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1 /*******************************************************************************
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2 * Copyright (c) 2005, 2008 IBM Corporation and others.
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3 * All rights reserved. This program and the accompanying materials
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4 * are made available under the terms of the Eclipse Public License v1.0
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5 * which accompanies this distribution, and is available at
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6 * http://www.eclipse.org/legal/epl-v10.html
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7 *
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8 * Contributors:
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9 * Anton Leherbauer (anton.leherbauer@windriver.com) - initial API and implementation
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10 * Port to the D programming language:
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11 * Frank Benoit <benoit@tionex.de>
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12 *******************************************************************************/
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13 module dwtx.jface.text.CopyOnWriteTextStore;
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14
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15 import dwt.dwthelper.utils;
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16
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17 import dwtx.core.runtime.Assert;
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18
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19
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20 /**
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21 * Copy-on-write <code>ITextStore</code> wrapper.
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22 * <p>
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23 * This implementation uses an unmodifiable text store for the initial content.
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24 * Upon first modification attempt, the unmodifiable store is replaced with
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25 * a modifiable instance which must be supplied in the constructor.</p>
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26 * <p>
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27 * This class is not intended to be subclassed.
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28 * </p>
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29 *
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30 * @since 3.2
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31 * @noextend This class is not intended to be subclassed by clients.
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32 */
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33 public class CopyOnWriteTextStore : ITextStore {
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34
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35 /**
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36 * An unmodifiable String based text store. It is not possible to modify the content
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37 * other than using {@link #set}. Trying to {@link #replace} a text range will
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38 * throw an <code>UnsupportedOperationException</code>.
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39 */
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40 private static class StringTextStore : ITextStore {
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41
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42 /** Represents the content of this text store. */
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43 private String fText= ""; //$NON-NLS-1$
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44
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45 /**
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46 * Create an empty text store.
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47 */
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48 private StringTextStore() {
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49 super();
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50 }
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51
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52 /**
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53 * Create a text store with initial content.
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54 * @param text the initial content
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55 */
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56 private StringTextStore(String text) {
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57 super();
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58 set(text);
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59 }
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60
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61 /*
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62 * @see dwtx.jface.text.ITextStore#get(int)
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63 */
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64 public char get(int offset) {
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65 return fText.charAt(offset);
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66 }
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67
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68 /*
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69 * @see dwtx.jface.text.ITextStore#get(int, int)
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70 */
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71 public String get(int offset, int length) {
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72 return fText.substring(offset, offset + length);
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73 }
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74
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75 /*
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76 * @see dwtx.jface.text.ITextStore#getLength()
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77 */
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78 public int getLength() {
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79 return fText.length();
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80 }
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81
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82 /*
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83 * @see dwtx.jface.text.ITextStore#replace(int, int, java.lang.String)
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84 */
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85 public void replace(int offset, int length, String text) {
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86 // modification not supported
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87 throw new UnsupportedOperationException();
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88 }
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89
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90 /*
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91 * @see dwtx.jface.text.ITextStore#set(java.lang.String)
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92 */
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93 public void set(String text) {
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94 fText= text !is null ? text : ""; //$NON-NLS-1$
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95 }
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96
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97 }
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98
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99 /** The underlying "real" text store */
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100 protected ITextStore fTextStore= new StringTextStore();
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101
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102 /** A modifiable <code>ITextStore</code> instance */
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103 private final ITextStore fModifiableTextStore;
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104
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105 /**
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106 * Creates an empty text store. The given text store will be used upon first
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107 * modification attempt.
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108 *
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109 * @param modifiableTextStore
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110 * a modifiable <code>ITextStore</code> instance, may not be
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111 * <code>null</code>
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112 */
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113 public CopyOnWriteTextStore(ITextStore modifiableTextStore) {
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114 Assert.isNotNull(modifiableTextStore);
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115 fTextStore= new StringTextStore();
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116 fModifiableTextStore= modifiableTextStore;
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117 }
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118
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119 /*
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120 * @see dwtx.jface.text.ITextStore#get(int)
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121 */
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122 public char get(int offset) {
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123 return fTextStore.get(offset);
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124 }
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125
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126 /*
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127 * @see dwtx.jface.text.ITextStore#get(int, int)
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128 */
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129 public String get(int offset, int length) {
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130 return fTextStore.get(offset, length);
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131 }
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132
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133 /*
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134 * @see dwtx.jface.text.ITextStore#getLength()
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135 */
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136 public int getLength() {
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137 return fTextStore.getLength();
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138 }
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139
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140 /*
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141 * @see dwtx.jface.text.ITextStore#replace(int, int, java.lang.String)
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142 */
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143 public void replace(int offset, int length, String text) {
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144 if (fTextStore !is fModifiableTextStore) {
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145 String content= fTextStore.get(0, fTextStore.getLength());
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146 fTextStore= fModifiableTextStore;
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147 fTextStore.set(content);
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148 }
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149 fTextStore.replace(offset, length, text);
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150 }
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151
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152 /*
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153 * @see dwtx.jface.text.ITextStore#set(java.lang.String)
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154 */
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155 public void set(String text) {
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156 fTextStore= new StringTextStore(text);
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157 fModifiableTextStore.set(""); //$NON-NLS-1$
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158 }
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159
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160 }
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