browser: allow backward/forward re-searches with Alt+Up/Alt+Down

Also bind 'N' to a backward re-search, while retaining 'n' for a
forward one,  This matches the functionality in the help viewer.

src/browser.c

@@ -171,11 +171,15 @@ char *do_browser(char *path)
 	    say_there_is_no_help();
 #endif
 	} else if (func == do_search) {
-	    /* Search for a filename. */
 	    do_filesearch();
 	} else if (func == do_research) {
-	    /* Search for another filename. */
-	    do_fileresearch();
+	    do_fileresearch(FALSE);
+#ifndef NANO_TINY
+	} else if (func == do_findprevious) {
+	    do_fileresearch(TRUE);
+	} else if (func == do_findnext) {
+	    do_fileresearch(FALSE);
+#endif
 	} else if (func == do_left) {
 	    if (selected > 0)
 		selected--;
@@ -488,6 +492,9 @@ functionptrtype parse_browser_input(int *kbinput)
 	    case '/':
 		return do_search;
 	    case 'N':
+#ifndef NANO_TINY
+		return do_findprevious;
+#endif
 	    case 'n':
 		return do_research;
 	}
@@ -697,8 +704,9 @@ int filesearch_init(void)
     return input;
 }
 
-/* Look for the given needle in the list of files. */
-void findnextfile(const char *needle)
+/* Look for the given needle in the list of files.  If forwards is TRUE,
+ * search forward in the list; otherwise, search backward. */
+void findfile(const char *needle, bool forwards)
 {
     size_t looking_at = selected;
 	/* The location in the file list of the filename we're looking at. */
@@ -718,12 +726,16 @@ void findnextfile(const char *needle)
     /* Step through each filename in the list until a match is found or
      * we've come back to the point where we started. */
     while (TRUE) {
-	/* Move to the next filename in the list, or back to the first. */
-	if (looking_at < filelist_len - 1)
-	    looking_at++;
-	else {
-	    looking_at = 0;
-	    statusbar(_("Search Wrapped"));
+	if (forwards) {
+	    if (looking_at++ == filelist_len - 1) {
+		looking_at = 0;
+		statusbar(_("Search Wrapped"));
+	    }
+	} else {
+	    if (looking_at-- == 0) {
+		looking_at = filelist_len - 1;
+		statusbar(_("Search Wrapped"));
+	    }
 	}
 
 	/* Get the bare filename, without the path. */
@@ -770,16 +782,17 @@ void do_filesearch(void)
 	update_history(&search_history, answer);
 #endif
 
-    findnextfile(answer);
+    findfile(answer, TRUE);
 }
 
-/* Search again for the last given filename, without prompting. */
-void do_fileresearch(void)
+/* Search again without prompting for the last given search string,
+ * either forwards or backwards. */
+void do_fileresearch(bool forwards)
 {
     if (*last_search == '\0')
 	statusbar(_("No current search pattern"));
     else
-	findnextfile(last_search);
+	findfile(last_search, forwards);
 }
 
 /* Select the first file in the list. */

src/global.c

@@ -1143,8 +1143,8 @@ void shortcut_init(void)
 	add_to_sclist(MMAIN, "M-\xE2\x86\x92", ALT_RIGHT, switch_to_next_buffer_void, 0);
 #endif
 #ifndef NANO_TINY
-	add_to_sclist(MMAIN|MHELP, "M-\xE2\x86\x91", ALT_UP, do_findprevious, 0);
-	add_to_sclist(MMAIN|MHELP, "M-\xE2\x86\x93", ALT_DOWN, do_findnext, 0);
+	add_to_sclist(MMAIN|MHELP|MBROWSER, "M-\xE2\x86\x91", ALT_UP, do_findprevious, 0);
+	add_to_sclist(MMAIN|MHELP|MBROWSER, "M-\xE2\x86\x93", ALT_DOWN, do_findnext, 0);
 #endif
     } else
 #endif

src/proto.h

@@ -186,7 +186,7 @@ functionptrtype parse_browser_input(int *kbinput);
 void browser_refresh(void);
 void browser_select_dirname(const char *needle);
 void do_filesearch(void);
-void do_fileresearch(void);
+void do_fileresearch(bool forwards);
 void do_first_file(void);
 void do_last_file(void);
 char *strip_last_component(const char *path);