Introduction STP is a stack based expression parser. This article will first explain the parsing of four expressions, including binary and group expressions. Then it analyzes the basic expressions in programming language, such as GET, SET, UNARY, CALL and so on. The advantage is that you only need to traverse the tokens array once, set the priority and judge the relationship between the front and back token. Stack structure if a very simple data structure, PEEK the top value, POP the top value, PUSH value, first in first out principle. STP contains two stack and a top operator variable, the structure is as follows: Refer to PDF paper: https://bingxio.fun/STP.pdf