Compiling Graph Programs to C

We show how to generate efficient C code for a high-level domain-specific language for graphs. The experimental language GP 2 is based on graph transformation rules and aims to facilitate formal reasoning on programs. Implementing graph programs is challenging because rule matching is expensive in general. GP 2 addresses this problem by providing rooted rules which under mild conditions can be matched in constant time. Using a search plan, our compiler generates C code for matching rooted graph transformation rules. We present run-time experiments with our implementation in a case study on checking graphs for two-colourability: on grid graphs of up to 100,000 nodes, the compiled GP 2 program is as fast as the tailor-made C program given by Sedgewick.