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merged 1 commit into from
Apr 16, 2019
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Scanner: Implement scanning for hexdecimal floating point numbers. #2111

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221 changes: 89 additions & 132 deletions Foundation/Scanner.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,6 @@
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//

import CoreFoundation

open class Scanner: NSObject, NSCopying {
internal var _scanString: String
Expand Down Expand Up @@ -286,199 +285,145 @@ internal struct _NSStringBuffer {
}
}

private func isADigit(_ ch: unichar) -> Bool {
struct Local {
static let set = CharacterSet.decimalDigits
}
return Local.set.contains(UnicodeScalar(ch)!)
}


private func numericValue(_ ch: unichar) -> Int {
if (ch >= unichar(unicodeScalarLiteral: "0") && ch <= unichar(unicodeScalarLiteral: "9")) {
return Int(ch) - Int(unichar(unicodeScalarLiteral: "0"))
} else {
return __CFCharDigitValue(UniChar(ch))
}
private func decimalValue(_ ch: unichar) -> Int? {
guard let s = UnicodeScalar(ch), s.isASCII else { return nil }
return Character(s).wholeNumberValue
}

private func numericOrHexValue(_ ch: unichar) -> Int {
if (ch >= unichar(unicodeScalarLiteral: "0") && ch <= unichar(unicodeScalarLiteral: "9")) {
return Int(ch) - Int(unichar(unicodeScalarLiteral: "0"))
} else if (ch >= unichar(unicodeScalarLiteral: "A") && ch <= unichar(unicodeScalarLiteral: "F")) {
return Int(ch) + 10 - Int(unichar(unicodeScalarLiteral: "A"))
} else if (ch >= unichar(unicodeScalarLiteral: "a") && ch <= unichar(unicodeScalarLiteral: "f")) {
return Int(ch) + 10 - Int(unichar(unicodeScalarLiteral: "a"))
} else {
return -1
}
private func decimalOrHexValue(_ ch: unichar) -> Int? {
guard let s = UnicodeScalar(ch), s.isASCII else { return nil }
return Character(s).hexDigitValue
}

private func decimalSep(_ locale: Locale?) -> String {
if let loc = locale {
if let sep = loc._bridgeToObjectiveC().object(forKey: .decimalSeparator) as? NSString {
return sep._swiftObject
}
return "."
} else {
return decimalSep(Locale.current)
}
}

extension String {
internal func scan<T: FixedWidthInteger>(_ skipSet: CharacterSet?, locationToScanFrom: inout Int, to: (T) -> Void) -> Bool {
var buf = _NSStringBuffer(string: self, start: locationToScanFrom, end: length)

private func checkForNegative(inBuffer buf: inout _NSStringBuffer, skipping skipSet: CharacterSet? = nil) -> Bool {
buf.skip(skipSet)
var neg = false
var localResult: T = 0
if buf.currentCharacter == unichar(unicodeScalarLiteral: "-") || buf.currentCharacter == unichar(unicodeScalarLiteral: "+") {
neg = buf.currentCharacter == unichar(unicodeScalarLiteral: "-")
let neg = buf.currentCharacter == unichar(unicodeScalarLiteral: "-")
buf.advance()
buf.skip(skipSet)
return neg
}
if (!isADigit(buf.currentCharacter)) {
return false
}
repeat {
let numeral = numericValue(buf.currentCharacter)
if numeral == -1 {
break
return false
}

// If a string starts: 0[xX]<Valid Hex Digits> return with the buffer pointing to the hex digits otherwise point to the start of buffer.
private func skipHexStart(inBuffer buf: inout _NSStringBuffer) {
let locRewindTo = buf.location
if buf.currentCharacter == unichar(unicodeScalarLiteral: "0") {
buf.advance()
if buf.currentCharacter == unichar(unicodeScalarLiteral: "x") || buf.currentCharacter == unichar(unicodeScalarLiteral: "X") {
buf.advance()
if decimalOrHexValue(buf.currentCharacter) != nil {
return
}
}
buf.location = locRewindTo
}
}

internal func scan<T: FixedWidthInteger>(_ skipSet: CharacterSet?, locationToScanFrom: inout Int, to: (T) -> Void) -> Bool {
var buf = _NSStringBuffer(string: self, start: locationToScanFrom, end: length)
var localResult: T = 0
var retval = false
var neg = checkForNegative(inBuffer: &buf, skipping: skipSet)

while let numeral = decimalValue(buf.currentCharacter) {
retval = true
if (localResult >= T.max / 10) && ((localResult > T.max / 10) || T(numeral - (neg ? 1 : 0)) >= T.max - localResult * 10) {
// apply the clamps and advance past the ending of the buffer where there are still digits
localResult = neg ? T.min : T.max
neg = false
repeat {
buf.advance()
} while (isADigit(buf.currentCharacter))
} while decimalValue(buf.currentCharacter) != nil
break
} else {
// normal case for scanning
localResult = localResult * 10 + T(numeral)
}
buf.advance()
} while (isADigit(buf.currentCharacter))
}
to(neg ? -1 * localResult : localResult)
locationToScanFrom = buf.location
return true
return retval
}

internal func scanHex<T: FixedWidthInteger>(_ skipSet: CharacterSet?, locationToScanFrom: inout Int, to: (T) -> Void) -> Bool {
var buf = _NSStringBuffer(string: self, start: locationToScanFrom, end: length)
buf.skip(skipSet)
var localResult: T = 0
var curDigit: Int
if buf.currentCharacter == unichar(unicodeScalarLiteral: "0") {
buf.advance()
let locRewindTo = buf.location
curDigit = numericOrHexValue(buf.currentCharacter)
if curDigit == -1 {
if buf.currentCharacter == unichar(unicodeScalarLiteral: "x") || buf.currentCharacter == unichar(unicodeScalarLiteral: "X") {
buf.advance()
curDigit = numericOrHexValue(buf.currentCharacter)
}
}
if curDigit == -1 {
locationToScanFrom = locRewindTo
to(T(0))
return true
}
} else {
curDigit = numericOrHexValue(buf.currentCharacter)
if curDigit == -1 {
return false
}
}

repeat {
var retval = false
buf.skip(skipSet)
skipHexStart(inBuffer: &buf)

while let numeral = decimalOrHexValue(buf.currentCharacter) {
retval = true
if localResult > T.max >> T(4) {
localResult = T.max
} else {
localResult = (localResult << T(4)) + T(curDigit)
localResult = (localResult << T(4)) + T(numeral)
}
buf.advance()
curDigit = numericOrHexValue(buf.currentCharacter)
} while (curDigit != -1)

}

to(localResult)
locationToScanFrom = buf.location
return true
return retval
}

internal func scan<T: BinaryFloatingPoint>(_ skipSet: CharacterSet?, locale: Locale?, locationToScanFrom: inout Int, to: (T) -> Void) -> Bool {
let ds_chars = decimalSep(locale).utf16
let ds = ds_chars[ds_chars.startIndex]
var buf = _NSStringBuffer(string: self, start: locationToScanFrom, end: length)
buf.skip(skipSet)
var neg = false
private func _scan<T: BinaryFloatingPoint>(buffer buf: inout _NSStringBuffer, locale: Locale?, neg: Bool, to: (T) -> Void, base: UInt,
numericValue: ((_: unichar) -> Int?)) -> Bool {
let ds = (locale ?? Locale.current).decimalSeparator?.first ?? Character(".")
var localResult: T = T(0)

if buf.currentCharacter == unichar(unicodeScalarLiteral: "-") || buf.currentCharacter == unichar(unicodeScalarLiteral: "+") {
neg = buf.currentCharacter == unichar(unicodeScalarLiteral: "-")
buf.advance()
buf.skip(skipSet)
}
if (buf.currentCharacter != ds && !isADigit(buf.currentCharacter)) {
return false
}

repeat {
let numeral = numericValue(buf.currentCharacter)
if numeral == -1 {
break
}
var neg = neg

while let numeral = numericValue(buf.currentCharacter) {
// if (localResult >= T.greatestFiniteMagnitude / T(10)) && ((localResult > T.greatestFiniteMagnitude / T(10)) || T(numericValue(buf.currentCharacter) - (neg ? 1 : 0)) >= T.greatestFiniteMagnitude - localResult * T(10)) is evidently too complex; so break it down to more "edible chunks"
let limit1 = localResult >= T.greatestFiniteMagnitude / T(10)
let limit2 = localResult > T.greatestFiniteMagnitude / T(10)
let limit3 = T(numeral - (neg ? 1 : 0)) >= T.greatestFiniteMagnitude - localResult * T(10)
let limit1 = localResult >= T.greatestFiniteMagnitude / T(base)
let limit2 = localResult > T.greatestFiniteMagnitude / T(base)
let limit3 = T(numeral - (neg ? 1 : 0)) >= T.greatestFiniteMagnitude - localResult * T(base)
if (limit1) && (limit2 || limit3) {
// apply the clamps and advance past the ending of the buffer where there are still digits
localResult = neg ? -T.infinity : T.infinity
neg = false
repeat {
buf.advance()
} while (isADigit(buf.currentCharacter))
} while numericValue(buf.currentCharacter) != nil
break
} else {
localResult = localResult * T(10) + T(numeral)
localResult = localResult * T(base) + T(numeral)
}
buf.advance()
} while (isADigit(buf.currentCharacter))
}

if buf.currentCharacter == ds {
var factor = T(0.1)
if let us = UnicodeScalar(buf.currentCharacter), Character(us) == ds {
var factor = 1 / T(base)
buf.advance()
repeat {
let numeral = numericValue(buf.currentCharacter)
if numeral == -1 {
break
}
while let numeral = numericValue(buf.currentCharacter) {
localResult = localResult + T(numeral) * factor
factor = factor * T(0.1)
factor = factor / T(base)
buf.advance()
} while (isADigit(buf.currentCharacter))
}
}

// If this is used to parse a number in Hexadecimal, this will never be true as the 'e' or 'E' will be caught by the previous loop.
if buf.currentCharacter == unichar(unicodeScalarLiteral: "e") || buf.currentCharacter == unichar(unicodeScalarLiteral: "E") {
var exponent = Double(0)
var negExponent = false

buf.advance()
if buf.currentCharacter == unichar(unicodeScalarLiteral: "-") || buf.currentCharacter == unichar(unicodeScalarLiteral: "+") {
negExponent = buf.currentCharacter == unichar(unicodeScalarLiteral: "-")
buf.advance()
}
repeat {
let numeral = numericValue(buf.currentCharacter)
let negExponent = checkForNegative(inBuffer: &buf)

while let numeral = numericValue(buf.currentCharacter) {
buf.advance()
if numeral == -1 {
break
}
exponent *= 10
exponent *= Double(base)
exponent += Double(numeral)
} while (isADigit(buf.currentCharacter))
}

if exponent > 0 {
let multiplier = pow(10, exponent)
let multiplier = pow(Double(base), exponent)
if negExponent {
localResult /= T(multiplier)
} else {
Expand All @@ -488,12 +433,24 @@ extension String {
}

to(neg ? T(-1) * localResult : localResult)
locationToScanFrom = buf.location
return true
}


internal func scan<T: BinaryFloatingPoint>(_ skipSet: CharacterSet?, locale: Locale?, locationToScanFrom: inout Int, to: (T) -> Void) -> Bool {
var buf = _NSStringBuffer(string: self, start: locationToScanFrom, end: length)
let neg = checkForNegative(inBuffer: &buf, skipping: skipSet)
let result = _scan(buffer: &buf, locale: locale, neg: neg, to: to, base: 10, numericValue: decimalValue)
locationToScanFrom = buf.location
return result
}

internal func scanHex<T: BinaryFloatingPoint>(_ skipSet: CharacterSet?, locale: Locale?, locationToScanFrom: inout Int, to: (T) -> Void) -> Bool {
NSUnimplemented()
var buf = _NSStringBuffer(string: self, start: locationToScanFrom, end: length)
let neg = checkForNegative(inBuffer: &buf, skipping: skipSet)
skipHexStart(inBuffer: &buf)
let result = _scan(buffer: &buf, locale: locale, neg: neg, to: to, base: 16, numericValue: decimalOrHexValue)
locationToScanFrom = buf.location
return result
}
}

Expand Down
18 changes: 18 additions & 0 deletions TestFoundation/TestScanner.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -111,6 +111,23 @@ class TestScanner : XCTestCase {
expectTrue($0.isAtEnd, "The X was not consumed")
}
}

func testHexFloatingPoint() {
withScanner(for: "0xAA 3.14 0.1x 1g 3xx .F00x 1e00 -0xabcdef.02") {
expectEqual($0.scanDouble(representation: .hexadecimal), 0xAA, "Integer as Double")
expectEqual($0.scanDouble(representation: .hexadecimal), 3.078125, "Double")
expectEqual($0.scanDouble(representation: .hexadecimal), 0.0625, "Double")
expectEqual($0.scanString("x"), "x", "Consume non-hex-digit")
expectEqual($0.scanDouble(representation: .hexadecimal), Double(1), "Double")
expectEqual($0.scanString("g"), "g", "Consume non-hex-digit")
expectEqual($0.scanDouble(representation: .hexadecimal), Double(3), "Double")
expectEqual($0.scanString("xx"), "xx", "Consume non-hex-digits")
expectEqual($0.scanDouble(representation: .hexadecimal), 0.9375, "Double")
expectEqual($0.scanString("x"), "x", "Consume non-hex-digit")
expectEqual($0.scanDouble(representation: .hexadecimal), 0x1E00, "E is not for exponent")
expectEqual($0.scanDouble(representation: .hexadecimal), -11259375.0078125, "negative decimal")
}
}

func testUInt64() {
// UInt64 long sequence:
Expand Down Expand Up @@ -472,6 +489,7 @@ class TestScanner : XCTestCase {
return [
("testScanFloatingPoint", testScanFloatingPoint),
("testHexRepresentation", testHexRepresentation),
("testHexFloatingPoint", testHexFloatingPoint),
("testUInt64", testUInt64),
("testInt64", testInt64),
("testInt32", testInt32),
Expand Down