Explain any three parsing techniques.
Following are three parsing techniques:
Top-down parsing: This parsing can be viewed as an attempt to get left-most derivations of an input-stream through searching for parse trees by using a top-down expansion of the specified formal grammar rules. Tokens are used from left to right. Inclusive option is used to accommodate ambiguity through expanding all alternative right- hand-sides of grammar rules.
Bottom-up parsing: A parser can begin with the input and attempt to rewrite this to the start symbol. Instinctively, the parser attempts to place the most fundamental elements, then the elements having these, and so on. LR parsers are illustrations of bottom-up parsers. The other term used for this type parser is Shift-Reduce parsing.
Recursive descent parsing: This is a top down parsing without backtracking. This parsing technique utilizes a set of recursive processes to perform parsing. Salient features of recursive descent parsing are its generality and simplicity. This can be implemented in any language supporting recursive procedures.