private Exp parse()

in juneau-core/juneau-marshall/src/main/java/org/apache/juneau/utils/StringExpressionMatcher.java [96:218]
107 lines of code
36 McCabe index (conditional complexity)

	private Exp parse(String expression) throws ParseException {
		if (StringUtils.isEmptyOrBlank(expression))
			return new Never();

		expression = expression.trim();

		List<Exp> ors = list();
		List<Exp> ands = list();

		StateMachineState state = S01;
		int i = 0, mark = -1;
		int pDepth = 0;
		boolean error = false;

		for (i = 0; i < expression.length(); i++) {
			char c = expression.charAt(i);
			if (state == S01) {
				// S01 = Looking for start
				if (! WS.contains(c)) {
					if (c == '(') {
						state = S02;
						pDepth = 0;
						mark = i+1;
					} else if (OP.contains(c)) {
						error = true;
						break;
					} else {
						state = S03;
						mark = i;
					}
				}
			} else if (state == S02) {
				// S02 = Found [(], looking for [)].
				if (c == '(')
					pDepth++;
				if (c == ')') {
					if (pDepth > 0)
						pDepth--;
					else {
						ands.add(parse(expression.substring(mark, i)));
						mark = -1;
						state = S04;
					}
				}
			} else if (state == S03) {
				// S03 = Found [A], looking for end of A.
				if (WS.contains(c) || OP.contains(c)) {
					ands.add(parseOperand(expression.substring(mark, i)));
					mark = -1;
					if (WS.contains(c)) {
						state = S04;
					} else {
						i--;
						state = S05;
					}
				}
			} else if (state == S04) {
				// S04 = Found [A ], looking for & or | or ,.
				if (! WS.contains(c)) {
					if (OP.contains(c)) {
						i--;
						state = S05;
					} else {
						error = true;
						break;
					}
				}
			} else if (state == S05) {
				// S05 = Found & or | or ,.
				if (c == '&') {
					//ands.add(operand);
					state = S06;
				} else /* (c == '|' || c == ',') */ {
					 if (ands.size() == 1) {
						 ors.add(ands.get(0));
					 } else {
						 ors.add(new And(ands));
					 }
					 ands.clear();
					 if (c == '|') {
						 state = S07;
					 } else {
						 state = S01;
					 }
				}
			} else if (state == S06) {
				// S06 = Found &, looking for & or other
				if (! WS.contains(c)) {
					if (c != '&')
						i--;
					state = S01;
				}
			} else /* (state == S07) */ {
				// S07 = Found |, looking for | or other
				if (! WS.contains(c)) {
					if (c != '|')
						i--;
					state = S01;
				}
			}
		}

		if (error)
			throw new ParseException("Invalid character in expression '"+expression+"' at position " + i + ". state=" + state, i);

		if (state == S01)
			throw new ParseException("Could not find beginning of clause in '"+expression+"'", i);
		if (state == S02)
			throw new ParseException("Could not find matching parenthesis in expression '"+expression+"'", i);
		if (state == S05 || state == S06 || state == S07)
			throw new ParseException("Dangling clause in expression '"+expression+"'", i);

		if (mark != -1)
			ands.add(parseOperand(expression.substring(mark, expression.length())));
		if (ands.size() == 1)
			ors.add(ands.get(0));
		else
			ors.add(new And(ands));

		if (ors.size() == 1)
			return ors.get(0);
		return new Or(ors);
	}