[FEAT MERGE]4_1_sql_feature

Co-authored-by: leslieyuchen <leslieyuchen@gmail.com>
Co-authored-by: Charles0429 <xiezhenjiang@gmail.com>
Co-authored-by: raywill <hustos@gmail.com>

src/sql/resolver/expr/ob_shared_expr_resolver.h

@@ -0,0 +1,94 @@
+// (C) Copyright 2022 Alibaba Inc. All Rights Reserved.
+//  Authors:
+//    link.zt <link.zt@antfin.com>
+//  Normalizer:
+//
+//
+
+#ifndef OB_SHARED_EXPR_RESOLVER_H
+#define OB_SHARED_EXPR_RESOLVER_H
+
+#include "sql/resolver/expr/ob_raw_expr.h"
+
+namespace oceanbase {
+namespace sql {
+
+struct JoinedTable;
+struct TableItem;
+struct ObQuestionmarkEqualCtx : public ObExprEqualCheckContext
+{
+  ObQuestionmarkEqualCtx(bool need_check_deterministic = false):
+    ObExprEqualCheckContext(need_check_deterministic)
+  {
+    override_const_compare_ = true;
+  }
+
+  bool compare_const(const ObConstRawExpr &left,
+                     const ObConstRawExpr &right);
+
+  ObSEArray<ObPCParamEqualInfo, 4> equal_pairs_;
+};
+
+struct ObRawExprEntry
+{
+  ObRawExprEntry()  :expr_(NULL), stmt_scope_(0), hash_code_(0)
+  { }
+
+  ObRawExprEntry(ObRawExpr *expr, uint64_t scope_id, uint64_t hash_code)
+    : expr_(expr), stmt_scope_(scope_id), hash_code_(hash_code)
+  {}
+
+  bool compare(const ObRawExprEntry &node,
+               ObQuestionmarkEqualCtx &cmp_ctx) const;
+
+  TO_STRING_KV(K_(hash_code), K_(expr));
+
+  ObRawExpr *expr_;
+  uint64_t stmt_scope_;
+  uint64_t hash_code_;
+};
+
+class ObSharedExprResolver
+{
+public:
+  ObSharedExprResolver(ObQueryCtx *query_ctx)
+    : allocator_("MergeSharedExpr"),
+      scope_id_(0),
+      query_ctx_(query_ctx)
+  {}
+
+  virtual ~ObSharedExprResolver();
+
+  int get_shared_instance(ObRawExpr *expr,
+                          ObRawExpr *&shared_expr,
+                          bool &is_new);
+
+  int add_new_instance(ObRawExprEntry &entry);
+
+  uint64_t get_scope_id() const { return scope_id_; }
+
+  void set_new_scope() { scope_id_ ++; }
+
+  void revert_scope() { scope_id_ = 0; }
+
+  uint64_t hash_expr_tree(ObRawExpr *expr, uint64_t hash_code, const bool is_root = true);
+
+private:
+
+  int inner_get_shared_expr(ObRawExprEntry &entry,
+                            ObRawExpr *&new_expr);
+
+private:
+  typedef ObSEArray<ObRawExprEntry, 1> SharedExprs;
+
+  ObArenaAllocator allocator_;
+  hash::ObHashMap<uint64_t, SharedExprs *> shared_expr_map_;
+
+  uint64_t scope_id_;
+
+  ObQueryCtx *query_ctx_;
+};
+
+}
+}
+#endif // OB_SHARED_EXPR_RESOLVER_H