1 /**
2  * Copyright (c) 2004-2011 QOS.ch
3  * All rights reserved.
4  *
5  * Permission is hereby granted, free  of charge, to any person obtaining
6  * a  copy  of this  software  and  associated  documentation files  (the
7  * "Software"), to  deal in  the Software without  restriction, including
8  * without limitation  the rights to  use, copy, modify,  merge, publish,
9  * distribute,  sublicense, and/or sell  copies of  the Software,  and to
10  * permit persons to whom the Software  is furnished to do so, subject to
11  * the following conditions:
12  *
13  * The  above  copyright  notice  and  this permission  notice  shall  be
14  * included in all copies or substantial portions of the Software.
15  *
16  * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
17  * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
18  * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
19  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21  * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
22  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23  *
24  */
25 package org.slf4j.helpers;
26 
27 import java.text.MessageFormat;
28 import java.util.HashMap;
29 import java.util.Map;
30 
31 // contributors: lizongbo: proposed special treatment of array parameter values
32 // Joern Huxhorn: pointed out double[] omission, suggested deep array copy
33 /**
34  * Formats messages according to very simple substitution rules. Substitutions
35  * can be made 1, 2 or more arguments.
36  *
37  * <p>
38  * For example,
39  *
40  * <pre>
41  * MessageFormatter.format(&quot;Hi {}.&quot;, &quot;there&quot;)
42  * </pre>
43  *
44  * will return the string "Hi there.".
45  * <p>
46  * The {} pair is called the <em>formatting anchor</em>. It serves to designate
47  * the location where arguments need to be substituted within the message
48  * pattern.
49  * <p>
50  * In case your message contains the '{' or the '}' character, you do not have
51  * to do anything special unless the '}' character immediately follows '{'. For
52  * example,
53  *
54  * <pre>
55  * MessageFormatter.format(&quot;Set {1,2,3} is not equal to {}.&quot;, &quot;1,2&quot;);
56  * </pre>
57  *
58  * will return the string "Set {1,2,3} is not equal to 1,2.".
59  *
60  * <p>
61  * If for whatever reason you need to place the string "{}" in the message
62  * without its <em>formatting anchor</em> meaning, then you need to escape the
63  * '{' character with '\', that is the backslash character. Only the '{'
64  * character should be escaped. There is no need to escape the '}' character.
65  * For example,
66  *
67  * <pre>
68  * MessageFormatter.format(&quot;Set \\{} is not equal to {}.&quot;, &quot;1,2&quot;);
69  * </pre>
70  *
71  * will return the string "Set {} is not equal to 1,2.".
72  *
73  * <p>
74  * The escaping behavior just described can be overridden by escaping the escape
75  * character '\'. Calling
76  *
77  * <pre>
78  * MessageFormatter.format(&quot;File name is C:\\\\{}.&quot;, &quot;file.zip&quot;);
79  * </pre>
80  *
81  * will return the string "File name is C:\file.zip".
82  *
83  * <p>
84  * The formatting conventions are different than those of {@link MessageFormat}
85  * which ships with the Java platform. This is justified by the fact that
86  * SLF4J's implementation is 10 times faster than that of {@link MessageFormat}.
87  * This local performance difference is both measurable and significant in the
88  * larger context of the complete logging processing chain.
89  *
90  * <p>
91  * See also {@link #format(String, Object)},
92  * {@link #format(String, Object, Object)} and
93  * {@link #arrayFormat(String, Object[])} methods for more details.
94  *
95  * @author Ceki G&uuml;lc&uuml;
96  * @author Joern Huxhorn
97  */
98 final public class MessageFormatter {
99     static final char DELIM_START = '{';
100     static final char DELIM_STOP = '}';
101     static final String DELIM_STR = "{}";
102     private static final char ESCAPE_CHAR = '\\';
103 
104     /**
105      * Performs single argument substitution for the 'messagePattern' passed as
106      * parameter.
107      * <p>
108      * For example,
109      *
110      * <pre>
111      * MessageFormatter.format(&quot;Hi {}.&quot;, &quot;there&quot;);
112      * </pre>
113      *
114      * will return the string "Hi there.".
115      * <p>
116      *
117      * @param messagePattern
118      *          The message pattern which will be parsed and formatted
119      * @param argument
120      *          The argument to be substituted in place of the formatting anchor
121      * @return The formatted message
122      */
format(String messagePattern, Object arg)123     final public static FormattingTuple format(String messagePattern, Object arg) {
124         return arrayFormat(messagePattern, new Object[] { arg });
125     }
126 
127     /**
128      *
129      * Performs a two argument substitution for the 'messagePattern' passed as
130      * parameter.
131      * <p>
132      * For example,
133      *
134      * <pre>
135      * MessageFormatter.format(&quot;Hi {}. My name is {}.&quot;, &quot;Alice&quot;, &quot;Bob&quot;);
136      * </pre>
137      *
138      * will return the string "Hi Alice. My name is Bob.".
139      *
140      * @param messagePattern
141      *          The message pattern which will be parsed and formatted
142      * @param arg1
143      *          The argument to be substituted in place of the first formatting
144      *          anchor
145      * @param arg2
146      *          The argument to be substituted in place of the second formatting
147      *          anchor
148      * @return The formatted message
149      */
format(final String messagePattern, Object arg1, Object arg2)150     final public static FormattingTuple format(final String messagePattern, Object arg1, Object arg2) {
151         return arrayFormat(messagePattern, new Object[] { arg1, arg2 });
152     }
153 
getThrowableCandidate(Object[] argArray)154     static final Throwable getThrowableCandidate(Object[] argArray) {
155         if (argArray == null || argArray.length == 0) {
156             return null;
157         }
158 
159         final Object lastEntry = argArray[argArray.length - 1];
160         if (lastEntry instanceof Throwable) {
161             return (Throwable) lastEntry;
162         }
163         return null;
164     }
165 
166     /**
167      * Same principle as the {@link #format(String, Object)} and
168      * {@link #format(String, Object, Object)} methods except that any number of
169      * arguments can be passed in an array.
170      *
171      * @param messagePattern
172      *          The message pattern which will be parsed and formatted
173      * @param argArray
174      *          An array of arguments to be substituted in place of formatting
175      *          anchors
176      * @return The formatted message
177      */
arrayFormat(final String messagePattern, final Object[] argArray)178     final public static FormattingTuple arrayFormat(final String messagePattern, final Object[] argArray) {
179 
180         Throwable throwableCandidate = getThrowableCandidate(argArray);
181 
182         if (messagePattern == null) {
183             return new FormattingTuple(null, argArray, throwableCandidate);
184         }
185 
186         if (argArray == null) {
187             return new FormattingTuple(messagePattern);
188         }
189 
190         int i = 0;
191         int j;
192         // use string builder for better multicore performance
193         StringBuilder sbuf = new StringBuilder(messagePattern.length() + 50);
194 
195         int L;
196         for (L = 0; L < argArray.length; L++) {
197 
198             j = messagePattern.indexOf(DELIM_STR, i);
199 
200             if (j == -1) {
201                 // no more variables
202                 if (i == 0) { // this is a simple string
203                     return new FormattingTuple(messagePattern, argArray, throwableCandidate);
204                 } else { // add the tail string which contains no variables and return
205                     // the result.
206                     sbuf.append(messagePattern.substring(i, messagePattern.length()));
207                     return new FormattingTuple(sbuf.toString(), argArray, throwableCandidate);
208                 }
209             } else {
210                 if (isEscapedDelimeter(messagePattern, j)) {
211                     if (!isDoubleEscaped(messagePattern, j)) {
212                         L--; // DELIM_START was escaped, thus should not be incremented
213                         sbuf.append(messagePattern.substring(i, j - 1));
214                         sbuf.append(DELIM_START);
215                         i = j + 1;
216                     } else {
217                         // The escape character preceding the delimiter start is
218                         // itself escaped: "abc x:\\{}"
219                         // we have to consume one backward slash
220                         sbuf.append(messagePattern.substring(i, j - 1));
221                         deeplyAppendParameter(sbuf, argArray[L], new HashMap<Object[], Object>());
222                         i = j + 2;
223                     }
224                 } else {
225                     // normal case
226                     sbuf.append(messagePattern.substring(i, j));
227                     deeplyAppendParameter(sbuf, argArray[L], new HashMap<Object[], Object>());
228                     i = j + 2;
229                 }
230             }
231         }
232         // append the characters following the last {} pair.
233         sbuf.append(messagePattern.substring(i, messagePattern.length()));
234         if (L < argArray.length - 1) {
235             return new FormattingTuple(sbuf.toString(), argArray, throwableCandidate);
236         } else {
237             return new FormattingTuple(sbuf.toString(), argArray, null);
238         }
239     }
240 
isEscapedDelimeter(String messagePattern, int delimeterStartIndex)241     final static boolean isEscapedDelimeter(String messagePattern, int delimeterStartIndex) {
242 
243         if (delimeterStartIndex == 0) {
244             return false;
245         }
246         char potentialEscape = messagePattern.charAt(delimeterStartIndex - 1);
247         if (potentialEscape == ESCAPE_CHAR) {
248             return true;
249         } else {
250             return false;
251         }
252     }
253 
isDoubleEscaped(String messagePattern, int delimeterStartIndex)254     final static boolean isDoubleEscaped(String messagePattern, int delimeterStartIndex) {
255         if (delimeterStartIndex >= 2 && messagePattern.charAt(delimeterStartIndex - 2) == ESCAPE_CHAR) {
256             return true;
257         } else {
258             return false;
259         }
260     }
261 
262     // special treatment of array values was suggested by 'lizongbo'
deeplyAppendParameter(StringBuilder sbuf, Object o, Map<Object[], Object> seenMap)263     private static void deeplyAppendParameter(StringBuilder sbuf, Object o, Map<Object[], Object> seenMap) {
264         if (o == null) {
265             sbuf.append("null");
266             return;
267         }
268         if (!o.getClass().isArray()) {
269             safeObjectAppend(sbuf, o);
270         } else {
271             // check for primitive array types because they
272             // unfortunately cannot be cast to Object[]
273             if (o instanceof boolean[]) {
274                 booleanArrayAppend(sbuf, (boolean[]) o);
275             } else if (o instanceof byte[]) {
276                 byteArrayAppend(sbuf, (byte[]) o);
277             } else if (o instanceof char[]) {
278                 charArrayAppend(sbuf, (char[]) o);
279             } else if (o instanceof short[]) {
280                 shortArrayAppend(sbuf, (short[]) o);
281             } else if (o instanceof int[]) {
282                 intArrayAppend(sbuf, (int[]) o);
283             } else if (o instanceof long[]) {
284                 longArrayAppend(sbuf, (long[]) o);
285             } else if (o instanceof float[]) {
286                 floatArrayAppend(sbuf, (float[]) o);
287             } else if (o instanceof double[]) {
288                 doubleArrayAppend(sbuf, (double[]) o);
289             } else {
290                 objectArrayAppend(sbuf, (Object[]) o, seenMap);
291             }
292         }
293     }
294 
safeObjectAppend(StringBuilder sbuf, Object o)295     private static void safeObjectAppend(StringBuilder sbuf, Object o) {
296         try {
297             String oAsString = o.toString();
298             sbuf.append(oAsString);
299         } catch (Throwable t) {
300             System.err.println("SLF4J: Failed toString() invocation on an object of type [" + o.getClass().getName() + "]");
301             t.printStackTrace();
302             sbuf.append("[FAILED toString()]");
303         }
304 
305     }
306 
objectArrayAppend(StringBuilder sbuf, Object[] a, Map<Object[], Object> seenMap)307     private static void objectArrayAppend(StringBuilder sbuf, Object[] a, Map<Object[], Object> seenMap) {
308         sbuf.append('[');
309         if (!seenMap.containsKey(a)) {
310             seenMap.put(a, null);
311             final int len = a.length;
312             for (int i = 0; i < len; i++) {
313                 deeplyAppendParameter(sbuf, a[i], seenMap);
314                 if (i != len - 1)
315                     sbuf.append(", ");
316             }
317             // allow repeats in siblings
318             seenMap.remove(a);
319         } else {
320             sbuf.append("...");
321         }
322         sbuf.append(']');
323     }
324 
booleanArrayAppend(StringBuilder sbuf, boolean[] a)325     private static void booleanArrayAppend(StringBuilder sbuf, boolean[] a) {
326         sbuf.append('[');
327         final int len = a.length;
328         for (int i = 0; i < len; i++) {
329             sbuf.append(a[i]);
330             if (i != len - 1)
331                 sbuf.append(", ");
332         }
333         sbuf.append(']');
334     }
335 
byteArrayAppend(StringBuilder sbuf, byte[] a)336     private static void byteArrayAppend(StringBuilder sbuf, byte[] a) {
337         sbuf.append('[');
338         final int len = a.length;
339         for (int i = 0; i < len; i++) {
340             sbuf.append(a[i]);
341             if (i != len - 1)
342                 sbuf.append(", ");
343         }
344         sbuf.append(']');
345     }
346 
charArrayAppend(StringBuilder sbuf, char[] a)347     private static void charArrayAppend(StringBuilder sbuf, char[] a) {
348         sbuf.append('[');
349         final int len = a.length;
350         for (int i = 0; i < len; i++) {
351             sbuf.append(a[i]);
352             if (i != len - 1)
353                 sbuf.append(", ");
354         }
355         sbuf.append(']');
356     }
357 
shortArrayAppend(StringBuilder sbuf, short[] a)358     private static void shortArrayAppend(StringBuilder sbuf, short[] a) {
359         sbuf.append('[');
360         final int len = a.length;
361         for (int i = 0; i < len; i++) {
362             sbuf.append(a[i]);
363             if (i != len - 1)
364                 sbuf.append(", ");
365         }
366         sbuf.append(']');
367     }
368 
intArrayAppend(StringBuilder sbuf, int[] a)369     private static void intArrayAppend(StringBuilder sbuf, int[] a) {
370         sbuf.append('[');
371         final int len = a.length;
372         for (int i = 0; i < len; i++) {
373             sbuf.append(a[i]);
374             if (i != len - 1)
375                 sbuf.append(", ");
376         }
377         sbuf.append(']');
378     }
379 
longArrayAppend(StringBuilder sbuf, long[] a)380     private static void longArrayAppend(StringBuilder sbuf, long[] a) {
381         sbuf.append('[');
382         final int len = a.length;
383         for (int i = 0; i < len; i++) {
384             sbuf.append(a[i]);
385             if (i != len - 1)
386                 sbuf.append(", ");
387         }
388         sbuf.append(']');
389     }
390 
floatArrayAppend(StringBuilder sbuf, float[] a)391     private static void floatArrayAppend(StringBuilder sbuf, float[] a) {
392         sbuf.append('[');
393         final int len = a.length;
394         for (int i = 0; i < len; i++) {
395             sbuf.append(a[i]);
396             if (i != len - 1)
397                 sbuf.append(", ");
398         }
399         sbuf.append(']');
400     }
401 
doubleArrayAppend(StringBuilder sbuf, double[] a)402     private static void doubleArrayAppend(StringBuilder sbuf, double[] a) {
403         sbuf.append('[');
404         final int len = a.length;
405         for (int i = 0; i < len; i++) {
406             sbuf.append(a[i]);
407             if (i != len - 1)
408                 sbuf.append(", ");
409         }
410         sbuf.append(']');
411     }
412 }
413