Function stringToEnum [src]

Returns the variant of an enum type, T, which is named str, or null if no such variant exists.

Prototype

pub fn stringToEnum(comptime T: type, str: []const u8) ?T

Parameters

T: typestr: []const u8

Example

 test stringToEnum {
    const E1 = enum {
        A,
        B,
    };
    try testing.expect(E1.A == stringToEnum(E1, "A").?);
    try testing.expect(E1.B == stringToEnum(E1, "B").?);
    try testing.expect(null == stringToEnum(E1, "C"));
}

Source

  pub fn stringToEnum(comptime T: type, str: []const u8) ?T {
    // Using StaticStringMap here is more performant, but it will start to take too
    // long to compile if the enum is large enough, due to the current limits of comptime
    // performance when doing things like constructing lookup maps at comptime.
    // TODO The '100' here is arbitrary and should be increased when possible:
    // - https://github.com/ziglang/zig/issues/4055
    // - https://github.com/ziglang/zig/issues/3863
    if (@typeInfo(T).@"enum".fields.len <= 100) {
        const kvs = comptime build_kvs: {
            const EnumKV = struct { []const u8, T };
            var kvs_array: [@typeInfo(T).@"enum".fields.len]EnumKV = undefined;
            for (@typeInfo(T).@"enum".fields, 0..) |enumField, i| {
                kvs_array[i] = .{ enumField.name, @field(T, enumField.name) };
            }
            break :build_kvs kvs_array[0..];
        };
        const map = std.StaticStringMap(T).initComptime(kvs);
        return map.get(str);
    } else {
        inline for (@typeInfo(T).@"enum".fields) |enumField| {
            if (mem.eql(u8, str, enumField.name)) {
                return @field(T, enumField.name);
            }
        }
        return null;
    }
}  