Rewrite the missing-space rule without a negative lookahead (google-java-format #1460) - #104
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`//foo` gets a space after its slashes unless the comment is an IDE marker, `//noinspection` or `//$NON-NLS-n$`, which the tools recognise only as written. The exemption was a negative lookahead inside the matching pattern; it is now a second pattern that names the markers, checked after the first one matches. The two forms accept the same lines: the first pattern needs a non-space, non-slash character right after the slashes, so the lookahead was always evaluated after the whole run of slashes, which is where the second pattern looks as well. Taken from google/google-java-format#1460, whose motivation stands here too: regex engines without backtracking do not support lookahead, and the markers are easier to read, and to share with doc/Comment as #23 asks, as a pattern of their own. The rest of that change does not apply: `Strings.repeat` is already `String.repeat` here, and the markdown branch belongs to google-java-format's own `///` handling. FormatterTest pins the behaviour before and after: both markers, a marker followed by text, `//foo`, `///foo`, and comments that already have their space.
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Port of the applicable part of google/google-java-format#1460 (Éamonn McManus, author kept): the missing-space rule for line comments no longer uses a negative lookahead.
//foogets a space after its slashes unless the comment is an IDE marker,//noinspectionor//$NON-NLS-n$, which the tools recognise only as written. The exemption moves from a lookahead inside the pattern to a second pattern that names the markers. Both forms accept the same lines: the first pattern needs a non-space, non-slash character right after the slashes, so the lookahead was always evaluated after the whole run of slashes, which is where the second pattern looks too.Why take it: regex engines without backtracking do not support lookahead, which is upstream's reason, and a pattern that names the markers is the piece #23 wants to share with
doc/Comment, which today adds the space unconditionally.Not taken:
Strings.repeattoString.repeat, already done here, and the markdown javadoc branch, which belongs to google-java-format's own///handling; this fork wraps///runs (see #102).TDD
lineCommentGetsItsMissingSpaceExceptIdeMarkersinFormatterTestwas written first. It is a refactoring, so the test passes before and after; it pins both markers, a marker followed by text,//footo// foo,///footo/// foo, and comments that already have their space. The goldensI202,i221andNON-NLScover the markers in context.Checks
:open-java-format:teston JDK 21: 1598 tests, 0 failures.