--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dwtx/jface/text/rules/BufferedRuleBasedScanner.d	Sat Aug 23 19:10:48 2008 +0200
@@ -0,0 +1,139 @@
+/*******************************************************************************
+ * Copyright (c) 2000, 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:
+ *     IBM Corporation - initial API and implementation
+ * Port to the D programming language:
+ *     Frank Benoit <benoit@tionex.de>
+ *******************************************************************************/
+
+module dwtx.jface.text.rules.BufferedRuleBasedScanner;
+
+import dwt.dwthelper.utils;
+
+
+import dwtx.core.runtime.Assert;
+import dwtx.jface.text.BadLocationException;
+import dwtx.jface.text.IDocument;
+
+/**
+ * A buffered rule based scanner. The buffer always contains a section
+ * of a fixed size of the document to be scanned. Completely adheres to
+ * the contract of <code>RuleBasedScanner</code>.
+ */
+public class BufferedRuleBasedScanner : RuleBasedScanner {
+
+    /** The default buffer size. Value = 500 */
+    private final static int DEFAULT_BUFFER_SIZE= 500;
+    /** The actual size of the buffer. Initially set to <code>DEFAULT_BUFFER_SIZE</code> */
+    private int fBufferSize= DEFAULT_BUFFER_SIZE;
+    /** The buffer */
+    private char[] fBuffer= new char[DEFAULT_BUFFER_SIZE];
+    /** The offset of the document at which the buffer starts */
+    private int fStart;
+    /** The offset of the document at which the buffer ends */
+    private int fEnd;
+    /** The cached length of the document */
+    private int fDocumentLength;
+
+
+    /**
+     * Creates a new buffered rule based scanner which does
+     * not have any rule and a default buffer size of 500 characters.
+     */
+    protected BufferedRuleBasedScanner() {
+        super();
+    }
+
+    /**
+     * Creates a new buffered rule based scanner which does
+     * not have any rule. The buffer size is set to the given
+     * number of characters.
+     *
+     * @param size the buffer size
+     */
+    public BufferedRuleBasedScanner(int size) {
+        super();
+        setBufferSize(size);
+    }
+
+    /**
+     * Sets the buffer to the given number of characters.
+     *
+     * @param size the buffer size
+     */
+    protected void setBufferSize(int size) {
+        Assert.isTrue(size > 0);
+        fBufferSize= size;
+        fBuffer= new char[size];
+    }
+
+    /**
+     * Shifts the buffer so that the buffer starts at the
+     * given document offset.
+     *
+     * @param offset the document offset at which the buffer starts
+     */
+    private void shiftBuffer(int offset) {
+
+        fStart= offset;
+        fEnd= fStart + fBufferSize;
+        if (fEnd > fDocumentLength)
+            fEnd= fDocumentLength;
+
+        try {
+
+            String content= fDocument.get(fStart, fEnd - fStart);
+            content.getChars(0, fEnd - fStart, fBuffer, 0);
+
+        } catch (BadLocationException x) {
+        }
+    }
+
+    /*
+     * @see RuleBasedScanner#setRange(IDocument, int, int)
+     */
+    public void setRange(IDocument document, int offset, int length) {
+
+        super.setRange(document, offset, length);
+
+        fDocumentLength= document.getLength();
+        shiftBuffer(offset);
+    }
+
+    /*
+     * @see RuleBasedScanner#read()
+     */
+    public int read() {
+        fColumn= UNDEFINED;
+        if (fOffset >= fRangeEnd) {
+            ++ fOffset;
+            return EOF;
+        }
+
+        if (fOffset is fEnd)
+            shiftBuffer(fEnd);
+        else if (fOffset < fStart || fEnd < fOffset)
+            shiftBuffer(fOffset);
+
+        return fBuffer[fOffset++ - fStart];
+    }
+
+    /*
+     * @see RuleBasedScanner#unread()
+     */
+    public void unread() {
+
+        if (fOffset is fStart)
+            shiftBuffer(Math.max(0, fStart - (fBufferSize / 2)));
+
+        --fOffset;
+        fColumn= UNDEFINED;
+    }
+}
+
+