--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dwtx/jface/text/CopyOnWriteTextStore.d	Sat Aug 23 19:10:48 2008 +0200
@@ -0,0 +1,160 @@
+/*******************************************************************************
+ * Copyright (c) 2005, 2008 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     Anton Leherbauer (anton.leherbauer@windriver.com) - initial API and implementation
+ * Port to the D programming language:
+ *     Frank Benoit <benoit@tionex.de>
+ *******************************************************************************/
+module dwtx.jface.text.CopyOnWriteTextStore;
+
+import dwt.dwthelper.utils;
+
+import dwtx.core.runtime.Assert;
+
+
+/**
+ * Copy-on-write <code>ITextStore</code> wrapper.
+ * <p>
+ * This implementation uses an unmodifiable text store for the initial content.
+ * Upon first modification attempt, the unmodifiable store is replaced with
+ * a modifiable instance which must be supplied in the constructor.</p>
+ * <p>
+ * This class is not intended to be subclassed.
+ * </p>
+ *
+ * @since 3.2
+ * @noextend This class is not intended to be subclassed by clients.
+ */
+public class CopyOnWriteTextStore : ITextStore {
+
+    /**
+     * An unmodifiable String based text store. It is not possible to modify the content
+     * other than using {@link #set}. Trying to {@link #replace} a text range will
+     * throw an <code>UnsupportedOperationException</code>.
+     */
+    private static class StringTextStore : ITextStore {
+
+        /** Represents the content of this text store. */
+        private String fText= ""; //$NON-NLS-1$
+
+        /**
+         * Create an empty text store.
+         */
+        private StringTextStore() {
+            super();
+        }
+
+        /**
+         * Create a text store with initial content.
+         * @param text  the initial content
+         */
+        private StringTextStore(String text) {
+            super();
+            set(text);
+        }
+
+        /*
+         * @see dwtx.jface.text.ITextStore#get(int)
+         */
+        public char get(int offset) {
+            return fText.charAt(offset);
+        }
+
+        /*
+         * @see dwtx.jface.text.ITextStore#get(int, int)
+         */
+        public String get(int offset, int length) {
+            return fText.substring(offset, offset + length);
+        }
+
+        /*
+         * @see dwtx.jface.text.ITextStore#getLength()
+         */
+        public int getLength() {
+            return fText.length();
+        }
+
+        /*
+         * @see dwtx.jface.text.ITextStore#replace(int, int, java.lang.String)
+         */
+        public void replace(int offset, int length, String text) {
+            // modification not supported
+            throw new UnsupportedOperationException();
+        }
+
+        /*
+         * @see dwtx.jface.text.ITextStore#set(java.lang.String)
+         */
+        public void set(String text) {
+            fText= text !is null ? text : ""; //$NON-NLS-1$
+        }
+
+    }
+
+    /** The underlying "real" text store */
+    protected ITextStore fTextStore= new StringTextStore();
+
+    /** A modifiable <code>ITextStore</code> instance */
+    private final ITextStore fModifiableTextStore;
+
+    /**
+     * Creates an empty text store. The given text store will be used upon first
+     * modification attempt.
+     * 
+     * @param modifiableTextStore
+     *            a modifiable <code>ITextStore</code> instance, may not be
+     *            <code>null</code>
+     */
+    public CopyOnWriteTextStore(ITextStore modifiableTextStore) {
+        Assert.isNotNull(modifiableTextStore);
+        fTextStore= new StringTextStore();
+        fModifiableTextStore= modifiableTextStore;
+    }
+
+    /*
+     * @see dwtx.jface.text.ITextStore#get(int)
+     */
+    public char get(int offset) {
+        return fTextStore.get(offset);
+    }
+
+    /*
+     * @see dwtx.jface.text.ITextStore#get(int, int)
+     */
+    public String get(int offset, int length) {
+        return fTextStore.get(offset, length);
+    }
+
+    /*
+     * @see dwtx.jface.text.ITextStore#getLength()
+     */
+    public int getLength() {
+        return fTextStore.getLength();
+    }
+
+    /*
+     * @see dwtx.jface.text.ITextStore#replace(int, int, java.lang.String)
+     */
+    public void replace(int offset, int length, String text) {
+        if (fTextStore !is fModifiableTextStore) {
+            String content= fTextStore.get(0, fTextStore.getLength());
+            fTextStore= fModifiableTextStore;
+            fTextStore.set(content);
+        }
+        fTextStore.replace(offset, length, text);
+    }
+
+    /*
+     * @see dwtx.jface.text.ITextStore#set(java.lang.String)
+     */
+    public void set(String text) {
+        fTextStore= new StringTextStore(text);
+        fModifiableTextStore.set(""); //$NON-NLS-1$
+    }
+
+}