TextTreeText.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / System / Windows / Documents / TextTreeText.cs / 1 / TextTreeText.cs
                        

                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// 
// Description: A static class that manipulates an array TextTreeTextBlocks. 
//
// History: 
//  2/18/2004 : [....] - Created
//
//---------------------------------------------------------------------------
 
using System;
using System.Collections; 
using MS.Internal; 

namespace System.Windows.Documents 
{
    // Each TextContainer maintains an array of TextTreeTextBlocks that holds all
    // the raw text in the tree.  This class manipulates that array.
    // 
    // "Raw text" includes not only unicode covered by TextTreeTextNodes, but
    // also placeholders for element edges and embedded objects.  Inserting 
    // placeholders lets us map 1-to-1 with array offsets and symbol offsets. 
    internal static class TextTreeText
    { 
        //-----------------------------------------------------
        //
        //  Internal Methods
        // 
        //-----------------------------------------------------
 
        #region Internal Methods 

        // Inserts text into the text block array.  The text is either a string 
        // or an array of char.
        internal static void InsertText(TextTreeRootTextBlock rootTextBlock, int offset, object text)
        {
            TextTreeTextBlock block; 
            int localOffset;
            int insertCount; 
            int textLength; 

            Invariant.Assert(text is string || text is char[], "Bad text parameter!"); 

            // Get the block matching the insertion point.
            block = FindBlock(rootTextBlock, offset, out localOffset);
 
            // Fill this block to capacity.
            textLength = TextContainer.GetTextLength(text); 
            insertCount = block.InsertText(localOffset, text, 0, textLength); 

            if (insertCount < textLength) 
            {
                // Put all the text to the smaller side of the gap into the new block.
                if (block.GapOffset < TextTreeTextBlock.MaxBlockSize / 2)
                { 
                    InsertTextLeft(block, text, insertCount);
                } 
                else 
                {
                    InsertTextRight(block, text, insertCount); 
                }
            }
        }
 
        // Removes text from the block array.
        // 
 
        internal static void RemoveText(TextTreeRootTextBlock rootTextBlock, int offset, int count)
        { 
            int firstBlockLocalOffset;
            TextTreeTextBlock firstBlock;
            int lastBlockLocalOffset;
            TextTreeTextBlock lastBlock; 
            SplayTreeNode firstRemoveBlock;
            SplayTreeNode lastRemoveBlock; 
            int firstCount; 

            if (count == 0) 
            {
                // Early out on count == 0 so we don't get in trouble at the
                // very end of the array.
                return; 
            }
 
            // Get the block matching the offset. 
            firstBlock = FindBlock(rootTextBlock, offset, out firstBlockLocalOffset);
 
            if (firstBlock.Count == firstBlockLocalOffset)
            {
                // FindIndexForOffset always returns the lower block if we ask
                // for a cp between two blocks. 
                // For a remove, we want to work with the following block, which
                // actually contains the content. 
                firstBlock = (TextTreeTextBlock)firstBlock.GetNextNode(); 
                Invariant.Assert(firstBlock != null);
                firstBlockLocalOffset = 0; 
            }

            // And the block matching the offset + count.
            lastBlock = FindBlock(rootTextBlock, offset + count, out lastBlockLocalOffset); 

            if (firstBlockLocalOffset > 0 || count < firstBlock.Count) 
            { 
                // Remove text from the first block.
                firstCount = Math.Min(count, firstBlock.Count - firstBlockLocalOffset); 
                firstBlock.RemoveText(firstBlockLocalOffset, firstCount);
                // Don't remove the first block, since some text was left behind.
                firstRemoveBlock = firstBlock.GetNextNode();
            } 
            else
            { 
                // All text in the first block covered -- just remove it entirely. 
                firstCount = 0;
                firstRemoveBlock = firstBlock; 
            }

            if (count > firstCount)
            { 
                int lastCount;
 
                if (lastBlockLocalOffset < lastBlock.Count) 
                {
                    lastCount = lastBlockLocalOffset; 
                    // Remove some text.
                    lastBlock.RemoveText(0, lastBlockLocalOffset);
                    // There's text left over in the last block, so don't remove
                    // the block. 
                    lastRemoveBlock = lastBlock.GetPreviousNode();
                } 
                else 
                {
                    lastCount = 0; 
                    // All text in the last block covered -- just remove it entirely.
                    lastRemoveBlock = lastBlock;
                }
 
                // If firstRemoveBlock == lastBlock && lastRemoveBlock == firstBlock,
                // then there are no more blocks to remove -- we removed a portion 
                // from the first and last block and they are direct neighbors. 
                if (firstCount + lastCount < count)
                { 
                    // Remove any blocks in the middle of first, last.
                    Remove((TextTreeTextBlock)firstRemoveBlock, (TextTreeTextBlock)lastRemoveBlock);
                }
            } 
        }
 
        // Remove text from the block array, and return the removed text in a 
        // char array.
        internal static char[] CutText(TextTreeRootTextBlock rootTextBlock, int offset, int count) 
        {
            char[] text;

            text = new char[count]; 

            ReadText(rootTextBlock, offset, count, text, 0); 
            RemoveText(rootTextBlock, offset, count); 

            return text; 
        }

        // Read text in the block array.
        internal static void ReadText(TextTreeRootTextBlock rootTextBlock, int offset, int count, char[] chars, int startIndex) 
        {
            TextTreeTextBlock block; 
            int localOffset; 
            int blockCount;
 
            if (count > 0)
            {
                // Get the block matching the offset.
                block = FindBlock(rootTextBlock, offset, out localOffset); 

                while (true) 
                { 
                    Invariant.Assert(block != null, "Caller asked for too much text!");
                    blockCount = block.ReadText(localOffset, count, chars, startIndex); 
                    localOffset = 0;
                    count -= blockCount;
                    if (count == 0)
                        break; 

                    startIndex += blockCount; 
                    block = (TextTreeTextBlock)block.GetNextNode(); 
                }
            } 
        }

        // Inserts a placeholder character for an embedded object.
        // The actual value stored doesn't really matter, it will never be read. 
        internal static void InsertObject(TextTreeRootTextBlock rootTextBlock, int offset)
        { 
            InsertText(rootTextBlock, offset, new string((char)0xffff, 1)); 
        }
 
        // Insert placeholders for elements edges into the block array.
        // The actual value stored doesn't really matter, it will never be read.
        internal static void InsertElementEdges(TextTreeRootTextBlock rootTextBlock, int offset, int childSymbolCount)
        { 
            if (childSymbolCount == 0)
            { 
                InsertText(rootTextBlock, offset, new string((char)0xbeef, 2)); 
            }
            else 
            {
                InsertText(rootTextBlock, offset, new string((char)0xbeef, 1));
                InsertText(rootTextBlock, offset + childSymbolCount + 1, new string((char)0x0, 1));
            } 
        }
 
        // Remove placeholder element edge characters from the block array. 
        internal static void RemoveElementEdges(TextTreeRootTextBlock rootTextBlock, int offset, int symbolCount)
        { 
            Invariant.Assert(symbolCount >= 2, "Element must span at least two symbols!"); // 2 element edges == 2 symbols.

            if (symbolCount == 2)
            { 
                RemoveText(rootTextBlock, offset, 2);
            } 
            else 
            {
                RemoveText(rootTextBlock, offset + symbolCount - 1, 1); 
                RemoveText(rootTextBlock, offset, 1);
            }
        }
 
        #endregion Internal methods
 
        //------------------------------------------------------ 
        //
        //  Private Methods 
        //
        //-----------------------------------------------------

        #region Private Methods 

        // Finds the TextTreeTextBlock that contains the specified char offset. 
        // Returns the lower block for offsets that border two blocks. 
        private static TextTreeTextBlock FindBlock(TextTreeRootTextBlock rootTextBlock, int offset, out int localOffset)
        { 
            TextTreeTextBlock node;
            int nodeOffset;

            node = (TextTreeTextBlock)rootTextBlock.ContainedNode.GetSiblingAtOffset(offset, out nodeOffset); 

            // If offset is between two blocks, make sure we return the lower of the two. 
            if (node.LeftSymbolCount == offset) 
            {
                TextTreeTextBlock previousBlock = (TextTreeTextBlock)node.GetPreviousNode(); 
                if (previousBlock != null)
                {
                    node = previousBlock;
                    nodeOffset -= node.SymbolCount; 
                    Invariant.Assert(nodeOffset >= 0);
                } 
            } 

            localOffset = offset - nodeOffset; 
            Invariant.Assert(localOffset >= 0 && localOffset <= node.Count);

            return node;
        } 

        // Helper for InsertText.  Inserts text to the left of an existing block. 
        private static void InsertTextLeft(TextTreeTextBlock rightBlock, object text, int textOffset) 
        {
            int newBlockCount; 
            TextTreeTextBlock leftBlock;
            TextTreeTextBlock neighborBlock;
            TextTreeTextBlock newBlock;
            int count; 
            int textEndOffset = -1;
            int i; 
            int length; 

            length = TextContainer.GetTextLength(text); 

            if (rightBlock.GapOffset == 0)
            {
                // Try to fill neighbor block. 
                neighborBlock = (TextTreeTextBlock)rightBlock.GetPreviousNode();
                if (neighborBlock != null) 
                { 
                    textOffset += neighborBlock.InsertText(neighborBlock.Count, text, textOffset, length);
                } 
            }

            if (textOffset < length)
            { 
                // Try adding just one block.
                newBlockCount = 1; 
 
                leftBlock = rightBlock.SplitBlock();
 
                // Fill up the left block.
                textOffset += leftBlock.InsertText(leftBlock.Count, text, textOffset, length);

                if (textOffset < length) 
                {
                    // Fill up the larger block. 
                    // We need to copy from the end of the text here. 
                    count = Math.Min(rightBlock.FreeCapacity, length - textOffset);
                    textEndOffset = length - count; 
                    rightBlock.InsertText(0, text, textEndOffset, length);

                    if (textOffset < textEndOffset)
                    { 
                        // We've filled both blocks, and there's still more text to copy.
                        // Prepare to allocate some more blocks. 
                        newBlockCount += (textEndOffset - textOffset + TextTreeTextBlock.MaxBlockSize - 1) / TextTreeTextBlock.MaxBlockSize; 
                    }
                } 

                for (i = 1; i < newBlockCount; i++)
                {
                    newBlock = new TextTreeTextBlock(TextTreeTextBlock.MaxBlockSize); 
                    textOffset += newBlock.InsertText(0, text, textOffset, textEndOffset);
                    newBlock.InsertAtNode(leftBlock, false /* insertBefore */); 
                    leftBlock = newBlock; 
                }
                Invariant.Assert(newBlockCount == 1 || textOffset == textEndOffset, "Not all text copied!"); 
            }
        }

        // Helper for InsertText.  Inserts text to the right of an existing block. 
        private static void InsertTextRight(TextTreeTextBlock leftBlock, object text, int textOffset)
        { 
            int newBlockCount; 
            TextTreeTextBlock rightBlock;
            TextTreeTextBlock neighborBlock; 
            TextTreeTextBlock newBlock;
            int count;
            int textEndOffset;
            int i; 

            textEndOffset = TextContainer.GetTextLength(text); 
 
            if (leftBlock.GapOffset == leftBlock.Count)
            { 
                // Try to fill neighbor block.
                neighborBlock = (TextTreeTextBlock)leftBlock.GetNextNode();
                if (neighborBlock != null)
                { 
                    count = Math.Min(neighborBlock.FreeCapacity, textEndOffset - textOffset);
                    neighborBlock.InsertText(0, text, textEndOffset - count, textEndOffset); 
                    textEndOffset -= count; 
                }
            } 

            if (textOffset < textEndOffset)
            {
                // Try adding just one block. 
                newBlockCount = 1;
 
                rightBlock = leftBlock.SplitBlock(); 

                // Fill up the right block. 
                count = Math.Min(rightBlock.FreeCapacity, textEndOffset - textOffset);
                rightBlock.InsertText(0, text, textEndOffset - count, textEndOffset);
                textEndOffset -= count;
 
                if (textOffset < textEndOffset)
                { 
                    // Fill up the larger block. 
                    // We need to copy from the end of the text here.
                    textOffset += leftBlock.InsertText(leftBlock.Count, text, textOffset, textEndOffset); 

                    if (textOffset < textEndOffset)
                    {
                        // We've filled both blocks, and there's still more text to copy. 
                        // Prepare to allocate some more blocks.
                        newBlockCount += (textEndOffset - textOffset + TextTreeTextBlock.MaxBlockSize - 1) / TextTreeTextBlock.MaxBlockSize; 
                    } 
                }
 
                for (i=0; i

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