Make occur handle multi-line matches cleanly with context.

[bpt/emacs.git] / lisp / replace.el

diff --git a/lisp/replace.el b/lisp/replace.el
index a74da4b..14a1869 100644 (file)
--- a/lisp/replace.el
+++ b/lisp/replace.el
@@ -1005,8 +1005,10 @@ which means to discard all text properties."
   :group 'matching
   :version "22.1")
 
-(defun occur-accumulate-lines (count &optional keep-props)
+(defun occur-accumulate-lines (count &optional keep-props pt)
   (save-excursion
+    (when pt
+      (goto-char pt))
     (let ((forwardp (> count 0))
          result beg end moved)
       (while (not (or (zerop count)
@@ -1189,12 +1191,15 @@ See also `multi-occur'."
        (when (buffer-live-p buf)
          (let ((matches 0)     ;; count of matched lines
                (lines 1)       ;; line count
+               (prev-after-lines nil)  ;; context lines of prev match
+               (prev-lines nil)        ;; line number of prev match endpt
                (matchbeg 0)
                (origpt nil)
                (begpt nil)
                (endpt nil)
                (marker nil)
                (curstring "")
+               (ret nil)
                (inhibit-field-text-motion t)
                (headerpt (with-current-buffer out-buf (point))))
            (with-current-buffer buf
@@ -1271,14 +1276,17 @@ See also `multi-occur'."
                                ;; The simple display style
                                out-line
                              ;; The complex multi-line display style.
-                             (occur-context-lines out-line nlines keep-props)
-                             )))
+                             (setq ret (occur-context-lines
+                                        out-line nlines keep-props begpt endpt
+                                        lines prev-lines prev-after-lines))
+                             ;; Set first elem of the returned list to `data',
+                             ;; and the second elem to `prev-after-lines'.
+                             (setq prev-after-lines (nth 1 ret))
+                             (nth 0 ret))))
                      ;; Actually insert the match display data
                      (with-current-buffer out-buf
                        (let ((beg (point))
-                             (end (progn (insert data) (point))))
-                         (unless (= nlines 0)
-                           (insert "-------\n")))))
+                             (end (progn (insert data) (point)))))))
                    (goto-char endpt))
                  (if endpt
                      (progn
@@ -1289,7 +1297,13 @@ See also `multi-occur'."
                                       (if (and (bolp) (eolp)) 1 0)))
                        ;; On to the next match...
                        (forward-line 1))
-                   (goto-char (point-max))))))
+                   (goto-char (point-max)))
+                 (setq prev-lines (1- lines)))
+               ;; Flush remaining context after-lines.
+               (when prev-after-lines
+                 (with-current-buffer out-buf
+                   (insert (apply #'concat (occur-engine-add-prefix
+                                            prev-after-lines)))))))
            (when (not (zerop matches)) ;; is the count zero?
              (setq globalcount (+ globalcount matches))
              (with-current-buffer out-buf
@@ -1345,18 +1359,60 @@ See also `multi-occur'."
 ;; Generate context display for occur.
 ;; OUT-LINE is the line where the match is.
 ;; NLINES and KEEP-PROPS are args to occur-engine.
+;; LINES is line count of the current match,
+;; PREV-LINES is line count of the previous match,
+;; PREV-AFTER-LINES is a list of after-context lines of the previous match.
 ;; Generate a list of lines, add prefixes to all but OUT-LINE,
 ;; then concatenate them all together.
-(defun occur-context-lines (out-line nlines keep-props)
-  (apply #'concat
-        (nconc
-         (occur-engine-add-prefix
-          (nreverse (cdr (occur-accumulate-lines
-                          (- (1+ (abs nlines))) keep-props))))
-         (list out-line)
-         (if (> nlines 0)
-             (occur-engine-add-prefix
-              (cdr (occur-accumulate-lines (1+ nlines) keep-props)))))))
+(defun occur-context-lines (out-line nlines keep-props begpt endpt
+                                    lines prev-lines prev-after-lines)
+  ;; Find after- and before-context lines of the current match.
+  (let ((before-lines
+        (nreverse (cdr (occur-accumulate-lines
+                        (- (1+ (abs nlines))) keep-props begpt))))
+       (after-lines
+        (cdr (occur-accumulate-lines
+              (1+ nlines) keep-props endpt)))
+       separator)
+
+    ;; Combine after-lines of the previous match
+    ;; with before-lines of the current match.
+
+    (when prev-after-lines
+      ;; Don't overlap prev after-lines with current before-lines.
+      (if (>= (+ prev-lines (length prev-after-lines))
+             (- lines      (length before-lines)))
+         (setq prev-after-lines
+               (butlast prev-after-lines
+                        (- (length prev-after-lines)
+                           (- lines prev-lines (length before-lines) 1))))
+       ;; Separate non-overlapping context lines with a dashed line.
+       (setq separator "-------\n")))
+
+    (when prev-lines
+      ;; Don't overlap current before-lines with previous match line.
+      (if (<= (- lines (length before-lines))
+             prev-lines)
+         (setq before-lines
+               (nthcdr (- (length before-lines)
+                          (- lines prev-lines 1))
+                       before-lines))
+       ;; Separate non-overlapping before-context lines.
+       (unless (> nlines 0)
+         (setq separator "-------\n"))))
+
+    (list
+     ;; Return a list where the first element is the output line.
+     (apply #'concat
+           (append
+            (and prev-after-lines
+                 (occur-engine-add-prefix prev-after-lines))
+            (and separator (list separator))
+            (occur-engine-add-prefix before-lines)
+            (list out-line)))
+     ;; And the second element is the list of context after-lines.
+     (if (> nlines 0) after-lines))))
+
 \f
 ;; It would be nice to use \\[...], but there is no reasonable way
 ;; to make that display both SPC and Y.