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Fix range-based quantification fast path #653

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Merged
merged 2 commits into from
Apr 11, 2023
Merged

Fix range-based quantification fast path #653

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0b37083
Fix range-based quantification fast path
natecook1000 Apr 5, 2023
56ab01b
Expand test case
natecook1000 Apr 7, 2023
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17 changes: 10 additions & 7 deletions Sources/_StringProcessing/Engine/MEQuantify.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,14 @@ extension Processor {
}
}
let next = _doQuantifyMatch(payload)
guard let idx = next else { break }
guard let idx = next else {
if !savePoint.rangeIsEmpty {
// The last save point has saved the current, non-matching position,
// so it's unneeded.
savePoint.shrinkRange(input)
}
break
}
Comment on lines +43 to +50
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Moved the shrinkRange from below to this guard failure — the other break is up on line 36, the shrink shouldn't happen in that case.

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Latter code has an .eager check, is that needed or unneeded here?

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Unneeded — save points are only ever added when the quantification is eager, so the check is redundant.

currentPosition = idx
trips += 1
}
Expand All @@ -50,12 +57,8 @@ extension Processor {
return false
}

if payload.quantKind == .eager && !savePoint.rangeIsEmpty {
// The last save point has saved the current position, so it's unneeded
savePoint.shrinkRange(input)
if !savePoint.rangeIsEmpty {
savePoints.append(savePoint)
}
if !savePoint.rangeIsEmpty {
savePoints.append(savePoint)
}
return true
}
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22 changes: 22 additions & 0 deletions Tests/RegexTests/MatchTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -2574,4 +2574,26 @@ extension RegexTests {
func testFuzzerArtifacts() throws {
expectCompletion(regex: #"(b?)\1*"#, in: "a")
}

func testIssue640() throws {
// Original report from https://github.com/apple/swift-experimental-string-processing/issues/640
let r = try Regex("[1-9][0-9]{0,2}(?:,?[0-9]{3})*")
XCTAssertNotNil("36,769".wholeMatch(of: r))
XCTAssertNotNil("36769".wholeMatch(of: r))

for max in 1...8 {
let pattern = "a{0,\(max)}a"
let regex = try Regex(pattern)
for length in 1...(max + 1) {
let str = String(repeating: "a", count: length)
if str.wholeMatch(of: regex) == nil {
XCTFail("Didn't match '\(pattern)' in '\(str)' (\(max),\(length)).")
}
}

let possessiveRegex = try Regex("a{0,\(max)}+a")
let str = String(repeating: "a", count: max + 1)
XCTAssertNotNil(str.wholeMatch(of: possessiveRegex))
}
}
}