Support occur command operating on the region from Isearch.

* lisp/isearch.el (isearch-occur): Use region-bounds as region arg of occur.
(isearch-query-replace): Use use-region-p.

* lisp/replace.el (occur--region-start-line): Rename from
occur--matches-threshold.
(occur): Use complete lines when region is active for line-oriented occur.
(occur-engine): Count lines either from occur--region-start-line or 1.

2 files changed, 13 insertions, 10 deletions

diff --git a/lisp/isearch.el b/lisp/isearch.el
index 9297c0f95ba..729f629423c 100644
--- a/lisp/isearch.el
+++ b/lisp/isearch.el
@@ -1853,11 +1853,11 @@ replacements from Isearch is `M-s w ... M-%'."
       (concat "Query replace"
               (isearch--describe-regexp-mode (or delimited isearch-regexp-function) t)
               (if backward " backward" "")
-              (if (and transient-mark-mode mark-active) " in region" ""))
+              (if (use-region-p) " in region" ""))
       isearch-regexp)
      t isearch-regexp (or delimited isearch-regexp-function) nil nil
-     (if (and transient-mark-mode mark-active) (region-beginning))
-     (if (and transient-mark-mode mark-active) (region-end))
+     (if (use-region-p) (region-beginning))
+     (if (use-region-p) (region-end))
      backward))
   (and isearch-recursive-edit (exit-recursive-edit)))
 
@@ -1920,7 +1920,8 @@ characters in that string."
                            'isearch-regexp-function-descr
                            (isearch--describe-regexp-mode isearch-regexp-function))
              regexp)
-           nlines)))
+           nlines
+           (if (use-region-p) (region-bounds)))))
 
 (declare-function hi-lock-read-face-name "hi-lock" ())
 
diff --git a/lisp/replace.el b/lisp/replace.el
index 0efd0820966..c6892328d71 100644
--- a/lisp/replace.el
+++ b/lisp/replace.el
@@ -1387,7 +1387,7 @@ invoke `occur'."
 ;; Region limits when `occur' applies on a region.
 (defvar occur--region-start nil)
 (defvar occur--region-end nil)
-(defvar occur--matches-threshold nil)
+(defvar occur--region-start-line nil)
 (defvar occur--orig-line nil)
 (defvar occur--final-pos nil)
 
@@ -1441,13 +1441,15 @@ is not modified."
       (or end (setq end (point-max))))
     (let ((occur--region-start start)
           (occur--region-end end)
-          (occur--matches-threshold
+          (occur--region-start-line
            (and in-region-p
                 (line-number-at-pos (min start end))))
           (occur--orig-line
            (line-number-at-pos (point))))
       (save-excursion ; If no matches `occur-1' doesn't restore the point.
-        (and in-region-p (narrow-to-region start end))
+        (and in-region-p (narrow-to-region
+                          (save-excursion (goto-char start) (line-beginning-position))
+                          (save-excursion (goto-char end) (line-end-position))))
         (occur-1 regexp nlines (list (current-buffer)))
         (and in-region-p (widen))))))
 
@@ -1621,7 +1623,7 @@ See also `multi-occur'."
           (let ((lines 0)               ;; count of matching lines
                 (matches 0)             ;; count of matches
                 (curr-line              ;; line count
-                 (or occur--matches-threshold 1))
+                 (or occur--region-start-line 1))
                 (orig-line occur--orig-line)
                 (orig-line-shown-p)
                 (prev-line nil)         ;; line number of prev match endpt
@@ -1754,7 +1756,7 @@ See also `multi-occur'."
                                 (setq orig-line-shown-p t)
                                 (save-excursion
                                   (goto-char (point-min))
-                                  (forward-line (1- orig-line))
+                                  (forward-line (- orig-line (or occur--region-start-line 1)))
                                   (occur-engine-line (line-beginning-position)
                                                      (line-end-position) keep-props)))))
                         ;; Actually insert the match display data
@@ -1792,7 +1794,7 @@ See also `multi-occur'."
                     (let ((orig-line-str
                            (save-excursion
                              (goto-char (point-min))
-                             (forward-line (1- orig-line))
+                             (forward-line (- orig-line (or occur--region-start-line 1)))
                              (occur-engine-line (line-beginning-position)
                                                 (line-end-position) keep-props))))
                       (add-face-text-property