Hi all, I have a model with variables, let's call them a, b, c, ..., z. These are numerical values (time series loaded from a database) and I let the user specify their relationships in a JSON, say 'z = 12; x = a + 2/3 + 3*c; y = log(12*f) + exp(g)' etc. The syntax is trivial - it's basically just algebraic relationships + a few functions (log, log2, log10, exp, trigonometrics, ...; all 1:1 mappings to their math package equivalents).
Now, I get these relationships in a JSON and I parse them using go/parser. Then I walk the tree once and process it a bit - replacing keywords by pointers to my variable stores, replacing all the log/exp/sin with function pointers, leaving literals be literals etc. Each node is then a struct with a type and the actual contents (sadly a generic interface, because the value can be almost anything). The prep stage is now over. When actually running the model, I loop through years and within each year I solve each variable - I walk the tree and evaluate it where needed. The only non-trivial action is when I get to a model variable, I need to do a bit of lookup (it's a time series, so I need to look up the correct time period and other bits). Otherwise it's just literals, operators and function calls, all of which is fairly straightforward. This is all well and good. One of the issues is that it's rather slow. I thought it would be the recursive nature (and interface assertions), but converting all this into a shunting yard system didn't improve the performance dramatically. I've profiled the thing and removed a few hotspots, my question is not about profiling. I'm after a bit more general advice on how to handle these runtime evaluations and if there are better ways of doing so. Essentially some sort of a JIT (but Go does not have runtime assembly, right?), or maybe convert each expression into a closure or maybe a whole different algorithm or...? Thank you! -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
