Asserts the slice starts and ends with single-quotes. Returns an error if there is not exactly one UTF-8 codepoint in between.
pub fn parseCharLiteral(slice: []const u8) ParsedCharLiteralpub fn parseCharLiteral(slice: []const u8) ParsedCharLiteral {
if (slice.len < 3) return .{ .failure = .empty_char_literal };
assert(slice[0] == '\'');
assert(slice[slice.len - 1] == '\'');
switch (slice[1]) {
'\\' => {
var offset: usize = 1;
const result = parseEscapeSequence(slice, &offset);
if (result == .success and (offset + 1 != slice.len or slice[offset] != '\''))
return .{ .failure = .{ .expected_single_quote = offset } };
return result;
},
0 => return .{ .failure = .{ .invalid_character = 1 } },
else => {
const inner = slice[1 .. slice.len - 1];
const n = std.unicode.utf8ByteSequenceLength(inner[0]) catch return .{
.failure = .{ .invalid_unicode_codepoint = 1 },
};
if (inner.len > n) return .{ .failure = .{ .expected_single_quote = 1 + n } };
const codepoint = switch (n) {
1 => inner[0],
2 => std.unicode.utf8Decode2(inner[0..2].*),
3 => std.unicode.utf8Decode3(inner[0..3].*),
4 => std.unicode.utf8Decode4(inner[0..4].*),
else => unreachable,
} catch return .{ .failure = .{ .invalid_unicode_codepoint = 1 } };
return .{ .success = codepoint };
},
}
}