An automated screen interface generator for Pascal programs

One problem of executing a program is that the program aborts when input errors occur at runtime. Screen Pascal overcomes this problem by performing validity checks on the input data and by providing help messages at runtime. To do this it requires some information which is gathered during a preprocessing phase by interacting with the programmer. This dialogue with the programmer is used to design the frames which are to be displayed at runtime. However, it is tedious because if the programmer types in wrong information, then the preprocessing has to be done all over again. This thesis develops a program which automatically generates the required dialogue based on an analysis of the user source code. The source code is analyzed and all the declarations are stored in a symbol table. The information stored in the symbol table is used to generate validity checks for the type, range and constraints of each input variable. Similarly, help messages regarding the size of arrays, the possible values of an enumerated type, the range of a subrange type, etc., are derived from the symbol table. Theses assist the user in correcting data entry errors. The frame layout design arranges fields for the input variables on the display. Several techniques like video attributes and other CRT features are used to increase the screen readability. This system is running on the VAX/VMS and has been applied to several examples.