string

pub fn string(self: *Serializer, val: []const u8, options: StringOptions) Writer.Error!void {
    try self.writer.writeByte('"');
    // Batch write sequences of "raw" bytes (printable ASCII or non-escaped non-ASCII) for performance.
    // `val[start..i]` contains pending raw bytes to write.
    var start: usize = 0;
    var i: usize = 0;
    while (i < val.len) {
        const byte = val[i];
        // Check if this byte can be written as-is
        const is_raw = switch (byte) {
            ' ', '!', '#'...'[', ']'...'~' => true,
            0x80...0xFF => !options.escape_non_ascii,
            else => false,
        };
        if (is_raw) {
            i += 1;
            continue;
        }
        // Flush pending raw bytes
        try self.writer.writeAll(val[start..i]);
        // Handle the special character
        if (byte >= 0x80) {
            // Decode UTF-8 sequence and write the codepoint
            const ulen = std.unicode.utf8ByteSequenceLength(byte) catch unreachable;
            const codepoint = std.unicode.utf8Decode(val[i..][0..ulen]) catch unreachable;
            // InvalidCodepoint cannot occur from valid UTF-8
            self.writeCodepoint(codepoint, .{
                .escape_non_ascii = options.escape_non_ascii,
                .quote_style = .double,
            }) catch unreachable;
            i += ulen;
        } else {
            // ASCII character that needs escaping
            self.writeCodepoint(byte, .{
                .escape_non_ascii = options.escape_non_ascii,
                .quote_style = .double,
            }) catch unreachable; // InvalidCodepoint cannot occur for valid ASCII values
            i += 1;
        }
        start = i;
    }

    try self.writer.writeAll(val[start..]);
    try self.writer.writeByte('"');
}