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Merge pull request #6416 from MasterQ32/meta-tuple

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Implements std.meta.Tuple(), implements #4607 in userland.
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Alexandros Naskos 2020-09-29 15:59:27 +03:00 committed by GitHub
commit 3342e28784
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1 changed files with 63 additions and 1 deletions
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lib/std/meta.zig
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@ -807,7 +807,7 @@ pub fn sizeof(target: anytype) usize {
// TODO to get the correct result we have to translate
// `1073741824 * 4` as `int(1073741824) *% int(4)` since
// sizeof(1073741824 * 4) != sizeof(4294967296).
// TODO test if target fits in int, long or long long
return @sizeOf(c_int);
},
@ -826,3 +826,65 @@ test "sizeof" {
testing.expect(sizeof(E.One) == @sizeOf(c_int));
testing.expect(sizeof(S) == 4);
}
/// For a given anonymous list of types, returns a new tuple type
/// with those types as fields.
///
/// Examples:
/// - `Tuple(&[_]type {})` ⇒ `tuple { }`
/// - `Tuple(&[_]type {f32})` ⇒ `tuple { f32 }`
/// - `Tuple(&[_]type {f32,u32})` ⇒ `tuple { f32, u32 }`
pub fn Tuple(comptime types: []const type) type {
var tuple_fields: [types.len]std.builtin.TypeInfo.StructField = undefined;
inline for (types) |T, i| {
@setEvalBranchQuota(10_000);
var num_buf: [128]u8 = undefined;
tuple_fields[i] = std.builtin.TypeInfo.StructField{
.name = std.fmt.bufPrint(&num_buf, "{d}", .{i}) catch unreachable,
.field_type = T,
.default_value = @as(?T, null),
.is_comptime = false,
};
}
return @Type(std.builtin.TypeInfo{
.Struct = std.builtin.TypeInfo.Struct{
.is_tuple = true,
.layout = .Auto,
.decls = &[_]std.builtin.TypeInfo.Declaration{},
.fields = &tuple_fields,
},
});
}
test "Tuple" {
const T = struct {
fn assertTypeEqual(comptime Expected: type, comptime Actual: type) void {
if (Expected != Actual)
@compileError("Expected type " ++ @typeName(Expected) ++ ", but got type " ++ @typeName(Actual));
}
fn assertTuple(comptime expected: anytype, comptime Actual: type) void {
const info = @typeInfo(Actual);
if (info != .Struct)
@compileError("Expected struct type");
if (!info.Struct.is_tuple)
@compileError("Struct type must be a tuple type");
const fields_list = std.meta.fields(Actual);
if (expected.len != fields_list.len)
@compileError("Argument count mismatch");
inline for (fields_list) |fld, i| {
if (expected[i] != fld.field_type) {
@compileError("Field " ++ fld.name ++ " expected to be type " ++ @typeName(expected[i]) ++ ", but was type " ++ @typeName(fld.field_type));
}
}
}
};
T.assertTuple(.{}, Tuple(&[_]type{}));
T.assertTuple(.{u32}, Tuple(&[_]type{u32}));
T.assertTuple(.{ u32, f16 }, Tuple(&[_]type{ u32, f16 }));
T.assertTuple(.{ u32, f16, []const u8 }, Tuple(&[_]type{ u32, f16, []const u8 }));
}