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1   /***
2    * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
3    */
4   package net.sourceforge.pmd.util;
5   
6   import java.util.ArrayList;
7   import java.util.Iterator;
8   import java.util.List;
9   
10  public class StringUtil {
11  
12  	public static final String[] EMPTY_STRINGS = new String[0];
13      private static final boolean supportsUTF8 = System.getProperty("net.sourceforge.pmd.supportUTF8", "no").equals("yes");
14      private static final String[] ENTITIES;
15  
16      static {
17          ENTITIES = new String[256 - 126];
18          for (int i = 126; i <= 255; i++) {
19              ENTITIES[i - 126] = "&#" + i + ';';
20          }
21      }
22  
23      public static String replaceString(String original, char oldChar, String newString) {
24          
25      	String fixedNew = newString == null ? "" : newString;
26  
27          StringBuffer desc = new StringBuffer();
28          int index = original.indexOf(oldChar);
29          int last = 0;
30          while (index != -1) {
31              desc.append(original.substring(last, index));
32              desc.append(fixedNew);
33              last = index + 1;
34              index = original.indexOf(oldChar, last);
35          }
36          desc.append(original.substring(last));
37          return desc.toString();
38      }
39  
40      public static String replaceString(String original, String oldString, String newString) {
41      	
42      	String fixedNew = newString == null ? "" : newString;
43      	
44          StringBuffer desc = new StringBuffer();
45          int index = original.indexOf(oldString);
46          int last = 0;
47          while (index != -1) {
48              desc.append(original.substring(last, index));
49              desc.append(fixedNew);
50              last = index + oldString.length();
51              index = original.indexOf(oldString, last);
52          }
53          desc.append(original.substring(last));
54          return desc.toString();
55      }
56  
57      /***
58       * Appends to a StringBuffer the String src where non-ASCII and
59       * XML special chars are escaped.
60       *
61       * @param buf The destination XML stream
62       * @param src The String to append to the stream
63       */
64      public static void appendXmlEscaped(StringBuffer buf, String src) {
65          appendXmlEscaped(buf, src, supportsUTF8);
66      }
67  
68      public static String htmlEncode(String string) {
69          String encoded = StringUtil.replaceString(string, '&', "&amp;");
70          encoded = StringUtil.replaceString(encoded, '<', "&lt;");
71          return StringUtil.replaceString(encoded, '>', "&gt;");
72      }
73      
74      // TODO - unify the method above with the one below
75      
76      private static void appendXmlEscaped(StringBuffer buf, String src, boolean supportUTF8) {
77          char c;
78          for (int i = 0; i < src.length(); i++) {
79              c = src.charAt(i);
80              if (c > '~') {// 126
81                  if (!supportUTF8) {
82                      if (c <= 255) {
83                          buf.append(ENTITIES[c - 126]);
84                      } else {
85                          buf.append("&u").append(Integer.toHexString(c)).append(';');
86                      }
87                  } else {
88                      buf.append(c);
89                  }
90              } else if (c == '&')
91                  buf.append("&amp;");
92              else if (c == '"')
93                  buf.append("&quot;");
94              else if (c == '<')
95                  buf.append("&lt;");
96              else if (c == '>')
97                  buf.append("&gt;");
98              else
99                  buf.append(c);
100         }
101     }
102 
103 	/***
104 	 * Parses the input source using the delimiter specified. This method is much
105 	 * faster than using the StringTokenizer or String.split(char) approach and
106 	 * serves as a replacement for String.split() for JDK1.3 that doesn't have it.
107 	 *
108 	 * @param source String
109 	 * @param delimiter char
110 	 * @return String[]
111 	 */
112 	public static String[] substringsOf(String source, char delimiter) {
113 
114 		if (source == null || source.length() == 0) {
115             return EMPTY_STRINGS;
116         }
117 		
118 		int delimiterCount = 0;
119 		int length = source.length();
120 		char[] chars = source.toCharArray();
121 
122 		for (int i=0; i<length; i++) {
123 			if (chars[i] == delimiter) delimiterCount++;
124 			}
125 
126 		if (delimiterCount == 0) return new String[] { source };
127 
128 		String results[] = new String[delimiterCount+1];
129 
130 		int i = 0;
131 		int offset = 0;
132 
133 		while (offset <= length) {
134 			int pos = source.indexOf(delimiter, offset);
135 			if (pos < 0) pos = length;
136 			results[i++] = pos == offset ? "" : source.substring(offset, pos);
137 			offset = pos + 1;
138 			}
139 
140 		return results;
141 	}
142 	
143 	/***
144 	 * Much more efficient than StringTokenizer.
145 	 * 
146 	 * @param str String
147 	 * @param separator char
148 	 * @return String[]
149 	 */
150 	  public static String[] substringsOf(String str, String separator) {
151 		  
152 	        if (str == null || str.length() == 0) {
153 	            return EMPTY_STRINGS;
154 	        }
155 
156 	        int index = str.indexOf(separator);
157 	        if (index == -1) {
158 	            return new String[]{str};
159 	        }
160 
161 	        List list = new ArrayList();
162 	        int currPos = 0;
163 	        int len = separator.length();
164 	        while (index != -1) {
165 	            list.add(str.substring(currPos, index));
166 	            currPos = index + len;
167 	            index = str.indexOf(separator, currPos);
168 	        }
169 	        list.add(str.substring(currPos));
170 	        return (String[]) list.toArray(new String[list.size()]);
171 	    }
172 	
173 	
174 	/***
175 	 * Copies the elements returned by the iterator onto the string buffer
176 	 * each delimited by the separator.
177 	 *
178 	 * @param sb StringBuffer
179 	 * @param iter Iterator
180 	 * @param separator String
181 	 */
182 	public static void asStringOn(StringBuffer sb, Iterator iter, String separator) {
183 		
184 	    if (!iter.hasNext()) return;
185 	    
186 	    sb.append(iter.next());
187 	    
188 	    while (iter.hasNext()) {
189 	    	sb.append(separator);
190 	        sb.append(iter.next());
191 	    }
192 	}
193 	/***
194 	 * Return the length of the shortest string in the array.
195 	 * If any one of them is null then it returns 0.
196 	 * 
197 	 * @param strings String[]
198 	 * @return int
199 	 */
200 	public static int lengthOfShortestIn(String[] strings) {
201 		
202 		int minLength = Integer.MAX_VALUE;
203 		
204 		for (int i=0; i<strings.length; i++) {
205 			if (strings[i] == null) return 0;
206 			minLength = Math.min(minLength, strings[i].length());
207 		}
208 		
209 		return minLength;
210 	}
211 	
212 	/***
213 	 * Determine the maximum number of common leading whitespace characters
214 	 * the strings share in the same sequence. Useful for determining how
215 	 * many leading characters can be removed to shift all the text in the
216 	 * strings to the left without misaligning them.
217 	 * 
218 	 * @param strings String[]
219 	 * @return int
220 	 */
221 	public static int maxCommonLeadingWhitespaceForAll(String[] strings) {
222 		
223 		int shortest = lengthOfShortestIn(strings);
224 		if (shortest == 0) return 0;
225 		
226 		char[] matches = new char[shortest];
227 		
228 		String str;
229 		for (int m=0; m<matches.length; m++) {
230 			matches[m] = strings[0].charAt(m);
231 			if (!Character.isWhitespace(matches[m])) return m;
232 			for (int i=0; i<strings.length; i++) {
233 				str = strings[i];
234 				if (str.charAt(m) != matches[m])  return m; 
235 				}
236 		}
237 		
238 		return shortest;
239 	}
240 	
241 	/***
242 	 * Trims off the leading characters off the strings up to the trimDepth 
243 	 * specified. Returns the same strings if trimDepth = 0
244 	 * 
245 	 * @param strings
246 	 * @param trimDepth
247 	 * @return String[]
248 	 */
249 	public static String[] trimStartOn(String[] strings, int trimDepth) {
250 		
251 		if (trimDepth == 0) return strings;
252 		
253 		String[] results = new String[strings.length];
254 		for (int i=0; i<strings.length; i++) {
255 			results[i] = strings[i].substring(trimDepth);
256 		}
257 		return results;
258 	}
259 }