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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 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
//
//===----------------------------------------------------------------------===//
@inline(__always)
internal func _asciiDigit<CodeUnit : UnsignedInteger, Result : BinaryInteger>(
codeUnit u_: CodeUnit, radix: Result
) -> Result? {
let digit = _ascii16("0")..._ascii16("9")
let lower = _ascii16("a")..._ascii16("z")
let upper = _ascii16("A")..._ascii16("Z")
let u = UInt16(truncatingIfNeeded: u_)
let d: UInt16
if _fastPath(digit ~= u) { d = u &- digit.lowerBound }
else if _fastPath(upper ~= u) { d = u &- upper.lowerBound &+ 10 }
else if _fastPath(lower ~= u) { d = u &- lower.lowerBound &+ 10 }
else { return nil }
guard _fastPath(d < radix) else { return nil }
return Result(truncatingIfNeeded: d)
}
@inline(__always)
internal func _parseUnsignedASCII<
Rest : IteratorProtocol, Result: FixedWidthInteger
>(
first: Rest.Element, rest: inout Rest, radix: Result, positive: Bool
) -> Result?
where Rest.Element : UnsignedInteger {
let r0 = _asciiDigit(codeUnit: first, radix: radix)
guard _fastPath(r0 != nil), var result = r0 else { return nil }
if !positive {
let (result0, overflow0)
= (0 as Result).subtractingReportingOverflow(result)
guard _fastPath(!overflow0) else { return nil }
result = result0
}
while let u = rest.next() {
let d0 = _asciiDigit(codeUnit: u, radix: radix)
guard _fastPath(d0 != nil), let d = d0 else { return nil }
let (result1, overflow1) = result.multipliedReportingOverflow(by: radix)
let (result2, overflow2) = positive
? result1.addingReportingOverflow(d)
: result1.subtractingReportingOverflow(d)
guard _fastPath(!overflow1 && !overflow2)
else { return nil }
result = result2
}
return result
}
@inline(__always)
internal func _parseASCII<
CodeUnits : IteratorProtocol, Result: FixedWidthInteger
>(
codeUnits: inout CodeUnits, radix: Result
) -> Result?
where CodeUnits.Element : UnsignedInteger {
let c0_ = codeUnits.next()
guard _fastPath(c0_ != nil), let c0 = c0_ else { return nil }
if _fastPath(c0 != _ascii16("+") && c0 != _ascii16("-")) {
return _parseUnsignedASCII(
first: c0, rest: &codeUnits, radix: radix, positive: true)
}
let c1_ = codeUnits.next()
guard _fastPath(c1_ != nil), let c1 = c1_ else { return nil }
if _fastPath(c0 == _ascii16("-")) {
return _parseUnsignedASCII(
first: c1, rest: &codeUnits, radix: radix, positive: false)
}
else {
return _parseUnsignedASCII(
first: c1, rest: &codeUnits, radix: radix, positive: true)
}
}
extension FixedWidthInteger {
// _parseASCII function thunk that prevents inlining used as an implementation
// detail for FixedWidthInteger.init(_: radix:) on the slow path to save code
// size.
@_semantics("optimize.sil.specialize.generic.partial.never")
@inline(never)
internal static func _parseASCIISlowPath<
CodeUnits : IteratorProtocol, Result: FixedWidthInteger
>(
codeUnits: inout CodeUnits, radix: Result
) -> Result?
where CodeUnits.Element : UnsignedInteger {
return _parseASCII(codeUnits: &codeUnits, radix: radix)
}
/// Creates a new integer value from the given string and radix.
///
/// The string passed as `text` may begin with a plus or minus sign character
/// (`+` or `-`), followed by one or more numeric digits (`0-9`) or letters
/// (`a-z` or `A-Z`). The string is case insensitive.
///
/// let x = Int("123")
/// // x == 123
///
/// let y = Int("-123", radix: 8)
/// // y == -83
/// let y = Int("+123", radix: 8)
/// // y == +83
///
/// let z = Int("07b", radix: 16)
/// // z == 123
///
/// If `text` is in an invalid format or contains characters that are out of
/// range for the given `radix`, or if the value it denotes in the given
/// `radix` is not representable, the result is `nil`. For example, the
/// following conversions result in `nil`:
///
/// Int(" 100") // Includes whitespace
/// Int("21-50") // Invalid format
/// Int("ff6600") // Characters out of bounds
/// Int("zzzzzzzzzzzzz", radix: 36) // Out of range
///
/// - Parameters:
/// - text: The ASCII representation of a number in the radix passed as
/// `radix`.
/// - radix: The radix, or base, to use for converting `text` to an integer
/// value. `radix` must be in the range `2...36`. The default is 10.
@_semantics("optimize.sil.specialize.generic.partial.never")
public init?<S : StringProtocol>(_ text: S, radix: Int = 10) {
_precondition(2...36 ~= radix, "Radix not in range 2...36")
let r = Self(radix)
let s = text._ephemeralString
defer { _fixLifetime(s) }
let c = s._core
let result: Self?
if _slowPath(c._baseAddress == nil) {
var i = s.utf16.makeIterator()
result = Self._parseASCIISlowPath(codeUnits: &i, radix: r)
}
else if _fastPath(c.elementWidth == 1), let a = c.asciiBuffer {
var i = a.makeIterator()
result = _parseASCII(codeUnits: &i, radix: r)
}
else {
let b = UnsafeBufferPointer(start: c.startUTF16, count: c.count)
var i = b.makeIterator()
result = Self._parseASCIISlowPath(codeUnits: &i, radix: r)
}
guard _fastPath(result != nil) else { return nil }
self = result!
}
}