001/**
002 * Copyright (c) 2004-2011 QOS.ch
003 * All rights reserved.
004 *
005 * Permission is hereby granted, free  of charge, to any person obtaining
006 * a  copy  of this  software  and  associated  documentation files  (the
007 * "Software"), to  deal in  the Software without  restriction, including
008 * without limitation  the rights to  use, copy, modify,  merge, publish,
009 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
010 * permit persons to whom the Software  is furnished to do so, subject to
011 * the following conditions:
012 *
013 * The  above  copyright  notice  and  this permission  notice  shall  be
014 * included in all copies or substantial portions of the Software.
015 *
016 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
017 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
018 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
019 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
020 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
021 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
022 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
023 *
024 */
025package org.slf4j.helpers;
026
027import java.text.MessageFormat;
028import java.util.HashMap;
029import java.util.Map;
030
031// contributors: lizongbo: proposed special treatment of array parameter values
032// Joern Huxhorn: pointed out double[] omission, suggested deep array copy
033/**
034 * Formats messages according to very simple substitution rules. Substitutions
035 * can be made 1, 2 or more arguments.
036 *
037 * <p>
038 * For example,
039 *
040 * <pre>
041 * MessageFormatter.format(&quot;Hi {}.&quot;, &quot;there&quot;)
042 * </pre>
043 *
044 * will return the string "Hi there.".
045 * <p>
046 * The {} pair is called the <em>formatting anchor</em>. It serves to designate
047 * the location where arguments need to be substituted within the message
048 * pattern.
049 * <p>
050 * In case your message contains the '{' or the '}' character, you do not have
051 * to do anything special unless the '}' character immediately follows '{'. For
052 * example,
053 *
054 * <pre>
055 * MessageFormatter.format(&quot;Set {1,2,3} is not equal to {}.&quot;, &quot;1,2&quot;);
056 * </pre>
057 *
058 * will return the string "Set {1,2,3} is not equal to 1,2.".
059 *
060 * <p>
061 * If for whatever reason you need to place the string "{}" in the message
062 * without its <em>formatting anchor</em> meaning, then you need to escape the
063 * '{' character with '\', that is the backslash character. Only the '{'
064 * character should be escaped. There is no need to escape the '}' character.
065 * For example,
066 *
067 * <pre>
068 * MessageFormatter.format(&quot;Set \\{} is not equal to {}.&quot;, &quot;1,2&quot;);
069 * </pre>
070 *
071 * will return the string "Set {} is not equal to 1,2.".
072 *
073 * <p>
074 * The escaping behavior just described can be overridden by escaping the escape
075 * character '\'. Calling
076 *
077 * <pre>
078 * MessageFormatter.format(&quot;File name is C:\\\\{}.&quot;, &quot;file.zip&quot;);
079 * </pre>
080 *
081 * will return the string "File name is C:\file.zip".
082 *
083 * <p>
084 * The formatting conventions are different than those of {@link MessageFormat}
085 * which ships with the Java platform. This is justified by the fact that
086 * SLF4J's implementation is 10 times faster than that of {@link MessageFormat}.
087 * This local performance difference is both measurable and significant in the
088 * larger context of the complete logging processing chain.
089 *
090 * <p>
091 * See also {@link #format(String, Object)},
092 * {@link #format(String, Object, Object)} and
093 * {@link #arrayFormat(String, Object[])} methods for more details.
094 *
095 * @author Ceki G&uuml;lc&uuml;
096 * @author Joern Huxhorn
097 */
098final public class MessageFormatter {
099    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 arg
120     *          The argument to be substituted in place of the formatting anchor
121     * @return The formatted message
122     */
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     */
150    final public static FormattingTuple format(final String messagePattern, Object arg1, Object arg2) {
151        return arrayFormat(messagePattern, new Object[] { arg1, arg2 });
152    }
153
154
155    static final Throwable getThrowableCandidate(Object[] argArray) {
156        if (argArray == null || argArray.length == 0) {
157            return null;
158        }
159
160        final Object lastEntry = argArray[argArray.length - 1];
161        if (lastEntry instanceof Throwable) {
162            return (Throwable) lastEntry;
163        }
164        return null;
165    }
166
167    final public static FormattingTuple arrayFormat(final String messagePattern, final Object[] argArray) {
168        Throwable throwableCandidate = getThrowableCandidate(argArray);
169        Object[] args = argArray;
170        if (throwableCandidate != null) {
171            args = trimmedCopy(argArray);
172        }
173        return arrayFormat(messagePattern, args, throwableCandidate);
174    }
175
176    private static Object[] trimmedCopy(Object[] argArray) {
177        if (argArray == null || argArray.length == 0) {
178            throw new IllegalStateException("non-sensical empty or null argument array");
179        }
180        final int trimemdLen = argArray.length - 1;
181        Object[] trimmed = new Object[trimemdLen];
182        System.arraycopy(argArray, 0, trimmed, 0, trimemdLen);
183        return trimmed;
184    }
185
186    final public static FormattingTuple arrayFormat(final String messagePattern, final Object[] argArray, Throwable throwable) {
187
188        if (messagePattern == null) {
189            return new FormattingTuple(null, argArray, throwable);
190        }
191
192        if (argArray == null) {
193            return new FormattingTuple(messagePattern);
194        }
195
196        int i = 0;
197        int j;
198        // use string builder for better multicore performance
199        StringBuilder sbuf = new StringBuilder(messagePattern.length() + 50);
200
201        int L;
202        for (L = 0; L < argArray.length; L++) {
203
204            j = messagePattern.indexOf(DELIM_STR, i);
205
206            if (j == -1) {
207                // no more variables
208                if (i == 0) { // this is a simple string
209                    return new FormattingTuple(messagePattern, argArray, throwable);
210                } else { // add the tail string which contains no variables and return
211                    // the result.
212                    sbuf.append(messagePattern, i, messagePattern.length());
213                    return new FormattingTuple(sbuf.toString(), argArray, throwable);
214                }
215            } else {
216                if (isEscapedDelimeter(messagePattern, j)) {
217                    if (!isDoubleEscaped(messagePattern, j)) {
218                        L--; // DELIM_START was escaped, thus should not be incremented
219                        sbuf.append(messagePattern, i, j - 1);
220                        sbuf.append(DELIM_START);
221                        i = j + 1;
222                    } else {
223                        // The escape character preceding the delimiter start is
224                        // itself escaped: "abc x:\\{}"
225                        // we have to consume one backward slash
226                        sbuf.append(messagePattern, i, j - 1);
227                        deeplyAppendParameter(sbuf, argArray[L], new HashMap<Object[], Object>());
228                        i = j + 2;
229                    }
230                } else {
231                    // normal case
232                    sbuf.append(messagePattern, i, j);
233                    deeplyAppendParameter(sbuf, argArray[L], new HashMap<Object[], Object>());
234                    i = j + 2;
235                }
236            }
237        }
238        // append the characters following the last {} pair.
239        sbuf.append(messagePattern, i, messagePattern.length());
240        return new FormattingTuple(sbuf.toString(), argArray, throwable);
241    }
242
243    final static boolean isEscapedDelimeter(String messagePattern, int delimeterStartIndex) {
244
245        if (delimeterStartIndex == 0) {
246            return false;
247        }
248        char potentialEscape = messagePattern.charAt(delimeterStartIndex - 1);
249        if (potentialEscape == ESCAPE_CHAR) {
250            return true;
251        } else {
252            return false;
253        }
254    }
255
256    final static boolean isDoubleEscaped(String messagePattern, int delimeterStartIndex) {
257        if (delimeterStartIndex >= 2 && messagePattern.charAt(delimeterStartIndex - 2) == ESCAPE_CHAR) {
258            return true;
259        } else {
260            return false;
261        }
262    }
263
264    // special treatment of array values was suggested by 'lizongbo'
265    private static void deeplyAppendParameter(StringBuilder sbuf, Object o, Map<Object[], Object> seenMap) {
266        if (o == null) {
267            sbuf.append("null");
268            return;
269        }
270        if (!o.getClass().isArray()) {
271            safeObjectAppend(sbuf, o);
272        } else {
273            // check for primitive array types because they
274            // unfortunately cannot be cast to Object[]
275            if (o instanceof boolean[]) {
276                booleanArrayAppend(sbuf, (boolean[]) o);
277            } else if (o instanceof byte[]) {
278                byteArrayAppend(sbuf, (byte[]) o);
279            } else if (o instanceof char[]) {
280                charArrayAppend(sbuf, (char[]) o);
281            } else if (o instanceof short[]) {
282                shortArrayAppend(sbuf, (short[]) o);
283            } else if (o instanceof int[]) {
284                intArrayAppend(sbuf, (int[]) o);
285            } else if (o instanceof long[]) {
286                longArrayAppend(sbuf, (long[]) o);
287            } else if (o instanceof float[]) {
288                floatArrayAppend(sbuf, (float[]) o);
289            } else if (o instanceof double[]) {
290                doubleArrayAppend(sbuf, (double[]) o);
291            } else {
292                objectArrayAppend(sbuf, (Object[]) o, seenMap);
293            }
294        }
295    }
296
297    private static void safeObjectAppend(StringBuilder sbuf, Object o) {
298        try {
299            String oAsString = o.toString();
300            sbuf.append(oAsString);
301        } catch (Throwable t) {
302            Util.report("SLF4J: Failed toString() invocation on an object of type [" + o.getClass().getName() + "]", t);
303            sbuf.append("[FAILED toString()]");
304        }
305
306    }
307
308    private static void objectArrayAppend(StringBuilder sbuf, Object[] a, Map<Object[], Object> seenMap) {
309        sbuf.append('[');
310        if (!seenMap.containsKey(a)) {
311            seenMap.put(a, null);
312            final int len = a.length;
313            for (int i = 0; i < len; i++) {
314                deeplyAppendParameter(sbuf, a[i], seenMap);
315                if (i != len - 1)
316                    sbuf.append(", ");
317            }
318            // allow repeats in siblings
319            seenMap.remove(a);
320        } else {
321            sbuf.append("...");
322        }
323        sbuf.append(']');
324    }
325
326    private static void booleanArrayAppend(StringBuilder sbuf, boolean[] a) {
327        sbuf.append('[');
328        final int len = a.length;
329        for (int i = 0; i < len; i++) {
330            sbuf.append(a[i]);
331            if (i != len - 1)
332                sbuf.append(", ");
333        }
334        sbuf.append(']');
335    }
336
337    private static void byteArrayAppend(StringBuilder sbuf, byte[] a) {
338        sbuf.append('[');
339        final int len = a.length;
340        for (int i = 0; i < len; i++) {
341            sbuf.append(a[i]);
342            if (i != len - 1)
343                sbuf.append(", ");
344        }
345        sbuf.append(']');
346    }
347
348    private static void charArrayAppend(StringBuilder sbuf, char[] a) {
349        sbuf.append('[');
350        final int len = a.length;
351        for (int i = 0; i < len; i++) {
352            sbuf.append(a[i]);
353            if (i != len - 1)
354                sbuf.append(", ");
355        }
356        sbuf.append(']');
357    }
358
359    private static void shortArrayAppend(StringBuilder sbuf, short[] a) {
360        sbuf.append('[');
361        final int len = a.length;
362        for (int i = 0; i < len; i++) {
363            sbuf.append(a[i]);
364            if (i != len - 1)
365                sbuf.append(", ");
366        }
367        sbuf.append(']');
368    }
369
370    private static void intArrayAppend(StringBuilder sbuf, int[] a) {
371        sbuf.append('[');
372        final int len = a.length;
373        for (int i = 0; i < len; i++) {
374            sbuf.append(a[i]);
375            if (i != len - 1)
376                sbuf.append(", ");
377        }
378        sbuf.append(']');
379    }
380
381    private static void longArrayAppend(StringBuilder sbuf, long[] a) {
382        sbuf.append('[');
383        final int len = a.length;
384        for (int i = 0; i < len; i++) {
385            sbuf.append(a[i]);
386            if (i != len - 1)
387                sbuf.append(", ");
388        }
389        sbuf.append(']');
390    }
391
392    private static void floatArrayAppend(StringBuilder sbuf, float[] a) {
393        sbuf.append('[');
394        final int len = a.length;
395        for (int i = 0; i < len; i++) {
396            sbuf.append(a[i]);
397            if (i != len - 1)
398                sbuf.append(", ");
399        }
400        sbuf.append(']');
401    }
402
403    private static void doubleArrayAppend(StringBuilder sbuf, double[] a) {
404        sbuf.append('[');
405        final int len = a.length;
406        for (int i = 0; i < len; i++) {
407            sbuf.append(a[i]);
408            if (i != len - 1)
409                sbuf.append(", ");
410        }
411        sbuf.append(']');
412    }
413
414}