Function nameCast [src]

Cast an enum literal, value, or string to the enum value of type E with the same name.

Prototype

pub fn nameCast(comptime E: type, comptime value: anytype) E

Parameters

E: type

Example

 test nameCast {
    const A = enum(u1) { a = 0, b = 1 };
    const B = enum(u1) { a = 1, b = 0 };
    try testing.expectEqual(A.a, nameCast(A, .a));
    try testing.expectEqual(A.a, nameCast(A, A.a));
    try testing.expectEqual(A.a, nameCast(A, B.a));
    try testing.expectEqual(A.a, nameCast(A, "a"));
    try testing.expectEqual(A.a, nameCast(A, @as(*const [1]u8, "a")));
    try testing.expectEqual(A.a, nameCast(A, @as([:0]const u8, "a")));
    try testing.expectEqual(A.a, nameCast(A, @as([]const u8, "a")));

    try testing.expectEqual(B.a, nameCast(B, .a));
    try testing.expectEqual(B.a, nameCast(B, A.a));
    try testing.expectEqual(B.a, nameCast(B, B.a));
    try testing.expectEqual(B.a, nameCast(B, "a"));

    try testing.expectEqual(B.b, nameCast(B, .b));
    try testing.expectEqual(B.b, nameCast(B, A.b));
    try testing.expectEqual(B.b, nameCast(B, B.b));
    try testing.expectEqual(B.b, nameCast(B, "b"));
}

Source

  pub fn nameCast(comptime E: type, comptime value: anytype) E {
    return comptime blk: {
        const V = @TypeOf(value);
        if (V == E) break :blk value;
        const name: ?[]const u8 = switch (@typeInfo(V)) {
            .enum_literal, .@"enum" => @tagName(value),
            .pointer => value,
            else => null,
        };
        if (name) |n| {
            if (@hasField(E, n)) {
                break :blk @field(E, n);
            }
            @compileError("Enum " ++ @typeName(E) ++ " has no field named " ++ n);
        }
        @compileError("Cannot cast from " ++ @typeName(@TypeOf(value)) ++ " to " ++ @typeName(E));
    };
}  