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const expect = @import("std").testing.expect;
test "if optional" {
// If expressions test for null.
const a: ?u32 = 0;
if (a) |value| {
try expect(value == 0);
} else {
unreachable;
}
const b: ?u32 = null;
if (b) |_| {
unreachable;
} else {
try expect(true);
}
// The else is not required.
if (a) |value| {
try expect(value == 0);
}
// To test against null only, use the binary equality operator.
if (b == null) {
try expect(true);
}
// Access the value by reference using a pointer capture.
var c: ?u32 = 3;
if (c) |*value| {
value.* = 2;
}
if (c) |value| {
try expect(value == 2);
} else {
unreachable;
}
}
test "if error union with optional" {
// If expressions test for errors before unwrapping optionals.
// The |optional_value| capture's type is ?u32.
const a: anyerror!?u32 = 0;
if (a) |optional_value| {
try expect(optional_value.? == 0);
} else |err| {
_ = err;
unreachable;
}
const b: anyerror!?u32 = null;
if (b) |optional_value| {
try expect(optional_value == null);
} else |_| {
unreachable;
}
const c: anyerror!?u32 = error.BadValue;
if (c) |optional_value| {
_ = optional_value;
unreachable;
} else |err| {
try expect(err == error.BadValue);
}
// Access the value by reference by using a pointer capture each time.
var d: anyerror!?u32 = 3;
if (d) |*optional_value| {
if (optional_value.*) |*value| {
value.* = 9;
}
} else |_| {
unreachable;
}
if (d) |optional_value| {
try expect(optional_value.? == 9);
} else |_| {
unreachable;
}
}
// test
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