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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * particular file as subject to the "Classpath" exception as provided
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * accompanied this code).
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package javax.swing.text;

import java.util.Vector;
import java.io.Serializable;
import javax.swing.undo.*;
import javax.swing.SwingUtilities;

An implementation of the AbstractDocument.Content interface that is
a brute force implementation that is useful for relatively small
documents and/or debugging.  It manages the character content
as a simple character array.  It is also quite inefficient.

It is generally recommended that the gap buffer or piece table
implementations be used instead.  This buffer does not scale up
to large sizes.

Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing.  As of 1.4, support for long term storage
of all JavaBeansTM
has been added to the java.beans package. Please see XMLEncoder. 
Author:
 Timothy Prinzing/**
 * An implementation of the AbstractDocument.Content interface that is
 * a brute force implementation that is useful for relatively small
 * documents and/or debugging.  It manages the character content
 * as a simple character array.  It is also quite inefficient.
 * <p>
 * It is generally recommended that the gap buffer or piece table
 * implementations be used instead.  This buffer does not scale up
 * to large sizes.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans<sup><font size="-2">TM</font></sup>
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author  Timothy Prinzing
 */
public final class StringContent implements AbstractDocument.Content, Serializable {

    
Creates a new StringContent object.  Initial size defaults to 10.
/**
     * Creates a new StringContent object.  Initial size defaults to 10.
     */
    public StringContent() {
        this(10);
    }

    
Creates a new StringContent object, with the initial
size specified.  If the length is < 1, a size of 1 is used.
Params:
initialLength – the initial size/**
     * Creates a new StringContent object, with the initial
     * size specified.  If the length is < 1, a size of 1 is used.
     *
     * @param initialLength the initial size
     */
    public StringContent(int initialLength) {
        if (initialLength < 1) {
            initialLength = 1;
        }
        data = new char[initialLength];
        data[0] = '\n';
        count = 1;
    }

    
Returns the length of the content.
See Also:
Content.length
Returns:
the length >= 1/**
     * Returns the length of the content.
     *
     * @return the length >= 1
     * @see AbstractDocument.Content#length
     */
    public int length() {
        return count;
    }

    
Inserts a string into the content.
Params:
where – the starting position >= 0 && < length()
str – the non-null string to insert
Throws:
BadLocationException – if the specified position is invalid
See Also:
Content.insertString
Returns:
an UndoableEdit object for undoing/**
     * Inserts a string into the content.
     *
     * @param where the starting position >= 0 && < length()
     * @param str the non-null string to insert
     * @return an UndoableEdit object for undoing
     * @exception BadLocationException if the specified position is invalid
     * @see AbstractDocument.Content#insertString
     */
    public UndoableEdit insertString(int where, String str) throws BadLocationException {
        if (where >= count || where < 0) {
            throw new BadLocationException("Invalid location", count);
        }
        char[] chars = str.toCharArray();
        replace(where, 0, chars, 0, chars.length);
        if (marks != null) {
            updateMarksForInsert(where, str.length());
        }
        return new InsertUndo(where, str.length());
    }

    
Removes part of the content.  where + nitems must be < length().
Params:
where – the starting position >= 0
nitems – the number of characters to remove >= 0
Throws:
BadLocationException – if the specified position is invalid
See Also:
Content.remove
Returns:
an UndoableEdit object for undoing/**
     * Removes part of the content.  where + nitems must be < length().
     *
     * @param where the starting position >= 0
     * @param nitems the number of characters to remove >= 0
     * @return an UndoableEdit object for undoing
     * @exception BadLocationException if the specified position is invalid
     * @see AbstractDocument.Content#remove
     */
    public UndoableEdit remove(int where, int nitems) throws BadLocationException {
        if (where + nitems >= count) {
            throw new BadLocationException("Invalid range", count);
        }
        String removedString = getString(where, nitems);
        UndoableEdit edit = new RemoveUndo(where, removedString);
        replace(where, nitems, empty, 0, 0);
        if (marks != null) {
            updateMarksForRemove(where, nitems);
        }
        return edit;

    }

    
Retrieves a portion of the content.  where + len must be <= length().
Params:
where – the starting position >= 0
len – the length to retrieve >= 0
Throws:
BadLocationException – if the specified position is invalid
See Also:
Content.getString
Returns:
a string representing the content; may be empty/**
     * Retrieves a portion of the content.  where + len must be <= length().
     *
     * @param where the starting position >= 0
     * @param len the length to retrieve >= 0
     * @return a string representing the content; may be empty
     * @exception BadLocationException if the specified position is invalid
     * @see AbstractDocument.Content#getString
     */
    public String getString(int where, int len) throws BadLocationException {
        if (where + len > count) {
            throw new BadLocationException("Invalid range", count);
        }
        return new String(data, where, len);
    }

    
Retrieves a portion of the content.  where + len must be <= length()
Params:
where – the starting position >= 0
len – the number of characters to retrieve >= 0
chars – the Segment object to return the characters in
Throws:
BadLocationException – if the specified position is invalid
See Also:
Content.getChars/**
     * Retrieves a portion of the content.  where + len must be <= length()
     *
     * @param where the starting position >= 0
     * @param len the number of characters to retrieve >= 0
     * @param chars the Segment object to return the characters in
     * @exception BadLocationException if the specified position is invalid
     * @see AbstractDocument.Content#getChars
     */
    public void getChars(int where, int len, Segment chars) throws BadLocationException {
        if (where + len > count) {
            throw new BadLocationException("Invalid location", count);
        }
        chars.array = data;
        chars.offset = where;
        chars.count = len;
    }

    
Creates a position within the content that will
track change as the content is mutated.
Params:
offset – the offset to create a position for >= 0
Throws:
BadLocationException – if the specified position is invalid
Returns:
the position/**
     * Creates a position within the content that will
     * track change as the content is mutated.
     *
     * @param offset the offset to create a position for >= 0
     * @return the position
     * @exception BadLocationException if the specified position is invalid
     */
    public Position createPosition(int offset) throws BadLocationException {
        // some small documents won't have any sticky positions
        // at all, so the buffer is created lazily.
        if (marks == null) {
            marks = new Vector();
        }
        return new StickyPosition(offset);
    }

    // --- local methods ---------------------------------------

    
Replaces some of the characters in the array
Params:
offset –  offset into the array to start the replace
length –  number of characters to remove
replArray – replacement array
replOffset – offset into the replacement array
replLength – number of character to use from the
  replacement array./**
     * Replaces some of the characters in the array
     * @param offset  offset into the array to start the replace
     * @param length  number of characters to remove
     * @param replArray replacement array
     * @param replOffset offset into the replacement array
     * @param replLength number of character to use from the
     *   replacement array.
     */
    void replace(int offset, int length,
                 char[] replArray, int replOffset, int replLength) {
        int delta = replLength - length;
        int src = offset + length;
        int nmove = count - src;
        int dest = src + delta;
        if ((count + delta) >= data.length) {
            // need to grow the array
            int newLength = Math.max(2*data.length, count + delta);
            char[] newData = new char[newLength];
            System.arraycopy(data, 0, newData, 0, offset);
            System.arraycopy(replArray, replOffset, newData, offset, replLength);
            System.arraycopy(data, src, newData, dest, nmove);
            data = newData;
        } else {
            // patch the existing array
            System.arraycopy(data, src, data, dest, nmove);
            System.arraycopy(replArray, replOffset, data, offset, replLength);
        }
        count = count + delta;
    }

    void resize(int ncount) {
        char[] ndata = new char[ncount];
        System.arraycopy(data, 0, ndata, 0, Math.min(ncount, count));
        data = ndata;
    }

    synchronized void updateMarksForInsert(int offset, int length) {
        if (offset == 0) {
            // zero is a special case where we update only
            // marks after it.
            offset = 1;
        }
        int n = marks.size();
        for (int i = 0; i < n; i++) {
            PosRec mark = (PosRec) marks.elementAt(i);
            if (mark.unused) {
                // this record is no longer used, get rid of it
                marks.removeElementAt(i);
                i -= 1;
                n -= 1;
            } else if (mark.offset >= offset) {
                mark.offset += length;
            }
        }
    }

    synchronized void updateMarksForRemove(int offset, int length) {
        int n = marks.size();
        for (int i = 0; i < n; i++) {
            PosRec mark = (PosRec) marks.elementAt(i);
            if (mark.unused) {
                // this record is no longer used, get rid of it
                marks.removeElementAt(i);
                i -= 1;
                n -= 1;
            } else if (mark.offset >= (offset + length)) {
                mark.offset -= length;
            } else if (mark.offset >= offset) {
                mark.offset = offset;
            }
        }
    }

    
Returns a Vector containing instances of UndoPosRef for the
Positions in the range
offset to offset + length.
If v is not null the matching Positions are placed in
there. The vector with the resulting Positions are returned.

This is meant for internal usage, and is generally not of interest
to subclasses.
Params:
v – the Vector to use, with a new one created on null
offset – the starting offset >= 0
length – the length >= 0
Returns:
the set of instances/**
     * Returns a Vector containing instances of UndoPosRef for the
     * Positions in the range
     * <code>offset</code> to <code>offset</code> + <code>length</code>.
     * If <code>v</code> is not null the matching Positions are placed in
     * there. The vector with the resulting Positions are returned.
     * <p>
     * This is meant for internal usage, and is generally not of interest
     * to subclasses.
     *
     * @param v the Vector to use, with a new one created on null
     * @param offset the starting offset >= 0
     * @param length the length >= 0
     * @return the set of instances
     */
    protected Vector getPositionsInRange(Vector v, int offset,
                                                      int length) {
        int n = marks.size();
        int end = offset + length;
        Vector placeIn = (v == null) ? new Vector() : v;
        for (int i = 0; i < n; i++) {
            PosRec mark = (PosRec) marks.elementAt(i);
            if (mark.unused) {
                // this record is no longer used, get rid of it
                marks.removeElementAt(i);
                i -= 1;
                n -= 1;
            } else if(mark.offset >= offset && mark.offset <= end)
                placeIn.addElement(new UndoPosRef(mark));
        }
        return placeIn;
    }

    
Resets the location for all the UndoPosRef instances
in positions.

This is meant for internal usage, and is generally not of interest
to subclasses.
Params:
positions – the positions of the instances/**
     * Resets the location for all the UndoPosRef instances
     * in <code>positions</code>.
     * <p>
     * This is meant for internal usage, and is generally not of interest
     * to subclasses.
     *
     * @param positions the positions of the instances
     */
    protected void updateUndoPositions(Vector positions) {
        for(int counter = positions.size() - 1; counter >= 0; counter--) {
            UndoPosRef ref = (UndoPosRef)positions.elementAt(counter);
            // Check if the Position is still valid.
            if(ref.rec.unused) {
                positions.removeElementAt(counter);
            }
            else
                ref.resetLocation();
        }
    }

    private static final char[] empty = new char[0];
    private char[] data;
    private int count;
    transient Vector marks;

    
holds the data for a mark... separately from
the real mark so that the real mark can be
collected if there are no more references to
it.... the update table holds only a reference
to this grungy thing.
/**
     * holds the data for a mark... separately from
     * the real mark so that the real mark can be
     * collected if there are no more references to
     * it.... the update table holds only a reference
     * to this grungy thing.
     */
    final class PosRec {

        PosRec(int offset) {
            this.offset = offset;
        }

        int offset;
        boolean unused;
    }

    
This really wants to be a weak reference but
in 1.1 we don't have a 100% pure solution for
this... so this class trys to hack a solution
to causing the marks to be collected.
/**
     * This really wants to be a weak reference but
     * in 1.1 we don't have a 100% pure solution for
     * this... so this class trys to hack a solution
     * to causing the marks to be collected.
     */
    final class StickyPosition implements Position {

        StickyPosition(int offset) {
            rec = new PosRec(offset);
            marks.addElement(rec);
        }

        public int getOffset() {
            return rec.offset;
        }

        protected void finalize() throws Throwable {
            // schedule the record to be removed later
            // on another thread.
            rec.unused = true;
        }

        public String toString() {
            return Integer.toString(getOffset());
        }

        PosRec rec;
    }

    
Used to hold a reference to a Position that is being reset as the
result of removing from the content.
/**
     * Used to hold a reference to a Position that is being reset as the
     * result of removing from the content.
     */
    final class UndoPosRef {
        UndoPosRef(PosRec rec) {
            this.rec = rec;
            this.undoLocation = rec.offset;
        }

        
Resets the location of the Position to the offset when the
receiver was instantiated.
/**
         * Resets the location of the Position to the offset when the
         * receiver was instantiated.
         */
        protected void resetLocation() {
            rec.offset = undoLocation;
        }

        
Location to reset to when resetLocatino is invoked. /** Location to reset to when resetLocatino is invoked. */
        protected int undoLocation;
        
Position to reset offset. /** Position to reset offset. */
        protected PosRec rec;
    }

    
UnoableEdit created for inserts.
/**
     * UnoableEdit created for inserts.
     */
    class InsertUndo extends AbstractUndoableEdit {
        protected InsertUndo(int offset, int length) {
            super();
            this.offset = offset;
            this.length = length;
        }

        public void undo() throws CannotUndoException {
            super.undo();
            try {
                synchronized(StringContent.this) {
                    // Get the Positions in the range being removed.
                    if(marks != null)
                        posRefs = getPositionsInRange(null, offset, length);
                    string = getString(offset, length);
                    remove(offset, length);
                }
            } catch (BadLocationException bl) {
              throw new CannotUndoException();
            }
        }

        public void redo() throws CannotRedoException {
            super.redo();
            try {
                synchronized(StringContent.this) {
                    insertString(offset, string);
                    string = null;
                    // Update the Positions that were in the range removed.
                    if(posRefs != null) {
                        updateUndoPositions(posRefs);
                        posRefs = null;
                    }
              }
            } catch (BadLocationException bl) {
              throw new CannotRedoException();
            }
        }

        // Where the string goes.
        protected int offset;
        // Length of the string.
        protected int length;
        // The string that was inserted. To cut down on space needed this
        // will only be valid after an undo.
        protected String string;
        // An array of instances of UndoPosRef for the Positions in the
        // range that was removed, valid after undo.
        protected Vector posRefs;
    }


    
UndoableEdit created for removes.
/**
     * UndoableEdit created for removes.
     */
    class RemoveUndo extends AbstractUndoableEdit {
        protected RemoveUndo(int offset, String string) {
            super();
            this.offset = offset;
            this.string = string;
            this.length = string.length();
            if(marks != null)
                posRefs = getPositionsInRange(null, offset, length);
        }

        public void undo() throws CannotUndoException {
            super.undo();
            try {
                synchronized(StringContent.this) {
                    insertString(offset, string);
                    // Update the Positions that were in the range removed.
                    if(posRefs != null) {
                        updateUndoPositions(posRefs);
                        posRefs = null;
                    }
                    string = null;
                }
            } catch (BadLocationException bl) {
              throw new CannotUndoException();
            }
        }

        public void redo() throws CannotRedoException {
            super.redo();
            try {
                synchronized(StringContent.this) {
                    string = getString(offset, length);
                    // Get the Positions in the range being removed.
                    if(marks != null)
                        posRefs = getPositionsInRange(null, offset, length);
                    remove(offset, length);
                }
            } catch (BadLocationException bl) {
              throw new CannotRedoException();
            }
        }

        // Where the string goes.
        protected int offset;
        // Length of the string.
        protected int length;
        // The string that was inserted. This will be null after an undo.
        protected String string;
        // An array of instances of UndoPosRef for the Positions in the
        // range that was removed, valid before undo.
        protected Vector posRefs;
    }
}