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   1 /**********************************************************************
   2  Copyright (c) 2000, 2002 IBM Corp. and others.
   3  All rights reserved. This program and the accompanying materials
   4  are made available under the terms of the Common Public License v1.0
   5  which accompanies this distribution, and is available at
   6  http://www.eclipse.org/legal/cpl-v10.html
   7
   8  Contributors:
   9  IBM Corporation - Initial implementation
  10  **********************************************************************/
  11
  12 package net.sourceforge.phpdt.internal.ui.text;
  13
  14 import java.io.IOException;
  15 import java.io.Reader;
  16
  17 import net.sourceforge.phpdt.internal.corext.phpdoc.SingleCharReader;
  18
  19 /**
  20  * Reads the text contents from a reader and computes for each character a
  21  * potential substitution. The substitution may eat more characters than only
  22  * the one passed into the computation routine.
  23  */
  24 public abstract class SubstitutionTextReader extends SingleCharReader {
  25
  26         protected static final String LINE_DELIM = System.getProperty(
  27                         "line.separator", "\n"); //$NON-NLS-1$ //$NON-NLS-2$
  28
  29         private Reader fReader;
  30
  31         private boolean fWasWhiteSpace;
  32
  33         private int fCharAfterWhiteSpace;
  34
  35         /**
  36          * Tells whether white space characters are skipped.
  37          */
  38         private boolean fSkipWhiteSpace = true;
  39
  40         private boolean fReadFromBuffer;
  41
  42         private StringBuffer fBuffer;
  43
  44         private int fIndex;
  45
  46         protected SubstitutionTextReader(Reader reader) {
  47                 fReader = reader;
  48                 fBuffer = new StringBuffer();
  49                 fIndex = 0;
  50                 fReadFromBuffer = false;
  51                 fCharAfterWhiteSpace = -1;
  52                 fWasWhiteSpace = true;
  53         }
  54
  55         /**
  56          * Implement to compute the substitution for the given character and if
  57          * necessary subsequent characters. Use <code>nextChar</code> to read
  58          * subsequent characters.
  59          */
  60         protected abstract String computeSubstitution(int c) throws IOException;
  61
  62         /**
  63          * Returns the internal reader.
  64          */
  65         protected Reader getReader() {
  66                 return fReader;
  67         }
  68
  69         /**
  70          * Returns the next character.
  71          */
  72         protected int nextChar() throws IOException {
  73                 fReadFromBuffer = (fBuffer.length() > 0);
  74                 if (fReadFromBuffer) {
  75                         char ch = fBuffer.charAt(fIndex++);
  76                         if (fIndex >= fBuffer.length()) {
  77                                 fBuffer.setLength(0);
  78                                 fIndex = 0;
  79                         }
  80                         return ch;
  81                 } else {
  82                         int ch = fCharAfterWhiteSpace;
  83                         if (ch == -1) {
  84                                 ch = fReader.read();
  85                         }
  86                         if (fSkipWhiteSpace && Character.isWhitespace((char) ch)) {
  87                                 do {
  88                                         ch = fReader.read();
  89                                 } while (Character.isWhitespace((char) ch));
  90                                 if (ch != -1) {
  91                                         fCharAfterWhiteSpace = ch;
  92                                         return ' ';
  93                                 }
  94                         } else {
  95                                 fCharAfterWhiteSpace = -1;
  96                         }
  97                         return ch;
  98                 }
  99         }
 100
 101         /**
 102          * @see Reader#read()
 103          */
 104         public int read() throws IOException {
 105                 int c;
 106                 do {
 107
 108                         c = nextChar();
 109                         while (!fReadFromBuffer) {
 110                                 String s = computeSubstitution(c);
 111                                 if (s == null)
 112                                         break;
 113                                 if (s.length() > 0)
 114                                         fBuffer.insert(0, s);
 115                                 c = nextChar();
 116                         }
 117
 118                 } while (fSkipWhiteSpace && fWasWhiteSpace && (c == ' '));
 119                 fWasWhiteSpace = (c == ' ' || c == '\r' || c == '\n');
 120                 return c;
 121         }
 122
 123         /**
 124          * @see Reader#ready()
 125          */
 126         public boolean ready() throws IOException {
 127                 return fReader.ready();
 128         }
 129
 130         /**
 131          * @see Reader#close()
 132          */
 133         public void close() throws IOException {
 134                 fReader.close();
 135         }
 136
 137         /**
 138          * @see Reader#reset()
 139          */
 140         public void reset() throws IOException {
 141                 fReader.reset();
 142                 fWasWhiteSpace = true;
 143                 fCharAfterWhiteSpace = -1;
 144                 fBuffer.setLength(0);
 145                 fIndex = 0;
 146         }
 147
 148         protected final void setSkipWhitespace(boolean state) {
 149                 fSkipWhiteSpace = state;
 150         }
 151
 152         protected final boolean isSkippingWhitespace() {
 153                 return fSkipWhiteSpace;
 154         }
 155 }