Re: [O] [RFC] Org syntax (draft)

[Carsten Dominik]

On 9.3.2013, at 11:52, Waldemar Quevedo <address@hidden> wrote:

> Hey Nicolas, this looks very detailed and I think it could be useful
> for people trying to write other parsers implementations for org-mode.
> Thanks for sharing!

Maybe someone knowledgeable can turn Nicola's description into a formal parser 
description that can then be used by something like yacc to produce code for 
arbitrary languages?  I am not sure if I am making sense though.

- Carsten

> 
> By the way, does it exist somewhere a set of examples of Emacs
> org-mode -> html conversion for all org-mode features?
> (How are changes from org-mode -> html converstion from Emacs tested
> during development?)
> 
> I am mantaining the org-ruby gem which is used to render org-mode texts to 
> html,
> and currently there is no "roadmap" of features to implement for it.
> As a result, features and tweaks are added to the library
> as long as someone submits a ticket requesting the feature in Github.
> (Here is a list of the export features supported in case someone wants
> to take a look:
> https://github.com/bdewey/org-ruby/tree/master/spec/html_examples )
> Having a set of examples features from org-mode would be very useful
> to see how much coverage other implementations of org-mode exporting
> features have.
> 
> Cheers everyone, keep org-mode being an awesome tool :)
> 
> - Waldemar
> 
> On Sat, Mar 9, 2013 at 7:06 AM, Nicolas Goaziou <address@hidden> wrote:
>> Hello,
>> 
>> "Nicolas Richard" <address@hidden> writes:
>> 
>>> Nicolas Goaziou <address@hidden> writes:
>>>> As discussed a few days ago, here is a document describing the complete
>>>> Org syntax as read by the parser. I also added some comments. I am going
>>>> to put the Org file on Worg, so anyone can update it and fix mistakes.
>>> 
>>> [for the record, the org file mentionned by Nicolas is currently at
>>> <http://orgmode.org/worg/dev/org-syntax.org>]
>>> 
>>> This looks truly awesome. I give some (naïve) comments below, from my
>>> non-expert point of view.
>> 
>> Thank you for your comments.
>> 
>>>> The paragraph is the unit of measurement.  An element defines
>>>> syntactical parts that are at the same level as a paragraph, i.e. which
>>>> cannot contain or be included in a paragraph.  An object is a part that
>>>> could be included in an element.  Greater elements are all parts that
>>>> can contain an element.
>>> 
>>> This is very clear but I'm slightly worried about confusion that might come
>>> from "Greater element" not being an "element", and the word "element"
>>> being a common word :
>> 
>> element means "Element + Greater Element". It is to be understood as the
>> opposite of object. I think there shouldn't be much ambiguity according
>> to context.
>> 
>>>> Empty lines belong to the largest element ending before them.  For
>>>> example, in a list, empty lines between items belong are part of the
>>>> item before them, but empty lines at the end of a list belong to the
>>>> plain list element.
>>> 
>>> Is the word "element" (in /largest element ending.../) to be understood
>>> as an "element" from the above definition ? I guess not (this would
>>> require both list items and plain lists to be on the level 'element',
>>> from your example)
>> 
>> Again, it's a shortcut for "in the largest element or greater element
>> ending before them".
>> 
>>>> 1 Headlines and Sections
>>>> ════════════════════════
>>>> 
>>>>  A headline is defined as:
>>>> 
>>>>  ╭────
>>>>  │ STARS KEYWORD PRIORITY TITLE TAGS
>>>>  ╰────
>>>> 
>>>>  STARS is a string starting at column 0 and containing at least one
>>>>  asterisk (and up to `org-inlinetask-min-level' if `org-inlinetask'
>>>>  library is loaded).  It’s the sole compulsory part of a headline.
>>> 
>>> Perhaps it should be mentionned that STARS has to end by a space (see
>>> below).
>> 
>> I agree.
>> 
>>> I suggest adding : The number of stars defines the level of the
>>> headline.
>> 
>> Does it belong to the syntax definition? Level is how Org uses syntax
>> internally. Also the sentence, although right, is misleading, because
>> level definition also depends on `org-odd-levels-only'.
>> 
>>>>  KEYWORD is a TODO keyword, which have to belong to the list defined in
>>>>  `org-todo-keywords'.  Case is significant.
>>> 
>>> The option #+TODO: is used also.
>> 
>> Then it should be ~org-todo-keywords-1~, which is where all TODO
>> keywords are added eventually.
>> 
>>>>  PRIORITY is a priority cookie, i.e. a single letter preceded by a hash
>>>>  sign # and enclosed within square brackets.  Case is significant.
>>> 
>>> I suggest dropping "Case is significant" (or maybe give the whole story :
>>> IIRC, it is the ascii code of the given letter that is used as
>>> priority)
>> 
>> I'm not sure that the purpose of this document should be to explain how
>> syntax will be used.
>> 
>>>>  ╭────
>>>>  │ *
>>> 
>>> I don't see a space character after that one in your email and it
>>> doesn't seem to be recognized as a headline by the exporter (hence my
>>> above suggestion)
>>> 
>>>>  If the first word appearing in the title is `org-comment-keyword',
>>>>  the
>>> 
>>> That should be `org-comment-string' I guess.
>> 
>> Indeed. Btw, I think this variable should be a defconst, not
>> a defcustom. It just makes things harder for little benefit.
>> 
>>>>  A headline contains directly at most one section, followed by any
>>>>  number of headlines.  Only a section can contain another section.
>>> 
>>> From what I understand, "A section is delimited by two headlines (and
>>> buffer limits)." [I initially thought it was "by two headlines of the
>>> same level", which it is not from the structure example you give
>>> later.]
>> 
>> "Only a section can contain another section" is wrong. It should be
>> removed.
>> 
>>>>  A section contains directly any greater element or element.  Only
>>>>  a headline can contain a section.  As an exception, text before the
>>>>  first headline in the document also belongs to a section.
>>> 
>>> 
>>>>  In a quoted headline contains a section, the latter will be considered
>>>>  as a “quote section”.
>>> 
>>> s/In/If/
>> 
>> Yes.
>> 
>>> unsure: s/quote section/quoted section/ ?
>> 
>> No, it is "quote section".
>> 
>>>>  BACKEND is a string constituted of alpha-numeric characters, hyphens
>>>>  or underscores.
>>> 
>>> I suggest: BACKEND is a string which is an element of (mapcar 'car
>>> org-export-registered-backends).
>> 
>> Not really. Parser can understand #+attr_foo even if foo is not
>> registered as a valid back-end.
>> 
>>>>  OPTIONAL and VALUE can contain any character but a new line.  Only
>>>>  keywords in `org-element-dual-keywords' can have an optional value.
>>> 
>>> I guess OPTIONAL cannot contain a closing square bracket ]
>> 
>> It can.
>> 
>>>>  An affiliated keyword can appear on multiple lines if KEY belongs to
>>>>  `org-element-multiple-keywords' or if its pattern is “#+ATTR_BACKEND:
>>>>  VALUE”.
>>> 
>>> I suggest s/on multiple lines/more than once/
>> 
>> Ok.
>> 
>>>>  PARAMETERS can contain any character, and can be omitted.
>>> 
>>> any other than new line, I guess.
>> 
>> Correct.
>> 
>>>>  CONTENTS can contain any element, but another greater block of the
>>>>  same type.
>>> 
>>> What is the type of a greater block ? the /name/ ?
>> 
>> Yes. I think it should be better to say something like: CONTENTS cannot
>> contain the string "#+END_NAME" on a line on its own.
>> 
>>> I did have a quick look at the rest of your mail, and it is very nice to
>>> have all of it written down explicitly, so again a big thanks for all of
>>> this (and the rest of your) work. Unfortunately I don't have much time
>>> right now to read it thoroughtfully, so just one single comment :
>>> 
>>>>       Even the LaTeX community suggests to use `\(...\)' over
>>>>       `$...$'.  — ngz
>>> 
>>> AFAIK that's not for technical reasons and also I would be curious to
>>> know who does that in real documents : '$' is so much more convenient.
>> 
>> Yes, I mixed $$...$$ and $...$. This sentence could be removed. Though
>> I still maintain my POV about $...$. It may be convenient in a latex
>> file, but in a free-form text format like Org, it's error prone.
>> 
>> I also forgot to write about optional #+tblfm: line below Org tables.
>> 
>> Would you (or Someone) mind updating the org-syntax.org file on Worg?
>> 
>> Thank you again.
>> 
>> 
>> Regards,
>> 
>> --
>> Nicolas Goaziou
>> 
>