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src/sql/engine/expr/ob_expr_elt.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 "sql/engine/expr/ob_expr_elt.h"
+#include "sql/session/ob_sql_session_info.h"
+#include "sql/engine/expr/ob_expr_equal.h"
+
+using namespace oceanbase::common;
+using namespace oceanbase::sql;
+
+namespace oceanbase {
+namespace sql {}
+}  // namespace oceanbase
+
+ObExprElt::ObExprElt(ObIAllocator& alloc)
+    : ObExprOperator(alloc, T_FUN_SYS_ELT, N_ELT, MORE_THAN_ONE, NOT_ROW_DIMENSION)
+{}
+
+int ObExprElt::calc_result_typeN(
+    ObExprResType& type, ObExprResType* types_stack, int64_t param_num, ObExprTypeCtx& type_ctx) const
+{
+  int ret = OB_SUCCESS;
+  if (OB_UNLIKELY(param_num < 2)) {
+    ret = OB_INVALID_ARGUMENT;
+    LOG_WARN("invalid argument, input arguments should > 2", K(ret));
+  } else if (OB_ISNULL(types_stack)) {
+    ret = OB_INVALID_ARGUMENT;
+    LOG_WARN("null stack", K(types_stack), K(ret));
+  } else {
+    type.set_varchar();
+    ret = aggregate_charsets_for_string_result(type, types_stack + 1, param_num - 1, type_ctx.get_coll_type());
+    if (OB_SUCC(ret)) {
+      int32_t length = 0;
+      for (int64_t i = 1; i < param_num; ++i) {
+        if (!types_stack[i].is_null() && length < types_stack[i].get_length()) {
+          length = types_stack[i].get_length();
+        }
+      }
+      type.set_length(length);
+    }
+    if (OB_SUCC(ret)) {
+      types_stack[0].set_calc_type(ObIntType);
+      type_ctx.set_cast_mode(type_ctx.get_cast_mode() | CM_STRING_INTEGER_TRUNC);
+      for (int64_t i = 1; i < param_num; ++i) {
+        types_stack[i].set_calc_meta(type);
+      }
+    }
+  }
+
+  return ret;
+}
+
+int ObExprElt::calc_resultN(
+    common::ObObj& result, const common::ObObj* obj_stack, int64_t param_num, ObExprCtx& expr_ctx) const
+{
+  int ret = OB_SUCCESS;
+  UNUSED(expr_ctx);
+  if (OB_ISNULL(obj_stack)) {
+    ret = OB_INVALID_ARGUMENT;
+    LOG_WARN("null stack", K(obj_stack), K(ret));
+    result.set_null();
+  } else if (OB_UNLIKELY(param_num < 2)) {
+    ret = OB_INVALID_ARGUMENT;
+    LOG_WARN("param error", K(param_num), K(ret));
+    result.set_null();
+  } else {
+    const ObObj& obj_judge = obj_stack[0];
+    int64_t index = -1;
+    if (OB_UNLIKELY(obj_judge.is_null())) {
+      result.set_null();
+    } else {
+      TYPE_CHECK(obj_judge, ObIntType);
+      index = obj_judge.get_int();
+      if (OB_UNLIKELY(index <= 0 || index >= param_num)) {
+        result.set_null();
+      } else if (obj_stack[index].is_null()) {
+        result.set_null();
+      } else {
+        TYPE_CHECK(obj_stack[index], ObVarcharType);
+        result = obj_stack[index];
+      }
+    }
+  }
+  return ret;
+}
+
+int ObExprElt::cg_expr(ObExprCGCtx&, const ObRawExpr&, ObExpr& expr) const
+{
+  int ret = OB_SUCCESS;
+  CK(expr.arg_cnt_ > 1);
+  expr.eval_func_ = eval_elt;
+  return ret;
+}
+
+int ObExprElt::eval_elt(const ObExpr& expr, ObEvalCtx& ctx, ObDatum& expr_datum)
+{
+  int ret = OB_SUCCESS;
+  ObDatum* first = NULL;
+  ObDatum* d = NULL;
+  if (OB_FAIL(expr.args_[0]->eval(ctx, first))) {
+    LOG_WARN("evaluate parameter failed", K(ret));
+  } else if (first->is_null() || first->get_int() <= 0 || first->get_int() >= expr.arg_cnt_) {
+    expr_datum.set_null();
+  } else if (OB_FAIL(expr.args_[first->get_int()]->eval(ctx, d))) {
+    LOG_WARN("evaluate parameter failed", K(ret));
+  } else {
+    expr_datum.set_datum(*d);
+  }
+  return ret;
+}