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enum WireType {
Varint = 0,
LengthDelimited = 2,
}
pub struct Encoder {
pub encoded: Vec<u8>
}
impl Encoder {
fn write_tagged_varint(&mut self,
field_number: u32,
wire_type: WireType,
value: u64) {
if value > 0 {
self.write_tag(field_number, wire_type);
self.write_varint(value);
}
}
fn write_tag(&mut self, field_number: u32, wire_type: WireType) {
self.write_varint((field_number << 3 | wire_type as u32) as u64);
}
fn write_varint(&mut self, mut value: u64) {
loop {
let item = value as u8;
value >>= 7;
if value == 0 {
self.encoded.push(item);
break;
} else {
self.encoded.push(item | 0x80);
}
}
}
pub fn write_length_delimited(&mut self, field_number: u32, value: u64) {
self.write_tag(field_number, WireType::LengthDelimited);
self.write_varint(value);
}
pub fn write_string(&mut self, field_number: u32, value: &String) {
self.write_tagged_varint(field_number,
WireType::LengthDelimited,
value.len() as u64);
self.encoded.extend(value.as_bytes());
}
pub fn write_int32(&mut self, field_number: u32, value: i32) {
self.write_tagged_varint(field_number,
WireType::Varint,
value as i64 as u64);
}
}
pub struct Decoder {
pub pos: usize,
pub encoded: Vec<u8>
}
impl Decoder {
pub fn available(&self) -> bool {
self.pos < self.encoded.len()
}
pub fn read_tag(&mut self) -> (u32, u32) {
if self.pos < self.encoded.len() {
self.pos += 1;
(1, self.encoded[self.pos - 1] as u32)
} else {
(0, 0)
}
}
}