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31d6f95452
In answering a forum post I noiced that I wanted this and it was missing. Also, extensive comments Also, rename the length: init parameter to count:. When writing the comments for the init function it became painfully clear why we use "count" is better than "length" especially around pointers and memory: the former is much less easy to mistake for "length in bytes". Plus it's consistent with the new ".count" property Swift SVN r20609
73 lines
2.6 KiB
Swift
73 lines
2.6 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 - 2015 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 http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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// String interop with C
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//===----------------------------------------------------------------------===//
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@asmname("strlen")
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func _strlen(arg : UnsafePointer<CChar>) -> Int
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@asmname("strcpy")
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func _strcpy(dest: UnsafePointer<CChar>, src: UnsafePointer<CChar>)
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-> UnsafePointer<CChar>
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@asmname("strcmp")
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func _strcmp(dest: UnsafePointer<CChar>, src: UnsafePointer<CChar>)
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-> CInt
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extension String {
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/// Creates a new `String` by copying the nul-terminated UTF-8 data
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/// referenced by a `CString`.
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///
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/// Returns `nil` if the `CString` is `NULL` or if it contains ill-formed
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/// UTF-8 code unit sequences.
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public static func fromCString(cs: UnsafePointer<CChar>) -> String? {
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if cs._isNull {
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return .None
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}
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let len = Int(_strlen(cs))
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return String._fromCodeUnitSequence(UTF8.self,
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input: UnsafeBufferPointer(start: UnsafeMutablePointer(cs), count: len))
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}
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/// Creates a new `String` by copying the nul-terminated UTF-8 data
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/// referenced by a `CString`.
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///
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/// Returns `nil` if the `CString` is `NULL`. If `CString` contains
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/// ill-formed UTF-8 code unit sequences, replaces them with replacement
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/// characters (U+FFFD).
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public static func fromCStringRepairingIllFormedUTF8(
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cs: UnsafePointer<CChar>)
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-> (String?, hadError: Bool) {
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if cs._isNull {
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return (.None, hadError: false)
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}
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let len = Int(_strlen(cs))
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let (result, hadError) = String._fromCodeUnitSequenceWithRepair(UTF8.self,
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input: UnsafeBufferPointer(start: UnsafeMutablePointer(cs), count: len))
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return (result, hadError: hadError)
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}
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}
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/// From a non-`nil` `UnsafePointer` to a null-terminated string
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/// with possibly-transient lifetime, create a nul-terminated array of 'C' char.
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/// Returns `nil` if passed a null pointer.
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public func _persistCString(s: UnsafePointer<CChar>) -> [CChar]? {
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if s == nil {
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return .None
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}
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var length = _strlen(s)
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var result = [CChar](count: length + 1, repeatedValue: 0)
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for var i = 0; i < length; ++i {
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// FIXME: this will not compile on platforms where 'CChar' is unsigned.
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result[i] = s[i]
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}
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return result
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}
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