diff --git a/src/vs/editor/common/model/indentationGuesser.ts b/src/vs/editor/common/model/indentationGuesser.ts
index 56c6683c54381aea9b2c39a0de76e0909c488bb9..aa1dab5901a8fa85165d361984232a0ede0c26d4 100644
--- a/src/vs/editor/common/model/indentationGuesser.ts
+++ b/src/vs/editor/common/model/indentationGuesser.ts
@@ -6,6 +6,8 @@
 
 import { CharCode } from 'vs/base/common/charCode';
 import { TextBuffer } from 'vs/editor/common/model/textBuffer';
+import { TextBuffer as TextBuffer2 } from 'vs/editor/common/model/textBuffer2';
+import { IRawPTBuffer } from './textSource';
 
 export interface IIndentationGuesserTarget {
 	getLineCount(): number;
@@ -15,7 +17,7 @@ export interface IIndentationGuesserTarget {
 export class IndentationGuesserTextBufferTarget implements IIndentationGuesserTarget {
 
 	constructor(
-		private readonly _buffer: TextBuffer
+		private readonly _buffer: TextBuffer | TextBuffer2
 	) { }
 
 	public getLineCount(): number {
@@ -42,6 +44,27 @@ export class IndentationGuesserStringArrayTarget implements IIndentationGuesserT
 	}
 }
 
+export class IndentationGuesserRawTextBufferTarget implements IIndentationGuesserTarget {
+
+	constructor(
+		private readonly _rawBuffer: IRawPTBuffer
+	) { }
+
+	public getLineCount(): number {
+		return this._rawBuffer.length;
+	}
+
+	public getLineContent(lineNumber: number): string {
+		if (lineNumber === 1) {
+			return this._rawBuffer.text.substring(0, this._rawBuffer.lineStarts[0]);
+		} else if (lineNumber === this._rawBuffer.lineStarts.length + 1) {
+			return this._rawBuffer.text.substring(this._rawBuffer.lineStarts[this._rawBuffer.lineStarts.length - 1] + 1);
+		}
+
+		return this._rawBuffer.text.substring(this._rawBuffer.lineStarts[lineNumber - 2] + 1, this._rawBuffer.lineStarts[lineNumber - 1]);
+	}
+}
+
 /**
  * Compute the diff in spaces between two line's indentation.
  */
diff --git a/src/vs/editor/common/model/modelLine.ts b/src/vs/editor/common/model/modelLine.ts
index 68c616b7dec32cbb18a1b2e57d7d9e4bb2fe0622..80eaef912332f30b0991fe3ea8af7f206d2311d5 100644
--- a/src/vs/editor/common/model/modelLine.ts
+++ b/src/vs/editor/common/model/modelLine.ts
@@ -13,6 +13,7 @@ import { Range } from 'vs/editor/common/core/range';
 import { IModelTokensChangedEvent } from 'vs/editor/common/model/textModelEvents';
 import { onUnexpectedError } from 'vs/base/common/errors';
 import { TextBuffer } from 'vs/editor/common/model/textBuffer';
+import { TextBuffer as TextBuffer2 } from 'vs/editor/common/model/textBuffer2';
 import { TokenizationResult2 } from 'vs/editor/common/core/token';
 import { nullTokenize2 } from 'vs/editor/common/modes/nullMode';
 
@@ -253,7 +254,7 @@ export class ModelLinesTokens {
 		return (firstInvalidLineNumber >= lineNumber);
 	}
 
-	public hasLinesToTokenize(buffer: TextBuffer): boolean {
+	public hasLinesToTokenize(buffer: TextBuffer | TextBuffer2): boolean {
 		return (this._invalidLineStartIndex < buffer.getLineCount());
 	}
 
@@ -419,7 +420,7 @@ export class ModelLinesTokens {
 
 	//#region Tokenization
 
-	public _tokenizeOneLine(buffer: TextBuffer, eventBuilder: ModelTokensChangedEventBuilder): number {
+	public _tokenizeOneLine(buffer: TextBuffer | TextBuffer2, eventBuilder: ModelTokensChangedEventBuilder): number {
 		if (!this.hasLinesToTokenize(buffer)) {
 			return buffer.getLineCount() + 1;
 		}
@@ -428,7 +429,7 @@ export class ModelLinesTokens {
 		return lineNumber;
 	}
 
-	public _updateTokensUntilLine(buffer: TextBuffer, eventBuilder: ModelTokensChangedEventBuilder, lineNumber: number): void {
+	public _updateTokensUntilLine(buffer: TextBuffer | TextBuffer2, eventBuilder: ModelTokensChangedEventBuilder, lineNumber: number): void {
 		if (!this.tokenizationSupport) {
 			this._invalidLineStartIndex = buffer.getLineCount();
 			return;
diff --git a/src/vs/editor/common/model/textBuffer.ts b/src/vs/editor/common/model/textBuffer.ts
index 87f19776d657336f27deaf7b4d253a857bdf186f..c8c70440b01e9d093ae5be4850acbd21af69bc31 100644
--- a/src/vs/editor/common/model/textBuffer.ts
+++ b/src/vs/editor/common/model/textBuffer.ts
@@ -55,7 +55,7 @@ export class TextBuffer {
 	private _lineStarts: PrefixSumComputer;
 
 	constructor(textSource: ITextSource) {
-		this._lines = textSource.lines.slice(0);
+		this._lines = (<string[]>textSource.lines).slice(0);
 		this._BOM = textSource.BOM;
 		this._EOL = textSource.EOL;
 		this._mightContainRTL = textSource.containsRTL;
diff --git a/src/vs/editor/common/model/textBuffer2.ts b/src/vs/editor/common/model/textBuffer2.ts
new file mode 100644
index 0000000000000000000000000000000000000000..4b5a6da72a4a9801dc356ae45b43de2cef02eccb
--- /dev/null
+++ b/src/vs/editor/common/model/textBuffer2.ts
@@ -0,0 +1,1711 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+'use strict';
+
+import { Range } from 'vs/editor/common/core/range';
+import { Position } from 'vs/editor/common/core/position';
+import * as editorCommon from 'vs/editor/common/editorCommon';
+import * as strings from 'vs/base/common/strings';
+import { PrefixSumComputer, PrefixSumIndexOfResult } from 'vs/editor/common/viewModel/prefixSumComputer';
+import { ITextSource, IRawPTBuffer } from 'vs/editor/common/model/textSource';
+import { ApplyEditResult, IInternalModelContentChange } from 'vs/editor/common/model/textBuffer';
+import { IValidatedEditOperation } from 'vs/editor/common/model/editableTextModel';
+import { ModelRawChange, ModelRawLineChanged, ModelRawLinesDeleted, ModelRawLinesInserted } from 'vs/editor/common/model/textModelEvents';
+
+export const enum NodeColor {
+	Black = 0,
+	Red = 1,
+}
+
+export let error = {
+	sizeLeft: false
+};
+
+function getNodeColor(node: TreeNode) {
+	return node.color;
+}
+
+function setNodeColor(node: TreeNode, color: NodeColor) {
+	node.color = color;
+}
+
+function leftest(node: TreeNode): TreeNode {
+	while (node.left !== SENTINEL) {
+		node = node.left;
+	}
+	return node;
+}
+
+function righttest(node: TreeNode): TreeNode {
+	while (node.right !== SENTINEL) {
+		node = node.right;
+	}
+	return node;
+}
+
+function calculateSize(node: TreeNode): number {
+	if (node === SENTINEL) {
+		return 0;
+	}
+
+	return node.size_left + node.piece.length + calculateSize(node.right);
+}
+
+function calculateLF(node: TreeNode): number {
+	if (node === SENTINEL) {
+		return 0;
+	}
+
+	return node.lf_left + node.piece.lineFeedCnt + calculateLF(node.right);
+}
+
+function resetSentinel(): void {
+	SENTINEL.parent = SENTINEL;
+}
+
+export class TreeNode {
+	parent: TreeNode;
+	left: TreeNode;
+	right: TreeNode;
+	color: NodeColor;
+
+	// Piece
+	piece: Piece;
+	size_left: number; // size of the left subtree (not inorder)
+	lf_left: number; // line feeds cnt in the left subtree (not in order)
+
+	constructor(piece: Piece, color: NodeColor) {
+		this.piece = piece;
+		this.color = color;
+		this.size_left = 0;
+		this.lf_left = 0;
+		this.parent = null;
+		this.left = null;
+		this.right = null;
+	}
+
+	public next(): TreeNode {
+		if (this.right !== SENTINEL) {
+			return leftest(this.right);
+		}
+
+		let node: TreeNode = this;
+
+		while (node.parent !== SENTINEL) {
+			if (node.parent.left === node) {
+				break;
+			}
+
+			node = node.parent;
+		}
+
+		if (node.parent === SENTINEL) {
+			// root
+			// if (node.right === SENTINEL) {
+			return SENTINEL;
+			// }
+			// return leftest(node.right);
+		} else {
+			return node.parent;
+		}
+	}
+
+	public prev(): TreeNode {
+		if (this.left !== SENTINEL) {
+			return righttest(this.left);
+		}
+
+		let node: TreeNode = this;
+
+		while (node.parent !== SENTINEL) {
+			if (node.parent.right === node) {
+				break;
+			}
+
+			node = node.parent;
+		}
+
+		if (node.parent === SENTINEL) {
+			// root
+			// if (node.left === SENTINEL) {
+			return SENTINEL;
+			// }
+			// return righttest(node.left);
+		} else {
+			return node.parent;
+		}
+	}
+
+	public detach(): void {
+		this.parent = null;
+		this.left = null;
+		this.right = null;
+	}
+}
+
+export const SENTINEL: TreeNode = new TreeNode(null, NodeColor.Black);
+SENTINEL.parent = SENTINEL;
+SENTINEL.left = SENTINEL;
+SENTINEL.right = SENTINEL;
+setNodeColor(SENTINEL, NodeColor.Black);
+
+export interface BufferCursor {
+	/**
+	 * Piece Index
+	 */
+	node: TreeNode;
+	/**
+	 * remainer in current piece.
+	*/
+	remainder: number;
+}
+
+export class Piece {
+	isOriginalBuffer: boolean;
+	offset: number;
+	length: number; // size of current piece
+
+	lineFeedCnt: number;
+	lineStarts: PrefixSumComputer;
+
+	constructor(isOriginalBuffer: boolean, offset: number, length: number, lineFeedCnt: number, lineLengthsVal: Uint32Array) {
+		this.isOriginalBuffer = isOriginalBuffer;
+		this.offset = offset;
+		this.length = length;
+		this.lineFeedCnt = lineFeedCnt;
+		this.lineStarts = null;
+
+		if (lineLengthsVal) {
+			let newVal = new Uint32Array(lineLengthsVal.length);
+			newVal.set(lineLengthsVal);
+			this.lineStarts = new PrefixSumComputer(newVal);
+		}
+	}
+}
+
+export class TextBuffer {
+	private _BOM: string;
+	private _EOL: string;
+	private _mightContainRTL: boolean;
+	private _mightContainNonBasicASCII: boolean;
+
+	private _originalBuffer: string;
+	private _changeBuffer: string;
+	private _regex: RegExp;
+	root: TreeNode;
+
+	constructor(textSource: ITextSource) {
+		let rawBuffer = <IRawPTBuffer>textSource.lines;
+		this._originalBuffer = rawBuffer.text;
+		this._changeBuffer = '';
+		this.root = SENTINEL;
+		this._BOM = textSource.BOM;
+		this._EOL = textSource.EOL;
+		this._mightContainNonBasicASCII = !textSource.isBasicASCII;
+		this._mightContainRTL = textSource.containsRTL;
+		this._regex = new RegExp(/\r\n|\r|\n/g);
+
+		if (this._originalBuffer.length > 0) {
+			let { lineFeedCount, lineLengths } = this.calculateNewLineCount(this._originalBuffer);
+			let piece = new Piece(true, 0, this._originalBuffer.length, lineFeedCount, lineLengths);
+			this.rbInsertLeft(null, piece);
+		}
+	}
+
+	// #region TextBuffer
+	public getLinesContent() {
+		return this.getContentOfSubTree(this.root);
+	}
+
+	public getLineCount(): number {
+		let x = this.root;
+
+		let ret = 1;
+		while (x !== SENTINEL) {
+			ret += x.lf_left + x.piece.lineFeedCnt;
+			x = x.right;
+		}
+
+		return ret;
+	}
+
+	public getValueInRange(range: Range, eol: editorCommon.EndOfLinePreference = editorCommon.EndOfLinePreference.TextDefined): string {
+		// todo, validate range.
+		if (range.startLineNumber === range.endLineNumber && range.startColumn === range.endColumn) {
+			return '';
+		}
+
+		let startPosition = this.nodeAt2(new Position(range.startLineNumber, range.startColumn));
+		let endPosition = this.nodeAt2(new Position(range.endLineNumber, range.endColumn));
+
+		if (startPosition.node === endPosition.node) {
+			let node = startPosition.node;
+			let buffer = node.piece.isOriginalBuffer ? this._originalBuffer : this._changeBuffer;
+			return buffer.substring(node.piece.offset + startPosition.remainder, node.piece.offset + endPosition.remainder);
+		}
+
+
+		let x = startPosition.node;
+		let buffer = x.piece.isOriginalBuffer ? this._originalBuffer : this._changeBuffer;
+		let ret = buffer.substring(x.piece.offset + startPosition.remainder, x.piece.offset + x.piece.length);
+
+		x = x.next();
+		while (x !== SENTINEL) {
+			let buffer = x.piece.isOriginalBuffer ? this._originalBuffer : this._changeBuffer;
+
+			if (x === endPosition.node) {
+				ret += buffer.substring(x.piece.offset, x.piece.offset + endPosition.remainder);
+				break;
+			} else {
+				ret += buffer.substr(x.piece.offset, x.piece.length);
+			}
+
+			x = x.next();
+		}
+
+		return ret;
+	}
+
+	public getLineContent(lineNumber: number): string {
+		let x = this.root;
+
+		let ret = '';
+		while (x !== SENTINEL) {
+			if (x.left !== SENTINEL && x.lf_left >= lineNumber - 1) {
+				x = x.left;
+			} else if (x.lf_left + x.piece.lineFeedCnt > lineNumber - 1) {
+				let prevAccumualtedValue = x.piece.lineStarts.getAccumulatedValue(lineNumber - x.lf_left - 2);
+				let accumualtedValue = x.piece.lineStarts.getAccumulatedValue(lineNumber - x.lf_left - 1);
+				let buffer = x.piece.isOriginalBuffer ? this._originalBuffer : this._changeBuffer;
+
+				return buffer.substring(x.piece.offset + prevAccumualtedValue, x.piece.offset + accumualtedValue);
+			} else if (x.lf_left + x.piece.lineFeedCnt === lineNumber - 1) {
+				let prevAccumualtedValue = x.piece.lineStarts.getAccumulatedValue(lineNumber - x.lf_left - 2);
+				let buffer = x.piece.isOriginalBuffer ? this._originalBuffer : this._changeBuffer;
+
+				ret = buffer.substring(x.piece.offset + prevAccumualtedValue, x.piece.offset + x.piece.length);
+				break;
+			} else {
+				lineNumber -= x.lf_left + x.piece.lineFeedCnt;
+				x = x.right;
+			}
+		}
+
+		// if (x === SENTINEL) {
+		// 	throw('not possible');
+		// }
+
+		// search in order, to find the node contains end column
+		x = x.next();
+		while (x !== SENTINEL) {
+			let buffer = x.piece.isOriginalBuffer ? this._originalBuffer : this._changeBuffer;
+
+			if (x.piece.lineFeedCnt > 0) {
+				let accumualtedValue = x.piece.lineStarts.getAccumulatedValue(0);
+
+				ret += buffer.substring(x.piece.offset, x.piece.offset + accumualtedValue);
+				return ret;
+			} else {
+				ret += buffer.substr(x.piece.offset, x.piece.length);
+			}
+
+			x = x.next();
+		}
+
+		return ret;
+
+	}
+
+	public getOffsetAt(position: Position): number {
+		return this.getOffsetAt2(position.lineNumber, position.column);
+	}
+
+	public getOffsetAt2(lineNumber: number, column: number): number {
+		let leftLen = 0; // inorder
+
+		let x = this.root;
+
+		while (x !== SENTINEL) {
+			if (x.left !== SENTINEL && x.lf_left + 1 >= lineNumber) {
+				x = x.left;
+			} else if (x.lf_left + x.piece.lineFeedCnt + 1 >= lineNumber) {
+				leftLen += x.size_left;
+				// lineNumber >= 2
+				let accumualtedValInCurrentIndex = x.piece.lineStarts.getAccumulatedValue(lineNumber - x.lf_left - 2);
+				return leftLen += accumualtedValInCurrentIndex + column - 1;
+			} else {
+				lineNumber -= x.lf_left + x.piece.lineFeedCnt;
+				leftLen += x.size_left + x.piece.length;
+				x = x.right;
+			}
+		}
+
+		return leftLen;
+	}
+
+	public getPositionAt(offset: number): Position {
+		let x = this.root;
+		let lfCnt = 0;
+
+		while (x !== SENTINEL) {
+			if (x.size_left !== 0 && x.size_left >= offset) {
+				x = x.left;
+			} else if (x.size_left + x.piece.length >= offset) {
+				let out = x.piece.lineStarts.getIndexOf(offset - x.size_left);
+
+				let column = 0;
+
+				if (out.index === 0) {
+					let prev = x.prev();
+
+					if (prev !== SENTINEL) {
+						let lineLens = prev.piece.lineStarts.values;
+						column += lineLens[lineLens.length - 1];
+					}
+				}
+
+				lfCnt += x.lf_left + out.index;
+				return new Position(lfCnt + 1, column + out.remainder + 1);
+			} else {
+				offset -= x.size_left + x.piece.length;
+				lfCnt += x.lf_left + x.piece.lineFeedCnt;
+				x = x.right;
+			}
+		}
+
+		return null;
+	}
+
+	public equals(other: ITextSource): boolean {
+		if (this._BOM !== other.BOM) {
+			return false;
+		}
+		if (this._EOL !== other.EOL) {
+			return false;
+		}
+		if (this.getLinesContent() !== (<IRawPTBuffer>other.lines).text) {
+			return false;
+		}
+		return true;
+	}
+
+	public mightContainRTL(): boolean {
+		return this._mightContainRTL;
+	}
+
+	public mightContainNonBasicASCII(): boolean {
+		return this._mightContainNonBasicASCII;
+	}
+
+	public getBOM(): string {
+		return this._BOM;
+	}
+
+	public getEOL(): string {
+		return this._EOL;
+	}
+
+	public setEOL(newEOL: string): void {
+		this._EOL = newEOL;
+		// this._constructLineStarts();
+	}
+
+	public _applyEdits(rawOperations: editorCommon.IIdentifiedSingleEditOperation[], recordTrimAutoWhitespace: boolean): ApplyEditResult {
+		let mightContainRTL = this._mightContainRTL;
+		let mightContainNonBasicASCII = this._mightContainNonBasicASCII;
+		let canReduceOperations = true;
+
+		let operations: IValidatedEditOperation[] = [];
+		for (let i = 0; i < rawOperations.length; i++) {
+			let op = rawOperations[i];
+			if (canReduceOperations && op._isTracked) {
+				canReduceOperations = false;
+			}
+			let validatedRange = op.range;
+			if (!mightContainRTL && op.text) {
+				// check if the new inserted text contains RTL
+				mightContainRTL = strings.containsRTL(op.text);
+			}
+			if (!mightContainNonBasicASCII && op.text) {
+				mightContainNonBasicASCII = !strings.isBasicASCII(op.text);
+			}
+			operations[i] = {
+				sortIndex: i,
+				identifier: op.identifier,
+				range: validatedRange,
+				rangeOffset: this.getOffsetAt(validatedRange.getStartPosition()),
+				rangeLength: this.getValueLengthInRange(validatedRange),
+				lines: op.text ? op.text.split(/\r\n|\r|\n/) : null,
+				forceMoveMarkers: op.forceMoveMarkers,
+				isAutoWhitespaceEdit: op.isAutoWhitespaceEdit || false
+			};
+		}
+
+		// Sort operations ascending
+		operations.sort(TextBuffer._sortOpsAscending);
+
+		for (let i = 0, count = operations.length - 1; i < count; i++) {
+			let rangeEnd = operations[i].range.getEndPosition();
+			let nextRangeStart = operations[i + 1].range.getStartPosition();
+
+			if (nextRangeStart.isBefore(rangeEnd)) {
+				// overlapping ranges
+				throw new Error('Overlapping ranges are not allowed!');
+			}
+		}
+
+		if (canReduceOperations) {
+			// operations = this._reduceOperations(operations);
+		}
+
+		// Delta encode operations
+		let reverseRanges = TextBuffer._getInverseEditRanges(operations);
+		let newTrimAutoWhitespaceCandidates: { lineNumber: number, oldContent: string }[] = [];
+
+		for (let i = 0; i < operations.length; i++) {
+			let op = operations[i];
+			let reverseRange = reverseRanges[i];
+
+			if (recordTrimAutoWhitespace && op.isAutoWhitespaceEdit && op.range.isEmpty()) {
+				// Record already the future line numbers that might be auto whitespace removal candidates on next edit
+				for (let lineNumber = reverseRange.startLineNumber; lineNumber <= reverseRange.endLineNumber; lineNumber++) {
+					let currentLineContent = '';
+					if (lineNumber === reverseRange.startLineNumber) {
+						currentLineContent = this.getLineContent(op.range.startLineNumber);
+						if (strings.firstNonWhitespaceIndex(currentLineContent) !== -1) {
+							continue;
+						}
+					}
+					newTrimAutoWhitespaceCandidates.push({ lineNumber: lineNumber, oldContent: currentLineContent });
+				}
+			}
+		}
+
+		let reverseOperations: editorCommon.IIdentifiedSingleEditOperation[] = [];
+		for (let i = 0; i < operations.length; i++) {
+			let op = operations[i];
+			let reverseRange = reverseRanges[i];
+
+			reverseOperations[i] = {
+				identifier: op.identifier,
+				range: reverseRange,
+				text: this.getValueInRange(op.range),
+				forceMoveMarkers: op.forceMoveMarkers
+			};
+		}
+
+		this._mightContainRTL = mightContainRTL;
+		this._mightContainNonBasicASCII = mightContainNonBasicASCII;
+
+		const [rawContentChanges, contentChanges] = this._doApplyEdits(operations);
+
+		let trimAutoWhitespaceLineNumbers: number[] = null;
+		if (recordTrimAutoWhitespace && newTrimAutoWhitespaceCandidates.length > 0) {
+			// sort line numbers auto whitespace removal candidates for next edit descending
+			newTrimAutoWhitespaceCandidates.sort((a, b) => b.lineNumber - a.lineNumber);
+
+			trimAutoWhitespaceLineNumbers = [];
+			for (let i = 0, len = newTrimAutoWhitespaceCandidates.length; i < len; i++) {
+				let lineNumber = newTrimAutoWhitespaceCandidates[i].lineNumber;
+				if (i > 0 && newTrimAutoWhitespaceCandidates[i - 1].lineNumber === lineNumber) {
+					// Do not have the same line number twice
+					continue;
+				}
+
+				let prevContent = newTrimAutoWhitespaceCandidates[i].oldContent;
+				let lineContent = this.getLineContent(lineNumber);
+
+				if (lineContent.length === 0 || lineContent === prevContent || strings.firstNonWhitespaceIndex(lineContent) !== -1) {
+					continue;
+				}
+
+				trimAutoWhitespaceLineNumbers.push(lineNumber);
+			}
+		}
+
+		return new ApplyEditResult(
+			reverseOperations,
+			rawContentChanges,
+			contentChanges,
+			trimAutoWhitespaceLineNumbers
+		);
+	}
+
+	private _doApplyEdits(operations: IValidatedEditOperation[]): [ModelRawChange[], IInternalModelContentChange[]] {
+		operations.sort(TextBuffer._sortOpsDescending);
+
+		let rawContentChanges: ModelRawChange[] = [];
+		let contentChanges: IInternalModelContentChange[] = [];
+
+		// operations are from bottom to top
+		for (let i = 0; i < operations.length; i++) {
+			let op = operations[i];
+
+			const startLineNumber = op.range.startLineNumber;
+			const startColumn = op.range.startColumn;
+			const endLineNumber = op.range.endLineNumber;
+			const endColumn = op.range.endColumn;
+
+			if (startLineNumber === endLineNumber && startColumn === endColumn && (!op.lines || op.lines.length === 0)) {
+				// no-op
+				continue;
+			}
+
+			const deletingLinesCnt = endLineNumber - startLineNumber;
+			const insertingLinesCnt = (op.lines ? op.lines.length - 1 : 0);
+			const editingLinesCnt = Math.min(deletingLinesCnt, insertingLinesCnt);
+
+			const text = (op.lines ? op.lines.join(this.getEOL()) : '');
+
+			if (text) {
+				// replacement
+				this.delete(op.rangeOffset, op.rangeLength);
+				this.insert(text, op.rangeOffset);
+
+			} else {
+				// deletion
+				this.delete(op.rangeOffset, op.rangeLength);
+			}
+
+			for (let j = startLineNumber; j <= startLineNumber + editingLinesCnt; j++) {
+				rawContentChanges.push(
+					new ModelRawLineChanged(j, this.getLineContent(j))
+				);
+			}
+
+			if (editingLinesCnt < deletingLinesCnt) {
+				rawContentChanges.push(
+					new ModelRawLinesDeleted(startLineNumber + editingLinesCnt + 1, endLineNumber)
+				);
+			}
+
+			if (editingLinesCnt < insertingLinesCnt) {
+				let newLinesContent: string[] = [];
+				for (let j = editingLinesCnt + 1; j <= insertingLinesCnt; j++) {
+					newLinesContent.push(op.lines[j]);
+				}
+
+				newLinesContent[newLinesContent.length - 1] = this.getLineContent(startLineNumber + insertingLinesCnt - 1);
+
+				rawContentChanges.push(
+					new ModelRawLinesInserted(startLineNumber + editingLinesCnt + 1, startLineNumber + insertingLinesCnt, newLinesContent.join('\n'))
+				);
+			}
+
+			const contentChangeRange = new Range(startLineNumber, startColumn, endLineNumber, endColumn);
+			contentChanges.push({
+				range: contentChangeRange,
+				rangeLength: op.rangeLength,
+				text: text,
+				lines: op.lines,
+				rangeOffset: op.rangeOffset,
+				forceMoveMarkers: op.forceMoveMarkers
+			});
+		}
+		return [rawContentChanges, contentChanges];
+	}
+
+	public getValueLengthInRange(range: Range, eol: editorCommon.EndOfLinePreference = editorCommon.EndOfLinePreference.TextDefined): number {
+		if (range.isEmpty()) {
+			return 0;
+		}
+
+		if (range.startLineNumber === range.endLineNumber) {
+			return (range.endColumn - range.startColumn);
+		}
+
+		let startOffset = this.getOffsetAt(new Position(range.startLineNumber, range.startColumn));
+		let endOffset = this.getOffsetAt(new Position(range.endLineNumber, range.endColumn));
+		return endOffset - startOffset;
+	}
+
+	public getLineCharCode(lineNumber: number, index: number): number {
+		return this.getLineContent(lineNumber).charCodeAt(index);
+	}
+
+	public getLineLength(lineNumber: number): number {
+		return this.getLineContent(lineNumber).length;
+	}
+
+	public getLineMinColumn(lineNumber: number): number {
+		return 1;
+	}
+
+	public getLineMaxColumn(lineNumber: number): number {
+		return this.getLineLength(lineNumber) + 1;
+	}
+
+	public getLineFirstNonWhitespaceColumn(lineNumber: number): number {
+		const result = strings.firstNonWhitespaceIndex(this.getLineContent(lineNumber));
+		if (result === -1) {
+			return 0;
+		}
+		return result + 1;
+	}
+
+	public getLineLastNonWhitespaceColumn(lineNumber: number): number {
+		const result = strings.lastNonWhitespaceIndex(this.getLineContent(lineNumber));
+		if (result === -1) {
+			return 0;
+		}
+		return result + 2;
+	}
+
+	public getRangeAt(start: number, end: number): Range {
+		const startPosition = this.getPositionAt(start);
+		const endPosition = this.getPositionAt(end);
+		return new Range(startPosition.lineNumber, startPosition.column, endPosition.lineNumber, endPosition.column);
+	}
+
+	// #endregion
+
+	// #region Piece Table
+	insert(value: string, offset: number): void {
+		// todo, validate value and offset.
+		if (this.root !== SENTINEL) {
+			let { node, remainder } = this.nodeAt(offset);
+			let insertPos = node.piece.lineStarts.getIndexOf(remainder);
+			let nodeOffsetInDocument = this.offsetOfNode(node);
+			const startOffset = this._changeBuffer.length;
+
+			if (!node.piece.isOriginalBuffer && (node.piece.offset + node.piece.length === this._changeBuffer.length) && (nodeOffsetInDocument + node.piece.length === offset)) {
+				// append content to this node, we don't want to keep adding node when users simply type in sequence
+				// unless we want to make the structure immutable
+				this.appendToNode(node, value);
+			} else {
+				if (nodeOffsetInDocument === offset) {
+					// we are inserting content to the beginning of node
+					let nodesToDel = [];
+					if (value.charCodeAt(value.length - 1) === 13) {
+						// inserted content ends with \r
+						if (node !== SENTINEL) {
+							if (this.nodeCharCodeAt(node, 0) === 10) {
+								// move `\n` forward
+								value += '\n';
+								node.piece.offset++;
+								node.piece.length--;
+								node.piece.lineFeedCnt--;
+								node.piece.lineStarts.removeValues(0, 1); // remove the first line, which is empty.
+								this.updateMetadata(node, -1, -1);
+
+								if (node.piece.length === 0) {
+									nodesToDel.push(node);
+								}
+							}
+						}
+					}
+
+					this._changeBuffer += value;
+					const { lineFeedCount, lineLengths } = this.calculateNewLineCount(value);
+					let newPiece: Piece = new Piece(false, startOffset, value.length, lineFeedCount, lineLengths);
+					let newNode = this.rbInsertLeft(node, newPiece);
+					this.fixCRLFWithPrev(newNode);
+
+					for (let i = 0; i < nodesToDel.length; i++) {
+						this.rbDelete(nodesToDel[i]);
+					}
+				} else if (nodeOffsetInDocument + node.piece.length > offset) {
+					let nodesToDel = [];
+
+					// we need to split node. Create the new piece first as we are reading current node info before modifying it.
+					let newRightPiece = new Piece(
+						node.piece.isOriginalBuffer,
+						node.piece.offset + offset - nodeOffsetInDocument,
+						nodeOffsetInDocument + node.piece.length - offset,
+						node.piece.lineFeedCnt - insertPos.index,
+						node.piece.lineStarts.values
+					);
+
+					if (value.charCodeAt(value.length - 1) === 13 /** \r */) {
+						let headOfRight = this.nodeCharCodeAt(node, offset - nodeOffsetInDocument);
+
+						if (headOfRight === 10 /** \n */) {
+							newRightPiece.offset++;
+							newRightPiece.length--;
+							newRightPiece.lineFeedCnt--;
+							newRightPiece.lineStarts.removeValues(0, insertPos.index + 1);
+							value += '\n';
+						} else {
+							this.deletePrefixSumHead(newRightPiece.lineStarts, insertPos);
+						}
+					} else {
+						this.deletePrefixSumHead(newRightPiece.lineStarts, insertPos);
+					}
+
+					// reuse node
+					if (value.charCodeAt(0) === 10/** \n */) {
+						let tailOfLeft = this.nodeCharCodeAt(node, offset - nodeOffsetInDocument - 1);
+						if (tailOfLeft === 13 /** \r */) {
+							let previousPos = node.piece.lineStarts.getIndexOf(remainder - 1);
+							this.deleteNodeTail(node, previousPos);
+							value = '\r' + value;
+
+							if (node.piece.length === 0) {
+								nodesToDel.push(node);
+							}
+						} else {
+							this.deleteNodeTail(node, insertPos);
+						}
+					} else {
+						this.deleteNodeTail(node, insertPos);
+					}
+
+					this._changeBuffer += value;
+					const { lineFeedCount, lineLengths } = this.calculateNewLineCount(value);
+					let newPiece: Piece = new Piece(false, startOffset, value.length, lineFeedCount, lineLengths);
+
+					if (newRightPiece.length > 0) {
+						this.rbInsertRight(node, newRightPiece);
+					}
+					this.rbInsertRight(node, newPiece);
+					for (let i = 0; i < nodesToDel.length; i++) {
+						this.rbDelete(nodesToDel[i]);
+					}
+				} else {
+					// we are inserting to the right of this node.
+					if (this.adjustCarriageReturnFromNext(value, node)) {
+						value += '\n';
+					}
+
+					this._changeBuffer += value;
+					const { lineFeedCount, lineLengths } = this.calculateNewLineCount(value);
+					let newPiece: Piece = new Piece(false, startOffset, value.length, lineFeedCount, lineLengths);
+					let newNode = this.rbInsertRight(node, newPiece);
+					this.fixCRLFWithPrev(newNode);
+				}
+			}
+		} else {
+			// insert new node
+			const startOffset = this._changeBuffer.length;
+			this._changeBuffer += value;
+			const { lineFeedCount, lineLengths } = this.calculateNewLineCount(value);
+			let piece = new Piece(false, startOffset, value.length, lineFeedCount, lineLengths);
+
+			this.rbInsertLeft(null, piece);
+		}
+	}
+
+	delete(offset: number, cnt: number): void {
+		if (cnt <= 0) {
+			return;
+		}
+
+		if (this.root !== SENTINEL) {
+			let startPosition = this.nodeAt(offset);
+			let endPosition = this.nodeAt(offset + cnt);
+			let startNode = startPosition.node;
+			let endNode = endPosition.node;
+
+			let length = startNode.piece.length;
+			let startNodeOffsetInDocument = this.offsetOfNode(startNode);
+			let splitPos = startNode.piece.lineStarts.getIndexOf(offset - startNodeOffsetInDocument);
+
+			if (startNode === endNode) {
+				// deletion falls into one node.
+				let endSplitPos = startNode.piece.lineStarts.getIndexOf(offset - startNodeOffsetInDocument + cnt);
+
+				if (startNodeOffsetInDocument === offset) {
+					if (cnt === length) { // delete node
+						let next = startNode.next();
+						this.rbDelete(startNode);
+						this.fixCRLFWithPrev(next);
+						return;
+					}
+					this.deleteNodeHead(startNode, endSplitPos);
+					this.fixCRLFWithPrev(startNode);
+					return;
+				}
+
+				if (startNodeOffsetInDocument + length === offset + cnt) {
+					this.deleteNodeTail(startNode, splitPos);
+					this.fixCRLFWithNext(startNode);
+					return;
+				}
+
+				// delete content in the middle, this node will be splitted to nodes
+				return this.shrinkNode(startNode, splitPos, endSplitPos);
+			}
+
+			// perform read operations before any write operation.
+			let endNodeOffsetInDocument = this.offsetOfNode(endNode);
+
+			// update first touched node
+			this.deleteNodeTail(startNode, splitPos);
+			let nodesToDel = [];
+			if (startNode.piece.length === 0) {
+				nodesToDel.push(startNode);
+			}
+
+			// update last touched node
+			let endSplitPos = endNode.piece.lineStarts.getIndexOf(offset - endNodeOffsetInDocument + cnt);
+			this.deleteNodeHead(endNode, endSplitPos);
+
+			if (endNode.piece.length === 0) {
+				nodesToDel.push(endNode);
+			}
+
+			let secondNode = startNode.next();
+			for (let node = secondNode; node !== SENTINEL && node !== endNode; node = node.next()) {
+				nodesToDel.push(node);
+			}
+
+			let prev = startNode.piece.length === 0 ? startNode.prev() : startNode;
+
+			for (let i = 0; i < nodesToDel.length; i++) {
+				this.rbDelete(nodesToDel[i]);
+			}
+
+			if (prev !== SENTINEL) {
+				this.fixCRLFWithNext(prev);
+			}
+		}
+	}
+
+	// #region node operations
+	deleteNodeHead(node: TreeNode, pos?: PrefixSumIndexOfResult) {
+		// it's okay to delete CR in CRLF.
+		let cnt = node.piece.lineStarts.getAccumulatedValue(pos.index - 1) + pos.remainder;
+		node.piece.length -= cnt;
+		node.piece.offset += cnt;
+		node.piece.lineFeedCnt -= pos.index;
+		this.deletePrefixSumHead(node.piece.lineStarts, pos);
+		this.updateMetadata(node, -cnt, -pos.index);
+	}
+
+	deleteNodeTail(node: TreeNode, start: PrefixSumIndexOfResult) {
+		let cnt = node.piece.length - node.piece.lineStarts.getAccumulatedValue(start.index - 1) - start.remainder;
+		let hitCRLF = this.hitTestCRLF(node, node.piece.lineStarts.getAccumulatedValue(start.index - 1) + start.remainder, start);
+		node.piece.length -= cnt;
+		let lf_delta = start.index - node.piece.lineFeedCnt;
+		node.piece.lineFeedCnt = start.index;
+		this.deletePrefixSumTail(node.piece.lineStarts, start);
+
+		if (hitCRLF) {
+			node.piece.lineFeedCnt += 1;
+			lf_delta += 1;
+			node.piece.lineStarts.insertValues(node.piece.lineStarts.values.length, new Uint32Array(1) /*[0]*/);
+		}
+
+		this.updateMetadata(node, -cnt, lf_delta);
+	}
+
+	// remove start-end from node.
+	shrinkNode(node: TreeNode, start: PrefixSumIndexOfResult, end?: PrefixSumIndexOfResult) {
+		// read operation first
+		let oldLineLengthsVal = node.piece.lineStarts.values;
+		let offset = node.piece.lineStarts.getAccumulatedValue(start.index - 1) + start.remainder;
+		let endOffset = node.piece.lineStarts.getAccumulatedValue(end.index - 1) + end.remainder;
+
+		// write.
+		let startHitCRLF = this.hitTestCRLF(node, offset, start);
+		let nodeOldLength = node.piece.length;
+		node.piece.length = offset;
+		let lf_delta = start.index - node.piece.lineFeedCnt;
+		node.piece.lineFeedCnt = start.index;
+		node.piece.lineStarts = new PrefixSumComputer(oldLineLengthsVal.slice(0, start.index + 1));
+		node.piece.lineStarts.changeValue(start.index, start.remainder);
+
+		if (startHitCRLF) {
+			node.piece.lineFeedCnt += 1;
+			lf_delta += 1;
+			node.piece.lineStarts.insertValues(node.piece.lineStarts.values.length, new Uint32Array(1) /*[0]*/);
+		}
+		this.updateMetadata(node, offset - nodeOldLength, lf_delta);
+
+		let newPieceLength = nodeOldLength - endOffset;
+		if (newPieceLength <= 0) {
+			return;
+		}
+
+		let newPiece: Piece = new Piece(
+			node.piece.isOriginalBuffer,
+			endOffset + node.piece.offset,
+			newPieceLength,
+			oldLineLengthsVal.length - end.index - 1,
+			oldLineLengthsVal.slice(end.index)
+		);
+		newPiece.lineStarts.changeValue(0, newPiece.lineStarts.values[0] - end.remainder);
+
+		let newNode = this.rbInsertRight(node, newPiece);
+		this.fixCRLFWithPrev(newNode);
+	}
+
+	appendToNode(node: TreeNode, value: string): void {
+		if (this.adjustCarriageReturnFromNext(value, node)) {
+			value += '\n';
+		}
+
+		let hitCRLF = value.charCodeAt(0) === 10 && this.nodeCharCodeAt(node, node.piece.length - 1) === 13;
+		this._changeBuffer += value;
+		node.piece.length += value.length;
+		const { lineFeedCount, lineLengths } = this.calculateNewLineCount(value);
+
+		let lf_delta = lineFeedCount;
+		if (hitCRLF) {
+			node.piece.lineFeedCnt += lineFeedCount - 1;
+			lf_delta--;
+			let lineStarts = node.piece.lineStarts;
+			lineStarts.removeValues(lineStarts.values.length - 1, 1);
+			lineStarts.changeValue(lineStarts.values.length - 1, lineStarts.values[lineStarts.values.length - 1] + 1);
+			lineStarts.insertValues(lineStarts.values.length, lineLengths.slice(1));
+		} else {
+			node.piece.lineFeedCnt += lineFeedCount;
+			let lineStarts = node.piece.lineStarts;
+			lineStarts.changeValue(lineStarts.values.length - 1, lineStarts.values[lineStarts.values.length - 1] + lineLengths[0]);
+			lineStarts.insertValues(lineStarts.values.length, lineLengths.slice(1));
+		}
+
+		this.updateMetadata(node, value.length, lf_delta);
+	}
+
+	nodeAt(offset: number): BufferCursor {
+		let x = this.root;
+
+		while (x !== SENTINEL) {
+			if (x.size_left > offset) {
+				x = x.left;
+			} else if (x.size_left + x.piece.length >= offset) {
+				return {
+					node: x,
+					remainder: offset - x.size_left
+				};
+			} else {
+				offset -= x.size_left + x.piece.length;
+				x = x.right;
+			}
+		}
+
+		return null;
+	}
+
+	nodeAt2(position: Position): BufferCursor {
+		let x = this.root;
+		let lineNumber = position.lineNumber;
+		let column = position.column;
+
+		while (x !== SENTINEL) {
+			if (x.left !== SENTINEL && x.lf_left >= lineNumber - 1) {
+				x = x.left;
+			} else if (x.lf_left + x.piece.lineFeedCnt > lineNumber - 1) {
+				let prevAccumualtedValue = x.piece.lineStarts.getAccumulatedValue(lineNumber - x.lf_left - 2);
+				let accumualtedValue = x.piece.lineStarts.getAccumulatedValue(lineNumber - x.lf_left - 1);
+
+				return {
+					node: x,
+					remainder: Math.min(prevAccumualtedValue + column - 1, accumualtedValue)
+				};
+			} else if (x.lf_left + x.piece.lineFeedCnt === lineNumber - 1) {
+				let prevAccumualtedValue = x.piece.lineStarts.getAccumulatedValue(lineNumber - x.lf_left - 2);
+				if (prevAccumualtedValue + column - 1 <= x.piece.length) {
+					return {
+						node: x,
+						remainder: prevAccumualtedValue + column - 1
+					};
+				} else {
+					column -= x.piece.length - prevAccumualtedValue;
+					break;
+				}
+			} else {
+				lineNumber -= x.lf_left + x.piece.lineFeedCnt;
+				x = x.right;
+			}
+		}
+
+		// search in order, to find the node contains position.column
+		x = x.next();
+		while (x !== SENTINEL) {
+
+			if (x.piece.lineFeedCnt > 0) {
+				let accumualtedValue = x.piece.lineStarts.getAccumulatedValue(0);
+				return {
+					node: x,
+					remainder: Math.min(column - 1, accumualtedValue)
+				};
+			} else {
+				if (x.piece.length >= column - 1) {
+					return {
+						node: x,
+						remainder: column - 1
+					};
+				} else {
+					column -= x.piece.length;
+				}
+			}
+
+			x = x.next();
+		}
+
+		return null;
+	}
+
+	offsetOfNode(node: TreeNode): number {
+		if (!node) {
+			return 0;
+		}
+		let pos = node.size_left;
+		while (node !== this.root) {
+			if (node.parent.right === node) {
+				pos += node.parent.size_left + node.parent.piece.length;
+			}
+
+			node = node.parent;
+		}
+
+		return pos;
+	}
+
+	getNodeContent(node: TreeNode): string {
+		let buffer = node.piece.isOriginalBuffer ? this._originalBuffer : this._changeBuffer;
+		let currentContent = buffer.substr(node.piece.offset, node.piece.length);
+
+		return currentContent;
+	}
+
+	deletePrefixSumTail(prefixSum: PrefixSumComputer, position: PrefixSumIndexOfResult): void {
+		prefixSum.removeValues(position.index + 1, prefixSum.values.length - position.index - 1);
+		prefixSum.changeValue(position.index, position.remainder);
+	}
+
+	deletePrefixSumHead(prefixSum: PrefixSumComputer, position: PrefixSumIndexOfResult): void {
+		prefixSum.changeValue(position.index, prefixSum.values[position.index] - position.remainder);
+		if (position.index > 0) {
+			prefixSum.removeValues(0, position.index);
+		}
+	}
+
+	// #endregion
+
+	// #region CRLF
+	hitTestCRLF(node: TreeNode, offset: number, position: PrefixSumIndexOfResult) {
+		if (node.piece.lineFeedCnt < 1) {
+			return false;
+		}
+
+		let currentLineLen = node.piece.lineStarts.getAccumulatedValue(position.index);
+		if (offset === currentLineLen - 1) {
+			// charCodeAt becomes slow (single or even two digits ms) when the changed buffer is long
+			return this.nodeCharCodeAt(node, offset - 1) === 13/* \r */ && this.nodeCharCodeAt(node, offset) === 10 /* \n */;
+		}
+		return false;
+	}
+
+	fixCRLFWithPrev(nextNode: TreeNode) {
+		if (nextNode === SENTINEL || nextNode.piece.lineFeedCnt === 0) {
+			return;
+		}
+
+		if (nextNode.piece.lineStarts.getAccumulatedValue(0) !== 1 /* if it's \n, the first line is 1 char */) {
+			return;
+		}
+
+		if (this.nodeCharCodeAt(nextNode, 0) === 10 /* \n */) {
+			let node = nextNode.prev();
+
+			if (node === SENTINEL || node.piece.lineFeedCnt === 0) {
+				return;
+			}
+
+			if (this.nodeCharCodeAt(node, node.piece.length - 1) === 13) {
+				this.fixCRLF(node, nextNode);
+			}
+		}
+	}
+
+	fixCRLFWithNext(node: TreeNode) {
+		if (node === SENTINEL) {
+			return;
+		}
+
+		if (this.nodeCharCodeAt(node, node.piece.length - 1) === 13 /* \r */) {
+			let nextNode = node.next();
+			if (nextNode !== SENTINEL && this.nodeCharCodeAt(nextNode, 0) === 10 /* \n */) {
+				this.fixCRLF(node, nextNode);
+			}
+		}
+	}
+
+	fixCRLF(prev: TreeNode, next: TreeNode) {
+		let nodesToDel = [];
+		// update node
+		prev.piece.length -= 1;
+		prev.piece.lineFeedCnt -= 1;
+		let lineStarts = prev.piece.lineStarts;
+		// lineStarts.values.length >= 2 due to a `\r`
+		lineStarts.removeValues(lineStarts.values.length - 1, 1);
+		lineStarts.changeValue(lineStarts.values.length - 1, lineStarts.values[lineStarts.values.length - 1] - 1);
+		this.updateMetadata(prev, - 1, -1);
+
+		if (prev.piece.length === 0) {
+			nodesToDel.push(prev);
+		}
+
+		// update nextNode
+		next.piece.length -= 1;
+		next.piece.offset += 1;
+		next.piece.lineFeedCnt -= 1;
+		lineStarts = next.piece.lineStarts;
+		lineStarts.removeValues(0, 1);
+		this.updateMetadata(next, - 1, -1);
+		if (next.piece.length === 0) {
+			nodesToDel.push(next);
+		}
+
+		// create new piece which contains \r\n
+		let startOffset = this._changeBuffer.length;
+		this._changeBuffer += '\r\n';
+		const { lineFeedCount, lineLengths } = this.calculateNewLineCount('\r\n');
+		let piece = new Piece(false, startOffset, 2, lineFeedCount, lineLengths);
+		this.rbInsertRight(prev, piece);
+		// delete empty nodes
+
+		for (let i = 0; i < nodesToDel.length; i++) {
+			this.rbDelete(nodesToDel[i]);
+		}
+	}
+
+	adjustCarriageReturnFromNext(value: string, node: TreeNode): boolean {
+		if (value.charCodeAt(value.length - 1) === 13) {
+			// inserted content ends with \r
+			let nextNode = node.next();
+			if (nextNode !== SENTINEL) {
+				if (this.nodeCharCodeAt(nextNode, 0) === 10) {
+					// move `\n` forward
+					value += '\n';
+
+					if (nextNode.piece.length === 1) {
+						this.rbDelete(nextNode);
+					} else {
+						nextNode.piece.offset += 1;
+						nextNode.piece.length -= 1;
+						nextNode.piece.lineFeedCnt -= 1;
+						nextNode.piece.lineStarts.removeValues(0, 1); // remove the first line, which is empty.
+						this.updateMetadata(nextNode, -1, -1);
+					}
+					return true;
+				}
+			}
+		}
+
+		return false;
+	}
+
+	nodeCharCodeAt(node: TreeNode, offset: number): number {
+		if (node.piece.lineFeedCnt < 1) {
+			return -1;
+		}
+		let buffer = node.piece.isOriginalBuffer ? this._originalBuffer : this._changeBuffer;
+
+		return buffer.charCodeAt(node.piece.offset + offset);
+	}
+	// #endregion
+
+	// #endregion
+
+	// #region Red Black Tree
+
+	leftRotate(x: TreeNode) {
+		let y = x.right;
+
+		// fix size_left
+		y.size_left += x.size_left + (x.piece ? x.piece.length : 0);
+		y.lf_left += x.lf_left + (x.piece ? x.piece.lineFeedCnt : 0);
+		x.right = y.left;
+
+		if (y.left !== SENTINEL) {
+			y.left.parent = x;
+		}
+		y.parent = x.parent;
+		if (x.parent === SENTINEL) {
+			this.root = y;
+		} else if (x.parent.left === x) {
+			x.parent.left = y;
+		} else {
+			x.parent.right = y;
+		}
+		y.left = x;
+		x.parent = y;
+	}
+
+	rightRotate(y: TreeNode) {
+		let x = y.left;
+		y.left = x.right;
+		if (x.right !== SENTINEL) {
+			x.right.parent = y;
+		}
+		x.parent = y.parent;
+
+		// fix size_left
+		y.size_left -= x.size_left + (x.piece ? x.piece.length : 0);
+		y.lf_left -= x.lf_left + (x.piece ? x.piece.lineFeedCnt : 0);
+
+		if (y.parent === SENTINEL) {
+			this.root = x;
+		} else if (y === y.parent.right) {
+			y.parent.right = x;
+		} else {
+			y.parent.left = x;
+		}
+
+		x.right = y;
+		y.parent = x;
+	}
+
+	/**
+	 *      node              node
+	 *     /  \              /  \
+	 *    a   b    <----   a    b
+	 *                         /
+	 *                        z
+	 */
+	rbInsertRight(node: TreeNode, p: Piece): TreeNode {
+		let z = new TreeNode(p, NodeColor.Red);
+		z.left = SENTINEL;
+		z.right = SENTINEL;
+		z.parent = SENTINEL;
+		z.size_left = 0;
+		z.lf_left = 0;
+
+		let x = this.root;
+		if (x === SENTINEL) {
+			this.root = z;
+			setNodeColor(z, NodeColor.Black);
+		} else if (node.right === SENTINEL) {
+			node.right = z;
+			z.parent = node;
+		} else {
+			let nextNode = leftest(node.right);
+			nextNode.left = z;
+			z.parent = nextNode;
+		}
+
+		this.fixInsert(z);
+		return z;
+	}
+
+	/**
+	 *      node              node
+	 *     /  \              /  \
+	 *    a   b     ---->   a    b
+	 *                       \
+	 *                        z
+	 */
+	rbInsertLeft(node: TreeNode, p: Piece): TreeNode {
+		let z = new TreeNode(p, NodeColor.Red);
+		z.left = SENTINEL;
+		z.right = SENTINEL;
+		z.parent = SENTINEL;
+		z.size_left = 0;
+		z.lf_left = 0;
+
+		let x = this.root;
+		if (x === SENTINEL) {
+			this.root = z;
+			setNodeColor(z, NodeColor.Black);
+		} else if (node.left === SENTINEL) {
+			node.left = z;
+			z.parent = node;
+		} else {
+			let prevNode = righttest(node.left); // a
+			prevNode.right = z;
+			z.parent = prevNode;
+		}
+
+		this.fixInsert(z);
+		return z;
+	}
+
+	rbDelete(z: TreeNode) {
+		let x: TreeNode;
+		let y: TreeNode;
+
+		if (z.left === SENTINEL) {
+			y = z;
+			x = y.right;
+		} else if (z.right === SENTINEL) {
+			y = z;
+			x = y.left;
+		} else {
+			y = leftest(z.right);
+			x = y.right;
+		}
+
+		if (y === this.root) {
+			this.root = x;
+
+			// if x is null, we are removing the only node
+			setNodeColor(x, NodeColor.Black);
+
+			z.detach();
+			resetSentinel();
+			this.root.parent = SENTINEL;
+
+			return;
+		}
+
+		let yWasRed = (getNodeColor(y) === NodeColor.Red);
+
+		if (y === y.parent.left) {
+			y.parent.left = x;
+		} else {
+			y.parent.right = x;
+		}
+
+		if (y === z) {
+			x.parent = y.parent;
+			this.recomputeMetadata(x);
+		} else {
+			if (y.parent === z) {
+				x.parent = y;
+			} else {
+				x.parent = y.parent;
+			}
+
+			// as we make changes to x's hierarchy, update size_left of subtree first
+			this.recomputeMetadata(x);
+
+			y.left = z.left;
+			y.right = z.right;
+			y.parent = z.parent;
+			setNodeColor(y, getNodeColor(z));
+
+			if (z === this.root) {
+				this.root = y;
+			} else {
+				if (z === z.parent.left) {
+					z.parent.left = y;
+				} else {
+					z.parent.right = y;
+				}
+			}
+
+			if (y.left !== SENTINEL) {
+				y.left.parent = y;
+			}
+			if (y.right !== SENTINEL) {
+				y.right.parent = y;
+			}
+			// update metadata
+			// we replace z with y, so in this sub tree, the length change is z.item.length
+			y.size_left = z.size_left;
+			y.lf_left = z.lf_left;
+			this.recomputeMetadata(y);
+		}
+
+		z.detach();
+
+		if (x.parent.left === x) {
+			let newSizeLeft = calculateSize(x);
+			let newLFLeft = calculateLF(x);
+			if (newSizeLeft !== x.parent.size_left || newLFLeft !== x.parent.lf_left) {
+				let delta = newSizeLeft - x.parent.size_left;
+				let lf_delta = newLFLeft - x.parent.lf_left;
+				x.parent.size_left = newSizeLeft;
+				x.parent.lf_left = newLFLeft;
+				this.updateMetadata(x.parent, delta, lf_delta);
+			}
+		}
+
+		this.recomputeMetadata(x.parent);
+
+		if (yWasRed) {
+			resetSentinel();
+			return;
+		}
+
+		// RB-DELETE-FIXUP
+		let w: TreeNode;
+		while (x !== this.root && getNodeColor(x) === NodeColor.Black) {
+			if (x === x.parent.left) {
+				w = x.parent.right;
+
+				if (getNodeColor(w) === NodeColor.Red) {
+					setNodeColor(w, NodeColor.Black);
+					setNodeColor(x.parent, NodeColor.Red);
+					this.leftRotate(x.parent);
+					w = x.parent.right;
+				}
+
+				if (getNodeColor(w.left) === NodeColor.Black && getNodeColor(w.right) === NodeColor.Black) {
+					setNodeColor(w, NodeColor.Red);
+					x = x.parent;
+				} else {
+					if (getNodeColor(w.right) === NodeColor.Black) {
+						setNodeColor(w.left, NodeColor.Black);
+						setNodeColor(w, NodeColor.Red);
+						this.rightRotate(w);
+						w = x.parent.right;
+					}
+
+					setNodeColor(w, getNodeColor(x.parent));
+					setNodeColor(x.parent, NodeColor.Black);
+					setNodeColor(w.right, NodeColor.Black);
+					this.leftRotate(x.parent);
+					x = this.root;
+				}
+			} else {
+				w = x.parent.left;
+
+				if (getNodeColor(w) === NodeColor.Red) {
+					setNodeColor(w, NodeColor.Black);
+					setNodeColor(x.parent, NodeColor.Red);
+					this.rightRotate(x.parent);
+					w = x.parent.left;
+				}
+
+				if (getNodeColor(w.left) === NodeColor.Black && getNodeColor(w.right) === NodeColor.Black) {
+					setNodeColor(w, NodeColor.Red);
+					x = x.parent;
+
+				} else {
+					if (getNodeColor(w.left) === NodeColor.Black) {
+						setNodeColor(w.right, NodeColor.Black);
+						setNodeColor(w, NodeColor.Red);
+						this.leftRotate(w);
+						w = x.parent.left;
+					}
+
+					setNodeColor(w, getNodeColor(x.parent));
+					setNodeColor(x.parent, NodeColor.Black);
+					setNodeColor(w.left, NodeColor.Black);
+					this.rightRotate(x.parent);
+					x = this.root;
+				}
+			}
+		}
+		setNodeColor(x, NodeColor.Black);
+		resetSentinel();
+	}
+
+	fixInsert(x: TreeNode) {
+		this.recomputeMetadata(x);
+
+		while (x !== this.root && getNodeColor(x.parent) === NodeColor.Red) {
+			if (x.parent === x.parent.parent.left) {
+				const y = x.parent.parent.right;
+
+				if (getNodeColor(y) === NodeColor.Red) {
+					setNodeColor(x.parent, NodeColor.Black);
+					setNodeColor(y, NodeColor.Black);
+					setNodeColor(x.parent.parent, NodeColor.Red);
+					x = x.parent.parent;
+				} else {
+					if (x === x.parent.right) {
+						x = x.parent;
+						this.leftRotate(x);
+					}
+
+					setNodeColor(x.parent, NodeColor.Black);
+					setNodeColor(x.parent.parent, NodeColor.Red);
+					this.rightRotate(x.parent.parent);
+				}
+			} else {
+				const y = x.parent.parent.left;
+
+				if (getNodeColor(y) === NodeColor.Red) {
+					setNodeColor(x.parent, NodeColor.Black);
+					setNodeColor(y, NodeColor.Black);
+					setNodeColor(x.parent.parent, NodeColor.Red);
+					x = x.parent.parent;
+				} else {
+					if (x === x.parent.left) {
+						x = x.parent;
+						this.rightRotate(x);
+					}
+					setNodeColor(x.parent, NodeColor.Black);
+					setNodeColor(x.parent.parent, NodeColor.Red);
+					this.leftRotate(x.parent.parent);
+				}
+			}
+		}
+
+		setNodeColor(this.root, NodeColor.Black);
+	}
+
+	updateMetadata(x: TreeNode, delta: number, lineFeedCntDelta: number): void {
+		// node length change, we need to update the roots of all subtrees containing this node.
+		while (x !== this.root && x !== SENTINEL) {
+			if (x.parent.left === x) {
+				x.parent.size_left += delta;
+				x.parent.lf_left += lineFeedCntDelta;
+			}
+
+			x = x.parent;
+		}
+	}
+
+	recomputeMetadata(x: TreeNode) {
+		let delta = 0;
+		let lf_delta = 0;
+		if (x === this.root) {
+			return;
+		}
+
+		if (delta === 0) {
+			// go upwards till the node whose left subtree is changed.
+			while (x !== this.root && x === x.parent.right) {
+				x = x.parent;
+			}
+
+			if (x === this.root) {
+				// well, it means we add a node to the end (inorder)
+				return;
+			}
+
+			// x is the node whose right subtree is changed.
+			x = x.parent;
+
+			delta = calculateSize(x.left) - x.size_left;
+			lf_delta = calculateLF(x.left) - x.lf_left;
+			x.size_left += delta;
+			x.lf_left += lf_delta;
+		}
+
+		// go upwards till root. O(logN)
+		while (x !== this.root && (delta !== 0 || lf_delta !== 0)) {
+			if (x.parent.left === x) {
+				x.parent.size_left += delta;
+				x.parent.lf_left += lf_delta;
+			}
+
+			x = x.parent;
+		}
+	}
+
+	getContentOfSubTree(node: TreeNode): string {
+		if (node === SENTINEL) {
+			return '';
+		}
+
+		let buffer = node.piece.isOriginalBuffer ? this._originalBuffer : this._changeBuffer;
+		let currentContent = buffer.substr(node.piece.offset, node.piece.length);
+
+		return this.getContentOfSubTree(node.left) + currentContent + this.getContentOfSubTree(node.right);
+	}
+
+	calculateNewLineCount(chunk: string): { lineFeedCount: number, lineLengths: Uint32Array } {
+		let lineStarts = [0];
+
+		// Reset regex to search from the beginning
+		this._regex.lastIndex = 0;
+		let prevMatchStartIndex = -1;
+		let prevMatchLength = 0;
+
+		let m: RegExpExecArray;
+		do {
+			if (prevMatchStartIndex + prevMatchLength === chunk.length) {
+				// Reached the end of the line
+				break;
+			}
+
+			m = this._regex.exec(chunk);
+			if (!m) {
+				break;
+			}
+
+			const matchStartIndex = m.index;
+			const matchLength = m[0].length;
+
+			if (matchStartIndex === prevMatchStartIndex && matchLength === prevMatchLength) {
+				// Exit early if the regex matches the same range twice
+				break;
+			}
+
+			prevMatchStartIndex = matchStartIndex;
+			prevMatchLength = matchLength;
+
+			lineStarts.push(matchStartIndex + matchLength);
+
+		} while (m);
+
+		const lineLengths = new Uint32Array(lineStarts.length);
+		for (let i = 1; i < lineStarts.length; i++) {
+			lineLengths[i - 1] = lineStarts[i] - lineStarts[i - 1];
+		}
+
+		lineLengths[lineStarts.length - 1] = chunk.length - lineStarts[lineStarts.length - 1];
+
+		return {
+			lineFeedCount: lineLengths.length - 1,
+			lineLengths: lineLengths
+		};
+	}
+	// #endregion
+
+	// #region helper
+	/**
+	 * Assumes `operations` are validated and sorted ascending
+	 */
+	public static _getInverseEditRanges(operations: IValidatedEditOperation[]): Range[] {
+		let result: Range[] = [];
+
+		let prevOpEndLineNumber: number;
+		let prevOpEndColumn: number;
+		let prevOp: IValidatedEditOperation = null;
+		for (let i = 0, len = operations.length; i < len; i++) {
+			let op = operations[i];
+
+			let startLineNumber: number;
+			let startColumn: number;
+
+			if (prevOp) {
+				if (prevOp.range.endLineNumber === op.range.startLineNumber) {
+					startLineNumber = prevOpEndLineNumber;
+					startColumn = prevOpEndColumn + (op.range.startColumn - prevOp.range.endColumn);
+				} else {
+					startLineNumber = prevOpEndLineNumber + (op.range.startLineNumber - prevOp.range.endLineNumber);
+					startColumn = op.range.startColumn;
+				}
+			} else {
+				startLineNumber = op.range.startLineNumber;
+				startColumn = op.range.startColumn;
+			}
+
+			let resultRange: Range;
+
+			if (op.lines && op.lines.length > 0) {
+				// the operation inserts something
+				let lineCount = op.lines.length;
+				let firstLine = op.lines[0];
+				let lastLine = op.lines[lineCount - 1];
+
+				if (lineCount === 1) {
+					// single line insert
+					resultRange = new Range(startLineNumber, startColumn, startLineNumber, startColumn + firstLine.length);
+				} else {
+					// multi line insert
+					resultRange = new Range(startLineNumber, startColumn, startLineNumber + lineCount - 1, lastLine.length + 1);
+				}
+			} else {
+				// There is nothing to insert
+				resultRange = new Range(startLineNumber, startColumn, startLineNumber, startColumn);
+			}
+
+			prevOpEndLineNumber = resultRange.endLineNumber;
+			prevOpEndColumn = resultRange.endColumn;
+
+			result.push(resultRange);
+			prevOp = op;
+		}
+
+		return result;
+	}
+
+	private static _sortOpsAscending(a: IValidatedEditOperation, b: IValidatedEditOperation): number {
+		let r = Range.compareRangesUsingEnds(a.range, b.range);
+		if (r === 0) {
+			return a.sortIndex - b.sortIndex;
+		}
+		return r;
+	}
+
+	private static _sortOpsDescending(a: IValidatedEditOperation, b: IValidatedEditOperation): number {
+		let r = Range.compareRangesUsingEnds(a.range, b.range);
+		if (r === 0) {
+			return b.sortIndex - a.sortIndex;
+		}
+		return -r;
+	}
+	// #endregion
+}
\ No newline at end of file
diff --git a/src/vs/editor/common/model/textModel.ts b/src/vs/editor/common/model/textModel.ts
index 2fdc06ca5b4edfd7131eee9ee885dd4c3e0767a5..575d26bedca3bcc8b529bbbf584ea2725bca0da9 100644
--- a/src/vs/editor/common/model/textModel.ts
+++ b/src/vs/editor/common/model/textModel.ts
@@ -10,13 +10,14 @@ import { Position, IPosition } from 'vs/editor/common/core/position';
 import { Range, IRange } from 'vs/editor/common/core/range';
 import { Selection } from 'vs/editor/common/core/selection';
 import * as editorCommon from 'vs/editor/common/editorCommon';
-import { guessIndentation, IndentationGuesserTextBufferTarget, IndentationGuesserStringArrayTarget } from 'vs/editor/common/model/indentationGuesser';
+import { guessIndentation, IndentationGuesserTextBufferTarget, IndentationGuesserStringArrayTarget, IndentationGuesserRawTextBufferTarget } from 'vs/editor/common/model/indentationGuesser';
 import { EDITOR_MODEL_DEFAULTS } from 'vs/editor/common/config/editorOptions';
 import { TextModelSearch, SearchParams } from 'vs/editor/common/model/textModelSearch';
 import { TextSource, ITextSource, IRawTextSource, RawTextSource } from 'vs/editor/common/model/textSource';
 import { IModelContentChangedEvent, ModelRawContentChangedEvent, ModelRawFlush, ModelRawEOLChanged, IModelOptionsChangedEvent, InternalModelContentChangeEvent } from 'vs/editor/common/model/textModelEvents';
 import { Disposable, IDisposable } from 'vs/base/common/lifecycle';
-import { TextBuffer } from 'vs/editor/common/model/textBuffer';
+// import { TextBuffer } from 'vs/editor/common/model/textBuffer';
+import { TextBuffer } from 'vs/editor/common/model/textBuffer2';
 
 const LIMIT_FIND_COUNT = 999;
 export const LONG_LINE_BOUNDARY = 10000;
@@ -48,7 +49,13 @@ export class TextModel extends Disposable implements editorCommon.ITextModel {
 
 		let resolvedOpts: editorCommon.TextModelResolvedOptions;
 		if (options.detectIndentation) {
-			const guessedIndentation = guessIndentation(new IndentationGuesserStringArrayTarget(textSource.lines), options.tabSize, options.insertSpaces);
+			const guessedIndentation = guessIndentation(
+				Array.isArray(textSource.lines) ?
+					new IndentationGuesserStringArrayTarget(textSource.lines) :
+					new IndentationGuesserRawTextBufferTarget(textSource.lines),
+				options.tabSize,
+				options.insertSpaces
+			);
 			resolvedOpts = new editorCommon.TextModelResolvedOptions({
 				tabSize: guessedIndentation.tabSize,
 				insertSpaces: guessedIndentation.insertSpaces,
@@ -412,7 +419,7 @@ export class TextModel extends Disposable implements editorCommon.ITextModel {
 
 	public getLinesContent(): string[] {
 		this._assertNotDisposed();
-		return this._buffer.getLinesContent();
+		return this._buffer.getLinesContent().split(/\r\n|\r|\n/);
 	}
 
 	public getEOL(): string {
diff --git a/src/vs/editor/common/model/textSource.ts b/src/vs/editor/common/model/textSource.ts
index 3eb9cf653e8a0dbfe15b81e93ac900b3b1d7a35f..0bba12b196ec5ca2082c4ae3e3af086b73eeebf2 100644
--- a/src/vs/editor/common/model/textSource.ts
+++ b/src/vs/editor/common/model/textSource.ts
@@ -7,6 +7,18 @@
 import * as strings from 'vs/base/common/strings';
 import { DefaultEndOfLine } from 'vs/editor/common/editorCommon';
 
+/**
+ * Raw text buffer for Piece Table.
+ */
+export interface IRawPTBuffer {
+	text: string;
+	lineStarts: number[];
+	/**
+	 * lines count
+	 */
+	length: number;
+}
+
 /**
  * A processed string ready to be turned into an editor model.
  */
@@ -18,7 +30,7 @@ export interface IRawTextSource {
 	/**
 	 * The text split into lines.
 	 */
-	readonly lines: string[];
+	readonly lines: string[] | IRawPTBuffer;
 	/**
 	 * The BOM (leading character sequence of the file).
 	 */
@@ -51,18 +63,28 @@ export class RawTextSource {
 		const isBasicASCII = (containsRTL ? false : strings.isBasicASCII(rawText));
 
 		// Split the text into lines
-		const lines = rawText.split(/\r\n|\r|\n/);
+		// const lines = rawText.split(/\r\n|\r|\n/);
 
 		// Remove the BOM (if present)
 		let BOM = '';
-		if (strings.startsWithUTF8BOM(lines[0])) {
+		if (strings.startsWithUTF8BOM(rawText)) {
 			BOM = strings.UTF8_BOM_CHARACTER;
-			lines[0] = lines[0].substr(1);
+			rawText = rawText.substr(1);
+		}
+
+		let lastLineFeed = -1;
+		var lineStarts = [];
+		while ((lastLineFeed = rawText.indexOf('\n', lastLineFeed + 1)) !== -1) {
+			lineStarts.push(lastLineFeed + 1);
 		}
 
 		return {
 			BOM: BOM,
-			lines: lines,
+			lines: {
+				text: rawText,
+				lineStarts: lineStarts,
+				length: lineStarts.length
+			},
 			length: rawText.length,
 			containsRTL: containsRTL,
 			isBasicASCII: isBasicASCII,
@@ -83,7 +105,7 @@ export interface ITextSource {
 	/**
 	 * The text split into lines.
 	 */
-	readonly lines: string[];
+	readonly lines: string[] | IRawPTBuffer;
 	/**
 	 * The BOM (leading character sequence of the file).
 	 */
diff --git a/src/vs/editor/common/services/modelServiceImpl.ts b/src/vs/editor/common/services/modelServiceImpl.ts
index bda67f4f9b5d86d6fb5cd88a615674909384eb79..9faaf7880474c5370f5bb95fea489a23274d246b 100644
--- a/src/vs/editor/common/services/modelServiceImpl.ts
+++ b/src/vs/editor/common/services/modelServiceImpl.ts
@@ -409,10 +409,25 @@ export class ModelServiceImpl implements IModelService {
 		};
 		const textSourceLineSequence = new class implements ISequence {
 			public getLength(): number {
-				return textSource.lines.length;
+				return textSource.lines.length + 1;
 			}
 			public getElementHash(index: number): string {
-				return textSource.lines[index];
+				if (Array.isArray(textSource.lines)) {
+					return textSource.lines[index];
+				} else {
+					if (textSource.lines.length === 0) {
+						return textSource.lines.text;
+					}
+					if (index === 0) {
+						return textSource.lines.text.substring(0, textSource.lines.lineStarts[0]);
+					}
+
+					if (index === textSource.lines.length) {
+						return textSource.lines.text.substring(textSource.lines.lineStarts[index - 1]);
+					}
+
+					return textSource.lines.text.substring(textSource.lines.lineStarts[index - 1], textSource.lines.lineStarts[index]);
+				}
 			}
 		};
 
diff --git a/src/vs/editor/common/viewModel/prefixSumComputer.ts b/src/vs/editor/common/viewModel/prefixSumComputer.ts
index 8730795093f8ec21bfd9dd1319ce7b9069c1e819..291ec21fa35ec0ad4c71aca9875f41c75d01b8eb 100644
--- a/src/vs/editor/common/viewModel/prefixSumComputer.ts
+++ b/src/vs/editor/common/viewModel/prefixSumComputer.ts
@@ -23,7 +23,7 @@ export class PrefixSumComputer {
 	/**
 	 * values[i] is the value at index i
 	 */
-	private values: Uint32Array;
+	values: Uint32Array;
 
 	/**
 	 * prefixSum[i] = SUM(heights[j]), 0 <= j <= i
diff --git a/src/vs/workbench/common/editor/textEditorModel.ts b/src/vs/workbench/common/editor/textEditorModel.ts
index 3a6006306898b61f806de43884f17a4426b3bcf0..c4b2db3f0822c2c8e172360e616273b5682896c0 100644
--- a/src/vs/workbench/common/editor/textEditorModel.ts
+++ b/src/vs/workbench/common/editor/textEditorModel.ts
@@ -106,8 +106,10 @@ export abstract class BaseTextEditorModel extends EditorModel implements ITextEd
 			}
 
 			return firstLineText.substr(0, Math.min(crIndex, lfIndex));
-		} else {
+		} else if (Array.isArray(value.lines)) {
 			return value.lines[0].substr(0, 100);
+		} else {
+			return value.lines.text.substr(0, 100);
 		}
 	}
 
diff --git a/src/vs/workbench/parts/welcome/walkThrough/node/walkThroughContentProvider.ts b/src/vs/workbench/parts/welcome/walkThrough/node/walkThroughContentProvider.ts
index 5688f82055a4dadb1722440a5cb4c3f4414f5f84..c2bd91ae57487d604db961944b7a15c85a09bdab 100644
--- a/src/vs/workbench/parts/welcome/walkThrough/node/walkThroughContentProvider.ts
+++ b/src/vs/workbench/parts/welcome/walkThrough/node/walkThroughContentProvider.ts
@@ -81,7 +81,7 @@ export class WalkThroughSnippetContentProvider implements ITextModelContentProvi
 					return '';
 				};
 
-				const markdown = content.value.lines.join('\n');
+				const markdown = Array.isArray(content.value.lines) ? content.value.lines.join('\n') : content.value.lines.text;
 				marked(markdown, { renderer });
 
 				const modeId = this.modeService.getModeIdForLanguageName(languageName);
diff --git a/src/vs/workbench/services/backup/node/backupFileService.ts b/src/vs/workbench/services/backup/node/backupFileService.ts
index 1a00d797b91ffa1e0f10a744f3649162aa38e572..dfa8348aaf7b6df2596b28d0681c41572af1d1d9 100644
--- a/src/vs/workbench/services/backup/node/backupFileService.ts
+++ b/src/vs/workbench/services/backup/node/backupFileService.ts
@@ -215,7 +215,7 @@ export class BackupFileService implements IBackupFileService {
 
 	public parseBackupContent(rawTextSource: IRawTextSource): string {
 		const textSource = TextSource.fromRawTextSource(rawTextSource, DefaultEndOfLine.LF);
-		return textSource.lines.slice(1).join(textSource.EOL); // The first line of a backup text file is the file name
+		return (<string[]>textSource.lines).slice(1).join(textSource.EOL); // The first line of a backup text file is the file name
 	}
 
 	public toBackupResource(resource: Uri): Uri {
diff --git a/src/vs/workbench/services/textfile/electron-browser/modelBuilder.ts b/src/vs/workbench/services/textfile/electron-browser/modelBuilder.ts
index 2d5c9a2e694e7de9500b0c5aab493b6a93769e5b..ace7732de7885f24e525b54dc135069cc5f82900 100644
--- a/src/vs/workbench/services/textfile/electron-browser/modelBuilder.ts
+++ b/src/vs/workbench/services/textfile/electron-browser/modelBuilder.ts
@@ -56,6 +56,61 @@ function optimizeStringMemory(buff: Buffer, s: string): string {
 	return s;
 }
 
+class PTBasedBuilder {
+	private lineStarts: number[];
+	private text: string;
+	private BOM: string;
+	private chunkIndex: number;
+	private totalLength: number;
+
+	constructor() {
+		this.text = '';
+		this.BOM = '';
+		this.chunkIndex = 0;
+		this.totalLength = 0;
+		this.lineStarts = [];
+	}
+
+	public acceptChunk(chunk: string): void {
+		if (this.chunkIndex === 0) {
+			if (strings.startsWithUTF8BOM(chunk)) {
+				this.BOM = strings.UTF8_BOM_CHARACTER;
+				chunk = chunk.substr(1);
+			}
+		}
+
+		let lastLineFeed = -1;
+		while ((lastLineFeed = chunk.indexOf('\n', lastLineFeed + 1)) !== -1) {
+			this.lineStarts.push(this.totalLength + lastLineFeed + 1);
+		}
+
+		this.text += chunk;
+		this.chunkIndex++;
+	}
+
+	public finish(containsRTL: boolean, isBasicASCII: boolean): ModelBuilderResult {
+		if (this.lineStarts[this.lineStarts.length - 1] > this.totalLength) {
+			this.lineStarts.pop();
+		}
+
+		return {
+			hash: null,
+			value: {
+				length: this.totalLength,
+				lines: {
+					text: this.text,
+					lineStarts: this.lineStarts,
+					length: this.lineStarts.length
+				},
+				BOM: this.BOM,
+				totalCRCount: 0,
+				containsRTL: containsRTL,
+				isBasicASCII: isBasicASCII
+			}
+		};
+	}
+}
+
 class ModelLineBasedBuilder {
 
 	private computeHash: boolean;
@@ -126,13 +181,15 @@ export class ModelBuilder {
 	private containsRTL: boolean;
 	private isBasicASCII: boolean;
 
+	private ptBasedBuilder: PTBasedBuilder;
+
 	public static fromStringStream(stream: IStringStream): TPromise<ModelBuilderResult> {
 		return new TPromise<ModelBuilderResult>((c, e, p) => {
 			let done = false;
 			let builder = new ModelBuilder(false);
 
 			stream.on('data', (chunk) => {
-				builder.acceptChunk(chunk);
+				builder.acceptChunk2(chunk);
 			});
 
 			stream.on('error', (error) => {
@@ -145,7 +202,7 @@ export class ModelBuilder {
 			stream.on('end', () => {
 				if (!done) {
 					done = true;
-					c(builder.finish());
+					c(builder.finish2());
 				}
 			});
 		});
@@ -159,6 +216,7 @@ export class ModelBuilder {
 		this.totalLength = 0;
 		this.containsRTL = false;
 		this.isBasicASCII = true;
+		this.ptBasedBuilder = new PTBasedBuilder();
 	}
 
 	private _updateCRCount(chunk: string): void {
@@ -210,6 +268,22 @@ export class ModelBuilder {
 		this.leftoverPrevChunk = lines[lines.length - 1];
 	}
 
+	public acceptChunk2(chunk: string): void {
+		if (chunk.length === 0) {
+			return;
+		}
+
+		// update lineStart to offset mapping
+		if (!this.containsRTL) {
+			this.containsRTL = strings.containsRTL(chunk);
+		}
+		if (this.isBasicASCII) {
+			this.isBasicASCII = strings.isBasicASCII(chunk);
+		}
+
+		this.ptBasedBuilder.acceptChunk(chunk);
+	}
+
 	public finish(): ModelBuilderResult {
 		let finalLines = [this.leftoverPrevChunk];
 		if (this.leftoverEndsInCR) {
@@ -218,4 +292,8 @@ export class ModelBuilder {
 		this.lineBasedBuilder.acceptLines(finalLines);
 		return this.lineBasedBuilder.finish(this.totalLength, this.totalCRCount, this.containsRTL, this.isBasicASCII);
 	}
+
+	public finish2(): ModelBuilderResult {
+		return this.ptBasedBuilder.finish(this.containsRTL, this.isBasicASCII);
+	}
 }
diff --git a/src/vs/workbench/test/workbenchTestServices.ts b/src/vs/workbench/test/workbenchTestServices.ts
index 0dcf628ee66325f3c46bffcee3c6cbc209ce560b..b12327198a302e2e01b4f5542756317d980548b7 100644
--- a/src/vs/workbench/test/workbenchTestServices.ts
+++ b/src/vs/workbench/test/workbenchTestServices.ts
@@ -859,7 +859,7 @@ export class TestBackupFileService implements IBackupFileService {
 	}
 
 	public parseBackupContent(rawText: IRawTextSource): string {
-		return rawText.lines.join('\n');
+		return Array.isArray(rawText.lines) ? rawText.lines.join('\n') : rawText.lines.text;
 	}
 
 	public discardResourceBackup(resource: URI): TPromise<void> {