coalescefunctionnode.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.impl.sql.compile.CoalesceFunctionNode

   Copyright 2004 The Apache Software Foundation or its licensors, as applicable.

   Licensed 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 org.apache.derby.iapi.reference.ClassName;
import org.apache.derby.iapi.reference.SQLState;

import org.apache.derby.iapi.services.classfile.VMOpcode;

import org.apache.derby.iapi.services.sanity.SanityManager;

import org.apache.derby.iapi.error.StandardException;

import org.apache.derby.impl.sql.compile.ExpressionClassBuilder;

import org.apache.derby.iapi.services.compiler.LocalField;
import org.apache.derby.iapi.services.compiler.MethodBuilder;

import java.lang.reflect.Modifier;

import java.util.Vector;

/**
 * This node represents coalesce/value function which returns the first argument that is not null.
 * The arguments are evaluated in the order in which they are specified, and the result of the
 * function is the first argument that is not null. The result can be null only if all the arguments
 * can be null. The selected argument is converted, if necessary, to the attributes of the result.
 *
 *
 * SQL Reference Guide for DB2 has section titled "Rules for result data types" at the following url
 * http://publib.boulder.ibm.com/infocenter/db2help/index.jsp?topic=/com.ibm.db2.udb.doc/admin/r0008480.htm

 * I have constructed following table based on various tables and information under "Rules for result data types"
 * This table has FOR BIT DATA TYPES broken out into separate columns for clarity
 *
 * Note that are few differences between Cloudscape and DB2
 * 1)there are few differences between what datatypes are consdiered compatible
 * In DB2, CHAR FOR BIT DATA datatypes are compatible with CHAR datatypes
 * ie in addition to following table, CHAR is compatible with CHAR FOR BIT DATA, VARCHAR FOR BIT DATA and LONG VARCHAR FOR BIT DATA
 * ie in addition to following table, VARCHAR is compatible with CHAR FOR BIT DATA, VARCHAR FOR BIT DATA and LONG VARCHAR FOR BIT DATA
 * ie in addition to following table, LONG VARCHAR is compatible with CHAR FOR BIT DATA, VARCHAR FOR BIT DATA and LONG VARCHAR FOR BIT DATA
 * ie in addition to following table, CHAR FOR BIT DATA is compatible with DATE, TIME, TIMESTAMP
 * ie in addition to following table, VARCHAR FOR BIT DATA is compatible with DATE, TIME, TIMESTAMP
 *
 * 2)few datatypes donot have matching precision in Cloudscape and DB2
 * In DB2, precision of TIME is 8. In Cloudscape, precision of TIME is 0.
 * In DB2, precision,scale of TIMESTAMP is 26,6. In Cloudscape, precision of TIMESTAMP is 0,0.
 * In DB2, precision of DOUBLE is 15. In Cloudscape, precision of DOUBLE is 52.
 * In DB2, precision of REAL is 23. In Cloudscape, precision of REAL is 7.
 * In DB2, precision calculation equation is incorrect when we have int and decimal arguments.
 * The equation should be p=x+max(w-x,10) since precision of integer is 10 in both db2 and cloudscape. Instead, DB2 has p=x+max(w-x,11) 
 *
 * Types.             S  I  B  D  R  D  C  V  L  C  V  L  C  D  T  T  B
 *                    M  N  I  E  E  O  H  A  O  H  A  O  L  A  I  I  L
 *                    A  T  G  C  A  U  A  R  N  A  R  N  O  T  M  M  O
 *                    L  E  I  I  L  B  R  C  G  R  C  G  B  E  E  E  B
 *                    L  G  N  M     L     H  V  .  H  V           S
 *                    I  E  T  A     E     A  A  B  A  A           T
 *                    N  R     L           R  R  I  R  R           A
 *                    T                       C  T  .  .           M
 *                                            H     B  B           P
 *                                            A     I  I
 *                                            R     T   T
 * SMALLINT         { "SMALLINT", "INTEGER", "BIGINT", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
 * INTEGER          { "INTEGER", "INTEGER", "BIGINT", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
 * BIGINT           { "BIGINT", "BIGINT", "BIGINT", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
 * DECIMAL          { "DECIMAL", "DECIMAL", "DECIMAL", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
 * REAL             { "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "REAL", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
 * DOUBLE           { "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
 * CHAR             { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "CHAR", "VARCHAR", "LONG VARCHAR", "ERROR", "ERROR", "ERROR", "CLOB", "DATE", "TIME", "TIMESTAMP", "ERROR" },
 * VARCHAR          { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "VARCHAR", "VARCHAR","LONG VARCHAR", "ERROR", "ERROR", "ERROR", "CLOB", "DATE", "TIME", "TIMESTAMP", "ERROR" },
 * LONGVARCHAR      { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "LONG VARCHAR", "LONG VARCHAR", "LONG VARCHAR", "ERROR", "ERROR", "ERROR", "CLOB", "ERROR", "ERROR", "ERROR", "ERROR" },
 * CHAR FOR BIT     { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "BIT", "BIT VARYING", "LONG BIT VARYING", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
 * VARCH. BIT       { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "BIT VARYING", "BIT VARYING", "LONG BIT VARYING", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
 * LONGVAR. BIT     { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "LONG BIT VARYING", "LONG BIT VARYING", "LONG BIT VARYING", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
 * CLOB             { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "CLOB", "CLOB", "CLOB", "ERROR", "ERROR", "ERROR", "CLOB", "ERROR", "ERROR", "ERROR", "ERROR" },
 * DATE             { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "DATE", "DATE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "DATE", "ERROR", "ERROR", "ERROR" },
 * TIME             { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIME", "TIME", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIME", "ERROR", "ERROR" },
 * TIMESTAMP        { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIMESTAMP", "TIMESTAMP", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIMESTAMP", "ERROR" },
 * BLOB             { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "BLOB" }
 */

public class CoalesceFunctionNode extends ValueNode
{
	String	functionName; //Are we here because of COALESCE function or VALUE function
	ValueNodeList	argumentsList; //this is the list of arguments to the function. We are interested in the first not-null argument
	ValueNode firstNonParameterNode;//The generated method will generate code to call coalesce on this non-parameter argument

	/**
	 * Initializer for a CalesceFunctionNode
	 *
	 * @param functionName	Tells if the function was called with name COALESCE or with name VALUE
	 * @param argumentsList	The list of arguments to the coalesce/value function
	 */
	public void init(Object functionName, Object argumentsList)
	{
		this.functionName = (String) functionName;
		this.argumentsList = (ValueNodeList) argumentsList;
	}

	/**
	 * Binding this expression means setting the result DataTypeServices.
	 * In this case, the result type is based on the rules in the table listed earlier.
	 *
	 * @param fromList			The FROM list for the statement.
	 * @param subqueryList		The subquery list being built as we find SubqueryNodes.
	 * @param aggregateVector	The aggregate vector being built as we find AggregateNodes.
	 *
	 * @return	The new top of the expression tree.
	 *
	 * @exception StandardException		Thrown on error
	 */
	public ValueNode bindExpression(FromList fromList, SubqueryList subqueryList,
							Vector	aggregateVector)
					throws StandardException
	{
		//bind all the arguments
		argumentsList.bindExpression(fromList, subqueryList, aggregateVector);

		//There should be more than one argument
		if (argumentsList.size() < 2)
			throw StandardException.newException(SQLState.LANG_DB2_NUMBER_OF_ARGS_INVALID, functionName);

		//check if all the arguments are parameters. If yes, then throw an exception
		if (argumentsList.containsAllParameterNodes())
			throw StandardException.newException(SQLState.LANG_DB2_COALESCE_FUNCTION_ALL_PARAMS);

		int argumentsListSize = argumentsList.size();
		//find the first non-param argument. The generated method will generate code to call coalesce on this argument
		for (int index = 0; index < argumentsListSize; index++)
		{
			if (!(((ValueNode) argumentsList.elementAt(index)).isParameterNode()))
			{
				firstNonParameterNode = (ValueNode) argumentsList.elementAt(index);
				break;
			}
		}

		//make sure these arguments are compatible to each other before coalesce can be allowed
		for (int index = 0; index < argumentsListSize; index++)
		{