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Decimal: init?(string:) and scanDecimal() should return nil on error. #2960

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Merged
merged 1 commit into from
Jan 5, 2021
Merged

Decimal: init?(string:) and scanDecimal() should return nil on error. #2960

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8 changes: 4 additions & 4 deletions Sources/Foundation/Decimal.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -2295,7 +2295,7 @@ extension Scanner {
repeat {
buf.advance()
} while decimalValue(buf.currentCharacter) != nil
return Decimal.nan
return nil
}
result._exponent += 1
}
Expand All @@ -2315,7 +2315,7 @@ extension Scanner {
repeat {
buf.advance()
} while decimalValue(buf.currentCharacter) != nil
return Decimal.nan
return nil
}
result._exponent -= 1
}
Expand All @@ -2339,7 +2339,7 @@ extension Scanner {
while let numeral = decimalValue(buf.currentCharacter) {
exponent = 10 * exponent + Int32(numeral)
guard exponent <= 2*Int32(Int8.max) else {
return Decimal.nan
return nil
}

buf.advance()
Expand All @@ -2350,7 +2350,7 @@ extension Scanner {
}
exponent += result._exponent
guard exponent >= Int32(Int8.min) && exponent <= Int32(Int8.max) else {
return Decimal.nan
return nil
}
result._exponent = exponent
}
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31 changes: 29 additions & 2 deletions Tests/Foundation/Tests/TestDecimal.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -749,7 +749,7 @@ class TestDecimal: XCTestCase {
}
}

func test_ScanDecimal() {
func test_ScanDecimal() throws {
let testCases = [
// expected, value
( 123.456e78, "123.456e78" ),
Expand All @@ -764,7 +764,7 @@ class TestDecimal: XCTestCase {
]
for testCase in testCases {
let (expected, string) = testCase
let decimal = Decimal(string:string)!
let decimal = try XCTUnwrap(Decimal(string:string))
let aboutOne = Decimal(expected) / decimal
let approximatelyRight = aboutOne >= Decimal(0.99999) && aboutOne <= Decimal(1.00001)
XCTAssertTrue(approximatelyRight, "\(expected) ~= \(decimal) : \(aboutOne) \(aboutOne >= Decimal(0.99999)) \(aboutOne <= Decimal(1.00001))" )
Expand All @@ -779,6 +779,33 @@ class TestDecimal: XCTestCase {
return
}
XCTAssertEqual(answer,num,"\(ones) / 9 = \(answer) \(num)")

// Exponent overflow, returns nil
XCTAssertNil(Decimal(string: "1e200"))
XCTAssertNil(Decimal(string: "1e-200"))
XCTAssertNil(Decimal(string: "1e300"))
XCTAssertNil(Decimal(string: "1" + String(repeating: "0", count: 170)))
XCTAssertNil(Decimal(string: "0." + String(repeating: "0", count: 170) + "1"))
XCTAssertNil(Decimal(string: "0e200"))

// Parsing zero in different forms
let zero1 = try XCTUnwrap(Decimal(string: "000.000e123"))
XCTAssertTrue(zero1.isZero)
XCTAssertEqual(zero1._isNegative, 0)
XCTAssertEqual(zero1._length, 0)
XCTAssertEqual(zero1.description, "0")

let zero2 = try XCTUnwrap(Decimal(string: "+000.000e-123"))
XCTAssertTrue(zero2.isZero)
XCTAssertEqual(zero2._isNegative, 0)
XCTAssertEqual(zero2._length, 0)
XCTAssertEqual(zero2.description, "0")

let zero3 = try XCTUnwrap(Decimal(string: "-0.0e1"))
XCTAssertTrue(zero3.isZero)
XCTAssertEqual(zero3._isNegative, 0)
XCTAssertEqual(zero3._length, 0)
XCTAssertEqual(zero3.description, "0")
}

func test_SimpleMultiplication() {
Expand Down