Displays
The array of pointer which is used to access activation records is known as displays,
For each level, Moro will be an array wary a;; given below
Current activation record at level 1.
Current activation record at level 2.
Current activation record at level 3,.
Error Detection and Recovery
- The parser should be able to five an error free message which should be meaningful.
- The parser should also be capable of recovering from the errors and it should be able enough to continue the parsing with the rest of the input.
Error Recovery Techniques
Panic Mode Error Recovery
Skipping the input symbols until a synchronising token is found.
Phrase Level Error Recovery
Each empty entry in the parsing table is filled with a pointer to a specific error routine to take care that error case.
Error Productions
If we have a good idea of the common errors that might be encountered, we can augment the grammar with productions that generate erroneous constructs. When an error production is used by the parser, we can generate appropriate error diagnostics. Since, it is almost impossible to know all the errors that can be made by the programmers, this method Is not practical.
Global Correction
Ideally, we would like a compiler to make as few changes as possible in processing incorrect inputs. We have to globally analyze the input to find the error. This is an expensive method and it is not in practice.