Faster, better (recursive descent) expression parser.

[ginac.git] / check / time_parser.cpp

diff --git a/check/time_parser.cpp b/check/time_parser.cpp
new file mode 100644 (file)
index 0000000..ca35fb6
--- /dev/null
+++ b/check/time_parser.cpp
@@ -0,0 +1,79 @@
+#include <iostream>
+#include <string>
+#include <sstream>
+#include <cstddef>
+#include <cstdlib>
+#include <vector>
+#include <stdexcept>
+#include "ginac.h"
+#include "parser/parser.hpp"
+#include "timer.h"
+extern void randomify_symbol_serials();
+using namespace std;
+using namespace GiNaC;
+
+/// make a string "1+x+2*x^2+...+n*x^n"
+static string prepare_str(const unsigned n, const char x = 'x')
+{
+       ostringstream s;
+       s << x;
+       for (unsigned i = 2; i < n; i++)
+               s << '+' << i << '*' << x << '^' << i; 
+       return s.str();
+}
+
+void benchmark_and_cmp(const string& srep, double& t_new, double& t_old)
+{
+       parser the_parser;
+       timer RSD10;
+       RSD10.start();
+       ex e = the_parser(srep);
+       t_new = RSD10.read();
+       RSD10.stop();
+       if (t_new > 2.0)
+               cout << '.' << flush;
+
+       symtab syms = the_parser.get_syms();
+       const symbol x = find_or_insert_symbol("x", syms, true);
+       lst sl;
+       sl = x;
+       RSD10.start();
+       ex e2(srep, sl);
+       t_old = RSD10.read();
+       
+       if (t_old > 2.0)
+               cout << '.' << flush;
+
+       ex dif = (e - e2).expand();
+       if (!dif.is_zero()) {
+               cerr << "Got a difference: " << dif << endl;
+               throw std::logic_error("New and old parser give different results");
+       }
+}
+
+int main(int argc, char** argv)
+{
+       cout << "timing GiNaC parser..." << flush;
+       randomify_symbol_serials();
+       unsigned n_min = 1024;
+       unsigned n_max = 32768;
+       if (argc > 1)
+               n_max = atoi(argv[1]);
+
+       vector<double> times_new, times_old;
+       vector<unsigned> ns;
+       for (unsigned n = n_min; n <= n_max; n = n << 1) {
+               double t_new, t_old;
+               string srep = prepare_str(n);
+               benchmark_and_cmp(srep, t_new, t_old);
+               times_new.push_back(t_new);
+               times_old.push_back(t_old);
+               ns.push_back(n);
+       }
+
+       cout << "OK" << endl;
+       cout << "# terms  new parser, s  old parser, s" << endl;
+       for (size_t i = 0; i < times_new.size(); i++)
+               cout << " " << ns[i] << '\t' << times_new[i] << '\t' << times_old[i] << endl;
+       return 0;
+}