def toXML(self, writer, ttFont):
            for i, value in enumerate(self.values):
                writer.simpletag("cv", value=value, index=i)
                writer.newline()

        def fromXML(self, name, attrs, content, ttFont):
            if not hasattr(self, "values"):
                self.values = array.array("h")
            if name == "cv":
                index = safeEval(attrs["index"])
                value = safeEval(attrs["value"])
                for i in range(1 + index - len(self.values)):
                    self.values.append(0)
                self.values[index] = value

        def __len__(self):
            return len(self.values)

        def __getitem__(self, index):
            return self.values[index]

        def __setitem__(self, index, value):
            self.values[index] = value

        def __delitem__(self, index):
            del self.values[index]