feat: implement more stl wrappers (#648)

Signed-off-by: Yuchen Liang <[email protected]>

src/include/storage/index/stl_equal_wrapper.h

@@ -0,0 +1,15 @@
+#pragma once
+
+namespace bustub {
+
+template <typename K, typename KC>
+class StlEqualWrapper {
+ public:
+  explicit StlEqualWrapper(const KC &cmp) : cmp_{cmp} {}
+
+  inline auto operator()(const K &lhs, const K &rhs) const -> bool { return cmp_(lhs, rhs) == 0; }
+
+  KC cmp_;
+};
+
+}  // namespace bustub

src/include/storage/index/stl_hasher_wrapper.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include "container/hash/hash_function.h"
+
+namespace bustub {
+
+template <typename K>
+class StlHasherWrapper {
+ public:
+  explicit StlHasherWrapper(const HashFunction<K> &hash_fn) : hash_fn_{hash_fn} {}
+
+  inline auto operator()(const K &key) const -> std::size_t { return hash_fn_.GetHash(key); }
+
+  HashFunction<K> hash_fn_;
+};
+
+}  // namespace bustub