tiny.preserves.PackedTag

1/// The tag byte that starts each encoded value, as an enum over `u8`, so code that writes encoded2/// bytes by hand names each tag through it. The packed reader rejects a byte outside these fourteen3/// values as `UnknownTag`.4pub const Tag = enum(u8) {5    false_ = 0x80,6    true_ = 0x81,7    /// The byte 0x84, which closes a record, sequence, set or dictionary. At the start of a value,8    /// the packed reader rejects it as `UnexpectedEndMarker`.9    end = 0x84,10    /// The byte 0x85, which starts an annotation in the binary syntax. The packed writer never11    /// writes it, and the packed reader rejects it as `AnnotationNotSupported`.12    annotation = 0x85,13    /// The byte 0x86, which starts an embedded value. The packed writer writes it before an14    /// embedded value's bytes, which come from its type's `encodePacked`. The packed reader rejects15    /// it as `EmbeddedNotSupported`, so bytes holding an embedded value never decode.16    embedded = 0x86,17    /// The byte 0x87, which starts a double: a length of 8, then the double's eight bytes,18    /// big-endian.19    ieee754 = 0x87,20    signed_integer = 0xb0,21    string = 0xb1,22    byte_string = 0xb2,23    symbol = 0xb3,24    record = 0xb4,25    sequence = 0xb5,26    set = 0xb6,27    dictionary = 0xb7,2829    /// Returns the byte value of the tag, for code that writes a tag into a byte buffer.30    pub fn byte(self: Tag) u8 {31        return @backingInt(self);32    }3334    /// Returns the tag whose byte is `b`, or null otherwise, so the packed reader calls it on each35    /// tag byte for the kind of value that follows. `fromByte(t.byte())` returns `t` for every tag.36    pub fn fromByte(b: u8) ?Tag {37        return switch (b) {38            0x80 => .false_,39            0x81 => .true_,40            0x84 => .end,41            0x85 => .annotation,42            0x86 => .embedded,43            0x87 => .ieee754,44            0xb0 => .signed_integer,45            0xb1 => .string,46            0xb2 => .byte_string,47            0xb3 => .symbol,48            0xb4 => .record,49            0xb5 => .sequence,50            0xb6 => .set,51            0xb7 => .dictionary,52            else => null,53        };54    }55};

1pub const PackedTag = @"packed".Tag;