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   1 /*
   2  * (c) Copyright IBM Corp. 2000, 2001.
   3  * All Rights Reserved.
   4  */
   5 package net.sourceforge.phpdt.internal.corext.template;
   6
   7 import java.io.Reader;
   8 import java.io.StringReader;
   9 import java.util.HashMap;
  10 import java.util.Iterator;
  11 import java.util.Map;
  12 import java.util.Set;
  13 import java.util.Vector;
  14
  15 import org.eclipse.core.runtime.CoreException;
  16
  17 /**
  18  * The template translator translates a string into a template buffer.
  19  * The EBNF grammer of a valid string is as follows:
  20  *
  21  * <p>
  22  * template := (text | escape)*.<br />
  23  * text := character - dollar.<br />
  24  * escape := dollar ('{' identifier '}' | dollar).<br />
  25  * dollar := '$'.<br />
  26  * </p>
  27  */
  28 public class TemplateTranslator {
  29
  30         // states
  31         private static final int TEXT= 0;
  32         private static final int ESCAPE= 1;
  33         private static final int IDENTIFIER= 2;
  34
  35         // tokens
  36         private static final char ESCAPE_CHARACTER= '$';
  37         private static final char IDENTIFIER_BEGIN= '{';
  38         private static final char IDENTIFIER_END= '}';
  39
  40         /** a buffer for the translation result string */
  41     private final StringBuffer fBuffer= new StringBuffer();
  42     /** position offsets of variables */
  43     private final Vector fOffsets= new Vector();
  44     /** position lengths of variables */
  45     private final Vector fLengths= new Vector();
  46
  47         /** the current parsing state */
  48     private int fState;
  49     /** the last translation error */
  50     private String fErrorMessage;
  51
  52         /**
  53          * Returns an error message if an error occured for the last translation, <code>null</code>
  54          * otherwise.
  55          */
  56         public String getErrorMessage() {
  57             return fErrorMessage;
  58         }
  59
  60         /**
  61          * Translates a template string to <code>TemplateBuffer</code>. <code>null</code>
  62          * is returned if there was an error. <code>getErrorMessage()</code> retrieves the
  63          * associated error message.
  64          *
  65          * @param string the string to translate.
  66          * @return returns the template buffer corresponding to the string, <code>null</code>
  67          *         if there was an error.
  68          * @see #getErrorMessage()
  69          */
  70         public TemplateBuffer translate(String string) throws CoreException {
  71
  72             fBuffer.setLength(0);
  73             fOffsets.clear();
  74             fLengths.clear();
  75             fState= TEXT;
  76             fErrorMessage= null;
  77
  78                 if (!parse(string))
  79                         return null;
  80
  81                 switch (fState) {
  82                 case TEXT:
  83                         break;
  84
  85                 // illegal, but be tolerant
  86                 case ESCAPE:
  87                         fErrorMessage= TemplateMessages.getString("TemplateTranslator.error.incomplete.variable"); //$NON-NLS-1$
  88                         fBuffer.append(ESCAPE_CHARACTER);
  89                         return null;
  90
  91                 // illegal, but be tolerant
  92                 case IDENTIFIER:
  93                         fErrorMessage= TemplateMessages.getString("TemplateTranslator.error.incomplete.variable"); //$NON-NLS-1$
  94                         fBuffer.append(ESCAPE_CHARACTER);
  95                         return null;
  96                 }
  97
  98                 int[] offsets= new int[fOffsets.size()];
  99                 int[] lengths= new int[fLengths.size()];
 100
 101                 for (int i= 0; i < fOffsets.size(); i++) {
 102                         offsets[i]= ((Integer) fOffsets.get(i)).intValue();
 103                         lengths[i]= ((Integer) fLengths.get(i)).intValue();
 104                 }
 105
 106                 String translatedString= fBuffer.toString();
 107                 TemplatePosition[] variables= findVariables(translatedString, offsets, lengths);
 108
 109                 return new TemplateBuffer(translatedString, variables);
 110         }
 111
 112         private static TemplatePosition[] findVariables(String string, int[] offsets, int[] lengths) {
 113
 114                 Map map= new HashMap();
 115
 116                 for (int i= 0; i != offsets.length; i++) {
 117                     int offset= offsets[i];
 118                     int length= lengths[i];
 119
 120                     String content= string.substring(offset, offset + length);
 121                     Vector vector= (Vector) map.get(content);
 122                     if (vector == null) {
 123                         vector= new Vector();
 124                         map.put(content, vector);
 125                     }
 126                     vector.add(new Integer(offset));
 127                 }
 128
 129                 TemplatePosition[] variables= new TemplatePosition[map.size()];
 130                 int k= 0;
 131
 132                 Set keys= map.keySet();
 133                 for (Iterator i= keys.iterator(); i.hasNext(); ) {
 134                         String name= (String) i.next();
 135                         Vector vector= (Vector) map.get(name);
 136
 137                         int[] offsets_= new int[vector.size()];
 138                         for (int j= 0; j != offsets_.length; j++)
 139                                 offsets_[j]= ((Integer) vector.get(j)).intValue();
 140
 141                         variables[k]= new TemplatePosition(name, name, offsets_, name.length());
 142                         k++;
 143                 }
 144
 145                 return variables;
 146         }
 147
 148         /** internal parser */
 149         private boolean parse(String string) {
 150
 151                 for (int i= 0; i != string.length(); i++) {
 152                     char ch= string.charAt(i);
 153
 154                         switch (fState) {
 155                         case TEXT:
 156                                 switch (ch) {
 157                                 case ESCAPE_CHARACTER:
 158                                         fState= ESCAPE;
 159                                         break;
 160
 161                                 default:
 162                                         fBuffer.append(ch);
 163                                         break;
 164                                 }
 165                                 break;
 166
 167                         case ESCAPE:
 168                                 switch (ch) {
 169                                 case ESCAPE_CHARACTER:
 170                                         fBuffer.append(ch);
 171                                         fState= TEXT;
 172                                         break;
 173
 174                                 case IDENTIFIER_BEGIN:
 175                                         fOffsets.add(new Integer(fBuffer.length()));
 176                                         fState= IDENTIFIER;
 177                                         break;
 178
 179                                 default:
 180                                         // illegal single escape character, but be tolerant
 181                                         fErrorMessage= TemplateMessages.getString("TemplateTranslator.error.incomplete.variable"); //$NON-NLS-1$
 182                                         fBuffer.append(ESCAPE_CHARACTER);
 183                                         fBuffer.append(ch);
 184                                         fState= TEXT;
 185                                         return false;
 186                                 }
 187                                 break;
 188
 189                         case IDENTIFIER:
 190                                 switch (ch) {
 191                                 case IDENTIFIER_END:
 192                                         int offset = ((Integer) fOffsets.get(fOffsets.size() - 1)).intValue();
 193                                         fLengths.add(new Integer(fBuffer.length() - offset));
 194                                         fState= TEXT;
 195                                         break;
 196
 197                                 default:
 198                                         if (!Character.isUnicodeIdentifierStart((char) ch) &&
 199                                                 !Character.isUnicodeIdentifierPart((char) ch))
 200                                         {
 201                                                 // illegal identifier character
 202                                                 fErrorMessage= TemplateMessages.getString("TemplateTranslator.error.invalid.identifier"); //$NON-NLS-1$
 203                                                 return false;
 204                                         }
 205
 206                                         fBuffer.append(ch);
 207                                         break;
 208                                 }
 209                                 break;
 210                         }
 211                 }
 212
 213                 return true;
 214         }
 215
 216 }