private static List participle()

in common/src/main/java/org/apache/rocketmq/common/filter/impl/PolishExpr.java [89:165]
66 lines of code
29 McCabe index (conditional complexity)

    private static List<Op> participle(String expression) {
        List<Op> segments = new ArrayList<>();

        int size = expression.length();
        int wordStartIndex = -1;
        int wordLen = 0;
        Type preType = Type.NULL;

        for (int i = 0; i < size; i++) {
            int chValue = (int) expression.charAt(i);

            if (97 <= chValue && chValue <= 122 || 65 <= chValue && chValue <= 90
                || 49 <= chValue && chValue <= 57 || 95 == chValue) {

                if (Type.OPERATOR == preType || Type.SEPAERATOR == preType || Type.NULL == preType
                    || Type.PARENTHESIS == preType) {
                    if (Type.OPERATOR == preType) {
                        segments.add(createOperator(expression.substring(wordStartIndex, wordStartIndex
                            + wordLen)));
                    }
                    wordStartIndex = i;
                    wordLen = 0;
                }
                preType = Type.OPERAND;
                wordLen++;
            } else if (40 == chValue || 41 == chValue) {

                if (Type.OPERATOR == preType) {
                    segments.add(createOperator(expression
                        .substring(wordStartIndex, wordStartIndex + wordLen)));
                    wordStartIndex = -1;
                    wordLen = 0;
                } else if (Type.OPERAND == preType) {
                    segments.add(new Operand(expression.substring(wordStartIndex, wordStartIndex + wordLen)));
                    wordStartIndex = -1;
                    wordLen = 0;
                }

                preType = Type.PARENTHESIS;
                segments.add(createOperator((char) chValue + ""));
            } else if (38 == chValue || 124 == chValue) {

                if (Type.OPERAND == preType || Type.SEPAERATOR == preType || Type.PARENTHESIS == preType) {
                    if (Type.OPERAND == preType) {
                        segments.add(new Operand(expression.substring(wordStartIndex, wordStartIndex
                            + wordLen)));
                    }
                    wordStartIndex = i;
                    wordLen = 0;
                }
                preType = Type.OPERATOR;
                wordLen++;
            } else if (32 == chValue || 9 == chValue) {

                if (Type.OPERATOR == preType) {
                    segments.add(createOperator(expression
                        .substring(wordStartIndex, wordStartIndex + wordLen)));
                    wordStartIndex = -1;
                    wordLen = 0;
                } else if (Type.OPERAND == preType) {
                    segments.add(new Operand(expression.substring(wordStartIndex, wordStartIndex + wordLen)));
                    wordStartIndex = -1;
                    wordLen = 0;
                }
                preType = Type.SEPAERATOR;
            } else {

                throw new IllegalArgumentException("illegal expression, at index " + i + " " + (char) chValue);
            }

        }

        if (wordLen > 0) {
            segments.add(new Operand(expression.substring(wordStartIndex, wordStartIndex + wordLen)));
        }
        return segments;
    }