Function directEnumArrayDefault [src]

Initializes an array of Data which can be indexed by @intCast(usize, @intFromEnum(enum_value)). The enum must be exhaustive. If the enum contains any fields with values that cannot be represented by usize, a compile error is issued. The max_unused_slots parameter limits the total number of items which have no matching enum key (holes in the enum numbering). So for example, if an enum has values 1, 2, 5, and 6, max_unused_slots must be at least 3, to allow unused slots 0, 3, and 4. The init_values parameter must be a struct with field names that match the enum values. If the enum has multiple fields with the same value, the name of the first one must be used.

Prototype

 pub fn directEnumArrayDefault( comptime E: type, comptime Data: type, comptime default: ?Data, comptime max_unused_slots: comptime_int, init_values: EnumFieldStruct(E, Data, default), ) [directEnumArrayLen(E, max_unused_slots)]Data

Parameters

E: typeData: typedefault: ?Datamax_unused_slots: comptime_intinit_values: EnumFieldStruct(E, Data, default)

Example

 test directEnumArrayDefault {
    const E = enum(i4) { a = 4, b = 6, c = 2 };
    var runtime_false: bool = false;
    _ = &runtime_false;
    const array = directEnumArrayDefault(E, bool, false, 4, .{
        .a = true,
        .b = runtime_false,
    });

    try testing.expectEqual([7]bool, @TypeOf(array));
    try testing.expectEqual(true, array[4]);
    try testing.expectEqual(false, array[6]);
    try testing.expectEqual(false, array[2]);
}

Source

  pub fn directEnumArrayDefault(
    comptime E: type,
    comptime Data: type,
    comptime default: ?Data,
    comptime max_unused_slots: comptime_int,
    init_values: EnumFieldStruct(E, Data, default),
) [directEnumArrayLen(E, max_unused_slots)]Data {
    const len = comptime directEnumArrayLen(E, max_unused_slots);
    var result: [len]Data = if (default) |d| [_]Data{d} ** len else undefined;
    inline for (@typeInfo(@TypeOf(init_values)).@"struct".fields) |f| {
        const enum_value = @field(E, f.name);
        const index = @as(usize, @intCast(@intFromEnum(enum_value)));
        result[index] = @field(init_values, f.name);
    }
    return result;
}  