Asymmetry in next/previous-property-change

Asymmetry in next/previous-property-change

[Juri Linkov]

In a new buffer eval:

  M-: (progn (insert "abc") (add-text-properties 2 3 '(prop t)))

Then while searching in different directions, the result of get-text-property
is different between forward/backward search:

  (get-text-property (next-single-property-change     (point-min) 'prop) 'prop)
  => t

  (get-text-property (previous-single-property-change (point-max) 'prop) 'prop)
  => nil

This is because get-text-property returns the property value of the character
AFTER the given position.  But while searching backwards, what is needed is
BEFORE the given position.

Has anybody given any thought to address this inconsistency?

Maybe a new function get-text-property-before could help
while searching backwards simply by using:

  (get-text-property-before (point) 'prop)

instead of currently required such ugly code:

  (unless (bobp) (get-text-property (1- (point)) 'prop))