Function parseCharLiteral [src]

Alias for std.zig.string_literal.parseCharLiteral

Asserts the slice starts and ends with single-quotes. Returns an error if there is not exactly one UTF-8 codepoint in between.

Prototype

pub fn parseCharLiteral(slice: []const u8) ParsedCharLiteral

Parameters

slice: []const u8

Example

 test parseCharLiteral {
    try std.testing.expectEqual(
        ParsedCharLiteral{ .success = 'a' },
        parseCharLiteral("'a'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .success = 'ä' },
        parseCharLiteral("'ä'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .success = 0 },
        parseCharLiteral("'\\x00'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .success = 0x4f },
        parseCharLiteral("'\\x4f'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .success = 0x4f },
        parseCharLiteral("'\\x4F'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .success = 0x3041 },
        parseCharLiteral("'ぁ'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .success = 0 },
        parseCharLiteral("'\\u{0}'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .success = 0x3041 },
        parseCharLiteral("'\\u{3041}'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .success = 0x7f },
        parseCharLiteral("'\\u{7f}'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .success = 0x7fff },
        parseCharLiteral("'\\u{7FFF}'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .failure = .{ .expected_hex_digit = 4 } },
        parseCharLiteral("'\\x0'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .failure = .{ .expected_single_quote = 5 } },
        parseCharLiteral("'\\x000'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .failure = .{ .invalid_escape_character = 2 } },
        parseCharLiteral("'\\y'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .failure = .{ .expected_lbrace = 3 } },
        parseCharLiteral("'\\u'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .failure = .{ .expected_lbrace = 3 } },
        parseCharLiteral("'\\uFFFF'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .failure = .{ .empty_unicode_escape_sequence = 4 } },
        parseCharLiteral("'\\u{}'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .failure = .{ .invalid_unicode_codepoint = 9 } },
        parseCharLiteral("'\\u{FFFFFF}'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .failure = .{ .expected_hex_digit_or_rbrace = 8 } },
        parseCharLiteral("'\\u{FFFF'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .failure = .{ .expected_single_quote = 9 } },
        parseCharLiteral("'\\u{FFFF}x'"),
    );
    try std.testing.expectEqual(
        ParsedCharLiteral{ .failure = .{ .invalid_character = 1 } },
        parseCharLiteral("'\x00'"),
    );
}

Source

  pub 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 };
        },
    }
}  