add benches for find slicing

regex bench without cache
                        time:   [85.023 µs 85.199 µs 85.434 µs]
Found 18 outliers among 100 measurements (18.00%)
  4 (4.00%) high mild
  14 (14.00%) high severe

regex bench with cache  time:   [550.84 ns 551.27 ns 551.69 ns]
Found 2 outliers among 100 measurements (2.00%)
  2 (2.00%) high severe

Cargo.toml

@@ -20,3 +20,8 @@ thiserror = "1.0.50"
 
 [dev-dependencies]
 lazy_static = "1.0"
+criterion = "0.5.1"
+
+[[bench]]
+name = "regex_bench"
+harness = false

benches/regex_bench.rs

@@ -0,0 +1,41 @@
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use jsonpath_rust::{JsonPathInst, JsonPathQuery};
+use serde_json::json;
+use std::str::FromStr;
+
+struct SearchData {
+    json: serde_json::Value,
+    path: JsonPathInst,
+}
+
+const PATH: &'static str = "$.[?(@.author ~= '.*(?i)d\\(Rees\\)')]";
+
+fn path_with_cache(cfg: &SearchData) {
+    let _v = jsonpath_rust::find(&cfg.path, &cfg.json);
+}
+
+fn path_without_cache() {
+    let json = Box::new(json!({
+        "author":"abcd(Rees)",
+    }));
+
+    let _v = json.path(PATH).expect("the path is correct");
+}
+
+pub fn criterion_benchmark(c: &mut Criterion) {
+    let data = SearchData {
+        json: json!({
+            "author":"abcd(Rees)",
+        }),
+        path: JsonPathInst::from_str("$..book[?(@.author size 10)].title").unwrap(),
+    };
+    c.bench_function("regex bench without cache", |b| {
+        b.iter(|| path_without_cache())
+    });
+    c.bench_function("regex bench with cache", |b| {
+        b.iter(|| path_with_cache(&data))
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);