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src/sql/engine/expr/ob_expr_right.cpp

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+/**
+ * Copyright (c) 2021 OceanBase
+ * OceanBase CE is licensed under Mulan PubL v2.
+ * You can use this software according to the terms and conditions of the Mulan PubL v2.
+ * You may obtain a copy of Mulan PubL v2 at:
+ *          http://license.coscl.org.cn/MulanPubL-2.0
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PubL v2 for more details.
+ */
+
+#define USING_LOG_PREFIX SQL_ENG
+#include "ob_expr_right.h"
+#include <string.h>
+#include "lib/charset/ob_charset.h"
+#include "share/object/ob_obj_cast.h"
+#include "sql/parser/ob_item_type.h"
+#include "sql/session/ob_sql_session_info.h"
+
+using namespace oceanbase::common;
+using namespace oceanbase::sql;
+
+namespace oceanbase {
+namespace sql {
+
+ObExprRight::ObExprRight(ObIAllocator& alloc) : ObStringExprOperator(alloc, T_FUN_SYS_RIGHT, "right", 2)
+{}
+
+ObExprRight::~ObExprRight()
+{}
+
+int ObExprRight::calc_result_type2(
+    ObExprResType& type, ObExprResType& type1, ObExprResType& type2, ObExprTypeCtx& type_ctx) const
+{
+  int ret = OB_SUCCESS;
+  type2.set_calc_type(ObIntType);
+  type_ctx.set_cast_mode(type_ctx.get_cast_mode() | CM_STRING_INTEGER_TRUNC);
+  type.set_varchar();
+  type.set_length(type1.get_length());
+  OZ(aggregate_charsets_for_string_result(type, &type1, 1, type_ctx.get_coll_type()));
+  OX(type1.set_calc_type(ObVarcharType));
+  OX(type1.set_calc_collation_type(type.get_collation_type()));
+  return ret;
+}
+
+int do_right(const ObString& input_value, const ObCollationType& cs_type, const int64_t length, ObString& res_str)
+{
+  int ret = OB_SUCCESS;
+  const char* input_start = input_value.ptr();
+  int64_t input_length = input_value.length();
+  if (OB_ISNULL(input_start) && 0 != input_length) {
+    LOG_WARN("String invalid", K(input_start), K(input_length));
+  } else {
+    int64_t char_beyond_end = input_length;
+    int64_t wanted = min(length, input_length);
+    int64_t got = 0;
+    int64_t char_length = 0;
+    while (OB_SUCC(ret) && (got < wanted) && (-1 < char_beyond_end)) {
+      if (OB_FAIL(ObCharset::last_valid_char(cs_type, input_start, char_beyond_end, char_length))) {
+        LOG_WARN("Get last valid char failed ", K(ret));
+      } else {
+        char_beyond_end -= char_length;
+        ++got;
+      }
+    }
+    if (OB_SUCC(ret)) {
+      res_str.assign_ptr(input_start + char_beyond_end, static_cast<int32_t>(input_length - char_beyond_end));
+    }
+  }
+  return ret;
+}
+
+int ObExprRight::calc_result2(ObObj& result, const ObObj& obj1, const ObObj& obj2, ObExprCtx& expr_ctx) const
+{
+  int ret = OB_SUCCESS;
+  UNUSED(expr_ctx);
+  if (obj1.is_null() || obj2.is_null()) {
+    result.set_null();
+  } else {
+    TYPE_CHECK(obj2, ObIntType);
+    int64_t length = obj2.get_int();
+    ObString res_str;
+    if (OB_FAIL(do_right(obj1.get_string(), obj1.get_collation_type(), length, res_str))) {
+      LOG_WARN("Failed to calc", K(ret));
+    } else {
+      result.set_varchar(res_str);
+      result.set_collation(result_type_);
+    }
+  }
+  return ret;
+}
+
+int calc_right_expr(const ObExpr& expr, ObEvalCtx& ctx, ObDatum& res_datum)
+{
+  int ret = OB_SUCCESS;
+  // right(s, n)
+  ObDatum* s_datum = NULL;
+  ObDatum* n_datum = NULL;
+  if (OB_FAIL(expr.args_[0]->eval(ctx, s_datum)) || OB_FAIL(expr.args_[1]->eval(ctx, n_datum))) {
+    LOG_WARN("eval arg failed", K(ret), KP(s_datum), KP(n_datum));
+  } else if (s_datum->is_null() || n_datum->is_null()) {
+    res_datum.set_null();
+  } else {
+    ObString res_str;
+    const ObCollationType arg_cs_type = expr.args_[0]->datum_meta_.cs_type_;
+    if (OB_FAIL(do_right(s_datum->get_string(), arg_cs_type, n_datum->get_int(), res_str))) {
+      LOG_WARN("failed to calculate right expression", K(ret));
+    } else {
+      if (res_str.empty() && is_oracle_mode()) {
+        res_datum.set_null();
+      } else {
+        res_datum.set_string(res_str);
+      }
+    }
+  }
+  return ret;
+}
+
+int ObExprRight::cg_expr(ObExprCGCtx& expr_cg_ctx, const ObRawExpr& raw_expr, ObExpr& rt_expr) const
+{
+  int ret = OB_SUCCESS;
+  UNUSED(expr_cg_ctx);
+  UNUSED(raw_expr);
+  rt_expr.eval_func_ = calc_right_expr;
+  return ret;
+}
+
+}  // namespace sql
+}  // namespace oceanbase