src/vs/editor/common/model/textModel.ts/TextModel/findPreviousMatch
class TextModel:	public findPreviousMatch(searchString: string, rawSearchStart: IPosition, isRegex: boolean, matchCase: boolean, wordSeparators: string, captureMatches: boolean): model.FindMatch | null {
		this._assertNotDisposed();
		const searchStart = this.validatePosition(rawSearchStart);
		return TextModelSearch.findPreviousMatch(this, new SearchParams(searchString, isRegex, matchCase, wordSeparators), searchStart, captureMatches);
	}