import SwiftSyntax extension SourceFileSyntax { func windowsOfThreeTokens() -> [(TokenSyntax, TokenSyntax, TokenSyntax)] { Array(tokens) .windows(ofCount: 3) .map { tokens in let previous = tokens[tokens.startIndex] let current = tokens[tokens.startIndex + 1] let next = tokens[tokens.startIndex + 2] return (previous, current, next) } } }