说明：  这是编译原理的源代码，涉及了编译原理的各个过程：词法分析，LL1语法分析，语义分析，中间代码生成，中间代码优化,中间代码生成目标代码，目标代码的解释执行
(This is the principle of compiling source code, the various principles involved in the compilation process: lexical analysis, LL1 parsing, semantic analysis, intermediate code generation, intermediate code optimization (regular expression optimization, public expression optimization, loop invariant optimization) , intermediate code generation object code, object code interpretation of the implementation of detailed description of a compiler design and implementation. It is the outline of teaching, curriculum design, a good model, but also a good reference to improve programming enthusiasts, of which this is part of the intermediate code generation object code. Hope for an early opening of my account, and we interact more, to become good friends who love programming.)