Introduction - If you have any usage issues, please Google them yourself
each programming language has described procedures grammatical structure of rules. For example, Pascal procedures block (also known as sub-procedures), with procedures block composed by the statement, statement by the composition of expression, etc. from the component mark. These rules can be used context-free grammar or paradigm BNF (Backus- Naur Form) Description. Compiler grammar analysis of the commonly used methods are both top-down and bottom-up. As their name implies, top-down analysis of the establishment of analyzers from the root node of the tree to the leaf nodes, and the bottom-up analyzer exactly the contrary. The common denominator is to scan from left to right input, each a symbol. The most effective top-down and bottom-up analysis can only deal with