--- a/mercurial/commands.py	Wed Jul 17 18:15:51 2019 +0200
+++ b/mercurial/commands.py	Mon Jul 15 22:23:31 2019 +0530
@@ -1893,6 +1893,32 @@
         return 0
     return 1
 
+@command('continue',
+    dryrunopts, helpcategory=command.CATEGORY_CHANGE_MANAGEMENT,
+    helpbasic=True)
+def continuecmd(ui, repo, **opts):
+    """resumes an interrupted operation (EXPERIMENTAL)
+
+    Finishes a multistep operation like graft, histedit, rebase, merge,
+    and unshelve if they are in an interrupted state.
+
+    use --dry-run/-n to dry run the command.
+    A new operation can be added to this by registering the operation and
+    continue logic in the unfinishedstates list under statemod.
+    """
+    dryrun = opts.get(r'dry_run')
+    contstate = cmdutil.getunfinishedstate(repo)
+    if not contstate:
+        raise error.Abort(_('no operation in progress'))
+    if not contstate.continuefunc:
+        raise error.Abort((_("%s in progress but does not support "
+                             "'hg continue'") % (contstate._opname)),
+                             hint=contstate.continuemsg())
+    if dryrun:
+        ui.status(_('%s in progress, will be resumed\n') % (contstate._opname))
+        return
+    return contstate.continuefunc(ui, repo)
+
 @command('copy|cp',
     [('A', 'after', None, _('record a copy that has already occurred')),
     ('f', 'force', None, _('forcibly copy over an existing managed file')),

--- a/mercurial/state.py	Wed Jul 17 18:15:51 2019 +0200
+++ b/mercurial/state.py	Mon Jul 15 22:23:31 2019 +0530
@@ -99,7 +99,7 @@
 
     def __init__(self, opname, fname, clearable, allowcommit, reportonly,
                  continueflag, stopflag, cmdmsg, cmdhint, statushint,
-                 abortfunc):
+                 abortfunc, continuefunc):
         self._opname = opname
         self._fname = fname
         self._clearable = clearable
@@ -111,6 +111,7 @@
         self._cmdhint = cmdhint
         self._statushint = statushint
         self.abortfunc = abortfunc
+        self.continuefunc = continuefunc
 
     def statusmsg(self):
         """returns the hint message corresponding to the command for
@@ -159,7 +160,8 @@
 
 def addunfinished(opname, fname, clearable=False, allowcommit=False,
                   reportonly=False, continueflag=False, stopflag=False,
-                  cmdmsg="", cmdhint="", statushint="", abortfunc=None):
+                  cmdmsg="", cmdhint="", statushint="", abortfunc=None,
+                  continuefunc=None):
     """this registers a new command or operation to unfinishedstates
     opname is the name the command or operation
     fname is the file name in which data should be stored in .hg directory.
@@ -184,10 +186,12 @@
     message of the format ('To continue:    hg cmdname --continue'
     'To abort:       hg cmdname --abort') is not desired
     abortfunc stores the function required to abort an unfinished state.
+    continuefunc stores the function required to finish an interrupted
+    operation.
     """
     statecheckobj = _statecheck(opname, fname, clearable, allowcommit,
                                 reportonly, continueflag, stopflag, cmdmsg,
-                                cmdhint, statushint, abortfunc)
+                                cmdhint, statushint, abortfunc, continuefunc)
     if opname == 'merge':
         _unfinishedstates.append(statecheckobj)
     else:

--- a/tests/test-completion.t	Wed Jul 17 18:15:51 2019 +0200
+++ b/tests/test-completion.t	Mon Jul 15 22:23:31 2019 +0530
@@ -15,6 +15,7 @@
   clone
   commit
   config
+  continue
   copy
   diff
   export
@@ -252,6 +253,7 @@
   clone: noupdate, updaterev, rev, branch, pull, uncompressed, stream, ssh, remotecmd, insecure
   commit: addremove, close-branch, amend, secret, edit, force-close-branch, interactive, include, exclude, message, logfile, date, user, subrepos
   config: untrusted, edit, local, global, template
+  continue: dry-run
   copy: after, force, include, exclude, dry-run
   debugancestor: 
   debugapplystreamclonebundle: 

--- a/tests/test-help.t	Wed Jul 17 18:15:51 2019 +0200
+++ b/tests/test-help.t	Mon Jul 15 22:23:31 2019 +0530
@@ -408,6 +408,7 @@
                  show changeset information by line for each file
    clone         make a copy of an existing repository
    commit, ci    commit the specified files or all outstanding changes
+   continue      resumes an interrupted operation (EXPERIMENTAL)
    diff          diff repository (or selected files)
    export        dump the header and diffs for one or more changesets
    forget        forget the specified files on the next commit
@@ -2389,6 +2390,13 @@
   commit the specified files or all outstanding changes
   </td></tr>
   <tr><td>
+  <a href="/help/continue">
+  continue
+  </a>
+  </td><td>
+  resumes an interrupted operation (EXPERIMENTAL)
+  </td></tr>
+  <tr><td>
   <a href="/help/diff">
   diff
   </a>

--- a/tests/test-hgweb-json.t	Wed Jul 17 18:15:51 2019 +0200
+++ b/tests/test-hgweb-json.t	Mon Jul 15 22:23:31 2019 +0530
@@ -1895,6 +1895,10 @@
         "topic": "commit"
       },
       {
+        "summary": "resumes an interrupted operation (EXPERIMENTAL)",
+        "topic": "continue"
+      },
+      {
         "summary": "diff repository (or selected files)",
         "topic": "diff"
       },