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fix: support optional custom formats #15

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Merged
lalinsky merged 1 commit into from
Apr 30, 2026
Merged

fix: support optional custom formats #15

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74 changes: 68 additions & 6 deletions src/struct.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -144,7 +144,7 @@ pub fn packStruct(writer: *std.Io.Writer, comptime T: type, value_or_maybe_null:
if (has_custom_write_fn) {
return try value.msgpackWrite(packer(writer));
} else {
const format = comptime if (std.meta.hasFn(Type, "msgpackFormat")) T.msgpackFormat() else default_struct_format;
const format = comptime if (std.meta.hasFn(Type, "msgpackFormat")) Type.msgpackFormat() else default_struct_format;
switch (format) {
.as_map => |opts| {
return packStructAsMap(writer, Type, value, opts);
Expand All @@ -160,7 +160,7 @@ pub fn unpackStructFromMapBody(reader: *std.Io.Reader, allocator: std.mem.Alloca
const Type = NonOptional(T);
const type_info = @typeInfo(Type);
const fields = type_info.@"struct".fields;
const FieldEnum = std.meta.FieldEnum(T);
const FieldEnum = std.meta.FieldEnum(Type);

var fields_seen = std.bit_set.StaticBitSet(fields.len).initEmpty();

Expand Down Expand Up @@ -208,10 +208,10 @@ pub fn unpackStructFromMapBody(reader: *std.Io.Reader, allocator: std.mem.Alloca
}
},
.custom => {
const KeyType = comptime @typeInfo(@TypeOf(T.msgpackFieldKey)).@"fn".return_type.?;
const KeyType = comptime @typeInfo(@TypeOf(Type.msgpackFieldKey)).@"fn".return_type.?;
const key = try unpackAny(reader, allocator, KeyType);
inline for (fields, 0..) |field, i| {
if (T.msgpackFieldKey(@field(FieldEnum, field.name)) == key) {
if (Type.msgpackFieldKey(@field(FieldEnum, field.name)) == key) {
fields_seen.set(i);
@field(result, field.name) = try unpackAny(reader, allocator, field.type);
break;
Expand Down Expand Up @@ -280,9 +280,9 @@ pub fn unpackStruct(reader: *std.Io.Reader, allocator: std.mem.Allocator, compti

const has_custom_read_fn = std.meta.hasFn(Type, "msgpackRead");
if (has_custom_read_fn) {
return try T.msgpackRead(unpacker(reader, allocator));
return try Type.msgpackRead(unpacker(reader, allocator));
} else {
const format = comptime if (std.meta.hasFn(Type, "msgpackFormat")) T.msgpackFormat() else default_struct_format;
const format = comptime if (std.meta.hasFn(Type, "msgpackFormat")) Type.msgpackFormat() else default_struct_format;
switch (format) {
.as_map => |opts| {
return try unpackStructAsMap(reader, allocator, T, opts);
Expand Down Expand Up @@ -318,6 +318,68 @@ test "writeStruct: map_by_index" {
}, writer.buffered());
}

test "writeStruct: optional custom format" {
const Msg = struct {
a: u32,

pub fn msgpackFormat() StructFormat {
return .{ .as_map = .{ .key = .field_index } };
}
};

var buffer: [100]u8 = undefined;
var writer = std.Io.Writer.fixed(&buffer);
try packStruct(&writer, ?Msg, Msg{ .a = 1 });

try std.testing.expectEqualSlices(u8, &.{
0x81,
0x00,
0x01,
}, writer.buffered());
}

test "readStruct: optional custom field key" {
const Msg = struct {
a: u32,

pub fn msgpackFormat() StructFormat {
return .{ .as_map = .{ .key = .custom } };
}

pub fn msgpackFieldKey(field: std.meta.FieldEnum(@This())) u8 {
return switch (field) {
.a => 1,
};
}
};

const packed_msg = [_]u8{
0x81,
0x01,
0x2a,
};
var reader = std.Io.Reader.fixed(&packed_msg);
const decoded = try unpackStruct(&reader, std.testing.allocator, ?Msg);

try std.testing.expectEqual(@as(?Msg, Msg{ .a = 42 }), decoded);
}

test "readStruct: optional custom reader" {
const Msg = struct {
a: u32,

pub fn msgpackRead(unpacker_value: anytype) !@This() {
return .{ .a = try unpacker_value.readInt(u32) };
}
};

const packed_msg = [_]u8{0x2a};
var reader = std.Io.Reader.fixed(&packed_msg);
const decoded = try unpackStruct(&reader, std.testing.allocator, ?Msg);

try std.testing.expectEqual(@as(?Msg, Msg{ .a = 42 }), decoded);
}

test "writeStruct: map by field_name" {
const Msg = struct {
a: u32,
Expand Down
46 changes: 44 additions & 2 deletions src/union.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -139,7 +139,7 @@ pub fn packUnion(writer: *std.Io.Writer, comptime T: type, value_or_maybe_null:
@compileError("Expected union type");
}

const format = if (std.meta.hasFn(Type, "msgpackFormat")) T.msgpackFormat() else default_union_format;
const format = if (std.meta.hasFn(Type, "msgpackFormat")) Type.msgpackFormat() else default_union_format;
switch (format) {
.as_map => |opts| {
return packUnionAsMap(writer, Type, value, opts);
Expand Down Expand Up @@ -281,7 +281,7 @@ pub fn unpackUnionAsTagged(reader: *std.Io.Reader, allocator: std.mem.Allocator,
pub fn unpackUnion(reader: *std.Io.Reader, allocator: std.mem.Allocator, comptime T: type) !T {
const Type = NonOptional(T);

const format = if (std.meta.hasFn(Type, "msgpackFormat")) T.msgpackFormat() else default_union_format;
const format = if (std.meta.hasFn(Type, "msgpackFormat")) Type.msgpackFormat() else default_union_format;
switch (format) {
.as_map => |opts| {
return try unpackUnionAsMap(reader, allocator, T, opts);
Expand Down Expand Up @@ -329,6 +329,48 @@ test "writeUnion: int field" {
try std.testing.expectEqualSlices(u8, &msg1_packed, writer.buffered());
}

test "writeUnion: optional custom format" {
const Msg = union(enum) {
a: u32,
b: u64,

pub fn msgpackFormat() UnionFormat {
return .{ .as_map = .{ .key = .field_index } };
}
};

var buffer: [100]u8 = undefined;
var writer = std.Io.Writer.fixed(&buffer);
try packUnion(&writer, ?Msg, Msg{ .a = 1 });

try std.testing.expectEqualSlices(u8, &.{
0x81,
0x00,
0x01,
}, writer.buffered());
}

test "readUnion: optional custom format" {
const Msg = union(enum) {
a: u32,
b: u64,

pub fn msgpackFormat() UnionFormat {
return .{ .as_map = .{ .key = .field_index } };
}
};

const packed_msg = [_]u8{
0x81,
0x00,
0x2a,
};
var reader = std.Io.Reader.fixed(&packed_msg);
const decoded = try unpackUnion(&reader, std.testing.allocator, ?Msg);

try std.testing.expectEqualDeep(@as(?Msg, Msg{ .a = 42 }), decoded);
}

test "writeUnion: void field" {
var buffer: [100]u8 = undefined;
var writer = std.Io.Writer.fixed(&buffer);
Expand Down
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