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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2018 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
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
// TODO(String performance): Unfortunately, this slice struct seems to add
// overhead. We may want to wean ourselves off of this and have all users just
// also store a range.
// A sliced _StringGuts, convenient for unifying String/Substring comparison,
// hashing, and RRC.
internal struct _StringGutsSlice {
internal var _guts: _StringGuts
internal var _offsetRange: Range<Int>
@inline(__always)
internal init(_ guts: _StringGuts) {
self._guts = guts
self._offsetRange = Range(_uncheckedBounds: (0, guts.count))
}
@inline(__always)
internal init(_ guts: _StringGuts, _ offsetRange: Range<Int>) {
_internalInvariant(
offsetRange.lowerBound >= 0 && offsetRange.upperBound <= guts.count)
self._guts = guts
self._offsetRange = offsetRange
}
internal var start: Int {
@inline(__always) get { return _offsetRange.lowerBound }
}
internal var end: Int {
@inline(__always) get { return _offsetRange.upperBound }
}
internal var count: Int {
@inline(__always) get { return _offsetRange.count }
}
internal var isNFCFastUTF8: Bool {
@inline(__always) get { return _guts.isNFCFastUTF8 }
}
internal var isASCII: Bool {
@inline(__always) get { return _guts.isASCII }
}
internal var isFastUTF8: Bool {
@inline(__always) get { return _guts.isFastUTF8 }
}
internal var utf8Count: Int {
@inline(__always) get {
if _fastPath(self.isFastUTF8) {
return _offsetRange.count
}
return Substring(self).utf8.count
}
}
internal var range: Range<String.Index> {
@inline(__always) get {
let lower = String.Index(_encodedOffset: _offsetRange.lowerBound)
._scalarAligned
let higher = String.Index(_encodedOffset: _offsetRange.upperBound)
._scalarAligned
return Range(_uncheckedBounds: (lower, higher))
}
}
@inline(__always)
internal func withFastUTF8<R>(
_ f: (UnsafeBufferPointer<UInt8>) throws -> R
) rethrows -> R {
return try _guts.withFastUTF8(range: _offsetRange, f)
}
@_effects(releasenone)
internal func foreignErrorCorrectedScalar(
startingAt idx: String.Index
) -> (Unicode.Scalar, scalarLength: Int) {
let (scalar, len) = _guts.foreignErrorCorrectedScalar(startingAt: idx)
if _slowPath(idx.encoded(offsetBy: len) > range.upperBound) {
return (Unicode.Scalar._replacementCharacter, 1)
}
return (scalar, len)
}
}
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