Decode the protobuf wire format in Gleam!
Wire type module
Gavin Morrow
(Sep 19, 2025, 9:19 PM EDT)
bc8d212e
c0fa6050
+31
-28
+13
-28
src/protobuf_decode_gleam.gleam
+13
-28
src/protobuf_decode_gleam.gleam
···
3
3
import gleam/dynamic/decode.{type Decoder}
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4
import gleam/int
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5
import gleam/list
6
-
import gleam/option.{type Option, None, Some}
6
+
import gleam/option
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7
import gleam/result
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+
9
+
import internal/wire_type.{type WireType}
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10
9
11
pub fn parse(
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from bits: BitArray,
···
25
27
case value {
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Ok(value) -> decode.success(value)
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Error(_) -> decode.failure(default, name)
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-
}
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-
}
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-
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-
type WireType {
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-
VarInt
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-
I64
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-
Len
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-
I32
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-
}
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-
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-
fn parse_wire_type(i: Int) -> Option(WireType) {
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-
case i {
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-
0 -> Some(VarInt)
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-
1 -> Some(I64)
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-
2 -> Some(Len)
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-
5 -> Some(I32)
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-
_ -> None
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-
}
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-
}
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-
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-
fn wire_type_read_fn(ty: WireType) -> fn(BitArray) -> ValueResult {
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-
case ty {
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-
VarInt -> read_varint
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-
I64 -> read_fixed(64)
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-
Len -> read_len
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-
I32 -> read_fixed(32)
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30
}
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31
}
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32
···
96
72
#(field.key, field.value)
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73
}
98
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+
fn wire_type_read_fn(ty: WireType) -> fn(BitArray) -> ValueResult {
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+
case ty {
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+
wire_type.VarInt -> read_varint
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+
wire_type.I64 -> read_fixed(64)
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+
wire_type.Len -> read_len
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+
wire_type.I32 -> read_fixed(32)
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+
}
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+
}
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+
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fn read_field(bits: BitArray) -> DecodeResult(Parsed(Field)) {
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use Parsed(value: tag, rest: bits) <- result.try(read_varint(bits))
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let tag = bit_array_to_uint(tag)
···
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89
let wire_type = tag |> int.bitwise_and(0b111)
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90
106
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use wire_type <- result.try(option.to_result(
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-
parse_wire_type(wire_type),
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+
wire_type.parse(wire_type),
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93
UnknownWireType(wire_type),
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94
))
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95
+18
src/internal/wire_type.gleam
+18
src/internal/wire_type.gleam
···
1
+
import gleam/option.{type Option, None, Some}
2
+
3
+
pub type WireType {
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+
VarInt
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+
I64
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+
Len
7
+
I32
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+
}
9
+
10
+
pub fn parse(i: Int) -> Option(WireType) {
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+
case i {
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+
0 -> Some(VarInt)
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+
1 -> Some(I64)
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+
2 -> Some(Len)
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+
5 -> Some(I32)
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+
_ -> None
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+
}
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+
}