1 package org.djunits.unit;
2
3 import java.io.Serializable;
4 import java.util.EnumMap;
5
6 /**
7 * <p>
8 * Copyright (c) 2015-2019 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
9 * BSD-style license. See <a href="http://djunits.org/docs/license.html">DJUNITS License</a>.
10 * <p>
11 * $LastChangedDate: 2019-04-01 02:14:38 +0200 (Mon, 01 Apr 2019) $, @version $Revision: 370 $, by $Author: averbraeck $,
12 * initial version Jun 15, 2014 <br>
13 * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
14 */
15 public class SICoefficients implements Serializable
16 {
17 /** */
18 private static final long serialVersionUID = 1L;
19
20 /** the map with SI base units and corresponding coefficients. */
21 private final EnumMap<SI, Integer> coefficientsMap;
22
23 /**
24 * Construct an instance of SICoefficients.
25 * @param coefficients EnumMap<SI,Integer>; the map with SI base units and corresponding coefficients
26 */
27 protected SICoefficients(final EnumMap<SI, Integer> coefficients)
28 {
29 this.coefficientsMap = coefficients;
30 }
31
32 /** {@inheritDoc} */
33 @Override
34 public final String toString()
35 {
36 return enumMapToString(this.coefficientsMap);
37 }
38
39 /**
40 * Convert an enumMap of coefficient to the normalized string representation.
41 * @param map EnumMap<{@link SI}, Integer>; the EnumMap
42 * @return String
43 */
44 protected static String enumMapToString(final EnumMap<SI, Integer> map)
45 {
46 StringBuffer result = new StringBuffer();
47 for (SI si : map.keySet())
48 {
49 if (map.get(si) > 0)
50 {
51 result.append(si.name());
52 if (map.get(si) != 1)
53 {
54 result.append(map.get(si));
55 }
56 }
57 }
58
59 if (result.length() == 0)
60 {
61 result.append("1");
62 }
63
64 boolean first = true;
65 for (SI si : map.keySet())
66 {
67 if (map.get(si) < 0)
68 {
69 if (first)
70 {
71 result.append("/");
72 first = false;
73 }
74 result.append(si.name());
75 if (map.get(si) != -1)
76 {
77 result.append(-map.get(si));
78 }
79 }
80 }
81 return result.toString();
82 }
83
84 /**
85 * @return coefficientsMap
86 */
87 public final EnumMap<SI, Integer> getCoefficientsMap()
88 {
89 return this.coefficientsMap;
90 }
91
92 /**
93 * Convert a coefficient string to <i>standard format</i>.
94 * @param coefficientString String; the string to convert
95 * @return String; the normalized coefficient string
96 * @throws UnitException when the coefficientString could not be parsed
97 */
98 public static String normalize(final String coefficientString) throws UnitException
99 {
100 return enumMapToString(parse(coefficientString));
101 }
102
103 /**
104 * @param coefficientString String; such as kgm/s2 or kg-2m^3/s2A or Kmmol3/Askcd4 or mol. <br> The grammar of a
105 * coefficientString is:<br>
106 * <table summary="">
107 * <tr>
108 * <td>coefficientString</td>
109 * <td>::=</td>
110 * <td><empty> | [ 1 | powerString ] | [ '1 /' powerString ]</td>
111 * </tr>
112 * <tr>
113 * <td>powerString</td>
114 * <td>::=</td>
115 * <td>unitName [ [ ^ ] integer ] [ [ dotOrSlash ] powerString ]</td>
116 * </tr>
117 * <tr>
118 * <td>dotOrSlash</td>
119 * <td>::=</td>
120 * <td>. | /</td>
121 * </tr>
122 * <tr>
123 * <td>unitName</td>
124 * <td>::=</td>
125 * <td>kg | m | s | A | K | cd | mol</td>
126 * </tr>
127 * </table>
128 * <br>
129 * White space can appear anywhere in a coefficientString. <br>
130 * If "integer" does not fit in an Integer, the resulting coefficient will be very wrong.
131 * @return an instance of SICoefficients
132 * @throws UnitException if the coefficientString is not parsable.
133 */
134 public static EnumMap<SI, Integer> parse(final String coefficientString) throws UnitException
135 {
136 // System.out.println("coefficientString is \"" + coefficientString + "\"");
137 EnumMap<SI, Integer> coefficients = new EnumMap<SI, Integer>(SI.class);
138 String cs = coefficientString;
139 cs = cs.replace(".", "").replace(" ", "");
140 if (cs.equals("1")) // This is a special case...
141 {
142 return coefficients;
143 }
144 if (cs.startsWith("1/"))
145 {
146 cs = cs.substring(1); // remove the leading "1"
147 }
148 int factor = 1;
149 while (cs.length() > 0)
150 {
151 if (cs.startsWith("/"))
152 {
153 cs = cs.substring(1);
154 if (cs.length() < 1)
155 {
156 throw new UnitException("No SI name after slash in " + coefficientString);
157 }
158 factor = -1;
159 }
160 boolean parsedPowerString = false;
161 int factor2 = 1;
162 for (SI si : SI.values())
163 {
164 factor2 = 1;
165 String name = si.name();
166 if (!cs.startsWith(name))
167 {
168 continue;
169 }
170 int endPos = name.length();
171 if (cs.substring(endPos).startsWith("ol"))
172 {
173 continue; // Don't confuse "m" (for meter) and "mol"
174 }
175 // Found the unit name
176 if (cs.substring(endPos).startsWith("^"))
177 {
178 endPos++;
179 }
180 int value = 1;
181 int digitsSeen = 0;
182 if (cs.substring(endPos).startsWith("-"))
183 {
184 factor2 = -1;
185 endPos++;
186 }
187 while (cs.length() > endPos)
188 {
189 char digit = cs.charAt(endPos);
190 if (digit >= '0' && digit <= '9')
191 {
192 if (0 == digitsSeen)
193 {
194 value = 0;
195 }
196 value = value * 10 + digit - '0';
197 endPos++;
198 digitsSeen++;
199 }
200 else
201 {
202 break;
203 }
204 }
205 Integer oldValue = coefficients.get(si);
206 if (null == oldValue)
207 {
208 oldValue = 0;
209 }
210 coefficients.put(si, oldValue + value * factor * factor2);
211 parsedPowerString = true;
212 cs = cs.substring(endPos);
213 break;
214 }
215 if (!parsedPowerString)
216 {
217 throw new UnitException("Not an SI unit name in \"" + coefficientString + "\" at \"" + cs + "\"");
218 }
219 }
220 return coefficients;
221 }
222
223 /**
224 * @param a SICoefficients; the first set of coefficients
225 * @param b SICoefficients; the second set of coefficients
226 * @return the coefficients of a*b (coefficients are added)
227 */
228 public static SICoefficients multiply(final SICoefficients a, final SICoefficients b)
229 {
230 EnumMap<SI, Integer> coefficients = new EnumMap<SI, Integer>(SI.class);
231 for (SI si : a.getCoefficientsMap().keySet())
232 {
233 coefficients.put(si, a.getCoefficientsMap().get(si));
234 }
235
236 for (SI si : b.getCoefficientsMap().keySet())
237 {
238 if (coefficients.containsKey(si))
239 {
240 coefficients.put(si, coefficients.get(si) + b.getCoefficientsMap().get(si));
241 }
242 else
243 {
244 coefficients.put(si, b.getCoefficientsMap().get(si));
245 }
246 }
247
248 for (SI si : coefficients.keySet())
249 {
250 if (coefficients.get(si) == 0)
251 {
252 coefficients.remove(si);
253 }
254 }
255 return new SICoefficients(coefficients);
256 }
257
258 /**
259 * @param a SICoefficients; the first set of coefficients
260 * @param b SICoefficients; the second set of coefficients
261 * @return the coefficients of a/b (coefficients are subtracted)
262 */
263 public static SICoefficients divide(final SICoefficients a, final SICoefficients b)
264 {
265 EnumMap<SI, Integer> coefficients = new EnumMap<SI, Integer>(SI.class);
266 for (SI si : a.getCoefficientsMap().keySet())
267 {
268 coefficients.put(si, a.getCoefficientsMap().get(si));
269 }
270
271 for (SI si : b.getCoefficientsMap().keySet())
272 {
273 if (coefficients.containsKey(si))
274 {
275 coefficients.put(si, coefficients.get(si) - b.getCoefficientsMap().get(si));
276 }
277 else
278 {
279 coefficients.put(si, -b.getCoefficientsMap().get(si));
280 }
281 }
282
283 for (SI si : coefficients.keySet())
284 {
285 if (coefficients.get(si) == 0)
286 {
287 coefficients.remove(si);
288 }
289 }
290 return new SICoefficients(coefficients);
291 }
292
293 }