Interpreter for CCS language (Calculus of Communicating Systems) written in SWI-Prolog.

Project for the Principles for Software Composition course 2020/2021 @ UniPi.

In addition to the parsing and execution of a CCS script, it is also possible to produce the derivation tree of a run, possibly saving it in a .tex file.

The source code has been split in 4 different files:

• /src/ccs.pl: main file of the project, contains macros to use the interpreter more easily;
• /src/parser.pl: parsing of a CCS code written using the same syntax allowed by CAAL;
• /src/interpreter.pl: operational semantics of CCS;
• /src/utils.pl: contains some utilities to write a derivation tree in LaTeX;

First, be sure to run SWI-Prolog and load the main file of the project:

swipl -s src/ccs.pl

To execute one step of your CCS code, you can use execute_step. Generally, you may want to pass your source code and the program starting point:

execute_step("P = done.0;", var('P'), A, T, D).

Which will produce:

A = in(done),
T = nil,
D = infer(const, red(var('P'), in(done), nil), [infer(pre, red(pre(in(done), nil), in(done), nil), []), infer('', in('P', pre(in(done), nil)), [])]) .

Where A is the action consumed in the step, T is the Target process after consuming A and D is the derivation tree.

You can also put your code in a separated file and then use execute_step_from_file to run it. Suppose you have a file test.ccs containing the CCS code written above, you can run it using:

execute_step_from_file('test.ccs', var('P'), A, T, D).

If you want to run more than one single step, you can use execute or execute_from_file.

To obtain a more readable derivation tree, you can write it in LaTeX using write_derivation_to_tex. An example usage of the predicate is the following:

execute_step("P = (x.0 | 'x.0) \\ {x};", var('P'), A, T, D), write_derivation_to_tex(D, 'out.tex').

Tests are located in /tests directory. You can run one of them using the command:

swipl -g run_tests -t halt PATH_TO_TEST