![]() Efficient top-down and bottom-up parsers can be implemented only for sub-classes of context-free grammars. ![]() Bottom-Up Parser the parse tree is created from bottom to top, starting from the leaves Both top-down and bottom-up parsers scan the input from left to right and one symbol at a time. ![]() The Role of the Parser We categorize the parsers into two groups: Top-Down Parser the parse tree is created from top to bottom, starting from the root. Otherwise the parser gives the error messages If it satisfies, the parser creates the parse tree of that program. The syntax analyzer (parser) checks whether a given source program satisfies the rules implied by a context-free grammar or not. ![]() We will use BNF (Backus-Naur Form) notation in the description of CFG ’s. The syntax of a programming is described by a context-free grammar (CFG). This syntactic structure is mostly a parse tree. Syntax Analyzer gets a stream of tokens from lexical analyzer and creates the syntactic structure of the given source program. The Role of the Parser Syntax Analyzer is also known as parser. THE ROLE OF THE PARSER Lexical Analyzer Parser source program token get next token parse tree Symbol table MODULE II Role of the Parser Context Free Grammars Top down Parsing Bottom Up Parsing Operator Precedence Parsing LR Parsers SLR Canonical LR LALR Parser Generator CS 04 605 COMPILER DESIGN Text book: Compilers,principles,techniques,and tools by Alfred V Aho,Ravi Sethi,Jeffrey D Ullman
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |