This repository implements a transpiler which enables macros to be used for counter program descriptions, as a project for Prof. Howard Straubing's CSCI3384: Computability and Computational Complexity.
The transpilation can be generated by running python3 transpile_macros.py <input_file> <output_file>. The output_file can now be run using countermachine.py since the macros are unwrapped.
Accepted instructions are of the form:
<label>:
goto <label>
goto <label> if <var>=0
inc <var>
dec <var>
halt
call <func> <var1> ... <varN>
macro <func> <var1> ... <varN>:
endmacro
Note that the identifiers are expected to be alphanumeric (+ underscore).
A few limitations:
- Macro definitions cannot be nested
- Macros can only call previously defined macros (this prevents infinite calling recursion)
- Macros can only modify variables which are passed in as arguments (allowing easy implementation of namespaces)
- Macros cannot "jump" to a label outside of the macro definition
All these conditions are verified by the transpiler.
The program resolves colliding labels (i.e., due to repeated macro calls) by incrementing a hash. Macros are unwrapped recursively.
Sample cases are provided in tests/. Notably ok_1.mcp/ok_1.cp demonstrates how a 3-counter machine can be implemented using 2-counters via prime-factorization, aided by macros.