`text-property-search-forward' doc string improvement

* lisp/emacs-lisp/text-property-search.el
(text-property-search-forward): Correct and clarify the doc string
(bug#48317).

1 files changed, 22 insertions, 13 deletions

diff --git a/lisp/emacs-lisp/text-property-search.el b/lisp/emacs-lisp/text-property-search.el
index 69943a83f1c..49e196d3bfc 100644
--- a/lisp/emacs-lisp/text-property-search.el
+++ b/lisp/emacs-lisp/text-property-search.el
@@ -32,27 +32,36 @@
 (defun text-property-search-forward (property &optional value predicate
                                               not-current)
   "Search for the next region of text whose PROPERTY matches VALUE.
-
-If not found, return nil and don't move point.
-If found, move point to the start of the region and return a
-`prop-match' object describing the match.  To access the details
-of the match, use `prop-match-beginning' and `prop-match-end' for
-the buffer positions that limit the region, and
-`prop-match-value' for the value of PROPERTY in the region.
-
 PREDICATE is used to decide whether a value of PROPERTY should be
 considered as matching VALUE.
-If PREDICATE is t, that means a value must `equal' VALUE to be
-considered a match.
-If PREDICATE is nil, a value will match if it is non-nil and
-is NOT `equal' to VALUE.
+
 If PREDICATE is a function, it will be called with two arguments:
 VALUE and the value of PROPERTY.  The function should return
 non-nil if these two values are to be considered a match.
 
+Two special values of PREDICATE can also be used:
+If PREDICATE is t, that means a value must `equal' VALUE to be
+considered a match.
+If PREDICATE is nil, a value will match if is not `equal' to
+VALUE.  Furthermore, the match region is ended if the value
+changes.  For instance, this means that if you loop with
+
+  (while (text-property-search-forward 'face)
+    ...)
+
+you will get all distinct regions with different `face' values in
+the buffer.
+
 If NOT-CURRENT is non-nil, the function will search for the first
 region that doesn't include point and has a value of PROPERTY
-that matches VALUE."
+that matches VALUE.
+
+If no matches can be found, return nil and don't move point.
+If found, move point to the start of the region and return a
+`prop-match' object describing the match.  To access the details
+of the match, use `prop-match-beginning' and `prop-match-end' for
+the buffer positions that limit the region, and
+`prop-match-value' for the value of PROPERTY in the region."
   (interactive
    (list
     (let ((string (completing-read "Search for property: " obarray)))