src/vs/editor/common/model/tokenizationTextModelPart.ts/TokenizationTextModelPart/getWordUntilPosition
class TokenizationTextModelPart:	public getWordUntilPosition(position: IPosition): IWordAtPosition {
		const wordAtPosition = this.getWordAtPosition(position);
		if (!wordAtPosition) {
			return {
				word: '',
				startColumn: position.column,
				endColumn: position.column,
			};
		}
		return {
			word: wordAtPosition.word.substr(
				0,
				position.column - wordAtPosition.startColumn
			),
			startColumn: wordAtPosition.startColumn,
			endColumn: position.column,
		};
	}