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/re2/unicode_groups.h

@@ -0,0 +1,64 @@
+// Copyright 2008 The RE2 Authors.  All Rights Reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#ifndef RE2_UNICODE_GROUPS_H_
+#define RE2_UNICODE_GROUPS_H_
+
+// Unicode character groups.
+
+// The codes get split into ranges of 16-bit codes
+// and ranges of 32-bit codes.  It would be simpler
+// to use only 32-bit ranges, but these tables are large
+// enough to warrant extra care.
+//
+// Using just 32-bit ranges gives 27 kB of data.
+// Adding 16-bit ranges gives 18 kB of data.
+// Adding an extra table of 16-bit singletons would reduce
+// to 16.5 kB of data but make the data harder to use;
+// we don't bother.
+
+#include <stdint.h>
+
+#include "util/utf.h"
+#include "util/util.h"
+
+namespace re2 {
+
+struct URange16 {
+    uint16_t lo;
+    uint16_t hi;
+};
+
+struct URange32 {
+    Rune lo;
+    Rune hi;
+};
+
+struct UGroup {
+    const char *name;
+    int sign; // +1 for [abc], -1 for [^abc]
+    const URange16 *r16;
+    int nr16;
+    const URange32 *r32;
+    int nr32;
+};
+
+// Named by property or script name (e.g., "Nd", "N", "Han").
+// Negated groups are not included.
+extern const UGroup unicode_groups[];
+extern const int num_unicode_groups;
+
+// Named by POSIX name (e.g., "[:alpha:]", "[:^lower:]").
+// Negated groups are included.
+extern const UGroup posix_groups[];
+extern const int num_posix_groups;
+
+// Named by Perl name (e.g., "\\d", "\\D").
+// Negated groups are included.
+extern const UGroup perl_groups[];
+extern const int num_perl_groups;
+
+} // namespace re2
+
+#endif // RE2_UNICODE_GROUPS_H_