private static int read()

in src/main/java/org/apache/commons/jexl3/parser/StringParser.java [206:260]
52 lines of code
16 McCabe index (conditional complexity)

    private static int read(final StringBuilder strb, final CharSequence str, final int begin, final int end, final char sep, final boolean esc) {
        boolean escape = false;
        int index = begin;
        for (; index < end; ++index) {
            final char c = str.charAt(index);
            if (escape) {
                if (c == 'u' && index + UCHAR_LEN < end && readUnicodeChar(strb, str, index + 1) > 0) {
                    index += UCHAR_LEN;
                } else {
                    // if c is not an escapable character, re-emmit the backslash before it
                    final boolean notSeparator = sep == 0 ? c != '\'' && c != '"' : c != sep;
                    if (notSeparator && c != '\\') {
                        if (!esc) {
                            strb.append('\\').append(c);
                        } else {
                            switch (c) {
                                // https://es5.github.io/x7.html#x7.8.4
                                case 'b':
                                    strb.append('\b');
                                    break; // backspace \u0008
                                case 't':
                                    strb.append('\t');
                                    break; // horizontal tab \u0009
                                case 'n':
                                    strb.append('\n');
                                    break; // line feed \u000A
                                // We don't support vertical tab. If needed, the unicode (\u000B) should be used instead
                                case 'f':
                                    strb.append('\f');
                                    break; // form feed \u000C
                                case 'r':
                                    strb.append('\r');
                                    break; // carriage return \u000D
                                default:
                                    strb.append('\\').append(c);
                            }
                        }
                    } else {
                        strb.append(c);
                    }
                }
                escape = false;
                continue;
            }
            if (c == '\\') {
                escape = true;
                continue;
            }
            strb.append(c);
            if (c == sep) {
                break;
            }
        }
        return index;
    }