Recursive Descent Parser Program in C
The parsing process involves determining whether or not the given program is legitimate. It examines a string as input to see if it follows to the established grammar.
Parsers come in two varieties:
1. Top-Down Parser:
These parsers start at the tree's root and work their way down to its leaf. The Recursive Descent Parser and LL parsers are two examples of top-down parsers.
2. Bottom-Up Parsers:
With this parsing technique, the entire program is reduced to the start symbol. The Bottom-Up parsers are Operator Precedence Parser, LR(0) Parser, SLR Parser, LALR Parser, and CLR Parser.
What is a Recursive Descent Parser?
Continuative Descent Top-down parsers, like Parser, construct the parse tree from the root to the leaf. It recognizes the input using recursive functions and may or may not employ backtracking. Predictive parsing is another name for the recursive descent parser variant that does not require backtracking.
You can follow the several steps to utilize backtracking:
Now, we are going to create a separate program for each variable in the recursive descent parser.
Enter the string Input Action -------------------------------- i+(i+i)*i E -> T E' i+(i+i)*i T -> F T' +(i+i)*i F ->i +(i+i)*i T' -> $ +(i+i)*i E' -> + T E' (i+i)*i T -> F T' (i+i)*i F -> ( E ) i+i)*i E -> T E' i+i)*i T -> F T' +i)*i F ->i +i)*i T' -> $ +i)*i E' -> + T E' i)*i T -> F T' )*i F ->i )*i T' -> $ )*i E' -> $ *i T' -> * F T' F ->i T' -> $ E' -> $ -------------------------------- String is successfully parsed
Recursive Descent Parser: Advantages and Drawbacks
There are several advantages and disadvantages of Recursive Descent Parser. Some main advantages and disadvantages of Recursive Descent Parser as follows: