private int readArgumentIndex()

in src/main/java/org/apache/commons/text/ExtendedMessageFormat.java [464:497]
32 lines of code
11 McCabe index (conditional complexity)

    private int readArgumentIndex(final String pattern, final ParsePosition pos) {
        final int start = pos.getIndex();
        seekNonWs(pattern, pos);
        final StringBuilder result = new StringBuilder();
        boolean error = false;
        for (; !error && pos.getIndex() < pattern.length(); next(pos)) {
            char c = pattern.charAt(pos.getIndex());
            if (Character.isWhitespace(c)) {
                seekNonWs(pattern, pos);
                c = pattern.charAt(pos.getIndex());
                if (c != START_FMT && c != END_FE) {
                    error = true;
                    continue;
                }
            }
            if ((c == START_FMT || c == END_FE) && result.length() > 0) {
                try {
                    return Integer.parseInt(result.toString());
                } catch (final NumberFormatException e) { // NOPMD
                    // we've already ensured only digits, so unless something
                    // outlandishly large was specified we should be okay.
                }
            }
            error = !Character.isDigit(c);
            result.append(c);
        }
        if (error) {
            throw new IllegalArgumentException(
                    "Invalid format argument index at position " + start + ": "
                            + pattern.substring(start, pos.getIndex()));
        }
        throw new IllegalArgumentException(
                "Unterminated format element at position " + start);
    }