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add std.meta.intToEnum

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Andrew Kelley 2018-11-18 20:18:24 -05:00
parent 3829e200ec
commit 921d9c9bcb
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1 changed files with 29 additions and 0 deletions
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std/meta/index.zig
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@ -483,3 +483,32 @@ test "std.meta.eql" {
debug.assert(eql(EU.tst(false), EU.tst(false)));
debug.assert(!eql(EU.tst(false), EU.tst(true)));
}
test "intToEnum with error return" {
const E1 = enum {
A,
};
const E2 = enum {
A,
B,
};
var zero: u8 = 0;
var one: u16 = 1;
debug.assert(intToEnum(E1, zero) catch unreachable == E1.A);
debug.assert(intToEnum(E2, one) catch unreachable == E2.B);
debug.assertError(intToEnum(E1, one), error.InvalidEnumTag);
}
pub const IntToEnumError = error{InvalidEnumTag};
pub fn intToEnum(comptime Tag: type, tag_int: var) IntToEnumError!Tag {
comptime var i = 0;
inline while (i != @memberCount(Tag)) : (i += 1) {
const this_tag_value = @field(Tag, @memberName(Tag, i));
if (tag_int == @enumToInt(this_tag_value)) {
return this_tag_value;
}
}
return error.InvalidEnumTag;
}