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  /*
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     Derby - Class org.apache.derby.impl.sql.compile.GetCurrentConnectionNode
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     Licensed to the Apache Software Foundation (ASF) under one or more
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     contributor license agreements.  See the NOTICE file distributed with
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     this work for additional information regarding copyright ownership.
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     The ASF licenses this file to you under the Apache License, Version 2.0
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     (the "License"); you may not use this file except in compliance with
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    the License.  You may obtain a copy of the License at
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       http://www.apache.org/licenses/LICENSE-2.0
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    Unless required by applicable law or agreed to in writing, software
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    distributed under the License is distributed on an "AS IS" BASIS,
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    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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    See the License for the specific language governing permissions and
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    limitations under the License.
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  */
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 package	org.apache.derby.impl.sql.compile;
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 import  org.apache.derby.iapi.services.sanity.SanityManager;
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 import  org.apache.derby.iapi.services.classfile.VMOpcode;
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 import  org.apache.derby.iapi.reference.ClassName;
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 import java.sql.Types;
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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. 
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 public final class GetCurrentConnectionNode extends JavaValueNode
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 {
Constructor for a GetCurrentConnectionNode 
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 	{
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 		/*
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 		** The result type of getCurrentConnection is
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 		** java.sql.Connection
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 		*/
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 		setJavaTypeName("java.sql.Connection");
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 	}
Bind this operator

Parameters:
fromList The query's FROM list
subqueryList The subquery list being built as we find SubqueryNodes
aggregateVector The aggregate vector being built as we find AggregateNodes
Throws:
StandardException Thrown on error
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 		FromList	fromList, SubqueryList subqueryList,
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 		Vector	aggregateVector)
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 	{
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 		return this;
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	}
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.

Parameters:
numTables Number of tables in the DML Statement
outerFromList FromList from outer query block
outerSubqueryList SubqueryList from outer query block
outerPredicateList PredicateList from outer query block
Throws:
StandardException Thrown on error
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	public void preprocess(int numTables,
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								FromList outerFromList,
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								SubqueryList outerSubqueryList,
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								PredicateList outerPredicateList) 
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	{
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	}
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.

Parameters:
referencedTabs JBitSet with bit map of referenced FromTables
simplePredsOnly Whether or not to consider method calls, field references and conditional nodes when building bit map
Returns:
boolean Whether or not source.expression is a ColumnReference or a VirtualColumnNode.
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	public boolean categorize(JBitSet referencedTabs, boolean simplePredsOnly)
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	{
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		return false;
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	}
Remap all ColumnReferences in this tree to be clones of the underlying expression.

Returns:
JavaValueNode The remapped expression tree.
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	{
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		return this;
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	}
Bind a ? parameter operand of the char_length function. 
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	{
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	}
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)

Returns:
The variant type for the underlying expression.
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	protected int getOrderableVariantType()
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	{
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	}

Parameters:
acb The ExpressionClassBuilder for the class being built
mb The method the code to place the code
Throws:
StandardException Thrown on error
See also:
ConstantNode.generateExpression
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	{
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		mb.callMethod(VMOpcode.INVOKEVIRTUAL, ClassName.BaseActivation, "getCurrentConnection", getJavaTypeName(), 0);
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	}
Check the reliability type of this java value.

Throws:
StandardException Thrown on error
See also:
org.apache.derby.iapi.sql.compile.CompilerContext
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	public void checkReliability(ValueNode sqlNode)
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		sqlNode.checkReliability("getCurrentConnection()",
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	}
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