src/vs/editor/common/commands/trimTrailingWhitespaceCommand.ts/trimTrailingWhitespace
export function trimTrailingWhitespace(model: ITextModel, cursors: Position[]): ISingleEditOperation[] {
	// Sort cursors ascending
	cursors.sort((a, b) => {
		if (a.lineNumber === b.lineNumber) {
			return a.column - b.column;
		}
		return a.lineNumber - b.lineNumber;
	});

	// Reduce multiple cursors on the same line and only keep the last one on the line
	for (let i = cursors.length - 2; i >= 0; i--) {
		if (cursors[i].lineNumber === cursors[i + 1].lineNumber) {
			// Remove cursor at `i`
			cursors.splice(i, 1);
		}
	}

	const r: ISingleEditOperation[] = [];
	let rLen = 0;
	let cursorIndex = 0;
	const cursorLen = cursors.length;

	for (let lineNumber = 1, lineCount = model.getLineCount(); lineNumber <= lineCount; lineNumber++) {
		const lineContent = model.getLineContent(lineNumber);
		const maxLineColumn = lineContent.length + 1;
		let minEditColumn = 0;

		if (cursorIndex < cursorLen && cursors[cursorIndex].lineNumber === lineNumber) {
			minEditColumn = cursors[cursorIndex].column;
			cursorIndex++;
			if (minEditColumn === maxLineColumn) {
				// The cursor is at the end of the line => no edits for sure on this line
				continue;
			}
		}

		if (lineContent.length === 0) {
			continue;
		}

		const lastNonWhitespaceIndex = strings.lastNonWhitespaceIndex(lineContent);

		let fromColumn = 0;
		if (lastNonWhitespaceIndex === -1) {
			// Entire line is whitespace
			fromColumn = 1;
		} else if (lastNonWhitespaceIndex !== lineContent.length - 1) {
			// There is trailing whitespace
			fromColumn = lastNonWhitespaceIndex + 2;
		} else {
			// There is no trailing whitespace
			continue;
		}

		fromColumn = Math.max(minEditColumn, fromColumn);
		r[rLen++] = EditOperation.delete(new Range(
			lineNumber, fromColumn,
			lineNumber, maxLineColumn
		));
	}

	return r;
}