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Re: trouble with pattern, character collections

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  • Christian Brabandt
    Hi Marc! ... No, it is because n is evaluated to a true line feed, so [^ n] matches anything but ASCII NUL and ASCII 10, while [^ n] matches anything
    Message 1 of 28 , Feb 18, 2013
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      Hi Marc!

      On Mo, 18 Feb 2013, Marc Weber wrote:

      > I don't think that additional threads are going to help
      > There is an issue, and we should find a way to fix (IMHO).
      > Let me summarize again - and tell me if you feel differently.
      >
      > Test cases:
      > [1] echo len(matchstr("\n",'\zs[^\n]\ze'))
      > [2] echo len(matchstr("\n","\\zs[^\n]\\ze"))
      >
      > I expect both do the same, the difference is that the second as chr(10) in [^],
      > while the first has \n (which should be translated to chr(10).
      >
      > However I obsorve that [2] returns 0 as expected , but [1] does return
      > 1, thus it matches \n even though I told Vim that I do not want to match
      > it. People told me this was because '.' is equal to [^\n].

      No, it is because "\n" is evaluated to a true line feed, so "[^\n]"
      matches anything but ASCII NUL and ASCII 10, while '[^\n]' matches
      anything but ASCII NUL (which is used internally by Vim to distinguish
      lines from each other (e.g. a line seperator), so that a . matches
      anyhing in the buffer but the line seperator)

      > If so which is the best way to fix this - and which should be the way to
      > express [^\n] meaning do not match \n rather than behave like '.' then ?

      [^\n] should always behave like '.'

      Mit freundlichen Grüßen
      Christian
      --
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      "Hallo Süße, wie wär's mit uns beiden?"

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    • Marc Weber
      ... Christian: Once and for all - I don t want anybody to explain me that [^ n] behaves in a wired way because . should behave the way it does. I m *not*
      Message 2 of 28 , Feb 18, 2013
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        > No, it is because "\n" is evaluated to a true line feed, so "[^\n]"
        > matches anything but ASCII NUL and ASCII 10, while '[^\n]' matches
        > anything but ASCII NUL (which is used internally by Vim to distinguish
        > lines from each other (e.g. a line seperator), so that a . matches
        > anyhing in the buffer but the line seperator)

        Christian: Once and for all - I don't want anybody to explain me that
        [^\n] behaves in a wired way because '.' should behave the way it does.

        I'm *not* talking about internals. I'm talking the user interface you
        and me and new users are faced with every day. So help me think about
        whether there is a way to improve the situation.

        So why should anybody write [^\n] if you can use '.'? So why make [^\n]
        behave the same way? Why not make it raise an error such as:

        E99999: For odd reasons you should try "[\n]" instead of '[^\n]' and be
        done. True reason see long reply by Christian on ml ..

        Trouble solved within 2 min. No debugging why vim does not behave the
        way you expect. This guard would be trival to implement. if []
        collections are negated and contain \n show the message.
        And it would not break backward compatibility. Which is the use case for
        allowing '[^\n]' at all?

        I'm not saying it solves the issue, but it would cause less pain,
        do you agree on this?

        I wrote vim-addon-manager to improve usage experience for users - and
        this is another case just driving me crazy which I think needs to
        improved - the issue is in which way.

        Marc Weber

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      • Erik Christiansen
        ... Vim already uses $ for EOL, documented at :h $ , which even seems to offer the synonym . Vim already has . to mean . , so does not need
        Message 3 of 28 , Feb 18, 2013
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          On 18.02.13 23:06, Christian Brabandt wrote:
          > No, it is because "\n" is evaluated to a true line feed, so "[^\n]"
          > matches anything but ASCII NUL and ASCII 10, while '[^\n]' matches
          > anything but ASCII NUL (which is used internally by Vim to distinguish
          > lines from each other (e.g. a line seperator), so that a . matches
          > anyhing in the buffer but the line seperator)
          >
          > > If so which is the best way to fix this - and which should be the way to
          > > express [^\n] meaning do not match \n rather than behave like '.' then ?

          Vim already uses '$' for EOL, documented at ":h $", which even seems to
          offer the synonym "<End>". Vim already has '.' to mean '.', so does not
          need <elephant> for the same. So why do it???

          > [^\n] should always behave like '.'

          No, sorry, only in a line devoid of newlines. By definition.
          In regex terms, i.e the user view, [^\n] may match anything other than a
          newline, while '.' may match any single character. Only if newlines have
          been stripped in the internal line representation, and e.g. replaced
          with NUL, can '.' legitimately fail to match \n. Otherwise, we can only
          reasonably say the [^\n] should NOT always behave like '.'

          In contrast, "[^\n]" _is_ identical to '[^\n]' in regex syntax, so must
          be identical in behaviour, devoid of even subtle differences, in any
          context.

          On 18.02.13 23:38, Marc Weber wrote:
          > I'm *not* talking about internals. I'm talking the user interface you
          > and me and new users are faced with every day. So help me think about
          > whether there is a way to improve the situation.
          >
          > So why should anybody write [^\n] if you can use '.'? So why make [^\n]
          > behave the same way? Why not make it raise an error such as:
          >
          > E99999: For odd reasons you should try "[\n]" instead of '[^\n]' and be
          > done. True reason see long reply by Christian on ml ..

          Or E99999: Unsupported syntax. Vim fails to give rational syntax-relevant
          effect to this regex. Try <whatever> instead.

          Sorry, [^\n] can never match \n ; not even in pink. That is broken
          behaviour.

          Erik

          --
          Why make things difficult, when it is possible to make them cryptic
          and totally illogical, with just a little bit more effort?"
          - A. P. J.

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        • Christian Brabandt
          Hi Erik! ... Well, if you think about it, $ matches something different. You can t say, /n$n can you? ... Because the . is a perfect valid alias to [^ n]
          Message 4 of 28 , Feb 19, 2013
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            Hi Erik!

            On Di, 19 Feb 2013, Erik Christiansen wrote:

            > On 18.02.13 23:06, Christian Brabandt wrote:
            > > No, it is because "\n" is evaluated to a true line feed, so "[^\n]"
            > > matches anything but ASCII NUL and ASCII 10, while '[^\n]' matches
            > > anything but ASCII NUL (which is used internally by Vim to distinguish
            > > lines from each other (e.g. a line seperator), so that a . matches
            > > anyhing in the buffer but the line seperator)
            > >
            > > > If so which is the best way to fix this - and which should be the way to
            > > > express [^\n] meaning do not match \n rather than behave like '.' then ?
            >
            > Vim already uses '$' for EOL, documented at ":h $", which even seems to
            > offer the synonym "<End>".


            Well, if you think about it, $ matches something different. You can't
            say, "/n$n" can you?

            > Vim already has '.' to mean '.', so does not
            > need <elephant> for the same. So why do it???

            Because the '.' is a perfect valid alias to [^\n] in most regexes
            anyway? Why cripple it?

            > > [^\n] should always behave like '.'
            >
            > No, sorry, only in a line devoid of newlines. By definition.
            > In regex terms, i.e the user view, [^\n] may match anything other than a
            > newline, while '.' may match any single character. Only if newlines have
            > been stripped in the internal line representation, and e.g. replaced
            > with NUL, can '.' legitimately fail to match \n. Otherwise, we can only
            > reasonably say the [^\n] should NOT always behave like '.'

            In all regexp engines that I know of, the '.' by default doesn't match a
            newline, so it is perfectly valid to have [^\n] match the same as '.'

            > In contrast, "[^\n]" _is_ identical to '[^\n]' in regex syntax, so must
            > be identical in behaviour, devoid of even subtle differences, in any
            > context.

            Please read again the article to which you replied. I already said, why
            this is different. This comes from the string-evaluation of the "[..]"
            expression. You can read about it at :h expr-string.

            > Sorry, [^\n] can never match \n ; not even in pink. That is broken
            > behaviour.

            Please come back with some arguments. I told you why this happens. If
            you don't want that, Vim already provides a setting to fix this.

            :set cpo+=l


            Mit freundlichen Grüßen
            Christian
            --
            Windows ist kein Virus - ein Virus tut etwas.

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          • Christian Brabandt
            Hi Marc! ... Bram, here is a patch, making [^ n] not match NL within the text and that also documents, that . matches CR and LF within the text. This makes
            Message 5 of 28 , Feb 19, 2013
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              Hi Marc!

              On Mo, 18 Feb 2013, Marc Weber wrote:

              > I don't think that additional threads are going to help
              > There is an issue, and we should find a way to fix (IMHO).
              > Let me summarize again - and tell me if you feel differently.
              >
              > Test cases:
              > [1] echo len(matchstr("\n",'\zs[^\n]\ze'))
              > [2] echo len(matchstr("\n","\\zs[^\n]\\ze"))
              >
              > I expect both do the same, the difference is that the second as chr(10) in [^],
              > while the first has \n (which should be translated to chr(10).
              >
              > However I obsorve that [2] returns 0 as expected , but [1] does return
              > 1, thus it matches \n even though I told Vim that I do not want to match
              > it. People told me this was because '.' is equal to [^\n].
              >
              >
              > Current situation: at least to be fixed
              > 1:
              > No matter whether '.' should behave like [^\n]
              > [1] and [2] should behave the same, right?
              > 2:
              > This should be documented.
              > (Do you all at least agree these two statments?)

              Bram, here is a patch, making [^\n] not match NL within the text and
              that also documents, that '.' matches CR and LF within the text.

              This makes both [1] and [2] behave the same and seems to better match
              the users expectations.

              regards,
              Christian
              --
              Ein Volk kann nicht auf seine Genies, sondern auf das Volk, auf die
              Menge stolz sein - die Genies können auf die Genies es sein.
              -- Jean Paul

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            • Christian Brabandt
              Hi Marc! ... Because [^ n] is perfectly valid? ... If you don t want that, use :set cpo+=l ... It is a perfect valid regular expression. What is the reason to
              Message 6 of 28 , Feb 19, 2013
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                Hi Marc!

                On Mo, 18 Feb 2013, Marc Weber wrote:

                > > No, it is because "\n" is evaluated to a true line feed, so "[^\n]"
                > > matches anything but ASCII NUL and ASCII 10, while '[^\n]' matches
                > > anything but ASCII NUL (which is used internally by Vim to distinguish
                > > lines from each other (e.g. a line seperator), so that a . matches
                > > anyhing in the buffer but the line seperator)
                >
                > Christian: Once and for all - I don't want anybody to explain me that
                > [^\n] behaves in a wired way because '.' should behave the way it does.
                >
                > I'm *not* talking about internals. I'm talking the user interface you
                > and me and new users are faced with every day. So help me think about
                > whether there is a way to improve the situation.
                >
                > So why should anybody write [^\n] if you can use '.'? So why make [^\n]
                > behave the same way? Why not make it raise an error such as:

                Because [^\n] is perfectly valid?

                >
                > E99999: For odd reasons you should try "[\n]" instead of '[^\n]' and be
                > done. True reason see long reply by Christian on ml ..
                >
                > Trouble solved within 2 min. No debugging why vim does not behave the
                > way you expect. This guard would be trival to implement. if []
                > collections are negated and contain \n show the message.

                If you don't want that, use :set cpo+=l

                > And it would not break backward compatibility. Which is the use case for
                > allowing '[^\n]' at all?

                It is a perfect valid regular expression. What is the reason to forbid
                its use?

                Anyway, I just made a patch, that should match your expectations.


                regards,
                Christian
                --
                Adam - der erste Entwurf für Eva.
                -- Jeanne Moreau

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              • Marc Weber
                I want Vim defaults to be - sane - follow the principle of least surprise. (I d like nocompatible to be set by default, but that s another story) Christian:
                Message 7 of 28 , Feb 19, 2013
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                  I want Vim defaults to be
                  - sane
                  - follow the principle of least surprise.
                  (I'd like nocompatible to be set by default, but that's another story)

                  Christian: :set cpo+=l still makes my test cases fail:
                  [1] echo len(matchstr("\n",'\zs[^\n]\ze'))
                  [2] echo len(matchstr("\n","\\zs[^\n]\\ze")

                  You explained it by \n not being chr(10), so what is it?

                  Let's try by understanding \n's behaviour:
                  ==========================================

                  case 1) vim buf
                  To my undestanding $ matches end of line (in a vim buffer) without eating that
                  end of line whereas \n does both: it matches and eats the end of line.
                  Eg try /..\n.. and :set hlsearch

                  Thus \n is the same as $\n when applying regex to vim buffers. dos 1310 usually
                  is encoded in a ff setting, so \n does what you want if you want it.

                  case 2) matchstr, matchall, substitute =~ and whatnot (?)

                  So if \n is not chr(10), what is it then in this case?

                  echo len(matchstr("\n",'\zs[^\n]\ze'))

                  clearly indicates it matches \n and and I agree on Erik which called it this way

                  Sorry, [^\n] can never match \n ; not even in pink. That is broken
                  behaviour.

                  So from this point of view I'd say \n behavior is broken when regex get applied
                  to strings only (which your patch is supposed to fix - I'll test it
                  later)

                  Is there more to fix?
                  =====================

                  issue 1)

                  docs state:
                  [] (with 'nomagic': \[]) */[]* */\[]* */\_[]* */collection*
                  \_[]

                  Well - try /[] - it will not be treated as collection, it'll match [], because
                  its empty!! So there should be a comment that collections must contain at least
                  one char to be seen as one.

                  issue 2)
                  With "\_" prepended the collection also includes the end-of-line - why does it exist, because
                  [\n] is accepted and works as expected?

                  So can \_[] syntax be deprecated?


                  Marc Weber

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                • Christian Brabandt
                  Hi Marc! ... Well, you need to prevent that expr-quote (:h expr-quote) is being evaluated. You need to escape the then. ... No. Please read again what I
                  Message 8 of 28 , Feb 19, 2013
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                    Hi Marc!

                    On Di, 19 Feb 2013, Marc Weber wrote:

                    > I want Vim defaults to be
                    > - sane
                    > - follow the principle of least surprise.
                    > (I'd like nocompatible to be set by default, but that's another story)
                    >
                    > Christian: :set cpo+=l still makes my test cases fail:
                    > [1] echo len(matchstr("\n",'\zs[^\n]\ze'))
                    > [2] echo len(matchstr("\n","\\zs[^\n]\\ze")

                    Well, you need to prevent that expr-quote (:h expr-quote) is being
                    evaluated. You need to escape the \ then.

                    > You explained it by \n not being chr(10), so what is it?

                    No. Please read again what I wrote. I am not going to repeat myself.

                    > Let's try by understanding \n's behaviour:
                    > ==========================================
                    >
                    > case 1) vim buf
                    > To my undestanding $ matches end of line (in a vim buffer) without eating that
                    > end of line whereas \n does both: it matches and eats the end of line.
                    > Eg try /..\n.. and :set hlsearch
                    >
                    > Thus \n is the same as $\n when applying regex to vim buffers. dos 1310 usually
                    > is encoded in a ff setting, so \n does what you want if you want it.
                    >
                    > case 2) matchstr, matchall, substitute =~ and whatnot (?)
                    >
                    > So if \n is not chr(10), what is it then in this case?
                    >
                    > echo len(matchstr("\n",'\zs[^\n]\ze'))
                    >
                    > clearly indicates it matches \n and and I agree on Erik which called it this way
                    >

                    Vim internals do not distinguish between evaluating functions and
                    buffers. They work on matching a regular pattern on a string of text. In
                    Vim buffers, lines are distinguished in memory by NUL and that is the
                    only thing, that '.' does not match and so does [^\n] so that in a
                    buffer a search for /[^\n] will match any char (even control codes like
                    CR or LF)

                    What you want is, that in a text /[^\n] also does not match LF character
                    and that is what my patch provides thus it should do what you want.

                    > Is there more to fix?
                    > =====================
                    >
                    > issue 1)
                    >
                    > docs state:
                    > [] (with 'nomagic': \[]) */[]* */\[]* */\_[]* */collection*
                    > \_[]
                    >
                    > Well - try /[] - it will not be treated as collection, it'll match [], because
                    > its empty!! So there should be a comment that collections must contain at least
                    > one char to be seen as one.

                    I would call this a bug as well. I think, this should give an error.

                    > issue 2)
                    > With "\_" prepended the collection also includes the end-of-line - why does it exist, because
                    > [\n] is accepted and works as expected?
                    >
                    > So can \_[] syntax be deprecated?

                    Why is this an issue? I don't see a problem with \_ syntax at all.

                    Mit freundlichen Grüßen
                    Christian
                    --
                    Dem großen Publikum ist ein Buch nicht leicht zu schlecht, sehr
                    leicht aber zu gut.
                    -- Marie von Ebner-Eschenbach

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                  • Marc Weber
                    ... Let me tell you. People get to know Vim. Vim is a tool to serve users. They want to edit text, get their job done (At least that s what I assume). For this
                    Message 9 of 28 , Feb 19, 2013
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                      > Why is this an issue? I don't see a problem with \_ syntax at all.
                      Let me tell you. People get to know Vim. Vim is a tool to serve users.
                      They want to edit text, get their job done (At least that's what I
                      assume). For this reason every construct such as \_ which requires you
                      to lookup help is going to take your time - time which should be spent
                      on the wiki or the homepage (yes - there is much to improve).

                      So from technical point of view there is nothing wrong: Something is
                      documentented, and it works as expected.

                      If you look at the ruby community there are some voices which
                      dislike some aspects about ruby: That there are so many ways to do
                      something ..

                      If you look at the whole ecosystem it is wrong, because its
                      wasting resources in many ways (human resources being the most
                      expensive ones). You may disagree on this - but its true.
                      The best docs are the ones you don't have to read.

                      I'm not proposing dropping it (if Vim was my projcet I'd do so - showing
                      an error message instead) - but maybe docs can be adjusted so that
                      people use [\n] and maybe even miss the Vim only special case on the
                      first glance.

                      Christian, thanks for your support.

                      Marc Weber

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                    • Christian Brabandt
                      ... Attached is an updated patch, that also prevents /[] matching [] (a collation cannot be empty, so I think it should return an error and other vi clones do,
                      Message 10 of 28 , Feb 19, 2013
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                        On Di, 19 Feb 2013, Christian Brabandt wrote:

                        > On Mo, 18 Feb 2013, Marc Weber wrote:
                        > > I don't think that additional threads are going to help
                        > > There is an issue, and we should find a way to fix (IMHO).
                        > > Let me summarize again - and tell me if you feel differently.
                        > >
                        > > Test cases:
                        > > [1] echo len(matchstr("\n",'\zs[^\n]\ze'))
                        > > [2] echo len(matchstr("\n","\\zs[^\n]\\ze"))
                        > >
                        > > I expect both do the same, the difference is that the second as chr(10) in [^],
                        > > while the first has \n (which should be translated to chr(10).
                        > >
                        > > However I obsorve that [2] returns 0 as expected , but [1] does return
                        > > 1, thus it matches \n even though I told Vim that I do not want to match
                        > > it. People told me this was because '.' is equal to [^\n].
                        > >
                        > >
                        > > Current situation: at least to be fixed
                        > > 1:
                        > > No matter whether '.' should behave like [^\n]
                        > > [1] and [2] should behave the same, right?
                        > > 2:
                        > > This should be documented.
                        > > (Do you all at least agree these two statments?)
                        >
                        > Bram, here is a patch, making [^\n] not match NL within the text and
                        > that also documents, that '.' matches CR and LF within the text.
                        >
                        > This makes both [1] and [2] behave the same and seems to better match
                        > the users expectations.

                        Attached is an updated patch, that also prevents /[] matching []
                        (a collation cannot be empty, so I think it should return an error and
                        other vi clones do, also grep and perl throw an error).

                        Included are tests as well.

                        regards,
                        Christian
                        --
                        Sprachlexikon-Namen: GERRITT - gemütl. Schritt-Tempo b. Pferden

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                      • Marc Weber
                        ... We should discuss whether /[] is a bug or feature. docs state that /[abc matches [abc by purpose (which could also be treated as error because there is no
                        Message 11 of 28 , Feb 19, 2013
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                          > [..] patch, [..] prevents /[] matching []
                          > other vi clones do, also grep and perl throw an error).
                          :) You start comparing Vim against what other tools do.

                          We should discuss whether /[] is a bug or feature. docs state that /[abc
                          matches [abc by purpose (which could also be treated as error because
                          there is no closing ]. And I actually might agree on this being useful.

                          Marc Weber

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                        • Ben Fritz
                          ... Sometimes the meaning is clearer. What if you re searching for a sequence of certain characters including newlines, where the first character is NOT a
                          Message 12 of 28 , Feb 19, 2013
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                            On Monday, February 18, 2013 4:38:56 PM UTC-6, MarcWeber wrote:
                            >
                            > So why should anybody write [^\n] if you can use '.'? So why make [^\n]
                            >
                            > behave the same way?

                            Sometimes the meaning is clearer.

                            What if you're searching for a sequence of certain characters including newlines, where the first character is NOT a newline?

                            I'd probably want to use:

                            /[^\n]\&[a-f0-9\n]\+

                            which is equivalent to, but clearer in meaning than:

                            /.\&[a-f0-9\n]\+

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                          • Erik Christiansen
                            ... Christian, many thanks for the work you have done, and for putting users first. It is heartily appreciated. The consolation may be small, but vim is now
                            Message 13 of 28 , Feb 20, 2013
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                              On 19.02.13 10:23, Christian Brabandt wrote:
                              > Bram, here is a patch, making [^\n] not match NL within the text and
                              > that also documents, that '.' matches CR and LF within the text.
                              >
                              > This makes both [1] and [2] behave the same and seems to better match
                              > the users expectations.

                              Christian, many thanks for the work you have done, and for putting users
                              first. It is heartily appreciated.

                              The consolation may be small, but vim is now consistent with awk:

                              »
                              . This matches any single character, including the newline character.

                              « - xpdf gawk.pdf # "Effective AWK Programming"

                              O'Reilly's "Mastering Regular Expressions" has it as varying between
                              tools. (OK, we knew that. :-)

                              Regards,
                              Erik

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                            • Bram Moolenaar
                              ... This isn t right, there are no NL characters in the text. There are NUL characters which are stored as NL characters. That s an implementation detail,
                              Message 14 of 28 , Feb 20, 2013
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                                Christian Brabandt wrote:

                                > Hi Marc!
                                >
                                > On Mo, 18 Feb 2013, Marc Weber wrote:
                                >
                                > > I don't think that additional threads are going to help
                                > > There is an issue, and we should find a way to fix (IMHO).
                                > > Let me summarize again - and tell me if you feel differently.
                                > >
                                > > Test cases:
                                > > [1] echo len(matchstr("\n",'\zs[^\n]\ze'))
                                > > [2] echo len(matchstr("\n","\\zs[^\n]\\ze"))
                                > >
                                > > I expect both do the same, the difference is that the second as chr(10) in [^],
                                > > while the first has \n (which should be translated to chr(10).
                                > >
                                > > However I obsorve that [2] returns 0 as expected , but [1] does return
                                > > 1, thus it matches \n even though I told Vim that I do not want to match
                                > > it. People told me this was because '.' is equal to [^\n].
                                > >
                                > >
                                > > Current situation: at least to be fixed
                                > > 1:
                                > > No matter whether '.' should behave like [^\n]
                                > > [1] and [2] should behave the same, right?
                                > > 2:
                                > > This should be documented.
                                > > (Do you all at least agree these two statments?)
                                >
                                > Bram, here is a patch, making [^\n] not match NL within the text and
                                > that also documents, that '.' matches CR and LF within the text.
                                >
                                > This makes both [1] and [2] behave the same and seems to better match
                                > the users expectations.

                                This isn't right, there are no NL characters in the text. There are NUL
                                characters which are stored as NL characters. That's an implementation
                                detail, which sometimes becomes visible to the user.

                                It's good to explain this in the docs. I'm not sure we actually should
                                change the behavior, it might not really take away much confusion.


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                              • Marc Weber
                                Hi Bram, thanks for joining the discussion and participating. echo len(nr2char(0)) returns 0, where is the 0 char stored as n .. So please take care about the
                                Message 15 of 28 , Feb 20, 2013
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                                  Hi Bram,

                                  thanks for joining the discussion and participating.

                                  echo len(nr2char(0))
                                  returns 0, where is the 0 char stored as \n ..
                                  So please take care about the use case: I'm not talking about buffers,
                                  I'm talking about matchstr, substitute etc and viml strings.

                                  I'm aware that both should be tested and documented which becomes clear
                                  reading my later summary.

                                  Anyway [^\n] matching \n is a very very unexpected behaviour.
                                  Having \_[ syntax doesn't make sense, either. Because [\n] works and is
                                  standard. And this should be visible in docs.

                                  Marc Weber

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                                • Erik Christiansen
                                  ... Bram, is that meant to be There are NL characters which are stored as NUL characters ? Because if there are no NL characters in the text , then nothing
                                  Message 16 of 28 , Feb 20, 2013
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                                    On 20.02.13 13:32, Bram Moolenaar wrote:
                                    > Christian Brabandt wrote:
                                    > > Bram, here is a patch, making [^\n] not match NL within the text and
                                    > > that also documents, that '.' matches CR and LF within the text.
                                    > >
                                    > > This makes both [1] and [2] behave the same and seems to better match
                                    > > the users expectations.
                                    >
                                    > This isn't right, there are no NL characters in the text. There are NUL
                                    > characters which are stored as NL characters.

                                    Bram, is that meant to be "There are NL characters which are stored as
                                    NUL characters"? Because if "there are no NL characters in the text",
                                    then nothing can be stored as them, can it?

                                    > That's an implementation detail, which sometimes becomes visible to
                                    > the user.

                                    OK, but the actual problem is corruption of a regex syntax snippet in
                                    one quoting context. Letting "[^\n]" not be the same as '[^\n]' is the
                                    mark of a broken regex implementation. Other regex engines manage \n
                                    without their syntax breaking, so it is possible with Vim too.

                                    Vim has '.' to represent "any character", and so does not require a
                                    second representation for that. But if [^\n] is the same as '.', because
                                    there are no newlines present, then that must _always_ be the case,
                                    regardless of a bit of quoting flim-flam.

                                    > It's good to explain this in the docs.

                                    Yes, knowing that there are no newlines can help us avoid looking for
                                    them.

                                    Another fix is needed, though, for the problem that quote flavour is
                                    allowed to corrupt the regex in one case, causing behaviour contrary to
                                    the quoted regex syntax. That is an illogicality boobytrap to torment
                                    the user.

                                    > I'm not sure we actually should change the behavior, it might not
                                    > really take away much confusion.

                                    Excuse me, Bram but removing the broken behaviour of "[^\n]" not being
                                    the same as '[^\n]' does remove a mind boggling logical nonsense, and so
                                    does do away with major confusion.

                                    Deep knowledge if Vim internals is an asset when it fosters effective
                                    and robust fixes, but tends toward a liability if it blinds one to the
                                    failings of a self-contradicting user interface, I think.

                                    In all that we construct, it is _what_ should happen which guides _how_
                                    it is made to happen. Arguments defending the current broken status
                                    repeatedly refer to _how_ usurping _what_, as an implementational
                                    side effect, and accepting that as a justification. That is not
                                    intelligent design, and has here led to impaired functionality.

                                    Vim's supremacy would be improved by removing the user interface
                                    deficiency.

                                    Erik

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