private NameState findMatchPattern()

in src/main/software/amazon/event/ruler/ByteMachine.java [998:1049]
41 lines of code
13 McCabe index (conditional complexity)

    private NameState findMatchPattern(final InputCharacter[] characters, final Patterns pattern) {
        Set<SingleByteTransition> transitionsToProcess = new HashSet<>();
        transitionsToProcess.add(startState);
        ByteTransition shortcutTrans = null;

        // Iterate down all possible paths in machine that match characters.
        outerLoop: for (int i = 0; i < characters.length - 1; i++) {
            Set<SingleByteTransition> nextTransitionsToProcess = new HashSet<>();
            for (SingleByteTransition trans : transitionsToProcess) {
                ByteTransition nextTrans = getTransition(trans, characters[i]);
                for (SingleByteTransition eachTrans : nextTrans.expand()) {

                    // Shortcut and stop outer character loop
                    if (SHORTCUT_MATCH_TYPES.contains(pattern.type()) && eachTrans.isShortcutTrans()) {
                        shortcutTrans = eachTrans;
                        break outerLoop;
                    }

                    SingleByteTransition nextByteState = eachTrans.getNextByteState();
                    if (nextByteState == null) {
                        continue;
                    }

                    // We are interested in the first state that hasn't simply led back to trans
                    if (trans != nextByteState) {
                        nextTransitionsToProcess.add(nextByteState);
                    }
                }
            }
            transitionsToProcess = nextTransitionsToProcess;
        }

        // Get all possible transitions for final character.
        Set<ByteTransition> finalTransitionsToProcess = new HashSet<>();
        if (shortcutTrans != null) {
            finalTransitionsToProcess.add(shortcutTrans);
        } else {
            for (SingleByteTransition trans : transitionsToProcess) {
                finalTransitionsToProcess.add(getTransition(trans, characters[characters.length - 1]));
            }
        }

        // Check matches for all possible final transitions until we find the pattern we are looking for.
        for (ByteTransition nextTrans : finalTransitionsToProcess) {
            for (ByteMatch match : nextTrans.getMatches()) {
                if (match.getPattern().equals(pattern)) {
                    return match.getNextNameState();
                }
            }
        }
        return null;
    }