protected static Iterator readLines()

in src/main/java/org/apache/commons/jexl3/internal/TemplateEngine.java [1099:1147]
45 lines of code
8 McCabe index (conditional complexity)

    protected static Iterator<CharSequence> readLines(final Reader reader) {
        if (!reader.markSupported()) {
            throw new IllegalArgumentException("mark support in reader required");
        }
        return new Iterator<CharSequence>() {
            private CharSequence next = doNext();

            private CharSequence doNext() {
                final StringBuilder strb = new StringBuilder(64); // CSOFF: MagicNumber
                int c;
                boolean eol = false;
                try {
                    while ((c = reader.read()) >= 0) {
                        if (eol) {// && (c != '\n' && c != '\r')) {
                            reader.reset();
                            break;
                        }
                        if (c == '\n') {
                            eol = true;
                        }
                        strb.append((char) c);
                        reader.mark(1);
                    }
                } catch (final IOException xio) {
                    return null;
                }
                return strb.length() > 0 ? strb : null;
            }

            @Override
            public boolean hasNext() {
                return next != null;
            }

            @Override
            public CharSequence next() {
                final CharSequence current = next;
                if (current != null) {
                    next = doNext();
                }
                return current;
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException("Not supported.");
            }
        };
    }