Interface for hidl forward reference test

Test proofs that forward reference can now be used.
Test contains trie implementation and some forward reference examples.

Bug: 31827278

Test: hidl_test

Change-Id: I55cdde500baea3e70ebf4466c681ad652b6ff9fd
diff --git a/tests/trie/1.0/default/Trie.h b/tests/trie/1.0/default/Trie.h
new file mode 100644
index 0000000..c2ef40b
--- /dev/null
+++ b/tests/trie/1.0/default/Trie.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_TESTS_TRIE_V1_0_TRIE_H
+#define ANDROID_HARDWARE_TESTS_TRIE_V1_0_TRIE_H
+
+#include <android/hardware/tests/trie/1.0/ITrie.h>
+#include <hidl/Status.h>
+
+#include <string>
+
+namespace android {
+namespace hardware {
+namespace tests {
+namespace trie {
+namespace V1_0 {
+namespace implementation {
+
+using ::android::hardware::Return;
+using ::android::hardware::Void;
+using ::android::hardware::hidl_string;
+using ::android::hardware::hidl_vec;
+using ::android::hardware::tests::trie::V1_0::ITrie;
+using ::android::hardware::tests::trie::V1_0::TrieNode;
+
+struct Trie : public ITrie {
+    // Methods from ::android::hardware::tests::trie::V1_0::ITrie follow.
+    virtual Return<void> newTrie(newTrie_cb _hidl_cb) override;
+    virtual Return<void> addStrings(const TrieNode& trie, const hidl_vec<hidl_string>& strings,
+                                    addStrings_cb _hidl_cb) override;
+    virtual Return<void> containsStrings(const TrieNode& trie, const hidl_vec<hidl_string>& strings,
+                                         containsStrings_cb _hidl_cb) override;
+
+   private:
+    void addString(TrieNode* trieRoot, const std::string& str);
+    bool containsString(const TrieNode* trieRoot, const std::string& str);
+};
+
+extern "C" ITrie* HIDL_FETCH_ITrie(const char* name);
+
+}  // namespace implementation
+}  // namespace V1_0
+}  // namespace trie
+}  // namespace tests
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_TESTS_TRIE_V1_0_TRIE_H