Constraints and Update Rules Compiler

A compiler is provided to generate C++ code for the constraints and the update rules. First, the syntax of the language that is used to describe the constraints and the update rules is described. Second, the generated code is determined. Using a compiler instead of generic on-line evaluator for the constraints and the update rules has the following advantages:

• All constraints are saved in one text file (likewise the update rules). This makes the data entry very easy. We can add, update, and delete any constraint or update rule using any text editor.

• Complicated data structures are not required for evaluation.

• The database is very simple, which facilitates maintaining the design history.

• Format changes, or changes in the generated code require only changes to the compiler, and no changes in the system are required.

On the other hand, it has the following disadvantages:

• The generated code has to be included in the system and the whole system must be recompiled.

• A compiler needs to be implemented.

By analyzing the design constraints and the update rules, we constructed a simple description of the language to be input to the compiler. There are two options in this design, either to have one compiler for both the constraints and the rules, or to build two compilers, one for each. From the analysis of the constraints and the rules we found that there are many similarities between them; thus building one compiler for both is the logical option in this case.