mirror of
https://github.com/apple/swift.git
synced 2026-06-20 15:42:51 +02:00
Doug Gregor
75 lines
2.5 KiB
Swift
75 lines
2.5 KiB
Swift
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import SwiftShims
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#if SWIFT_STDLIB_HAS_STDIN
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/// Returns a string read from standard input through the end of the current
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/// line or until EOF is reached.
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///
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/// Standard input is interpreted as `UTF-8`. Invalid bytes are replaced by
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/// Unicode [replacement characters][rc].
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///
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/// [rc]:
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/// https://unicode.org/glossary/#replacement_character
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///
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/// - Parameter strippingNewline: If `true`, newline characters and character
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/// combinations are stripped from the result; otherwise, newline characters
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/// or character combinations are preserved. The default is `true`.
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/// - Returns: The string of characters read from standard input. If EOF has
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/// already been reached when `readLine()` is called, the result is `nil`.
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public func readLine(strippingNewline: Bool = true) -> String? {
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var utf8Start: UnsafeMutablePointer<UInt8>?
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let utf8Count = unsafe swift_stdlib_readLine_stdin(&utf8Start)
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defer {
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unsafe _swift_stdlib_free(utf8Start)
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}
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guard utf8Count > 0 else {
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return nil
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}
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let utf8Buffer = unsafe UnsafeBufferPointer(start: utf8Start, count: utf8Count)
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var result = unsafe String._fromUTF8Repairing(utf8Buffer).result
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if strippingNewline {
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result.removeNewline()
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}
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return result
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}
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extension String {
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/// Remove the newline from the string
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fileprivate mutating func removeNewline() {
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var scalars = unicodeScalars[...]
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// If the last character is not "\n", there's nothing to do.
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let newline: UnicodeScalar = "\n"
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guard let lastNewline = scalars.last, lastNewline == newline else {
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return
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}
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// Drop the "\n".
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scalars = scalars.dropLast()
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// Now remove "\r" if it's also there.
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let carriageReturn: UnicodeScalar = "\r"
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if let lastCR = scalars.last, lastCR == carriageReturn {
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// Drop the "\rn".
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scalars = scalars.dropLast()
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}
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// Remove from the end of the adjusted scalars to the end of this string.
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_guts.remove(from: scalars.endIndex, to: endIndex)
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}
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}
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#endif
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