recode/
encode.rs

1/// A trait to be implemented by types that encode [`Item`] values into a
2/// buffer of type [`B`].
3pub trait Encoder<B, Item = Self> {
4    /// The type of error that can occur if encoding fails.
5    type Error;
6
7    /// Encodes the given input into the output buffer.
8    ///
9    /// This method does not return a result because calls to
10    /// [`Encoder::encode`] never do.
11    ///
12    /// # Arguments
13    /// * `item` - The input to encode.
14    /// * `buf` - The output buffer to write the encoded input to.
15    fn encode(item: &Item, buf: &mut B) -> Result<(), Self::Error>;
16
17    /// Returns the number of bytes required to encode the given input.
18    ///
19    /// This method is useful for pre-allocating buffers that will be used for encoding.
20    ///
21    /// # Arguments
22    /// * `item` - The input to encode.
23    /// * `buf` - The output buffer used for encoding.
24    ///
25    /// # Returns
26    /// The number of bytes required to encode the given input.
27    fn size_of(item: &Item, buf: &B) -> usize;
28}
29
30#[cfg(test)]
31mod tests {
32    use crate as recode;
33    use crate::util::EncoderExt;
34    use crate::Encoder;
35
36    #[test]
37    fn basic_test() {
38        #[derive(Encoder)]
39        #[recode(encoder(buffer_name = "buf", error = "crate::Error"))]
40        struct TestType {
41            age: u32,
42            salary: u64,
43            first_name: crate::codec::Ascii<u8>,
44            last_name: crate::codec::Utf8<u16>,
45            image: crate::codec::Buffer<u32>,
46        }
47
48        const IMAGE_BUF: [u8; 32] = [
49            0xBA, 0x3E, 0x9D, 0x6B, 0xAE, 0xF5, 0x91, 0xCC, 0xE2, 0xF0, 0xCB,
50            0x4F, 0xBB, 0x5B, 0x2B, 0xBE, 0xA7, 0xF4, 0x9D, 0xFB, 0x87, 0x43,
51            0x0E, 0xDF, 0x30, 0x6F, 0x7D, 0x6E, 0x22, 0xAB, 0xCC, 0x47,
52        ];
53
54        let test_item = TestType {
55            age: 0x01234567,
56            salary: 0x1122334455667788,
57            first_name: "ayman".into(),
58            last_name: "القاضي".into(),
59            image: IMAGE_BUF.as_ref().into(),
60        };
61
62        let mut buf = bytes::BytesMut::new();
63
64        assert_eq!(test_item.age.size(&buf), 4);
65        assert_eq!(test_item.salary.size(&buf), 8);
66        assert_eq!(test_item.first_name.size(&buf), 1 + 5);
67        assert_eq!(test_item.last_name.size(&buf), 2 + 12);
68        assert_eq!(test_item.image.size(&buf), 4 + 32);
69        assert_eq!(test_item.size(&buf), 4 + 8 + (1 + 5) + (2 + 12) + (4 + 32));
70
71        TestType::encode(&test_item, &mut buf).unwrap();
72
73        const BUF: [u8; 68] = [
74            // age (4 bytes)
75            0x01, 0x23, 0x45, 0x67, // salary (8 bytes)
76            0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88,
77            // first name (1 bytes prefixed ascii; 6 bytes)
78            0x05, b'a', b'y', b'm', b'a', b'n',
79            // last name (2 bytes prefixed utf8; 6 bytes)
80            0x00, 0x0C, 0xD8, 0xA7, 0xD9, 0x84, 0xD9, 0x82, 0xD8, 0xA7, 0xD8,
81            0xB6, 0xD9, 0x8A,
82            // image (4 bytes prefixed buffer; 36 bytes)
83            0x00, 0x00, 0x00, 0x20, 0xBA, 0x3E, 0x9D, 0x6B, 0xAE, 0xF5, 0x91,
84            0xCC, 0xE2, 0xF0, 0xCB, 0x4F, 0xBB, 0x5B, 0x2B, 0xBE, 0xA7, 0xF4,
85            0x9D, 0xFB, 0x87, 0x43, 0x0E, 0xDF, 0x30, 0x6F, 0x7D, 0x6E, 0x22,
86            0xAB, 0xCC, 0x47,
87        ];
88
89        assert_eq!(buf, BUF.as_ref());
90    }
91}
recode/encode.rs

recode/
encode.rs
