(view-emacs-news): Rewrite to support new NEWS,

NEWS.major, and NEWS.1-17 file naming.  Add more intelligense,
e.g. version 10 matches 1.10, and don't be confused by version 1.1
begin a prefix of 1.12 (etc).  A numeric prefix arg also works.

1 files changed, 67 insertions, 54 deletions

diff --git a/lisp/help.el b/lisp/help.el
index 5efd58dfaf5..d9a48a0a4cf 100644
--- a/lisp/help.el
+++ b/lisp/help.el
@@ -326,63 +326,76 @@ of the key sequence that ran this command."
 ;; run describe-prefix-bindings.
 (setq prefix-help-command 'describe-prefix-bindings)
 
-(defun view-emacs-news (&optional arg)
+(defun view-emacs-news (&optional version)
   "Display info on recent changes to Emacs.
 With argument, display info only for the selected version."
   (interactive "P")
-  (if (not arg)
-      (view-file (expand-file-name "NEWS" data-directory))
-    (let* ((map (sort
-                 (delete-dups
-                  (apply
-                   'nconc
-                   (mapcar
-                    (lambda (file)
-                      (with-temp-buffer
-                        (insert-file-contents
-                         (expand-file-name file data-directory))
-                        (let (res)
-                          (while (re-search-forward
-                                  (if (string-match "^ONEWS\\.[0-9]+$" file)
-                                      "Changes in \\(?:Emacs\\|version\\)?[ \t]*\\([0-9]+\\(?:\\.[0-9]+\\)?\\)"
-                                    "^\* [^0-9\n]*\\([0-9]+\\.[0-9]+\\)") nil t)
-                            (setq res (cons (list (match-string-no-properties 1)
-                                                  file) res)))
-                          res)))
-                    (append '("NEWS" "ONEWS")
-                            (directory-files data-directory nil
-                                             "^ONEWS\\.[0-9]+$" nil)))))
-                 (lambda (a b)
-                   (string< (car b) (car a)))))
-           (current (caar map))
-           (version (completing-read
-                     (format "Read NEWS for the version (default %s): " current)
-                     (mapcar 'car map) nil nil nil nil current))
-           (file (cadr (assoc version map)))
-           res)
-      (if (not file)
-          (error "No news is good news")
-        (view-file (expand-file-name file data-directory))
-        (widen)
-        (goto-char (point-min))
-        (when (re-search-forward
-               (concat (if (string-match "^ONEWS\\.[0-9]+$" file)
-                           "Changes in \\(?:Emacs\\|version\\)?[ \t]*"
-                         "^\* [^0-9\n]*") version)
-               nil t)
-          (beginning-of-line)
-          (narrow-to-region
-           (point)
-           (save-excursion
-             (while (and (setq res
-                               (re-search-forward
-                                (if (string-match "^ONEWS\\.[0-9]+$" file)
-                                    "Changes in \\(?:Emacs\\|version\\)?[ \t]*\\([0-9]+\\(?:\\.[0-9]+\\)?\\)"
-                                  "^\* [^0-9\n]*\\([0-9]+\\.[0-9]+\\)") nil t))
-                         (equal (match-string-no-properties 1) version)))
-             (or res (goto-char (point-max)))
-             (beginning-of-line)
-             (point))))))))
+  (unless version
+    (setq version emacs-major-version))
+  (when (consp version)
+    (let* ((all-versions
+            (let (res)
+              (mapcar
+               (lambda (file)
+                 (with-temp-buffer
+                   (insert-file-contents
+                    (expand-file-name file data-directory))
+                   (while (re-search-forward
+                           (if (member file '("NEWS.18" "NEWS.1-17"))
+                               "Changes in \\(?:Emacs\\|version\\)?[ \t]*\\([0-9]+\\(?:\\.[0-9]+\\)?\\)"
+                             "^\* [^0-9\n]*\\([0-9]+\\.[0-9]+\\)") nil t)
+                     (setq res (cons (match-string-no-properties 1) res)))))
+               (cons "NEWS"
+                     (directory-files data-directory nil
+                                      "^NEWS\\.[0-9][-0-9]*$" nil)))
+              (sort (delete-dups res) (lambda (a b) (string< b a)))))
+           (current (car all-versions))
+           res)
+      (setq version (completing-read
+                     (format "Read NEWS for the version (default %s): " current)
+                     all-versions nil nil nil nil current))
+      (if (integerp (string-to-number version))
+          (setq version (string-to-number version))
+        (unless (or (member version all-versions)
+                    (<= (string-to-number version) (string-to-number current)))
+          (error "No news about version %s" version)))))
+  (when (integerp version)
+    (cond ((<= version 12)
+           (setq version (format "1.%d" version)))
+          ((<= version 18)
+           (setq version (format "%d" version)))
+          ((> version emacs-major-version)
+           (error "No news about emacs %d (yet)" version))))
+  (let* ((vn (if (stringp version)
+                 (string-to-number version)
+               version))
+         (file (cond
+                ((>= vn emacs-major-version) "NEWS")
+                ((< vn 18) "NEWS.1-17")
+                (t (format "NEWS.%d" vn)))))
+    (view-file (expand-file-name file data-directory))
+    (widen)
+    (goto-char (point-min))
+    (when (stringp version)
+      (when (re-search-forward
+             (concat (if (< vn 19)
+                         "Changes in Emacs[ \t]*"
+                       "^\* [^0-9\n]*") version "$")
+             nil t)
+        (beginning-of-line)
+        (narrow-to-region
+         (point)
+         (save-excursion
+           (while (and (setq res
+                             (re-search-forward
+                              (if (< vn 19)
+                                  "Changes in \\(?:Emacs\\|version\\)?[ \t]*\\([0-9]+\\(?:\\.[0-9]+\\)?\\)"
+                                "^\* [^0-9\n]*\\([0-9]+\\.[0-9]+\\)") nil t))
+                       (equal (match-string-no-properties 1) version)))
+           (or res (goto-char (point-max)))
+           (beginning-of-line)
+           (point)))))))
+
 
 (defun view-todo (&optional arg)
   "Display the Emacs TODO list."