Add benchmarks.

benches/eval_expression.rs

@@ -0,0 +1,43 @@
+#![feature(test)]
+
+///! Test evaluating expressions
+extern crate test;
+
+use rhai::{Engine, OptimizationLevel};
+use test::Bencher;
+
+#[bench]
+fn bench_eval_expression_single(bench: &mut Bencher) {
+    let script = "1";
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::None);
+
+    let ast = engine.compile_expression(script).unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}
+
+#[bench]
+fn bench_eval_expression_number_literal(bench: &mut Bencher) {
+    let script = "2 > 1";
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::None);
+
+    let ast = engine.compile_expression(script).unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}
+
+#[bench]
+fn bench_eval_expression_number_operators(bench: &mut Bencher) {
+    let script = "2 + 2 == 4";
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::None);
+
+    let ast = engine.compile_expression(script).unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}