src/vs/workbench/api/common/extHostDocumentData.ts/ExtHostDocumentData/_getTextInRange
class ExtHostDocumentData:	private _getTextInRange(_range: vscode.Range): string {
		const range = this._validateRange(_range);

		if (range.isEmpty) {
			return '';
		}

		if (range.isSingleLine) {
			return this._lines[range.start.line].substring(range.start.character, range.end.character);
		}

		const lineEnding = this._eol,
			startLineIndex = range.start.line,
			endLineIndex = range.end.line,
			resultLines: string[] = [];

		resultLines.push(this._lines[startLineIndex].substring(range.start.character));
		for (let i = startLineIndex + 1; i < endLineIndex; i++) {
			resultLines.push(this._lines[i]);
		}
		resultLines.push(this._lines[endLineIndex].substring(0, range.end.character));

		return resultLines.join(lineEnding);
	}