crecord: new keys g & G to navigate to the top and bottom respectively

This patch introduces two new keys 'g' and 'G' that helps to navigate to the
top and bottom of the file/hunk/line respectively. This is inline with the shortcuts
used in man, less, more and such tools that makes it convenient to navigate
swiftly.

'g' or HOME navigates to the top most file in the ncurses window.

'G' or END navigates to the bottom most file/hunk/line depending on the whether
the fold is active or not.

If the bottom most file is folded, it navigates to that file and stops there.
If the bottom most file is unfolded, it navigates to the bottom most hunk in
that file and stops there. If the bottom most hunk is unfolded, it navigates to
the bottom most line in that hunk.

Differential Revision: https://phab.mercurial-scm.org/D6178

mercurial/crecord.py

@@ -1467,6 +1467,8 b' the following are valid keystrokes:'
         pgup/pgdn [K/J] : go to previous/next item of same type
  right/left-arrow [l/h] : go to child item / parent item
  shift-left-arrow   [H] : go to parent header / fold selected header
+                      g : go to the top
+                      G : go to the bottom
                       f : fold / unfold item, hiding/revealing its children
                       F : fold / unfold parent item and all of its ancestors
                  ctrl-l : scroll the selected line to the top of the screen
@@ -1505,6 +1507,45 b' the following are valid keystrokes:'
         self.stdscr.refresh()
         self.stdscr.keypad(1) # allow arrow-keys to continue to function
 
+    def handlefirstlineevent(self):
+        """
+        Handle 'g' to navigate to the top most file in the ncurses window.
+        """
+        self.currentselecteditem = self.headerlist[0]
+        currentitem = self.currentselecteditem
+        # select the parent item recursively until we're at a header
+        while True:
+            nextitem = currentitem.parentitem()
+            if nextitem is None:
+                break
+            else:
+                currentitem = nextitem
+
+        self.currentselecteditem = currentitem
+
+    def handlelastlineevent(self):
+        """
+        Handle 'G' to navigate to the bottom most file/hunk/line depending
+        on the whether the fold is active or not.
+
+        If the bottom most file is folded, it navigates to that file and
+        stops there. If the bottom most file is unfolded, it navigates to
+        the bottom most hunk in that file and stops there. If the bottom most
+        hunk is unfolded, it navigates to the bottom most line in that hunk.
+        """
+        currentitem = self.currentselecteditem
+        nextitem = currentitem.nextitem()
+        # select the child item recursively until we're at a footer
+        while nextitem is not None:
+            nextitem = currentitem.nextitem()
+            if nextitem is None:
+                break
+            else:
+                currentitem = nextitem
+
+        self.currentselecteditem = currentitem
+        self.recenterdisplayedarea()
+
     def confirmationwindow(self, windowtext):
         "display an informational window, then wait for and return a keypress."
 
@@ -1725,6 +1766,10 b' are you sure you want to review/edit and'
             self.togglefolded(foldparent=True)
         elif keypressed in ["m"]:
             self.commitMessageWindow()
+        elif keypressed in ["g", "KEY_HOME"]:
+            self.handlefirstlineevent()
+        elif keypressed in ["G", "KEY_END"]:
+            self.handlelastlineevent()
         elif keypressed in ["?"]:
             self.helpwindow()
             self.stdscr.clear()