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regexp: syntax.wordRune() is a duplicate of syntax.IsWordChar() #21742

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sylvinus opened this issue Sep 2, 2017 · 3 comments
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regexp: syntax.wordRune() is a duplicate of syntax.IsWordChar() #21742

sylvinus opened this issue Sep 2, 2017 · 3 comments
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@sylvinus
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sylvinus commented Sep 2, 2017

Is there a valid reason for keeping both functions?
@gopherbot
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Change https://golang.org/cl/61034 mentions this issue: regexp: Remove duplicated function wordRune()

@odeke-em
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odeke-em commented Sep 3, 2017

Hmm, there seems to be a difference, being that IsWordChar recognizes _ but wordRune doesn't, as per the code pasted below:

IsWordChar

go/src/regexp/syntax/prog.go

Lines 104 to 109 in 03c3bb5

// IsWordChar reports whether r is consider a ``word character''
// during the evaluation of the \b and \B zero-width assertions.
// These assertions are ASCII-only: the word characters are [A-Za-z0-9_].
func IsWordChar(r rune) bool {
return 'A' <= r && r <= 'Z' || 'a' <= r && r <= 'z' || '0' <= r && r <= '9' || r == '_'
}

WordRune

go/src/regexp/syntax/prog.go

Lines 250 to 257 in 03c3bb5

// As per re2's Prog::IsWordChar. Determines whether rune is an ASCII word char.
// Since we act on runes, it would be easy to support Unicode here.
func wordRune(r rune) bool {
return r == '_' ||
('A' <= r && r <= 'Z') ||
('a' <= r && r <= 'z') ||
('0' <= r && r <= '9')
}

I haven't examined the entire context of the functions but it seems like perhaps we shouldn't be removing wordRune before figuring out what cases it handles.

@odeke-em
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odeke-em commented Sep 3, 2017

Oops, my biggest apologies, it is 5:25AM and I hadn't noticed that wordRune recognizes _ too, so they are the same. You have my vote now :)

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@sylvinus @odeke-em @gopherbot