New FP Parsing: Use relevant part of a substring #86018
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@milseman I would appreciate if someone could double-check my use of internal String APIs here. In particular, I've not made any effort to test cases where a string is not "fast UTF8" capable; advice appreciated. |
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This is a follow-on to #85797 |
| } else { | ||
| // Otherwise, make a copy so we have contiguous UTF8... | ||
| let string = String(text) | ||
| parsed = unsafe string._guts.withFastUTF8 { chars -> ${Self}? in |
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In particular, can I reliably assume that a copied string will always support withFastUTF8?
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Why not just use https://developer.apple.com/documentation/swift/string/makecontiguousutf8() ?
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The current implementation does always produce a string that supports withFastUTF8, but we might as well be sure and call makeContiguousUTF8(). I would suggest withUTF8, since it is a wrapper for makeContiguousUTF8() followed by _guts.withFastUTF8…
| expectNotNil(parsed) | ||
| expectEqual(parsed!.bitPattern, (2.0).bitPattern) | ||
| } | ||
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Do I need to test bridged strings specially here?
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I'm not going to turn down free test coverage of my code if it's offered, but I don't think it's at all necessary.
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@swift-ci Please test |
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@swift-ci test |
| @available(SwiftStdlib 5.3, *) | ||
| public init?(_ text: Substring) { | ||
| // TODO: Someday, this whole function should simplify down to just: | ||
| // ${Self}(text.utf8.span) |
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Can we spell it that way for the platforms that don't have availability issues?
There are examples of tests of bridged substrings in test/stdlib/Span/BridgedStringUTF8ViewSpanTests.swift |
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The new FP parsing code inadvertently used the entire backing string, even when the substring referred to just a portion.
This addresses a failure in the extended
UnicodeScalarProperties.swifttest, which parses an input file by reading a line into a String, then extracting Substrings. (rdar://166258748)