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//===----------------------------------------------------------*- swift -*-===//
//
// This source file is part of the Swift Argument Parser open source project
//
// Copyright (c) 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
import ArgumentParser
import Foundation
@main
@available(macOS 12, *)
struct CountLines: AsyncParsableCommand {
@Argument(
help: "A file to count lines in. If omitted, counts the lines of stdin.",
completion: .file(), transform: URL.init(fileURLWithPath:))
var inputFile: URL? = nil
@Option(help: "Only count lines with this prefix.")
var prefix: String? = nil
@Flag(help: "Include extra information in the output.")
var verbose = false
}
@available(macOS 12, *)
extension CountLines {
var fileHandle: FileHandle {
get throws {
guard let inputFile = inputFile else {
return .standardInput
}
return try FileHandle(forReadingFrom: inputFile)
}
}
func printCount(_ count: Int) {
guard verbose else {
print(count)
return
}
if let filename = inputFile?.lastPathComponent {
print("Lines in '\(filename)'", terminator: "")
} else {
print("Lines from stdin", terminator: "")
}
if let prefix = prefix {
print(", prefixed by '\(prefix)'", terminator: "")
}
print(": \(count)")
}
mutating func run() async throws {
let countAllLines = prefix == nil
let lineCount = try await fileHandle.bytes.lines.reduce(0) { count, line in
if countAllLines || line.starts(with: prefix!) {
return count + 1
} else {
return count
}
}
printCount(lineCount)
}
}
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