On the beach

2005-06-26T13:26:00.000-07:00

The summer is near. You will certainly want to be seen with Transformers project on the beach (like me), specially with version 0.4 (soon). But 0.4 will need more resources than ever. First, you will have to buy a 512 MB ram chip. But the challenge is not here. You will not want your computer to stop during compilation. But this summer, temperature will be hot, and your CPU may be hurt. I have the solution. Take a bucket. Put some bottle of ice in it like shown on the picture below. Then put you computer on this bucket. Your CPU will always be cold enough. You will ask me how to put ice in the bottle because the hole is too tight. Do not worry, i have the solution too. It is better you to fill the bottle with liquid water and then put it into the freezer. But you can try to put the ice in the hole with strenght as well if you are so masochist to trying to use Transformers on the beach.

Attribute grammar evaluation

2005-06-02T10:35:00.000-07:00

In the Transformers project, the disambiguation of C and C++ is made with an attribute grammar. The old system was using a greedy algorithm just for tests. But now, we need a faster system. I have tested to develop a new system using lazy evaluation. First, i have made a library for Stratego . A part was written in Stratego, only strategies to get and call pointers of strategies were written in C. But there is a graph. This graph was written with ATerm hash-tables. I did not finished to evaluate stdio.h. 1 line of typedef took 1s of evaluation. When profiling a little exemple that took approximatively 31s on a XP2400+, about 0.5s where used for the tree traversal (I think less because of problem of approximations during profiling). 0.12s where used for evaluation code. All the rest of time was used by the graph. I have written all the graph dependency resolution in C. It is not comparable. The evaluation of stdio.h (in asfix) takes now 0.99s. SGLR takes 7s to parse it, the ambiguity pruning (according to the evaluation results) takes 0.5s and implode-asfix takes 1.40s on the disambiguated tree.

Now the compilation time has to be resolved. The generated evaluator for C syntax, is about 16klines of Stratego. It takes 45 minutes to be translated into C.