| /* |
| |
| Derby - Class org.apache.derby.impl.sql.compile.GetCurrentConnectionNode |
| |
| Licensed to the Apache Software Foundation (ASF) under one or more |
| contributor license agreements. See the NOTICE file distributed with |
| this work for additional information regarding copyright ownership. |
| The ASF licenses this file to you 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 |
| |
| http://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. |
| |
| */ |
| |
| package org.apache.derby.impl.sql.compile; |
| |
| import java.util.List; |
| import org.apache.derby.iapi.error.StandardException; |
| import org.apache.derby.iapi.reference.ClassName; |
| import org.apache.derby.iapi.services.classfile.VMOpcode; |
| import org.apache.derby.iapi.services.compiler.MethodBuilder; |
| import org.apache.derby.iapi.services.context.ContextManager; |
| import org.apache.derby.iapi.sql.compile.CompilerContext; |
| import org.apache.derby.iapi.store.access.Qualifier; |
| import org.apache.derby.iapi.util.JBitSet; |
| |
| /** |
| * This node represents a unary getCurrentConnection operator |
| * RESOLVE - parameter will always be null for now. Someday |
| * we may want to allow user to specify which of their connections |
| * they want. Assume that we will use a String. |
| * |
| */ |
| |
| public final class GetCurrentConnectionNode extends JavaValueNode |
| { |
| /** |
| * Constructor for a GetCurrentConnectionNode |
| */ |
| |
| GetCurrentConnectionNode(ContextManager cm) |
| { |
| super(cm); |
| /* |
| ** The result type of getCurrentConnection is |
| ** java.sql.Connection |
| */ |
| |
| setJavaTypeName("java.sql.Connection"); |
| } |
| |
| /** |
| * Bind this operator |
| * |
| * @param fromList The query's FROM list |
| * @param subqueryList The subquery list being built as we find SubqueryNodes |
| * @param aggregates The aggregate list being built as we find AggregateNodes |
| * |
| * @exception StandardException Thrown on error |
| */ |
| JavaValueNode bindExpression(FromList fromList, |
| SubqueryList subqueryList, |
| List<AggregateNode> aggregates) |
| throws StandardException |
| { |
| return this; |
| } |
| |
| /** |
| * Preprocess an expression tree. We do a number of transformations |
| * here (including subqueries, IN lists, LIKE and BETWEEN) plus |
| * subquery flattening. |
| * NOTE: This is done before the outer ResultSetNode is preprocessed. |
| * |
| * @param numTables Number of tables in the DML Statement |
| * @param outerFromList FromList from outer query block |
| * @param outerSubqueryList SubqueryList from outer query block |
| * @param outerPredicateList PredicateList from outer query block |
| * |
| * @exception StandardException Thrown on error |
| */ |
| void preprocess(int numTables, |
| FromList outerFromList, |
| SubqueryList outerSubqueryList, |
| PredicateList outerPredicateList) |
| throws StandardException |
| { |
| } |
| |
| /** |
| * Categorize this predicate. Initially, this means |
| * building a bit map of the referenced tables for each predicate. |
| * If the source of this ColumnReference (at the next underlying level) |
| * is not a ColumnReference or a VirtualColumnNode then this predicate |
| * will not be pushed down. |
| * |
| * For example, in: |
| * select * from (select 1 from s) a (x) where x = 1 |
| * we will not push down x = 1. |
| * NOTE: It would be easy to handle the case of a constant, but if the |
| * inner SELECT returns an arbitrary expression, then we would have to copy |
| * that tree into the pushed predicate, and that tree could contain |
| * subqueries and method calls. |
| * RESOLVE - revisit this issue once we have views. |
| * |
| * @param referencedTabs JBitSet with bit map of referenced FromTables |
| * @param simplePredsOnly Whether or not to consider method |
| * calls, field references and conditional nodes |
| * when building bit map |
| * |
| * @return boolean Whether or not source.expression is a ColumnReference |
| * or a VirtualColumnNode. |
| */ |
| boolean categorize(JBitSet referencedTabs, boolean simplePredsOnly) |
| { |
| return false; |
| } |
| |
| /** |
| * Remap all ColumnReferences in this tree to be clones of the |
| * underlying expression. |
| * |
| * @return JavaValueNode The remapped expression tree. |
| * |
| */ |
| JavaValueNode remapColumnReferencesToExpressions() |
| { |
| return this; |
| } |
| |
| /** |
| * Bind a ? parameter operand of the char_length function. |
| */ |
| |
| void bindParameter() |
| { |
| } |
| |
| /** |
| * Return the variant type for the underlying expression. |
| * The variant type can be: |
| * VARIANT - variant within a scan |
| * (method calls and non-static field access) |
| * SCAN_INVARIANT - invariant within a scan |
| * (column references from outer tables) |
| * QUERY_INVARIANT - invariant within the life of a query |
| * (constant expressions) |
| * |
| * @return The variant type for the underlying expression. |
| */ |
| @Override |
| int getOrderableVariantType() |
| { |
| return Qualifier.QUERY_INVARIANT; |
| } |
| /** |
| * |
| * @see ConstantNode#generateExpression |
| * |
| * @param acb The ExpressionClassBuilder for the class being built |
| * @param mb The method the code to place the code |
| * |
| * @exception StandardException Thrown on error |
| */ |
| void generateExpression(ExpressionClassBuilder acb, MethodBuilder mb) |
| throws StandardException |
| { |
| mb.pushThis(); |
| mb.callMethod(VMOpcode.INVOKEVIRTUAL, ClassName.BaseActivation, "getCurrentConnection", getJavaTypeName(), 0); |
| } |
| |
| /** |
| Check the reliability type of this java value. |
| |
| @exception StandardException Thrown on error |
| |
| @see org.apache.derby.iapi.sql.compile.CompilerContext |
| */ |
| @Override |
| void checkReliability(ValueNode sqlNode) |
| throws StandardException { |
| sqlNode.checkReliability("getCurrentConnection()", |
| CompilerContext.CURRENT_CONNECTION_ILLEGAL); |
| } |
| |
| } |