Re: org-agenda queries for absent properties

[Jens Schmidt <jschmidt4gnu@vodafonemail.de>]

On 2023-07-31  08:45, Ihor Radchenko wrote:

> If you are up to a job of adding this to `org-make-tags-matcher' and
> not breaking things, you can try.

Depends a bit on the required collateral changes: Updating ORG-NEWS and
doc/org-guide.org should be no problem.  Doing a naive grep-based search
I haven't found tests on `org-tags-view' or `org-make-tags-matcher', so
I hopefully wouldn't need to add anything new in that direction.

Finally, the first step probably would be to make that humongous regexp
in `org-make-tags-matcher' a bit more readable.  What would you prefer?
`rx' or sth long the following lines (not checked for equality yet):

   (re (concat
        ;; AND operator (OR is done by global splitting)
        "^&?"
        ;; 1: exclusion and inclusion (the latter being
        ;; implicit)
        "\\([-+:]\\)?"
        ;; 2: query expression
        "\\("
	   ;; regular expression matching tag
	   "{[^}]+}\\|"
	   ;; LEVEL special property match (3: op, 4: level
	   ;; value)
	   "LEVEL\\([<=>]\\{1,2\\}\\)\\([0-9]+\\)\\|"
	   ;; property match
	   "\\(?:"
	       ;; 5: property name (with backslash escaping minus)
	       "\\(\\(?:[[:alnum:]_]+\\(?:\\\\-\\)*\\)+\\)"
	       ;; 6: property operator
	       "\\([<>=]\\{1,2\\}\\)"
	       ;; 7: property value/operand
	       "\\("
		   ;; regular expression
		   "{[^}]+}\\|"
		   ;; string
		   "\"[^\"]*\"\\|"
		   ;; number
		   "-?[.0-9]+\\(?:[eE][-+]?[0-9]+\\)?"
	       "\\)"
	   "\\)\\|"
	   ;; tag match
	   org-tag-re
        "\\)"))

 > But we should really provide more
 > readable match syntax, similar to org-ql; sooner or later.

Agreed on that if the new syntax will allow for equally succinct
queries.  Plus a very cursory, doc-only review of org-ql hasn't
revealed to me how I'd do numeric property comparisons with it.