Discussion of Some Error Correction Techniques

Summary

Four techniques of error correction will be presented which to our knowledge have not yet been incorporated in a compiler. Three of these techniques allow automatic generation of the error correction module from a given LL(k)-grammar. They are

• dynamic reliability checking: possible corrections are checked, whether they allow for an error free analysis of a dynamically determined number of input symbols following the error place.

• partial back-up possibility: back-up information is provided in order to enable the parser to withdraw from error situations into which analysis might have been brought by some erroneous symbols before the place where the error was detected.

• dialog form of error correction: the user has the possibility to insert and/or delete symbols around the error place.

• adaptability to a special user environment: the system accepts the descriptions of (preferably) the most common errors, recognizes the described error situation and initiates error correction earlier and therefore in a more efficient manner than without such a description.

Although up to now they have been applied only to a LL(k)-based analyser these techniques are applicable to other parsing-methods as well. A more detailed presentation of these techniques is given in [2].