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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.math.linear;
19  
20  import java.text.FieldPosition;
21  import java.text.NumberFormat;
22  import java.text.ParseException;
23  import java.text.ParsePosition;
24  import java.util.ArrayList;
25  import java.util.List;
26  import java.util.Locale;
27  
28  import org.apache.commons.math.MathRuntimeException;
29  import org.apache.commons.math.util.CompositeFormat;
30  
31  /**
32   * Formats a vector in components list format "{v0; v1; ...; vk-1}".
33   * <p>The prefix and suffix "{" and "}" and the separator "; " can be replaced by
34   * any user-defined strings. The number format for components can be configured.</p>
35   * <p>White space is ignored at parse time, even if it is in the prefix, suffix
36   * or separator specifications. So even if the default separator does include a space
37   * character that is used at format time, both input string "{1;1;1}" and
38   * " { 1 ; 1 ; 1 } " will be parsed without error and the same vector will be
39   * returned. In the second case, however, the parse position after parsing will be
40   * just after the closing curly brace, i.e. just before the trailing space.</p>
41   *
42   * @version $Revision: 783702 $ $Date: 2009-06-11 04:54:02 -0400 (Thu, 11 Jun 2009) $
43   * @since 2.0
44   */
45  public class RealVectorFormat extends CompositeFormat {
46  
47      /** Serializable version identifier */
48      private static final long serialVersionUID = -708767813036157690L;
49  
50      /** The default prefix: "{". */
51      private static final String DEFAULT_PREFIX = "{";
52  
53      /** The default suffix: "}". */
54      private static final String DEFAULT_SUFFIX = "}";
55  
56      /** The default separator: ", ". */
57      private static final String DEFAULT_SEPARATOR = "; ";
58  
59      /** Prefix. */
60      private final String prefix;
61  
62      /** Suffix. */
63      private final String suffix;
64  
65      /** Separator. */
66      private final String separator;
67  
68      /** Trimmed prefix. */
69      private final String trimmedPrefix;
70  
71      /** Trimmed suffix. */
72      private final String trimmedSuffix;
73  
74      /** Trimmed separator. */
75      private final String trimmedSeparator;
76  
77      /** The format used for components. */
78      private NumberFormat format;
79  
80      /**
81       * Create an instance with default settings.
82       * <p>The instance uses the default prefix, suffix and separator:
83       * "{", "}", and "; " and the default number format for components.</p>
84       */
85      public RealVectorFormat() {
86          this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR, getDefaultNumberFormat());
87      }
88  
89      /**
90       * Create an instance with a custom number format for components.
91       * @param format the custom format for components.
92       */
93      public RealVectorFormat(final NumberFormat format) {
94          this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR, format);
95      }
96  
97      /**
98       * Create an instance with custom prefix, suffix and separator.
99       * @param prefix prefix to use instead of the default "{"
100      * @param suffix suffix to use instead of the default "}"
101      * @param separator separator to use instead of the default "; "
102      */
103     public RealVectorFormat(final String prefix, final String suffix,
104                             final String separator) {
105         this(prefix, suffix, separator, getDefaultNumberFormat());
106     }
107 
108     /**
109      * Create an instance with custom prefix, suffix, separator and format
110      * for components.
111      * @param prefix prefix to use instead of the default "{"
112      * @param suffix suffix to use instead of the default "}"
113      * @param separator separator to use instead of the default "; "
114      * @param format the custom format for components.
115      */
116     public RealVectorFormat(final String prefix, final String suffix,
117                             final String separator, final NumberFormat format) {
118         this.prefix      = prefix;
119         this.suffix      = suffix;
120         this.separator   = separator;
121         trimmedPrefix    = prefix.trim();
122         trimmedSuffix    = suffix.trim();
123         trimmedSeparator = separator.trim();
124         this.format      = format;
125     }
126 
127     /**
128      * Get the set of locales for which real vectors formats are available.
129      * <p>This is the same set as the {@link NumberFormat} set.</p>
130      * @return available real vector format locales.
131      */
132     public static Locale[] getAvailableLocales() {
133         return NumberFormat.getAvailableLocales();
134     }
135 
136     /**
137      * Get the format prefix.
138      * @return format prefix.
139      */
140     public String getPrefix() {
141         return prefix;
142     }
143 
144     /**
145      * Get the format suffix.
146      * @return format suffix.
147      */
148     public String getSuffix() {
149         return suffix;
150     }
151 
152     /**
153      * Get the format separator between components.
154      * @return format separator.
155      */
156     public String getSeparator() {
157         return separator;
158     }
159 
160     /**
161      * Get the components format.
162      * @return components format.
163      */
164     public NumberFormat getFormat() {
165         return format;
166     }
167 
168     /**
169      * Returns the default real vector format for the current locale.
170      * @return the default real vector format.
171      */
172     public static RealVectorFormat getInstance() {
173         return getInstance(Locale.getDefault());
174     }
175 
176     /**
177      * Returns the default real vector format for the given locale.
178      * @param locale the specific locale used by the format.
179      * @return the real vector format specific to the given locale.
180      */
181     public static RealVectorFormat getInstance(final Locale locale) {
182         return new RealVectorFormat(getDefaultNumberFormat(locale));
183     }
184 
185     /**
186      * This static method calls {@link #format(Object)} on a default instance of
187      * RealVectorFormat.
188      *
189      * @param v RealVector object to format
190      * @return A formatted vector
191      */
192     public static String formatRealVector(RealVector v) {
193         return getInstance().format(v);
194     }
195 
196     /**
197      * Formats a {@link RealVector} object to produce a string.
198      * @param vector the object to format.
199      * @param toAppendTo where the text is to be appended
200      * @param pos On input: an alignment field, if desired. On output: the
201      *            offsets of the alignment field
202      * @return the value passed in as toAppendTo.
203      */
204     public StringBuffer format(RealVector vector, StringBuffer toAppendTo,
205                                FieldPosition pos) {
206 
207         pos.setBeginIndex(0);
208         pos.setEndIndex(0);
209 
210         // format prefix
211         toAppendTo.append(prefix);
212 
213         // format components
214         for (int i = 0; i < vector.getDimension(); ++i) {
215             if (i > 0) {
216                 toAppendTo.append(separator);
217             }
218             formatDouble(vector.getEntry(i), format, toAppendTo, pos);
219         }
220 
221         // format suffix
222         toAppendTo.append(suffix);
223 
224         return toAppendTo;
225 
226     }
227 
228     /**
229      * Formats a object to produce a string.
230      * <p><code>obj</code> must be a  {@link RealVector} object. Any other type of
231      * object will result in an {@link IllegalArgumentException} being thrown.</p>
232      * @param obj the object to format.
233      * @param toAppendTo where the text is to be appended
234      * @param pos On input: an alignment field, if desired. On output: the
235      *            offsets of the alignment field
236      * @return the value passed in as toAppendTo.
237      * @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition)
238      * @throws IllegalArgumentException is <code>obj</code> is not a valid type.
239      */
240     @Override
241     public StringBuffer format(Object obj, StringBuffer toAppendTo,
242                                FieldPosition pos) {
243 
244         if (obj instanceof RealVector) {
245             return format( (RealVector)obj, toAppendTo, pos);
246         }
247 
248         throw MathRuntimeException.createIllegalArgumentException(
249               "cannot format a {0} instance as a real vector",
250               obj.getClass().getName());
251 
252     }
253 
254     /**
255      * Parses a string to produce a {@link RealVector} object.
256      * @param source the string to parse
257      * @return the parsed {@link RealVector} object.
258      * @exception ParseException if the beginning of the specified string
259      *            cannot be parsed.
260      */
261     public ArrayRealVector parse(String source) throws ParseException {
262         ParsePosition parsePosition = new ParsePosition(0);
263         ArrayRealVector result = parse(source, parsePosition);
264         if (parsePosition.getIndex() == 0) {
265             throw MathRuntimeException.createParseException(
266                     parsePosition.getErrorIndex(),
267                     "unparseable real vector: \"{0}\"", source);
268         }
269         return result;
270     }
271 
272     /**
273      * Parses a string to produce a {@link RealVector} object.
274      * @param source the string to parse
275      * @param pos input/ouput parsing parameter.
276      * @return the parsed {@link RealVector} object.
277      */
278     public ArrayRealVector parse(String source, ParsePosition pos) {
279         int initialIndex = pos.getIndex();
280 
281         // parse prefix
282         parseAndIgnoreWhitespace(source, pos);
283         if (!parseFixedstring(source, trimmedPrefix, pos)) {
284             return null;
285         }
286 
287         // parse components
288         List<Number> components = new ArrayList<Number>();
289         for (boolean loop = true; loop;){
290 
291             if (!components.isEmpty()) {
292                 parseAndIgnoreWhitespace(source, pos);
293                 if (!parseFixedstring(source, trimmedSeparator, pos)) {
294                     loop = false;
295                 }
296             }
297 
298             if (loop) {
299                 parseAndIgnoreWhitespace(source, pos);
300                 Number component = parseNumber(source, format, pos);
301                 if (component != null) {
302                     components.add(component);
303                 } else {
304                     // invalid component
305                     // set index back to initial, error index should already be set
306                     pos.setIndex(initialIndex);
307                     return null;
308                 }
309             }
310 
311         }
312 
313         // parse suffix
314         parseAndIgnoreWhitespace(source, pos);
315         if (!parseFixedstring(source, trimmedSuffix, pos)) {
316             return null;
317         }
318 
319         // build vector
320         double[] data = new double[components.size()];
321         for (int i = 0; i < data.length; ++i) {
322             data[i] = components.get(i).doubleValue();
323         }
324         return new ArrayRealVector(data, false);
325 
326     }
327 
328     /**
329      * Parses a string to produce a object.
330      * @param source the string to parse
331      * @param pos input/ouput parsing parameter.
332      * @return the parsed object.
333      * @see java.text.Format#parseObject(java.lang.String, java.text.ParsePosition)
334      */
335     @Override
336     public Object parseObject(String source, ParsePosition pos) {
337         return parse(source, pos);
338     }
339 
340 }