* lisp/info.el (Info-file-completions): New variable.

(Info-read-node-name-1): Complete node names in the Info file
when a file name is given.  Call `Info-build-node-completions'
with a file name.
(Info-build-node-completions): Add new arg `file'.  When it is
non-nil, visit it in a temporary buffer and cache its completions in
`Info-current-file-completions'.  Move most of the function body to
`Info-build-node-completions-1'.
(Info-build-node-completions-1): New function with the body from
`Info-build-node-completions'.

Fixes: debbugs:12456

2 files changed, 78 insertions, 40 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 747662ee468..34cb50bb44c 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,18 @@
 2012-12-27  Juri Linkov  <juri@jurta.org>
 
+        * info.el (Info-file-completions): New variable.
+        (Info-read-node-name-1): Complete node names in the Info file
+        when a file name is given.  Call `Info-build-node-completions'
+        with a file name.
+        (Info-build-node-completions): Add new arg `file'.  When it is
+        non-nil, visit it in a temporary buffer and cache its completions in
+        `Info-current-file-completions'.  Move most of the function body to
+        `Info-build-node-completions-1'.
+        (Info-build-node-completions-1): New function with the body from
+        `Info-build-node-completions'.  (Bug#12456)
+
+2012-12-27  Juri Linkov  <juri@jurta.org>
+
         * frame.el (frame-maximization-style): Remove user option.
         (cycle-frame-maximized): Remove function.
         (toggle-frame-maximized): Rewrite and bind to M-<f10>.
diff --git a/lisp/info.el b/lisp/info.el
index 4c7bb981afc..19f9212f88a 100644
--- a/lisp/info.el
+++ b/lisp/info.el
@@ -397,6 +397,10 @@ Marker points nowhere if file has no tag table.")
 (defvar Info-current-file-completions nil
   "Cached completion list for current Info file.")
 
+(defvar Info-file-completions nil
+  "Cached completion alist of visited Info files.
+Each element of the alist is (FILE . COMPLETIONS)")
+
 (defvar Info-file-supports-index-cookies nil
   "Non-nil if current Info file supports index cookies.")
 
@@ -1771,12 +1775,20 @@ See `completing-read' for a description of arguments and usage."
      (substring string 1)
      predicate
      code))
-   ;; If a file name was given, then any node is fair game.
-   ((string-match "\\`(" string)
-    (cond
-     ((eq code nil) string)
-     ((eq code t) nil)
-     (t t)))
+   ;; If a file name was given, complete nodes in the file.
+   ((string-match "\\`(\\([^)]+\\))" string)
+    (let ((file0 (match-string 0 string))
+          (file1 (match-string 1 string))
+          (node (substring string (match-end 0))))
+      (completion-table-with-context
+       file0
+       (apply-partially
+        (lambda (string pred action)
+          (complete-with-action
+           action
+           (Info-build-node-completions (Info-find-file file1))
+           string pred)))
+       node predicate code)))
    ;; Otherwise use Info-read-node-completion-table.
    (t (complete-with-action
        code Info-read-node-completion-table string predicate))))
@@ -1793,41 +1805,54 @@ in the current Info file, or \"(FILENAME)NODENAME\"."
         (Info-read-node-name prompt)
       nodename)))
 
-(defun Info-build-node-completions ()
-  (or Info-current-file-completions
-      (let ((compl nil)
-            ;; Bind this in case the user sets it to nil.
-            (case-fold-search t)
-            (node-regexp "Node: *\\([^,\n]*\\) *[,\n\t]"))
-        (save-excursion
-          (save-restriction
-            (or Info-tag-table-marker
-                (error "No Info tags found"))
-            (if (marker-buffer Info-tag-table-marker)
-                (let ((marker Info-tag-table-marker))
-                  (set-buffer (marker-buffer marker))
-                  (widen)
-                  (goto-char marker)
-                  (while (re-search-forward "\n\\(Node\\|Ref\\): \\(.*\\)\177" nil t)
-                    (setq compl
-                          (cons (list (match-string-no-properties 2))
-                                compl))))
+(defun Info-build-node-completions (&optional file)
+  (if file
+      (or (cdr (assoc file Info-file-completions))
+          (with-temp-buffer
+            (Info-mode)
+            (Info-goto-node (format "(%s)Top" file))
+            (Info-build-node-completions-1)
+            (push (cons file Info-current-file-completions) Info-file-completions)
+            Info-current-file-completions))
+    (or Info-current-file-completions
+        (Info-build-node-completions-1))))
+
+(defun Info-build-node-completions-1 ()
+  (let ((compl nil)
+        ;; Bind this in case the user sets it to nil.
+        (case-fold-search t)
+        (node-regexp "Node: *\\([^,\n]*\\) *[,\n\t]"))
+    (save-excursion
+      (save-restriction
+        (or Info-tag-table-marker
+            (error "No Info tags found"))
+        (if (marker-buffer Info-tag-table-marker)
+            (let ((marker Info-tag-table-marker))
+              (set-buffer (marker-buffer marker))
               (widen)
-              (goto-char (point-min))
-              ;; If the buffer begins with a node header, process that first.
-              (if (Info-node-at-bob-matching node-regexp)
-                  (setq compl (list (match-string-no-properties 1))))
-              ;; Now for the rest of the nodes.
-              (while (search-forward "\n\^_" nil t)
-                (forward-line 1)
-                (let ((beg (point)))
-                  (forward-line 1)
-                  (if (re-search-backward node-regexp beg t)
-                      (setq compl
-                            (cons (list (match-string-no-properties 1))
-                                  compl))))))))
-        (setq compl (cons '("*") compl))
-        (set (make-local-variable 'Info-current-file-completions) compl))))
+              (goto-char marker)
+              (while (re-search-forward "\n\\(Node\\|Ref\\): \\(.*\\)\177" nil t)
+                (setq compl
+                      (cons (list (match-string-no-properties 2))
+                            compl))))
+          (widen)
+          (goto-char (point-min))
+          ;; If the buffer begins with a node header, process that first.
+          (if (Info-node-at-bob-matching node-regexp)
+              (setq compl (list (match-string-no-properties 1))))
+          ;; Now for the rest of the nodes.
+          (while (search-forward "\n\^_" nil t)
+            (forward-line 1)
+            (let ((beg (point)))
+              (forward-line 1)
+              (if (re-search-backward node-regexp beg t)
+                  (setq compl
+                        (cons (list (match-string-no-properties 1))
+                              compl))))))))
+    (setq compl (cons '("*") (nreverse compl)))
+    (set (make-local-variable 'Info-current-file-completions) compl)
+    compl))
+
 
 (defun Info-restore-point (hl)
   "If this node has been visited, restore the point value when we left."