Shift Reduce Parser
The shift-down parser constructs a Parse tree in a similar manner as that of the bottom-up Parser.
It constructs the parse tree from the bottom also called the leaves to the top also called the root.
The Shift-Down Parser needs some basic data Structures:
- It requires a buffer to store the input Strings.
- And a stack to access and store the production rules.
Basic Operations in Shift Reduce Parser
- Shift: It moves symbols from the input buffer to the stack
- Reduce: If the handle appears on the top of the stack then, its reduction by using appropriate production rules is done.
- Accept: If the input buffer is empty and contains only the start symbol, then this action is called the Parser. The parsing is successful when the accept action is achieved.
- Error: When neither of the shift, reduce or the accept actions can be performed, then this action is called Error.
Reference Link