Script Editing for Recovery and Reversal in Textual User Interfaces

摘要

The report presents an approach to interactive user interfaces that applies two common tools: text editors and one-pass language processors. Comfortable interaction results from a novel cooperation between a transcript editor and reversible processors. The user types and edits the input part of a transcript. The processor updates the output part using an automatic undo/redo mechanism. The editor-processor connection is simple, loose, and compatible with the usual textual read and write statements. The same transcript editor can be used with processors implemented in different ways in different languages. Traditional conversational processors can evolve gradually to reversible operation. It describes methods for making parsers and interpreters reversible. For bottom-up parsing, a pop action is added to the usual shift-reduce actions, or simulated with a grammar transformation. Top-down recursive descent parsers are made reversible with exceptions in the Ada style. Computation with local attributes is trivial to reverse. For other computation, applicative or persistent data structures are suggested.