add complex test

tests/complex/test.cpp

@@ -0,0 +1,32 @@
+#include <lars/parser_generator.h>
+#include <lars/event.h>
+
+int main() {
+  // Define the return value
+  int result = 1;
+
+  // Define grammar and evaluation rules
+  lars::ParserGenerator<float> g;
+  g.setSeparator(g["Whitespace"] << "[\t ]");
+  g["Sum"     ] << "Add | Subtract | Product";
+  g["Product" ] << "Multiply | Divide | Atomic";
+  g["Atomic"  ] << "Number | '(' Sum ')'";
+  g["Add"     ] << "Sum '+' Product"    >> [](auto e){ return e[0].evaluate() + e[1].evaluate(); };
+  g["Subtract"] << "Sum '-' Product"    >> [](auto e){ return e[0].evaluate() - e[1].evaluate(); };
+  g["Multiply"] << "Product '*' Atomic" >> [](auto e){ return e[0].evaluate() * e[1].evaluate(); };
+  g["Divide"  ] << "Product '/' Atomic" >> [](auto e){ return e[0].evaluate() / e[1].evaluate(); };
+  g["Number"  ] << "'-'? [0-9]+ ('.' [0-9]+)?" >> [](auto e){ return stof(e.string()); };
+  g.setStart(g["Sum"]);
+
+  // Execute a string
+
+  // create an event
+  lars::Event<float> onResult;
+  onResult.connect([&](float v){ result = !(int(v) == 5); });
+  
+  // emit the result of a parsed string
+  onResult.notify(g.run("1 + 2 * (3+4)/2 - 3"));
+
+  // return the result
+  return result;
+}