mirror of
https://github.com/apple/swift.git
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265 lines
9.6 KiB
Swift
265 lines
9.6 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 - 2021 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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@_alwaysEmitIntoClient
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internal func _parseIntegerDigits<Result: FixedWidthInteger>(
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ascii codeUnits: UnsafeBufferPointer<UInt8>, radix: Int, isNegative: Bool
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) -> Result? {
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_internalInvariant(radix >= 2 && radix <= 36)
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guard _fastPath(!codeUnits.isEmpty) else { return nil }
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// ASCII constants, named for clarity:
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let _0 = 48 as UInt8, _A = 65 as UInt8, _a = 97 as UInt8
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let numericalUpperBound: UInt8
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let uppercaseUpperBound: UInt8
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let lowercaseUpperBound: UInt8
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if radix <= 10 {
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numericalUpperBound = _0 &+ UInt8(truncatingIfNeeded: radix)
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uppercaseUpperBound = _A
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lowercaseUpperBound = _a
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} else {
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numericalUpperBound = _0 &+ 10
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uppercaseUpperBound = _A &+ UInt8(truncatingIfNeeded: radix &- 10)
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lowercaseUpperBound = _a &+ UInt8(truncatingIfNeeded: radix &- 10)
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}
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let multiplicand = Result(truncatingIfNeeded: radix)
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var result = 0 as Result
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for digit in codeUnits {
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let digitValue: Result
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if _fastPath(digit >= _0 && digit < numericalUpperBound) {
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digitValue = Result(truncatingIfNeeded: digit &- _0)
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} else if _fastPath(digit >= _A && digit < uppercaseUpperBound) {
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digitValue = Result(truncatingIfNeeded: digit &- _A &+ 10)
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} else if _fastPath(digit >= _a && digit < lowercaseUpperBound) {
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digitValue = Result(truncatingIfNeeded: digit &- _a &+ 10)
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} else {
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return nil
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}
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let overflow1: Bool
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(result, overflow1) = result.multipliedReportingOverflow(by: multiplicand)
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let overflow2: Bool
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(result, overflow2) = isNegative
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? result.subtractingReportingOverflow(digitValue)
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: result.addingReportingOverflow(digitValue)
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guard _fastPath(!overflow1 && !overflow2) else { return nil }
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}
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return result
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}
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@_alwaysEmitIntoClient
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internal func _parseInteger<Result: FixedWidthInteger>(
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ascii codeUnits: UnsafeBufferPointer<UInt8>, radix: Int
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) -> Result? {
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_internalInvariant(!codeUnits.isEmpty)
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// ASCII constants, named for clarity:
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let _plus = 43 as UInt8, _minus = 45 as UInt8
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let first = codeUnits[0]
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if first == _minus {
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return _parseIntegerDigits(
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ascii: UnsafeBufferPointer(rebasing: codeUnits[1...]),
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radix: radix, isNegative: true)
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}
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if first == _plus {
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return _parseIntegerDigits(
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ascii: UnsafeBufferPointer(rebasing: codeUnits[1...]),
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radix: radix, isNegative: false)
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}
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return _parseIntegerDigits(ascii: codeUnits, radix: radix, isNegative: false)
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}
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@_alwaysEmitIntoClient
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@inline(never)
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internal func _parseInteger<S: StringProtocol, Result: FixedWidthInteger>(
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ascii text: S, radix: Int
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) -> Result? {
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var str = String(text)
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return str.withUTF8 { _parseInteger(ascii: $0, radix: radix) }
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}
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extension FixedWidthInteger {
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/// Creates a new integer value from the given string and radix.
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///
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/// The string passed as `text` may begin with a plus or minus sign character
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/// (`+` or `-`), followed by one or more numeric digits (`0-9`) or letters
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/// (`a-z` or `A-Z`). Parsing of the string is case insensitive.
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///
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/// let x = Int("123")
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/// // x == 123
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///
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/// let y = Int("-123", radix: 8)
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/// // y == -83
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/// let y = Int("+123", radix: 8)
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/// // y == +83
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///
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/// let z = Int("07b", radix: 16)
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/// // z == 123
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///
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/// If `text` is in an invalid format or contains characters that are out of
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/// bounds for the given `radix`, or if the value it denotes in the given
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/// `radix` is not representable, the result is `nil`. For example, the
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/// following conversions result in `nil`:
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///
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/// Int(" 100") // Includes whitespace
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/// Int("21-50") // Invalid format
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/// Int("ff6600") // Characters out of bounds
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/// Int("zzzzzzzzzzzzz", radix: 36) // Out of range
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///
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/// - Parameters:
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/// - text: The ASCII representation of a number in the radix passed as
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/// `radix`.
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/// - radix: The radix, or base, to use for converting `text` to an integer
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/// value. `radix` must be in the range `2...36`. The default is 10.
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@inlinable
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@inline(__always)
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public init?<S: StringProtocol>(_ text: S, radix: Int = 10) {
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_precondition(2...36 ~= radix, "Radix not in range 2...36")
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guard _fastPath(!text.isEmpty) else { return nil }
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let result: Self? =
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text.utf8.withContiguousStorageIfAvailable {
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_parseInteger(ascii: $0, radix: radix)
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} ?? _parseInteger(ascii: text, radix: radix)
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guard let result_ = result else { return nil }
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self = result_
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}
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/// Creates a new integer value from the given string.
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///
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/// The string passed as `description` may begin with a plus or minus sign
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/// character (`+` or `-`), followed by one or more numeric digits (`0-9`).
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///
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/// let x = Int("123")
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/// // x == 123
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///
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/// If `description` is in an invalid format, or if the value it denotes in
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/// base 10 is not representable, the result is `nil`. For example, the
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/// following conversions result in `nil`:
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///
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/// Int(" 100") // Includes whitespace
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/// Int("21-50") // Invalid format
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/// Int("ff6600") // Characters out of bounds
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/// Int("10000000000000000000000000") // Out of range
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///
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/// - Parameter description: The ASCII representation of a number.
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@inlinable
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@inline(__always)
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public init?(_ description: String) {
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self.init(description, radix: 10)
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}
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}
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//===----------------------------------------------------------------------===//
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// Old entry points preserved for ABI compatibility.
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//===----------------------------------------------------------------------===//
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/// Returns c as a UTF16.CodeUnit. Meant to be used as _ascii16("x").
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@usableFromInline // Previously '@inlinable'.
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internal func _ascii16(_ c: Unicode.Scalar) -> UTF16.CodeUnit {
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_internalInvariant(c.value >= 0 && c.value <= 0x7F, "not ASCII")
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return UTF16.CodeUnit(c.value)
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}
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@usableFromInline // Previously '@inlinable @inline(__always)'.
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internal func _asciiDigit<CodeUnit: UnsignedInteger, Result: BinaryInteger>(
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codeUnit u_: CodeUnit, radix: Result
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) -> Result? {
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let digit = _ascii16("0")..._ascii16("9")
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let lower = _ascii16("a")..._ascii16("z")
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let upper = _ascii16("A")..._ascii16("Z")
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let u = UInt16(truncatingIfNeeded: u_)
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let d: UInt16
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if _fastPath(digit ~= u) { d = u &- digit.lowerBound }
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else if _fastPath(upper ~= u) { d = u &- upper.lowerBound &+ 10 }
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else if _fastPath(lower ~= u) { d = u &- lower.lowerBound &+ 10 }
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else { return nil }
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guard _fastPath(d < radix) else { return nil }
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return Result(truncatingIfNeeded: d)
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}
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@usableFromInline // Previously '@inlinable @inline(__always)'.
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internal func _parseUnsignedASCII<
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Rest: IteratorProtocol, Result: FixedWidthInteger
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>(
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first: Rest.Element, rest: inout Rest, radix: Result, positive: Bool
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) -> Result?
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where Rest.Element: UnsignedInteger {
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let r0 = _asciiDigit(codeUnit: first, radix: radix)
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guard _fastPath(r0 != nil), var result = r0 else { return nil }
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if !positive {
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let (result0, overflow0)
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= (0 as Result).subtractingReportingOverflow(result)
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guard _fastPath(!overflow0) else { return nil }
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result = result0
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}
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while let u = rest.next() {
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let d0 = _asciiDigit(codeUnit: u, radix: radix)
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guard _fastPath(d0 != nil), let d = d0 else { return nil }
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let (result1, overflow1) = result.multipliedReportingOverflow(by: radix)
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let (result2, overflow2) = positive
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? result1.addingReportingOverflow(d)
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: result1.subtractingReportingOverflow(d)
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guard _fastPath(!overflow1 && !overflow2)
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else { return nil }
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result = result2
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}
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return result
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}
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// This function has been superseded because it is about 20KB of previously
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// always-inline code, most of which are MOV instructions.
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@usableFromInline // Previously '@inlinable @inline(__always)'.
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internal func _parseASCII<
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CodeUnits: IteratorProtocol, Result: FixedWidthInteger
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>(
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codeUnits: inout CodeUnits, radix: Result
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) -> Result?
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where CodeUnits.Element: UnsignedInteger {
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let c0_ = codeUnits.next()
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guard _fastPath(c0_ != nil), let c0 = c0_ else { return nil }
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if _fastPath(c0 != _ascii16("+") && c0 != _ascii16("-")) {
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return _parseUnsignedASCII(
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first: c0, rest: &codeUnits, radix: radix, positive: true)
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}
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let c1_ = codeUnits.next()
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guard _fastPath(c1_ != nil), let c1 = c1_ else { return nil }
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if _fastPath(c0 == _ascii16("-")) {
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return _parseUnsignedASCII(
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first: c1, rest: &codeUnits, radix: radix, positive: false)
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}
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else {
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return _parseUnsignedASCII(
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first: c1, rest: &codeUnits, radix: radix, positive: true)
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}
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}
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extension FixedWidthInteger {
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// _parseASCII function thunk that prevents inlining used as an implementation
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// detail for FixedWidthInteger.init(_: radix:) on the slow path to save code
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// size.
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@_semantics("optimize.sil.specialize.generic.partial.never")
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@inline(never)
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@usableFromInline
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internal static func _parseASCIISlowPath<
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CodeUnits: IteratorProtocol, Result: FixedWidthInteger
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>(
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codeUnits: inout CodeUnits, radix: Result
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) -> Result?
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where CodeUnits.Element: UnsignedInteger {
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return _parseASCII(codeUnits: &codeUnits, radix: radix)
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}
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}
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