protobuf/
wire_format.rs

1//! Serialization constants.
2
3// TODO: temporary
4pub use self::WireType::*;
5
6/// Tag occupies 3 bits
7pub const TAG_TYPE_BITS: u32 = 3;
8/// Tag mask
9pub const TAG_TYPE_MASK: u32 = (1u32 << TAG_TYPE_BITS) - 1;
10/// Max possible field number
11pub const FIELD_NUMBER_MAX: u32 = 0x1fffffff;
12
13/// One of six defined protobuf wire types
14#[derive(PartialEq, Eq, Clone, Debug)]
15pub enum WireType {
16    /// Varint (e. g. `int32` or `sint64`)
17    WireTypeVarint = 0,
18    /// Fixed size 64 bit (e. g. `fixed64` or `double`)
19    WireTypeFixed64 = 1,
20    /// Length-delimited (e. g. `message` or `string`)
21    WireTypeLengthDelimited = 2,
22    /// Groups are not supported by rust-protobuf
23    WireTypeStartGroup = 3,
24    /// Groups are not supported by rust-protobuf
25    WireTypeEndGroup = 4,
26    /// Fixed size 64 bit (e. g. `fixed32` or `float`)
27    WireTypeFixed32 = 5,
28}
29
30impl Copy for WireType {}
31
32impl WireType {
33    /// Parse wire type
34    pub fn new(n: u32) -> Option<WireType> {
35        match n {
36            0 => Some(WireTypeVarint),
37            1 => Some(WireTypeFixed64),
38            2 => Some(WireTypeLengthDelimited),
39            3 => Some(WireTypeStartGroup),
40            4 => Some(WireTypeEndGroup),
41            5 => Some(WireTypeFixed32),
42            _ => None,
43        }
44    }
45}
46
47/// Parsed protobuf tag, which is a pair of field number and wire type
48#[derive(Clone)]
49pub struct Tag {
50    field_number: u32,
51    wire_type: WireType,
52}
53
54impl Copy for Tag {}
55
56impl Tag {
57    /// Pack a tag to integer
58    pub fn value(self) -> u32 {
59        (self.field_number << TAG_TYPE_BITS) | (self.wire_type as u32)
60    }
61
62    /// Parse integer into `Tag` object
63    // TODO: should return Result instead of Option
64    pub fn new(value: u32) -> Option<Tag> {
65        let wire_type = WireType::new(value & TAG_TYPE_MASK);
66        if wire_type.is_none() {
67            return None;
68        }
69        let field_number = value >> TAG_TYPE_BITS;
70        if field_number == 0 {
71            return None;
72        }
73        Some(Tag {
74            field_number: field_number,
75            wire_type: wire_type.unwrap(),
76        })
77    }
78
79    /// Create a tag from a field number and wire type.
80    ///
81    /// # Panics
82    ///
83    /// If field number is outside of allowed range.
84    pub fn make(field_number: u32, wire_type: WireType) -> Tag {
85        assert!(field_number > 0 && field_number <= FIELD_NUMBER_MAX);
86        Tag {
87            field_number: field_number,
88            wire_type: wire_type,
89        }
90    }
91
92    /// Tag as pair of (field number, wire type)
93    pub fn unpack(self) -> (u32, WireType) {
94        (self.field_number(), self.wire_type())
95    }
96
97    fn wire_type(self) -> WireType {
98        self.wire_type
99    }
100
101    /// Protobuf field number
102    pub fn field_number(self) -> u32 {
103        self.field_number
104    }
105}
protobuf/wire_format.rs

protobuf/
wire_format.rs
