java/engine/org/apache/derby/impl/sql/compile/CharTypeCompiler.java

/*

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

   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 org.apache.derby.iapi.reference.ClassName;
import org.apache.derby.iapi.services.io.StoredFormatIds;
import org.apache.derby.iapi.services.loader.ClassFactory;
import org.apache.derby.shared.common.sanity.SanityManager;
import org.apache.derby.iapi.sql.compile.TypeCompiler;
import org.apache.derby.iapi.types.DataTypeDescriptor;
import org.apache.derby.iapi.types.StringDataValue;
import org.apache.derby.iapi.types.TypeId;

/**
 * This class implements TypeCompiler for the SQL char datatypes.
 *
 */

public final class CharTypeCompiler extends BaseTypeCompiler
{
	   /**
         * Tell whether this type (char) can be converted to the given type.
         *
		 * @see TypeCompiler#convertible
         */
        public boolean convertible(TypeId otherType, boolean forDataTypeFunction)
        {
            if ( otherType.getBaseTypeId().isAnsiUDT() ) { return false; }
            
			// LONGVARCHAR can only be converted from  character types
			// or CLOB or boolean.
			if (getTypeId().isLongVarcharTypeId())
			{
				return (otherType.isStringTypeId() || otherType.isBooleanTypeId());
			}

			// The double function can convert CHAR and VARCHAR
			if (forDataTypeFunction && otherType.isDoubleTypeId())
				return (getTypeId().isStringTypeId());

			// can't CAST to CHAR and VARCHAR from REAL or DOUBLE
			// or binary types or XML
			// all other types are ok.
			if (otherType.isFloatingPointTypeId() || otherType.isBitTypeId() ||
				otherType.isBlobTypeId() || otherType.isXMLTypeId())
				return false;
						
			return true;
        }
	


	/**
	 * Tell whether this type (char) is compatible with the given type.
	 *
	 * @param otherType     The TypeId of the other type.
	 */
	public boolean compatible(TypeId otherType)
	{
		return (otherType.isStringTypeId() || (otherType.isDateTimeTimeStampTypeId() && !getTypeId().isLongVarcharTypeId()));
		
	}

    /**
     * Tell whether this type (char) can be stored into from the given type.
     *
     * @param otherType     The TypeId of the other type.
     * @param cf            A ClassFactory
     */

    public boolean storable(TypeId otherType, ClassFactory cf)
    {
        // Same rules as cast except we can't assign from numbers
        if (convertible(otherType,false) &&
                !otherType.isBlobTypeId() &&
                !otherType.isNumericTypeId())
            return true;

        /*
         ** If the other type is user-defined, use the java types to determine
         ** assignability.
         */
        return userTypeStorable(getTypeId(), otherType, cf);
    }

    /** @see TypeCompiler#interfaceName */
    public String interfaceName()
    {
        return ClassName.StringDataValue;
    }

    /**
     * @see TypeCompiler#getCorrespondingPrimitiveTypeName
     */

    public String getCorrespondingPrimitiveTypeName()
    {
        /* Only numerics and booleans get mapped to Java primitives */
        return "java.lang.String";
    }

    /**
     * @see TypeCompiler#getCastToCharWidth
     */
    public int getCastToCharWidth(DataTypeDescriptor dts)
    {
        return dts.getMaximumWidth();
    }

    String nullMethodName()
    {
        int formatId = getStoredFormatIdFromTypeId();
        switch (formatId)
        {
            case StoredFormatIds.CHAR_TYPE_ID:
                return "getNullChar";

            case StoredFormatIds.LONGVARCHAR_TYPE_ID:
                return "getNullLongvarchar";

            case StoredFormatIds.VARCHAR_TYPE_ID:
                return "getNullVarchar";

            default:
                if (SanityManager.DEBUG)
                {
                    SanityManager.THROWASSERT(
                        "unexpected formatId in nullMethodName() - " +
                        formatId);
                }
                return null;
        }
    }

    /**
     * Push the collation type if it is not COLLATION_TYPE_UCS_BASIC.
     *
     * @param collationType Collation type of character values.
     * @return {@code true} collationType will be pushed, {@code
     *         false} collationType will be ignored.
     */
    @Override
    boolean pushCollationForDataValue(int collationType)
    {
        return collationType != StringDataValue.COLLATION_TYPE_UCS_BASIC;
    }

    @Override
    String dataValueMethodName()
    {
        int formatId = getStoredFormatIdFromTypeId();
        switch (formatId)
        {
            case StoredFormatIds.CHAR_TYPE_ID:
                return "getCharDataValue";

            case StoredFormatIds.LONGVARCHAR_TYPE_ID:
                return "getLongvarcharDataValue";

            case StoredFormatIds.VARCHAR_TYPE_ID:
                return "getVarcharDataValue";

            default:
                if (SanityManager.DEBUG)
                {
                    SanityManager.THROWASSERT(
                        "unexpected formatId in dataValueMethodName() - " +
                        formatId);
                }
                return null;
        }
    }
}