根据规定的规则获取文档的出现次数

I'm having a huge difficulty in creating a program to check the number of occurrences of a document based on rules set by me. With the help of regex, I check some fields, and if a particular field exists , I can count the number of occurrences of it, or I create a deeper scan. It's a little confusing, and I do not know exactly how to explain.I'm having a huge difficulty in creating a prog