LR分析法是一种自下而上进行规范归约的语法分析法，L指从左到右扫描输入符号串，R是指构造最右推导的逆过程。对大多数无二义性上下文无关文法描述的语言都可用它进行有效的分析。主要分析器有LR（0），SLR（1），LR（1），LALR（1）：



LR（0）：在分析的每一步，只需根据当前栈顶状态而不必向前查看输入符号就能确定应采取的分析动作。所能分析的LR（0）文法要求文法的每一个LR（0）项目集中都不含冲突项目。

-LR analysis is a bottom-up norms to reduce the syntax analysis method, L refers to input symbol string scanning from left to right, R refers to the right structure of the inverse process of deduction. Goes for the justice for the majority of context-free grammar of the language to describe it are available for effective analysis. The main analyzer are LR (0), SLR (1), LR (1), LALR (1): LR (0): every step of the analysis, just the light of the current Top-state without having to enter the symbols on the forward view can be analyzed to determine actions to be taken. Beyond the analysis of LR (0) grammar requirements of each grammar LR (0) projects focus on the project are free of conflict.