Released Anton's patch as a partial fix for bug 75086: [implementation] Request for a memory efficient way of loading large documents (in the mega bytes range)

5 files changed, 162 insertions, 4 deletions

diff --git a/org.eclipse.text/component.xml b/org.eclipse.text/component.xml
index 33c210892ec..630ddca77cd 100644
--- a/org.eclipse.text/component.xml
+++ b/org.eclipse.text/component.xml
@@ -9,6 +9,7 @@
  <package name="org.eclipse.jface.text">
    <type name="Assert" instantiate="false"/>
    <type name="ConfigurableLineTracker" subclass="false"/>
+   <type name="CopyOnWriteTextStore" subclass="false"/>
    <type name="DefaultLineTracker" subclass="false"/>
    <type name="GapTextStore" subclass="false"/>
    <type name="TextUtilities" subclass="false" instantiate="false"/>
diff --git a/org.eclipse.text/src/org/eclipse/jface/text/CopyOnWriteTextStore.java b/org.eclipse.text/src/org/eclipse/jface/text/CopyOnWriteTextStore.java
new file mode 100644
index 00000000000..3600d1e5088
--- /dev/null
+++ b/org.eclipse.text/src/org/eclipse/jface/text/CopyOnWriteTextStore.java
@@ -0,0 +1,153 @@
+/*******************************************************************************
+ * Copyright (c) 2005 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
+ *******************************************************************************/
+
+package org.eclipse.jface.text;
+
+/**
+ * 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
+ */
+public class CopyOnWriteTextStore implements 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 implements 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 org.eclipse.jface.text.ITextStore#get(int)
+		 */
+		public char get(int offset) {
+			return fText.charAt(offset);
+		}
+
+		/*
+		 * @see org.eclipse.jface.text.ITextStore#get(int, int)
+		 */
+		public String get(int offset, int length) {
+			return fText.substring(offset, offset + length);
+		}
+
+		/*
+		 * @see org.eclipse.jface.text.ITextStore#getLength()
+		 */
+		public int getLength() {
+			return fText.length();
+		}
+
+		/*
+		 * @see org.eclipse.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 org.eclipse.jface.text.ITextStore#set(java.lang.String)
+		 */
+		public void set(String text) {
+			fText= text != 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 org.eclipse.jface.text.ITextStore#get(int)
+	 */
+	public char get(int offset) {
+		return fTextStore.get(offset);
+	}
+
+	/*
+	 * @see org.eclipse.jface.text.ITextStore#get(int, int)
+	 */
+	public String get(int offset, int length) {
+		return fTextStore.get(offset, length);
+	}
+
+	/*
+	 * @see org.eclipse.jface.text.ITextStore#getLength()
+	 */
+	public int getLength() {
+		return fTextStore.getLength();
+	}
+
+	/*
+	 * @see org.eclipse.jface.text.ITextStore#replace(int, int, java.lang.String)
+	 */
+	public void replace(int offset, int length, String text) {
+		if (fTextStore != fModifiableTextStore) {
+			String content= fTextStore.get(0, fTextStore.getLength());
+			fTextStore= fModifiableTextStore;
+			fTextStore.set(content);
+		}
+		fTextStore.replace(offset, length, text);
+	}
+
+	/*
+	 * @see org.eclipse.jface.text.ITextStore#set(java.lang.String)
+	 */
+	public void set(String text) {
+		fTextStore= new StringTextStore(text);
+		fModifiableTextStore.set(""); //$NON-NLS-1$
+	}
+
+}
diff --git a/org.eclipse.text/src/org/eclipse/jface/text/Document.java b/org.eclipse.text/src/org/eclipse/jface/text/Document.java
index 5ceb5af3516..af87ad62a51 100644
--- a/org.eclipse.text/src/org/eclipse/jface/text/Document.java
+++ b/org.eclipse.text/src/org/eclipse/jface/text/Document.java
@@ -14,7 +14,8 @@ package org.eclipse.jface.text;
 
 /**
  * Default document implementation. Uses a
- * {@link org.eclipse.jface.text.GapTextStore} as default text store and a
+ * {@link org.eclipse.jface.text.GapTextStore} wrapped inside a 
+ * {@link org.eclipse.jface.text.CopyOnWriteTextStore} as default text store and a
  * {@link org.eclipse.jface.text.SequentialRewriteTextStore} when in sequential
  * rewrite mode.
  * <p>
@@ -26,6 +27,7 @@ package org.eclipse.jface.text;
  *
  * @see org.eclipse.jface.text.GapTextStore
  * @see org.eclipse.jface.text.SequentialRewriteTextStore
+ * @see org.eclipse.jface.text.CopyOnWriteTextStore
  */
 public class Document extends AbstractDocument {
 
@@ -35,7 +37,7 @@ public class Document extends AbstractDocument {
 	 */
 	public Document() {
 		super();
-		setTextStore(new GapTextStore(50, 300));
+		setTextStore(new CopyOnWriteTextStore(new GapTextStore(50, 300)));
 		setLineTracker(new DefaultLineTracker());
 		completeInitialization();
 	}
@@ -47,7 +49,7 @@ public class Document extends AbstractDocument {
 	 */
 	public Document(String initialContent) {
 		super();
-		setTextStore(new GapTextStore(50, 300));
+		setTextStore(new CopyOnWriteTextStore(new GapTextStore(50, 300)));
 		setLineTracker(new DefaultLineTracker());
 		getStore().set(initialContent);
 		getTracker().set(initialContent);
diff --git a/org.eclipse.text/src/org/eclipse/jface/text/GapTextStore.java b/org.eclipse.text/src/org/eclipse/jface/text/GapTextStore.java
index 2ddc3a7ca07..67178a483ea 100644
--- a/org.eclipse.text/src/org/eclipse/jface/text/GapTextStore.java
+++ b/org.eclipse.text/src/org/eclipse/jface/text/GapTextStore.java
@@ -20,6 +20,7 @@ package org.eclipse.jface.text;
  * <p>
  * This class is not intended to be subclassed.
  * </p>
+ * @see CopyOnWriteTextStore for a copy-on-write text store wrapper
  */
 public class GapTextStore implements ITextStore {
 
diff --git a/org.eclipse.text/src/org/eclipse/jface/text/ITextStore.java b/org.eclipse.text/src/org/eclipse/jface/text/ITextStore.java
index 403e02663ec..85c470a77c1 100644
--- a/org.eclipse.text/src/org/eclipse/jface/text/ITextStore.java
+++ b/org.eclipse.text/src/org/eclipse/jface/text/ITextStore.java
@@ -17,7 +17,8 @@ package org.eclipse.jface.text;
  * Provides access to the stored text and allows to manipulate it.</p>
  * <p>
  * Clients may
- * implement this interface or use {@link org.eclipse.jface.text.GapTextStore} and
+ * implement this interface or use {@link org.eclipse.jface.text.GapTextStore},
+ * {@link org.eclipse.jface.text.CopyOnWriteTextStore} and
  * {@link org.eclipse.jface.text.SequentialRewriteTextStore}.</p>
  */
 public interface ITextStore {