Swift script helper to find and replace an array of substitutions.

FindReplace.swift

/// Performs a textual find and replace with the specified substitutions on all files in directory (recursive) that have the specified filename extensions.
func find(_ substitutions: [(find: String, replace: String)], allowedExtensions: Set<String>, directory rootURL: URL) {
    let fileURLs = FileManager.default.enumerator(at: rootURL, includingPropertiesForKeys: nil)!.map {
        $0 as! URL
    }
    .filter {
        $0.hasDirectoryPath == false
    }
    .filter {
        allowedExtensions.contains($0.pathExtension)
    }

    for url in fileURLs {
        var encoding = String.Encoding.japaneseEUC
        let contents = try! String(contentsOf: url, usedEncoding: &encoding)

        let modifiedContents = substitutions.reduce(contents) { contents, substitution -> String in
            contents.replacingOccurrences(of: substitution.find, with: substitution.replace)
        }

        if modifiedContents != contents {
            try! modifiedContents.write(to: url, atomically: false, encoding: encoding)
        }
    }
}