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const expect = @import("std").testing.expect;
const mem = @import("std").mem;
// Declare an enum.
const Type = enum {
ok,
not_ok,
};
// Declare a specific enum field.
const c = Type.ok;
// If you want access to the ordinal value of an enum, you
// can specify the tag type.
const Value = enum(u2) {
zero,
one,
two,
};
// Now you can cast between u2 and Value.
// The ordinal value starts from 0, counting up by 1 from the previous member.
test "enum ordinal value" {
try expect(@intFromEnum(Value.zero) == 0);
try expect(@intFromEnum(Value.one) == 1);
try expect(@intFromEnum(Value.two) == 2);
}
// You can override the ordinal value for an enum.
const Value2 = enum(u32) {
hundred = 100,
thousand = 1000,
million = 1000000,
};
test "set enum ordinal value" {
try expect(@intFromEnum(Value2.hundred) == 100);
try expect(@intFromEnum(Value2.thousand) == 1000);
try expect(@intFromEnum(Value2.million) == 1000000);
}
// You can also override only some values.
const Value3 = enum(u4) {
a,
b = 8,
c,
d = 4,
e,
};
test "enum implicit ordinal values and overridden values" {
try expect(@intFromEnum(Value3.a) == 0);
try expect(@intFromEnum(Value3.b) == 8);
try expect(@intFromEnum(Value3.c) == 9);
try expect(@intFromEnum(Value3.d) == 4);
try expect(@intFromEnum(Value3.e) == 5);
}
// Enums can have methods, the same as structs and unions.
// Enum methods are not special, they are only namespaced
// functions that you can call with dot syntax.
const Suit = enum {
clubs,
spades,
diamonds,
hearts,
pub fn isClubs(self: Suit) bool {
return self == Suit.clubs;
}
};
test "enum method" {
const p = Suit.spades;
try expect(!p.isClubs());
}
// An enum can be switched upon.
const Foo = enum {
string,
number,
none,
};
test "enum switch" {
const p = Foo.number;
const what_is_it = switch (p) {
Foo.string => "this is a string",
Foo.number => "this is a number",
Foo.none => "this is a none",
};
try expect(mem.eql(u8, what_is_it, "this is a number"));
}
// @typeInfo can be used to access the integer tag type of an enum.
const Small = enum {
one,
two,
three,
four,
};
test "std.meta.Tag" {
try expect(@typeInfo(Small).@"enum".tag_type == u2);
}
// @typeInfo tells us the field count and the fields names:
test "@typeInfo" {
try expect(@typeInfo(Small).@"enum".fields.len == 4);
try expect(mem.eql(u8, @typeInfo(Small).@"enum".fields[1].name, "two"));
}
// @tagName gives a [:0]const u8 representation of an enum value:
test "@tagName" {
try expect(mem.eql(u8, @tagName(Small.three), "three"));
}
// test
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