001/*
002 *  Copyright 2001-2006 Stephen Colebourne
003 *
004 *  Licensed under the Apache License, Version 2.0 (the "License");
005 *  you may not use this file except in compliance with the License.
006 *  You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 *  Unless required by applicable law or agreed to in writing, software
011 *  distributed under the License is distributed on an "AS IS" BASIS,
012 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 *  See the License for the specific language governing permissions and
014 *  limitations under the License.
015 */
016package org.joda.time.convert;
017
018import org.joda.time.Chronology;
019import org.joda.time.DateTimeUtils;
020import org.joda.time.DateTimeZone;
021import org.joda.time.PeriodType;
022import org.joda.time.ReadablePartial;
023import org.joda.time.chrono.ISOChronology;
024import org.joda.time.format.DateTimeFormatter;
025
026/**
027 * AbstractConverter simplifies the process of implementing a converter.
028 *
029 * @author Stephen Colebourne
030 * @since 1.0
031 */
032public abstract class AbstractConverter implements Converter {
033
034    /**
035     * Restricted constructor.
036     */
037    protected AbstractConverter() {
038        super();
039    }
040
041    //-----------------------------------------------------------------------
042    /**
043     * Extracts the millis from an object of this convertor's type.
044     * <p>
045     * This implementation returns the current time.
046     * 
047     * @param object  the object to convert
048     * @param chrono  the chronology to use, which is always non-null
049     * @return the millisecond value
050     */
051    public long getInstantMillis(Object object, Chronology chrono) {
052        return DateTimeUtils.currentTimeMillis();
053    }
054
055    //-----------------------------------------------------------------------
056    /**
057     * Extracts the chronology from an object of this convertor's type
058     * where the time zone is specified.
059     * <p>
060     * This implementation returns the ISO chronology.
061     * 
062     * @param object  the object to convert
063     * @param zone  the specified zone to use, null means default zone
064     * @return the chronology, never null
065     */
066    public Chronology getChronology(Object object, DateTimeZone zone) {
067        return ISOChronology.getInstance(zone);
068    }
069
070    /**
071     * Extracts the chronology from an object of this convertor's type
072     * where the chronology is specified.
073     * <p>
074     * This implementation returns the chronology specified, or the
075     * ISO chronology in the default zone if null passed in.
076     * 
077     * @param object  the object to convert
078     * @param chrono  the chronology to use, null means ISO default
079     * @return the chronology, never null
080     */
081    public Chronology getChronology(Object object, Chronology chrono) {
082        return DateTimeUtils.getChronology(chrono);
083    }
084
085    //-----------------------------------------------------------------------
086    /**
087     * Extracts the values of the partial from an object of this converter's type.
088     * The chrono parameter is a hint to the converter, should it require a
089     * chronology to aid in conversion.
090     * <p>
091     * This implementation calls {@link #getInstantMillis(Object, Chronology)}.
092     * 
093     * @param fieldSource  a partial that provides access to the fields.
094     *  This partial may be incomplete and only getFieldType(int) should be used
095     * @param object  the object to convert
096     * @param chrono  the chronology to use, which is the non-null result of getChronology()
097     * @return the array of field values that match the fieldSource, must be non-null valid
098     * @throws ClassCastException if the object is invalid
099     */
100    public int[] getPartialValues(ReadablePartial fieldSource, Object object, Chronology chrono) {
101        long instant = getInstantMillis(object, chrono);
102        return chrono.get(fieldSource, instant);
103    }
104
105    /**
106     * Extracts the values of the partial from an object of this converter's type.
107     * The chrono parameter is a hint to the converter, should it require a
108     * chronology to aid in conversion.
109     * <p>
110     * This implementation calls {@link #getPartialValues(ReadablePartial, Object, Chronology)}.
111     * 
112     * @param fieldSource  a partial that provides access to the fields.
113     *  This partial may be incomplete and only getFieldType(int) should be used
114     * @param object  the object to convert
115     * @param chrono  the chronology to use, which is the non-null result of getChronology()
116     * @param parser  if converting from a String, the given parser is preferred
117     * @return the array of field values that match the fieldSource, must be non-null valid
118     * @throws ClassCastException if the object is invalid
119     * @since 1.3
120     */
121    public int[] getPartialValues(ReadablePartial fieldSource,
122            Object object, Chronology chrono, DateTimeFormatter parser) {
123        return getPartialValues(fieldSource, object, chrono);
124    }
125
126    //-----------------------------------------------------------------------
127    /**
128     * Selects a suitable period type for the given object.
129     *
130     * @param object  the object to examine
131     * @return the period type, never null
132     */
133    public PeriodType getPeriodType(Object object) {
134        return PeriodType.standard();
135    }
136
137    //-----------------------------------------------------------------------
138    /**
139     * Checks if the input is a ReadableInterval.
140     * <p>
141     * If it is, then the calling code should cast and copy the fields directly.
142     *
143     * @param object  the object to convert
144     * @param chrono  the chronology to use, may be null
145     * @return true if the input is a ReadableInterval
146     */
147    public boolean isReadableInterval(Object object, Chronology chrono) {
148        return false;
149    }
150
151    //-----------------------------------------------------------------------
152    /**
153     * Gets a debugging string version of this converter.
154     * 
155     * @return a debugging string
156     */
157    public String toString() {
158        return "Converter[" + (getSupportedType() == null ? "null" : getSupportedType().getName()) + "]";
159    }
160
161}