Clarify documentation of 'bufferpos-to-filepos' and 'filepos-to-bufferpos'

* doc/lispref/nonascii.texi (Text Representations): Clarify that
'exact' value of QUALITY argument to 'bufferpos-to-filepos' and
'filepos-to-bufferpos' can lead to expensive and slow processing.

* lisp/international/mule-util.el (filepos-to-bufferpos)
(bufferpos-to-filepos): Doc fix.  (Bug#25626)

diff --git a/doc/lispref/nonascii.texi b/doc/lispref/nonascii.texi
index e3cb5d0d3695bc554f9851d18850821d4fb98d40..2c3e6ef2c6025588569aafce6481b4f3919d896b 100644 (file)
--- a/doc/lispref/nonascii.texi
+++ b/doc/lispref/nonascii.texi
@@ -142,7 +142,7 @@ be one of the following:
 @table @code
 @item exact
 The result must be accurate.  The function may need to encode and
-decode a large part of the buffer.
+decode a large part of the buffer, which is expensive and can be slow.
 @item approximate
 The value can be an approximation.  The function may avoid expensive
 processing and return an inexact result.

diff --git a/lisp/international/mule-util.el b/lisp/international/mule-util.el
index 06b63eae370b237ff6c2dce52f06e995a1bc98eb..7657e40eed88400aab5cf83311982fc5f49160f4 100644 (file)
--- a/lisp/international/mule-util.el
+++ b/lisp/international/mule-util.el
@@ -352,7 +352,7 @@ QUALITY can be:
   `approximate', in which case we may cut some corners to avoid
     excessive work.
   `exact', in which case we may end up re-(en/de)coding a large
-    part of the file/buffer.
+    part of the file/buffer, this can be expensive and slow.
   nil, in which case we may return nil rather than an approximation."
   (unless coding-system (setq coding-system buffer-file-coding-system))
   (let ((eol (coding-system-eol-type coding-system))
@@ -428,7 +428,7 @@ QUALITY can be:
   `approximate', in which case we may cut some corners to avoid
     excessive work.
   `exact', in which case we may end up re-(en/de)coding a large
-    part of the file/buffer.
+    part of the file/buffer, this can be expensive and slow.
   nil, in which case we may return nil rather than an approximation."
   (unless coding-system (setq coding-system buffer-file-coding-system))
   (let* ((eol (coding-system-eol-type coding-system))