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