    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017
    018    package org.apache.commons.math3.geometry;
    019
    020    import java.text.FieldPosition;
    021    import java.text.NumberFormat;
    022    import java.text.ParsePosition;
    023    import java.util.Locale;
    024
    025    import org.apache.commons.math3.util.CompositeFormat;
    026    import org.apache.commons.math3.exception.MathParseException;
    027
    028    /**
    029     * Formats a vector in components list format "{x; y; ...}".
    030     * <p>The prefix and suffix "{" and "}" and the separator "; " can be replaced by
    031     * any user-defined strings. The number format for components can be configured.</p>
    032     * <p>White space is ignored at parse time, even if it is in the prefix, suffix
    033     * or separator specifications. So even if the default separator does include a space
    034     * character that is used at format time, both input string "{1;1;1}" and
    035     * " { 1 ; 1 ; 1 } " will be parsed without error and the same vector will be
    036     * returned. In the second case, however, the parse position after parsing will be
    037     * just after the closing curly brace, i.e. just before the trailing space.</p>
    038     *
    039     * @param <S> Type of the space.
    040     * @version $Id: VectorFormat.java 1416643 2012-12-03 19:37:14Z tn $
    041     * @since 3.0
    042     */
    043    public abstract class VectorFormat<S extends Space> {
    044
    045        /** The default prefix: "{". */
    046        public static final String DEFAULT_PREFIX = "{";
    047
    048        /** The default suffix: "}". */
    049        public static final String DEFAULT_SUFFIX = "}";
    050
    051        /** The default separator: ", ". */
    052        public static final String DEFAULT_SEPARATOR = "; ";
    053
    054        /** Prefix. */
    055        private final String prefix;
    056
    057        /** Suffix. */
    058        private final String suffix;
    059
    060        /** Separator. */
    061        private final String separator;
    062
    063        /** Trimmed prefix. */
    064        private final String trimmedPrefix;
    065
    066        /** Trimmed suffix. */
    067        private final String trimmedSuffix;
    068
    069        /** Trimmed separator. */
    070        private final String trimmedSeparator;
    071
    072        /** The format used for components. */
    073        private final NumberFormat format;
    074
    075        /**
    076         * Create an instance with default settings.
    077         * <p>The instance uses the default prefix, suffix and separator:
    078         * "{", "}", and "; " and the default number format for components.</p>
    079         */
    080        protected VectorFormat() {
    081            this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR,
    082                 CompositeFormat.getDefaultNumberFormat());
    083        }
    084
    085        /**
    086         * Create an instance with a custom number format for components.
    087         * @param format the custom format for components.
    088         */
    089        protected VectorFormat(final NumberFormat format) {
    090            this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR, format);
    091        }
    092
    093        /**
    094         * Create an instance with custom prefix, suffix and separator.
    095         * @param prefix prefix to use instead of the default "{"
    096         * @param suffix suffix to use instead of the default "}"
    097         * @param separator separator to use instead of the default "; "
    098         */
    099        protected VectorFormat(final String prefix, final String suffix,
    100                              final String separator) {
    101            this(prefix, suffix, separator, CompositeFormat.getDefaultNumberFormat());
    102        }
    103
    104        /**
    105         * Create an instance with custom prefix, suffix, separator and format
    106         * for components.
    107         * @param prefix prefix to use instead of the default "{"
    108         * @param suffix suffix to use instead of the default "}"
    109         * @param separator separator to use instead of the default "; "
    110         * @param format the custom format for components.
    111         */
    112        protected VectorFormat(final String prefix, final String suffix,
    113                              final String separator, final NumberFormat format) {
    114            this.prefix      = prefix;
    115            this.suffix      = suffix;
    116            this.separator   = separator;
    117            trimmedPrefix    = prefix.trim();
    118            trimmedSuffix    = suffix.trim();
    119            trimmedSeparator = separator.trim();
    120            this.format      = format;
    121        }
    122
    123        /**
    124         * Get the set of locales for which point/vector formats are available.
    125         * <p>This is the same set as the {@link NumberFormat} set.</p>
    126         * @return available point/vector format locales.
    127         */
    128        public static Locale[] getAvailableLocales() {
    129            return NumberFormat.getAvailableLocales();
    130        }
    131
    132        /**
    133         * Get the format prefix.
    134         * @return format prefix.
    135         */
    136        public String getPrefix() {
    137            return prefix;
    138        }
    139
    140        /**
    141         * Get the format suffix.
    142         * @return format suffix.
    143         */
    144        public String getSuffix() {
    145            return suffix;
    146        }
    147
    148        /**
    149         * Get the format separator between components.
    150         * @return format separator.
    151         */
    152        public String getSeparator() {
    153            return separator;
    154        }
    155
    156        /**
    157         * Get the components format.
    158         * @return components format.
    159         */
    160        public NumberFormat getFormat() {
    161            return format;
    162        }
    163
    164        /**
    165         * Formats a {@link Vector} object to produce a string.
    166         * @param vector the object to format.
    167         * @return a formatted string.
    168         */
    169        public String format(Vector<S> vector) {
    170            return format(vector, new StringBuffer(), new FieldPosition(0)).toString();
    171        }
    172
    173        /**
    174         * Formats a {@link Vector} object to produce a string.
    175         * @param vector the object to format.
    176         * @param toAppendTo where the text is to be appended
    177         * @param pos On input: an alignment field, if desired. On output: the
    178         *            offsets of the alignment field
    179         * @return the value passed in as toAppendTo.
    180         */
    181        public abstract StringBuffer format(Vector<S> vector,
    182                                            StringBuffer toAppendTo, FieldPosition pos);
    183
    184        /**
    185         * Formats the coordinates of a {@link Vector} to produce a string.
    186         * @param toAppendTo where the text is to be appended
    187         * @param pos On input: an alignment field, if desired. On output: the
    188         *            offsets of the alignment field
    189         * @param coordinates coordinates of the object to format.
    190         * @return the value passed in as toAppendTo.
    191         */
    192        protected StringBuffer format(StringBuffer toAppendTo, FieldPosition pos,
    193                                      double ... coordinates) {
    194
    195            pos.setBeginIndex(0);
    196            pos.setEndIndex(0);
    197
    198            // format prefix
    199            toAppendTo.append(prefix);
    200
    201            // format components
    202            for (int i = 0; i < coordinates.length; ++i) {
    203                if (i > 0) {
    204                    toAppendTo.append(separator);
    205                }
    206                CompositeFormat.formatDouble(coordinates[i], format, toAppendTo, pos);
    207            }
    208
    209            // format suffix
    210            toAppendTo.append(suffix);
    211
    212            return toAppendTo;
    213
    214        }
    215
    216        /**
    217         * Parses a string to produce a {@link Vector} object.
    218         * @param source the string to parse
    219         * @return the parsed {@link Vector} object.
    220         * @throws MathParseException if the beginning of the specified string
    221         * cannot be parsed.
    222         */
    223        public abstract Vector<S> parse(String source) throws MathParseException;
    224
    225        /**
    226         * Parses a string to produce a {@link Vector} object.
    227         * @param source the string to parse
    228         * @param pos input/output parsing parameter.
    229         * @return the parsed {@link Vector} object.
    230         */
    231        public abstract Vector<S> parse(String source, ParsePosition pos);
    232
    233        /**
    234         * Parses a string to produce an array of coordinates.
    235         * @param dimension dimension of the space
    236         * @param source the string to parse
    237         * @param pos input/output parsing parameter.
    238         * @return coordinates array.
    239         */
    240        protected double[] parseCoordinates(int dimension, String source, ParsePosition pos) {
    241
    242            int initialIndex = pos.getIndex();
    243            double[] coordinates = new double[dimension];
    244
    245            // parse prefix
    246            CompositeFormat.parseAndIgnoreWhitespace(source, pos);
    247            if (!CompositeFormat.parseFixedstring(source, trimmedPrefix, pos)) {
    248                return null;
    249            }
    250
    251            for (int i = 0; i < dimension; ++i) {
    252
    253                // skip whitespace
    254                CompositeFormat.parseAndIgnoreWhitespace(source, pos);
    255
    256                // parse separator
    257                if (i > 0) {
    258                    if (!CompositeFormat.parseFixedstring(source, trimmedSeparator, pos)) {
    259                        return null;
    260                    }
    261                }
    262
    263                // skip whitespace
    264                CompositeFormat.parseAndIgnoreWhitespace(source, pos);
    265
    266                // parse coordinate
    267                Number c = CompositeFormat.parseNumber(source, format, pos);
    268                if (c == null) {
    269                    // invalid coordinate
    270                    // set index back to initial, error index should already be set
    271                    pos.setIndex(initialIndex);
    272                    return null;
    273                }
    274
    275                // store coordinate
    276                coordinates[i] = c.doubleValue();
    277
    278            }
    279
    280            // parse suffix
    281            CompositeFormat.parseAndIgnoreWhitespace(source, pos);
    282            if (!CompositeFormat.parseFixedstring(source, trimmedSuffix, pos)) {
    283                return null;
    284            }
    285
    286            return coordinates;
    287
    288        }
    289
    290    }