zig/test/cases/enum.zig

const assert = @import("std").debug.assert;
const mem = @import("std").mem;

test "enum type" {
    const foo1 = Foo{ .One = 13};
    const foo2 = Foo{. Two = Point { .x = 1234, .y = 5678, }};
    const bar = Bar.B;

    assert(bar == Bar.B);
    assert(@memberCount(Foo) == 3);
    assert(@memberCount(Bar) == 4);
    assert(@sizeOf(Foo) == @sizeOf(FooNoVoid));
    assert(@sizeOf(Bar) == 1);
}

test "enum as return value" {
    switch (returnAnInt(13)) {
        Foo.One => |value| assert(value == 13),
        else => unreachable,
    }
}

const Point = struct {
    x: u64,
    y: u64,
};
const Foo = union(enum) {
    One: i32,
    Two: Point,
    Three: void,
};
const FooNoVoid = union(enum) {
    One: i32,
    Two: Point,
};
const Bar = enum {
    A,
    B,
    C,
    D,
};

fn returnAnInt(x: i32) Foo {
    return Foo { .One = x };
}


test "constant enum with payload" {
    var empty = AnEnumWithPayload {.Empty = {}};
    var full = AnEnumWithPayload {.Full = 13};
    shouldBeEmpty(empty);
    shouldBeNotEmpty(full);
}

fn shouldBeEmpty(x: &const AnEnumWithPayload) void {
    switch (*x) {
        AnEnumWithPayload.Empty => {},
        else => unreachable,
    }
}

fn shouldBeNotEmpty(x: &const AnEnumWithPayload) void {
    switch (*x) {
        AnEnumWithPayload.Empty => unreachable,
        else => {},
    }
}

const AnEnumWithPayload = union(enum) {
    Empty: void,
    Full: i32,
};



const Number = enum {
    Zero,
    One,
    Two,
    Three,
    Four,
};

test "enum to int" {
    shouldEqual(Number.Zero, 0);
    shouldEqual(Number.One, 1);
    shouldEqual(Number.Two, 2);
    shouldEqual(Number.Three, 3);
    shouldEqual(Number.Four, 4);
}

fn shouldEqual(n: Number, expected: u3) void {
    assert(u3(n) == expected);
}


test "int to enum" {
    testIntToEnumEval(3);
}
fn testIntToEnumEval(x: i32) void {
    assert(IntToEnumNumber(u3(x)) == IntToEnumNumber.Three);
}
const IntToEnumNumber = enum {
    Zero,
    One,
    Two,
    Three,
    Four,
};


test "@tagName" {
    assert(mem.eql(u8, testEnumTagNameBare(BareNumber.Three), "Three"));
    comptime assert(mem.eql(u8, testEnumTagNameBare(BareNumber.Three), "Three"));
}

fn testEnumTagNameBare(n: BareNumber) []const u8 {
    return @tagName(n);
}

const BareNumber = enum {
    One,
    Two,
    Three,
};


test "enum alignment" {
    comptime {
        assert(@alignOf(AlignTestEnum) >= @alignOf([9]u8));
        assert(@alignOf(AlignTestEnum) >= @alignOf(u64));
    }
}

const AlignTestEnum = union(enum) {
    A: [9]u8,
    B: u64,
};

const ValueCount1 = enum { I0 };
const ValueCount2 = enum { I0, I1 };
const ValueCount256 = enum {
    I0, I1, I2, I3, I4, I5, I6, I7, I8, I9, I10, I11, I12, I13, I14, I15,
    I16, I17, I18, I19, I20, I21, I22, I23, I24, I25, I26, I27, I28, I29, I30, I31,
    I32, I33, I34, I35, I36, I37, I38, I39, I40, I41, I42, I43, I44, I45, I46, I47,
    I48, I49, I50, I51, I52, I53, I54, I55, I56, I57, I58, I59, I60, I61, I62, I63,
    I64, I65, I66, I67, I68, I69, I70, I71, I72, I73, I74, I75, I76, I77, I78, I79,
    I80, I81, I82, I83, I84, I85, I86, I87, I88, I89, I90, I91, I92, I93, I94, I95,
    I96, I97, I98, I99, I100, I101, I102, I103, I104, I105, I106, I107, I108, I109,
    I110, I111, I112, I113, I114, I115, I116, I117, I118, I119, I120, I121, I122, I123,
    I124, I125, I126, I127, I128, I129, I130, I131, I132, I133, I134, I135, I136, I137,
    I138, I139, I140, I141, I142, I143, I144, I145, I146, I147, I148, I149, I150, I151,
    I152, I153, I154, I155, I156, I157, I158, I159, I160, I161, I162, I163, I164, I165,
    I166, I167, I168, I169, I170, I171, I172, I173, I174, I175, I176, I177, I178, I179,
    I180, I181, I182, I183, I184, I185, I186, I187, I188, I189, I190, I191, I192, I193,
    I194, I195, I196, I197, I198, I199, I200, I201, I202, I203, I204, I205, I206, I207,
    I208, I209, I210, I211, I212, I213, I214, I215, I216, I217, I218, I219, I220, I221,
    I222, I223, I224, I225, I226, I227, I228, I229, I230, I231, I232, I233, I234, I235,
    I236, I237, I238, I239, I240, I241, I242, I243, I244, I245, I246, I247, I248, I249,
    I250, I251, I252, I253, I254, I255
};
const ValueCount257 = enum {
    I0, I1, I2, I3, I4, I5, I6, I7, I8, I9, I10, I11, I12, I13, I14, I15,
    I16, I17, I18, I19, I20, I21, I22, I23, I24, I25, I26, I27, I28, I29, I30, I31,
    I32, I33, I34, I35, I36, I37, I38, I39, I40, I41, I42, I43, I44, I45, I46, I47,
    I48, I49, I50, I51, I52, I53, I54, I55, I56, I57, I58, I59, I60, I61, I62, I63,
    I64, I65, I66, I67, I68, I69, I70, I71, I72, I73, I74, I75, I76, I77, I78, I79,
    I80, I81, I82, I83, I84, I85, I86, I87, I88, I89, I90, I91, I92, I93, I94, I95,
    I96, I97, I98, I99, I100, I101, I102, I103, I104, I105, I106, I107, I108, I109,
    I110, I111, I112, I113, I114, I115, I116, I117, I118, I119, I120, I121, I122, I123,
    I124, I125, I126, I127, I128, I129, I130, I131, I132, I133, I134, I135, I136, I137,
    I138, I139, I140, I141, I142, I143, I144, I145, I146, I147, I148, I149, I150, I151,
    I152, I153, I154, I155, I156, I157, I158, I159, I160, I161, I162, I163, I164, I165,
    I166, I167, I168, I169, I170, I171, I172, I173, I174, I175, I176, I177, I178, I179,
    I180, I181, I182, I183, I184, I185, I186, I187, I188, I189, I190, I191, I192, I193,
    I194, I195, I196, I197, I198, I199, I200, I201, I202, I203, I204, I205, I206, I207,
    I208, I209, I210, I211, I212, I213, I214, I215, I216, I217, I218, I219, I220, I221,
    I222, I223, I224, I225, I226, I227, I228, I229, I230, I231, I232, I233, I234, I235,
    I236, I237, I238, I239, I240, I241, I242, I243, I244, I245, I246, I247, I248, I249,
    I250, I251, I252, I253, I254, I255, I256
};

test "enum sizes" {
    comptime {
        assert(@sizeOf(ValueCount1) == 0);
        assert(@sizeOf(ValueCount2) == 1);
        assert(@sizeOf(ValueCount256) == 1);
        assert(@sizeOf(ValueCount257) == 2);
    }
}

const Small2 = enum (u2) {
    One,
    Two,
};
const Small = enum (u2) {
    One,
    Two,
    Three,
    Four,
};

test "set enum tag type" {
    {
        var x = Small.One;
        x = Small.Two;
        comptime assert(@TagType(Small) == u2);
    }
    {
        var x = Small2.One;
        x = Small2.Two;
        comptime assert(@TagType(Small2) == u2);
    }
}


const A = enum (u3) {
    One,
    Two,
    Three,
    Four,
    One2,
    Two2,
    Three2,
    Four2,
};

const B = enum (u3) {
    One3,
    Two3,
    Three3,
    Four3,
    One23,
    Two23,
    Three23,
    Four23,
};

const C = enum (u2) {
    One4,
    Two4,
    Three4,
    Four4,
};

const BitFieldOfEnums = packed struct {
    a: A,
    b: B,
    c: C,
};

const bit_field_1 = BitFieldOfEnums {
    .a = A.Two,
    .b = B.Three3,
    .c = C.Four4,
};

test "bit field access with enum fields" {
    var data = bit_field_1;
    assert(getA(&data) == A.Two);
    assert(getB(&data) == B.Three3);
    assert(getC(&data) == C.Four4);
    comptime assert(@sizeOf(BitFieldOfEnums) == 1);

    data.b = B.Four3;
    assert(data.b == B.Four3);

    data.a = A.Three;
    assert(data.a == A.Three);
    assert(data.b == B.Four3);
}

fn getA(data: &const BitFieldOfEnums) A {
    return data.a;
}

fn getB(data: &const BitFieldOfEnums) B {
    return data.b;
}

fn getC(data: &const BitFieldOfEnums) C {
    return data.c;
}

test "casting enum to its tag type" {
    testCastEnumToTagType(Small2.Two);
    comptime testCastEnumToTagType(Small2.Two);
}

fn testCastEnumToTagType(value: Small2) void {
    assert(u2(value) == 1);
}

const MultipleChoice = enum(u32) {
    A = 20,
    B = 40,
    C = 60,
    D = 1000,
};

test "enum with specified tag values" {
    testEnumWithSpecifiedTagValues(MultipleChoice.C);
    comptime testEnumWithSpecifiedTagValues(MultipleChoice.C);
}

fn testEnumWithSpecifiedTagValues(x: MultipleChoice) void {
    assert(u32(x) == 60);
    assert(1234 == switch (x) {
        MultipleChoice.A => 1,
        MultipleChoice.B => 2,
        MultipleChoice.C => u32(1234),
        MultipleChoice.D => 4,
    });
}

const MultipleChoice2 = enum(u32) {
    Unspecified1,
    A = 20,
    Unspecified2,
    B = 40,
    Unspecified3,
    C = 60,
    Unspecified4,
    D = 1000,
    Unspecified5,
};

test "enum with specified and unspecified tag values" {
    testEnumWithSpecifiedAndUnspecifiedTagValues(MultipleChoice2.D);
    comptime testEnumWithSpecifiedAndUnspecifiedTagValues(MultipleChoice2.D);
}

fn testEnumWithSpecifiedAndUnspecifiedTagValues(x: MultipleChoice2) void {
    assert(u32(x) == 1000);
    assert(1234 == switch (x) {
        MultipleChoice2.A => 1,
        MultipleChoice2.B => 2,
        MultipleChoice2.C => 3,
        MultipleChoice2.D => u32(1234),
        MultipleChoice2.Unspecified1 => 5,
        MultipleChoice2.Unspecified2 => 6,
        MultipleChoice2.Unspecified3 => 7,
        MultipleChoice2.Unspecified4 => 8,
        MultipleChoice2.Unspecified5 => 9,
    });
}

test "cast integer literal to enum" {
    assert(MultipleChoice2(0) == MultipleChoice2.Unspecified1);
    assert(MultipleChoice2(40) == MultipleChoice2.B);
}

const EnumWithOneMember = enum {
    Eof,
};

fn doALoopThing(id: EnumWithOneMember) void {
    while (true) {
        if (id == EnumWithOneMember.Eof) {
            break;
        }
        @compileError("above if condition should be comptime");
    }
}

test "comparison operator on enum with one member is comptime known" {
    doALoopThing(EnumWithOneMember.Eof);
}

const State = enum {
    Start,
};
test "switch on enum with one member is comptime known" {
    var state = State.Start;
    switch (state) {
        State.Start => return,
    }
    @compileError("analysis should not reach here");
}

const EnumWithTagValues = enum(u4) {
    A = 1 << 0,
    B = 1 << 1,
    C = 1 << 2,
    D = 1 << 3,
};
test "enum with tag values don't require parens" {
    assert(u4(EnumWithTagValues.C) == 0b0100);
}

test "enum with 1 field but explicit tag type should still have the tag type" {
    const Enum = enum(u8) { B = 2 };
    comptime @import("std").debug.assert(@sizeOf(Enum) == @sizeOf(u8));
}