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Scanner: When parsing floating point, use appropiate initialiser. #2820

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Merged
merged 1 commit into from
Jun 13, 2020
Merged

Scanner: When parsing floating point, use appropiate initialiser. #2820

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140 changes: 78 additions & 62 deletions Sources/Foundation/Scanner.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -377,90 +377,106 @@ extension String {
locationToScanFrom = buf.location
return retval
}
private func _scan<T: BinaryFloatingPoint>(buffer buf: inout _NSStringBuffer, locale: Locale?, neg: Bool, to: (T) -> Void, base: UInt,
numericValue: ((_: unichar) -> Int?)) -> Bool {

internal func scan<T: BinaryFloatingPoint & LosslessStringConvertible>(_ skipSet: CharacterSet?, locale: Locale?, locationToScanFrom: inout Int, to: (T) -> Void) -> Bool {
var buf = _NSStringBuffer(string: self, start: locationToScanFrom, end: length)
let ds = (locale ?? Locale.current).decimalSeparator?.first ?? Character(".")
var localResult: T! = nil
var neg = neg

while let numeral = numericValue(buf.currentCharacter) {
localResult = localResult ?? T(0)
// 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(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 numericValue(buf.currentCharacter) != nil
break
} else {
localResult = localResult * T(base) + T(numeral)
func nextDigit() -> Character? {
if let s = UnicodeScalar(buf.currentCharacter) {
let ch = Character(s)
if ch.isASCII && ch.isWholeNumber {
return ch
}
}
return nil
}

var hasValidCharacter = false
var stringToParse = checkForNegative(inBuffer: &buf, skipping: skipSet) ? "-" : ""

while let ch = nextDigit() {
hasValidCharacter = true
stringToParse.append(ch)
buf.advance()
}

if let us = UnicodeScalar(buf.currentCharacter), Character(us) == ds {
var factor = 1 / T(base)
stringToParse += "."
buf.advance()
while let numeral = numericValue(buf.currentCharacter) {
localResult = localResult ?? T(0)
localResult = localResult + T(numeral) * factor
factor = factor / T(base)
while let ch = nextDigit() {
hasValidCharacter = true
stringToParse.append(ch)
buf.advance()
}
}
guard hasValidCharacter else { return false }

guard localResult != nil else {
return false
}

// 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)

hasValidCharacter = false
stringToParse += "e"
buf.advance()
let negExponent = checkForNegative(inBuffer: &buf)

while let numeral = numericValue(buf.currentCharacter) {
buf.advance()
exponent *= Double(base)
exponent += Double(numeral)
if checkForNegative(inBuffer: &buf) {
stringToParse += "-"
}

if exponent > 0 {
let multiplier = pow(Double(base), exponent)
if negExponent {
localResult /= T(multiplier)
} else {
localResult *= T(multiplier)
}
while let ch = nextDigit() {
hasValidCharacter = true
stringToParse.append(ch)
buf.advance()
}
}
guard hasValidCharacter else { return false }

to(neg ? T(-1) * localResult : localResult)
return true
if let value = T(stringToParse) {
to(value)
locationToScanFrom = buf.location
return true
} else {
return false
}
}

internal func scan<T: BinaryFloatingPoint>(_ skipSet: CharacterSet?, locale: Locale?, locationToScanFrom: inout Int, to: (T) -> Void) -> Bool {
internal func scanHex<T: BinaryFloatingPoint & LosslessStringConvertible>(_ 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
}
let ds = (locale ?? Locale.current).decimalSeparator?.first ?? Character(".")

internal func scanHex<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)
func nextHexDigit() -> Character? {
if let s = UnicodeScalar(buf.currentCharacter), let ascii = Character(s).asciiValue {
switch ascii {
case 0x30...0x39, 0x41...0x46, 0x61...0x66: return Character(s)
default: return nil
}
} else {
return nil
}
}

var hasValidCharacter = false
var stringToParse = checkForNegative(inBuffer: &buf, skipping: skipSet) ? "-0x" : "0x"
skipHexStart(inBuffer: &buf)
let result = _scan(buffer: &buf, locale: locale, neg: neg, to: to, base: 16, numericValue: decimalOrHexValue)
locationToScanFrom = buf.location
return result

while let ch = nextHexDigit() {
hasValidCharacter = true
stringToParse.append(ch)
buf.advance()
}
if let us = UnicodeScalar(buf.currentCharacter), Character(us) == ds {
stringToParse += "."
buf.advance()
while let ch = nextHexDigit() {
hasValidCharacter = true
stringToParse.append(ch)
buf.advance()
}
}
guard hasValidCharacter else { return false }

if let value = T(stringToParse) {
to(value)
locationToScanFrom = buf.location
return true
} else {
return false
}
}
}

Expand Down
6 changes: 5 additions & 1 deletion Tests/Foundation/Tests/TestNSGeometry.swift
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Expand Up @@ -1352,7 +1352,11 @@ class TestNSGeometry : XCTestCase {
rect = NSRectFromString(stringRect)
XCTAssertTrue(_NSRect(expectedRect, equalsToRect: rect),
"\(NSStringFromRect(rect)) is not equal to expected \(NSStringFromRect(expectedRect))")


// SR-443
let point1 = NSPointFromString("{1.0, 1.2234234234}")
let point2 = NSPoint(x: CGFloat(1.0), y: CGFloat(1.2234234234))
XCTAssertEqual(point1, point2)
}

func test_DecodeEmptyStrings() {
Expand Down
8 changes: 6 additions & 2 deletions Tests/Foundation/Tests/TestScanner.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -74,12 +74,14 @@ class TestScanner : XCTestCase {
expectEqual($0.scanDouble(), atof("-100"), "Roundtrip: 2")
}

withScanner(for: "0.5 bla 0. .1 1e2 e+3 e4") {
withScanner(for: "0.5 bla 0. .1 . 1e2 e+3 e4") {
expectEqual($0.scanDouble(), 0.5, "Parse '0.5' as Double")
expectEqual($0.scanDouble(), nil, "Dont parse 'bla' as a Double") // "bla" doesnt parse as Double
expectEqual($0.scanString("bla"), "bla", "Consume the 'bla'")
expectEqual($0.scanDouble(), 0, "Parse '0.' as a Double")
expectEqual($0.scanDouble(), 0.1, "Parse '.1' as a Double")
expectEqual($0.scanDouble(), nil, "Dont parse '.' as a Double")
expectEqual($0.scanString("."), ".", "Consue '.'")
expectEqual($0.scanDouble(), 100, "Parse '1e2' as a Double")
expectEqual($0.scanDouble(), nil, "Dont parse 'e+3' as a Double") // "e+3" doesnt parse as Double
expectEqual($0.scanString("e+3"), "e+3", "Consume the 'e+3'")
Expand Down Expand Up @@ -124,7 +126,7 @@ class TestScanner : XCTestCase {
}

func testHexFloatingPoint() {
withScanner(for: "0xAA 3.14 0.1x 1g 3xx .F00x 1e00 -0xabcdef.02") {
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")
Expand All @@ -136,6 +138,8 @@ class TestScanner : XCTestCase {
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(), nil, "Dont parse '.' as a Double")
expectEqual($0.scanString("."), ".", "Consue '.'")
expectEqual($0.scanDouble(representation: .hexadecimal), -11259375.0078125, "negative decimal")
}
}
Expand Down