encodeJsonStringChars

pub fn encodeJsonStringChars(chars: []const u8, options: Options, writer: *Writer) Error!void {
    var write_cursor: usize = 0;
    var i: usize = 0;
    if (options.escape_unicode) {
        while (i < chars.len) : (i += 1) {
            switch (chars[i]) {
                // normal ascii character
                0x20...0x21, 0x23...0x5B, 0x5D...0x7E => {},
                0x00...0x1F, '\\', '\"' => {
                    // Always must escape these.
                    try writer.writeAll(chars[write_cursor..i]);
                    try outputSpecialEscape(chars[i], writer);
                    write_cursor = i + 1;
                },
                0x7F...0xFF => {
                    try writer.writeAll(chars[write_cursor..i]);
                    const ulen = std.unicode.utf8ByteSequenceLength(chars[i]) catch unreachable;
                    const codepoint = std.unicode.utf8Decode(chars[i..][0..ulen]) catch unreachable;
                    try outputUnicodeEscape(codepoint, writer);
                    i += ulen - 1;
                    write_cursor = i + 1;
                },
            }
        }
    } else {
        while (i < chars.len) : (i += 1) {
            switch (chars[i]) {
                // normal bytes
                0x20...0x21, 0x23...0x5B, 0x5D...0xFF => {},
                0x00...0x1F, '\\', '\"' => {
                    // Always must escape these.
                    try writer.writeAll(chars[write_cursor..i]);
                    try outputSpecialEscape(chars[i], writer);
                    write_cursor = i + 1;
                },
            }
        }
    }
    try writer.writeAll(chars[write_cursor..chars.len]);
}