RAGFlow go API server (#13240)

# RAGFlow Go Implementation Plan 🚀

This repository tracks the progress of porting RAGFlow to Go. We'll
implement core features and provide performance comparisons between
Python and Go versions.

## Implementation Checklist

- [x] User Management APIs
- [x] Dataset Management Operations
- [x] Retrieval Test
- [x] Chat Management Operations
- [x] Infinity Go SDK

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>
Co-authored-by: Yingfeng Zhang <yingfeng.zhang@gmail.com>

internal/cpp/wordnet_lemmatizer.h

@@ -0,0 +1,52 @@
+// Copyright(C) 2024 InfiniFlow, Inc. All rights reserved.
+//
+// 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
+//
+//     https://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.
+
+#pragma once
+
+#include <string>
+#include <vector>
+#include <unordered_map>
+#include <unordered_set>
+
+class WordNetLemmatizer {
+public:
+    explicit
+    WordNetLemmatizer(const std::string &wordnet_path);
+
+    ~WordNetLemmatizer();
+
+    int32_t Load();
+
+    std::string Lemmatize(const std::string &form, const std::string &pos = "");
+
+private:
+    int32_t LoadLemmas();
+
+    void LoadExceptions();
+
+    std::vector<std::string> Morphy(const std::string &form, const std::string &pos, bool check_exceptions = true);
+
+    std::vector<std::string> CollectSubstitutions(const std::vector<std::string> &forms, const std::string &pos);
+    std::vector<std::string> CollectSubstitutions(const std::string &form, const std::string &pos);
+
+    std::vector<std::string> FilterForms(const std::vector<std::string> &forms, const std::string &pos);
+
+    std::string wordnet_path_;
+
+    std::unordered_map<std::string, std::unordered_set<std::string>> lemmas_;
+    std::unordered_map<std::string, std::unordered_map<std::string, std::vector<std::string>>> exceptions_;
+    std::unordered_map<std::string, std::vector<std::pair<std::string, std::string>>> MORPHOLOGICAL_SUBSTITUTIONS;
+    std::vector<std::string> POS_LIST;
+    std::unordered_map<std::string, std::string> file_map_;
+};