org-list: Tweak `org-list-to-generic'

* lisp/org-list.el (org-list-to-generic): :istart, :icount, :iend
  and :isep are now called with an additional argument, the type of the
  list.  Also add a new property :ifmt.
(org-list--to-generic-item): Use new property.
(org-list-to-subtree): Adapt to new requirements for :istart and :iend.

* testing/lisp/test-org-list.el (test-org-list/to-generic): Update
  tests.

3 files changed, 51 insertions, 20 deletions

diff --git a/etc/ORG-NEWS b/etc/ORG-NEWS
index ec8a0c2..1d83983 100644
--- a/etc/ORG-NEWS
+++ b/etc/ORG-NEWS
@@ -12,6 +12,11 @@ Please send Org bug reports to mailto:emacs-orgmode@gnu.org.
 
 ** Incompatible changes
 
+*** Change signature for some properties in ~org-list-to-generic~
+
+~:istart~, ~:icount~, ~:iend~ and ~:isep~ now expect the type of the
+list as their first argument.
+
 *** ~org-capture-templates~ no longer accepts S-expressions as file names
 
 Since functions are allowed there, a straightforward way to migrate
@@ -27,7 +32,9 @@ into
 *** Agenda
 **** New variable : ~org-agenda-show-future-repeats~
 **** New variable : ~org-agenda-prefer-last-repeat~
+
 *** Babel
+
 **** Clojure: new setting ~org-babel-clojure-sync-nrepl-timeout~
 
 Creation of a new setting to specify the Cider timeout.  By setting
@@ -93,6 +100,11 @@ as descriptions of links, a.k.a. image links.  See its docstring for
 details.
 **** Horizontal rules are no longer ignored in LaTeX table math mode
 
+*** ~org-list-to-generic~ includes a new property: ~:ifmt~
+
+~:ifmt~ is a function to be called on the body of each item.  See
+~org-list-to-generic~ documentation for details.
+
 *** New variable : ~org-bibtex-headline-format-function~
 This allow to use a different title than entry title.
 
diff --git a/lisp/org-list.el b/lisp/org-list.el
index 325a248..abc6c53 100644
--- a/lisp/org-list.el
+++ b/lisp/org-list.el
@@ -3314,23 +3314,28 @@ Valid parameters are:
 
   Strings to start or end a list item, and to start a list item
   with a counter.  They can also be set to a function returning
-  a string or nil, which will be called with the depth of the
-  item, counting from 1.
+  a string or nil, which will be called with two arguments: the
+  type of list and the depth of the item, counting from 1.
 
 :icount
 
   Strings to start a list item with a counter.  It can also be
   set to a function returning a string or nil, which will be
-  called with two arguments: the depth of the item, counting from
-  1, and the counter.  Its value, when non-nil, has precedence
-  over `:istart'.
+  called with three arguments: the type of list, the depth of the
+  item, counting from 1, and the counter.  Its value, when
+  non-nil, has precedence over `:istart'.
 
 :isep
 
   String used to separate items.  It can also be set to
   a function returning a string or nil, which will be called with
-  the depth of the items, counting from 1.  It always start on
-  a new line.
+  two arguments: the type of list and the depth of the item,
+  counting from 1.  It always start on a new line.
+
+:ifmt
+
+  Function to be applied to the contents of every item.  It is
+  called with two arguments: the type of list and the contents.
 
 :cbon, :cboff, :cbtrans
 
@@ -3461,6 +3466,7 @@ PARAMS is a plist used to tweak the behavior of the transcoder."
 	(iend (plist-get params :iend))
 	(isep (plist-get params :isep))
 	(icount (plist-get params :icount))
+	(ifmt (plist-get params :ifmt))
 	(cboff (plist-get params :cboff))
 	(cbon  (plist-get params :cbon))
 	(cbtrans (plist-get params :cbtrans))
@@ -3474,9 +3480,9 @@ PARAMS is a plist used to tweak the behavior of the transcoder."
 	     (tag (org-element-property :tag item))
 	     (depth (org-list--depth item))
 	     (separator (and (org-export-get-next-element item info)
-			     (org-list--generic-eval isep depth)))
-	     (closing (pcase (org-list--generic-eval iend depth)
-			((or `nil `"") "\n")
+			     (org-list--generic-eval isep type depth)))
+	     (closing (pcase (org-list--generic-eval iend type depth)
+			((or `nil "") "\n")
 			((and (guard separator) s)
 			 (if (equal (substring s -1) "\n") s (concat s "\n")))
 			(s s))))
@@ -3493,10 +3499,10 @@ PARAMS is a plist used to tweak the behavior of the transcoder."
 	;; Build output.
 	(concat
 	 (let ((c (org-element-property :counter item)))
-	   (if c (org-list--generic-eval icount depth c)
-	     (org-list--generic-eval istart depth)))
+	   (if (and c icount) (org-list--generic-eval icount type depth c)
+	     (org-list--generic-eval istart type depth)))
 	 (let ((body
-		(if (or istart iend icount cbon cboff cbtrans (not backend)
+		(if (or istart iend icount ifmt cbon cboff cbtrans (not backend)
 			(and (eq type 'descriptive)
 			     (or dtstart dtend ddstart ddend)))
 		    (concat
@@ -3512,7 +3518,11 @@ PARAMS is a plist used to tweak the behavior of the transcoder."
 				    (org-element-interpret-data tag))
 				  dtend))
 		     (and tag ddstart)
-		     (if (= (length contents) 0) "" (substring contents 0 -1))
+		     (let ((contents
+			    (if (= (length contents) 0) ""
+			      (substring contents 0 -1))))
+		       (if ifmt (org-list--generic-eval ifmt type contents)
+			 contents))
 		     (and tag ddend))
 		  (org-export-with-backend backend item contents info))))
 	   ;; Remove final newline.
@@ -3556,7 +3566,7 @@ list with overruling parameters for `org-list-to-generic'."
 			   (org-previous-line-empty-p)))))
 	 (level (org-reduced-level (or (org-current-level) 0)))
 	 (make-stars
-	  (lambda (depth)
+	  (lambda (_type depth &optional _count)
 	    ;; Return the string for the heading, depending on DEPTH
 	    ;; of current sub-list.
 	    (let ((oddeven-level (+ level depth)))
diff --git a/testing/lisp/test-org-list.el b/testing/lisp/test-org-list.el
index 1ddbaa5..fe9da96 100644
--- a/testing/lisp/test-org-list.el
+++ b/testing/lisp/test-org-list.el
@@ -1157,13 +1157,13 @@
     "level1 a\nlevel2 b"
     (org-test-with-temp-text "- a\n  - b"
       (org-list-to-generic (org-list-to-lisp)
-			   '(:istart (lambda (l) (format "level%d "l)))))))
+			   '(:istart (lambda (type l) (format "level%d "l)))))))
   (should
    (equal
     "a\nblevel2level1"
     (org-test-with-temp-text "- a\n  - b"
       (org-list-to-generic (org-list-to-lisp)
-			   '(:iend (lambda (l) (format "level%d" l)))))))
+			   '(:iend (lambda (type l) (format "level%d" l)))))))
   ;; Test `:icount' parameter.
   (should
    (equal
@@ -1187,7 +1187,7 @@
     (org-test-with-temp-text "1. [@3] a"
       (org-list-to-generic
        (org-list-to-lisp)
-       '(:icount (lambda (l c) (format "level:%d, counter:%d " l c)))))))
+       '(:icount (lambda (type l c) (format "level:%d, counter:%d " l c)))))))
   ;; Test `:isep' parameter.
   (should
    (equal
@@ -1203,8 +1203,17 @@
    (equal
     "a\n- 1 -\nb"
     (org-test-with-temp-text "- a\n- b"
-      (org-list-to-generic (org-list-to-lisp)
-			   '(:isep (lambda (l) (format "- %d -" l)))))))
+      (org-list-to-generic
+       (org-list-to-lisp)
+       '(:isep (lambda (type depth) (format "- %d -" depth)))))))
+  ;; Test `:ifmt' parameter.
+  (should
+   (equal
+    ">> a <<"
+    (org-test-with-temp-text "1. [@3] a"
+      (org-list-to-generic
+       (org-list-to-lisp)
+       '(:ifmt (lambda (type c) (format ">> %s <<" c)))))))
   ;; Test `:cbon', `:cboff', `:cbtrans'
   (should
    (equal