diff --git a/hgext/purge.py b/hgext/purge.py
--- a/hgext/purge.py
+++ b/hgext/purge.py
@@ -25,16 +25,12 @@
 '''command to delete untracked files from the working directory'''
 from __future__ import absolute_import
 
-import os
-
 from mercurial.i18n import _
 from mercurial import (
     cmdutil,
-    error,
+    merge as mergemod,
     pycompat,
     registrar,
-    scmutil,
-    util,
 )
 
 cmdtable = {}
@@ -86,44 +82,27 @@
     option.
     '''
     opts = pycompat.byteskwargs(opts)
+
     act = not opts.get('print')
     eol = '\n'
     if opts.get('print0'):
         eol = '\0'
-        act = False # --print0 implies --print
+        act = False  # --print0 implies --print
+
     removefiles = opts.get('files')
     removedirs = opts.get('dirs')
+
     if not removefiles and not removedirs:
         removefiles = True
         removedirs = True
 
-    def remove(remove_func, name):
-        if act:
-            try:
-                remove_func(repo.wjoin(name))
-            except OSError:
-                m = _('%s cannot be removed') % name
-                if opts.get('abort_on_err'):
-                    raise error.Abort(m)
-                ui.warn(_('warning: %s\n') % m)
-        else:
-            ui.write('%s%s' % (name, eol))
+    paths = mergemod.purge(
+        repo, dirs, ignored=opts.get('all', False),
+        removeemptydirs=removedirs, removefiles=removefiles,
+        abortonerror=opts.get('abort_on_err'),
+        include=opts.get('include'), exclude=opts.get('exclude'),
+        noop=opts.get('print') or opts.get('print0'))
 
-    match = scmutil.match(repo[None], dirs, opts)
-    if removedirs:
-        directories = []
-        match.explicitdir = match.traversedir = directories.append
-    status = repo.status(match=match, ignored=opts.get('all'), unknown=True)
-
-    if removefiles:
-        for f in sorted(status.unknown + status.ignored):
-            if act:
-                ui.note(_('removing file %s\n') % f)
-            remove(util.unlink, f)
-
-    if removedirs:
-        for f in sorted(directories, reverse=True):
-            if match(f) and not os.listdir(repo.wjoin(f)):
-                if act:
-                    ui.note(_('removing directory %s\n') % f)
-                remove(os.rmdir, f)
+    for path in paths:
+        if not act:
+            ui.write('%s%s' % (path, eol))
diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -9,6 +9,7 @@
 
 import errno
 import hashlib
+import os
 import shutil
 import struct
 
@@ -2240,3 +2241,63 @@
         # fix up dirstate for copies and renames
         copies.duplicatecopies(repo, repo[None], ctx.rev(), pctx.rev())
     return stats
+
+def purge(repo, dirs=None, ignored=False, removeemptydirs=True,
+          removefiles=True, abortonerror=False, include=None, exclude=None,
+          noop=False):
+    """Purge the working directory of untracked files.
+
+    ``dirs`` is an iterable of directories to purge. If not defined, all
+    directories will be examined.
+
+    ``ignored`` controls whether ignored files should also be purged.
+
+    ``removeemptydirs`` controls whether empty directories should be removed.
+
+    ``removefiles`` controls whether files are removed.
+
+    ``abortonerror`` causes an exception to be raised if an error occurs
+    deleting a file or directory.
+
+    ``include`` and ``exclude`` are optional path filters to include or exclude.
+
+    ``noop`` controls whether to actually remove files. If not defined, actions
+    will be taken.
+
+    The function is a generator of relative paths in the working directory
+    that were or would be removed.
+    """
+
+    def remove(removefn, path):
+        try:
+            removefn(repo.wvfs.join(path))
+        except OSError:
+            m = _('%s cannot be removed') % path
+            if abortonerror:
+                raise error.Abort(m)
+            else:
+                repo.ui.warn(_('warning: %s\n') % m)
+
+    match = scmutil.match(repo[None], dirs or (),
+                          {'include': include, 'exclude': exclude})
+
+    if removeemptydirs:
+        directories = []
+        match.explicitdir = match.traversedir = directories.append
+
+    status = repo.status(match=match, ignored=ignored, unknown=True)
+
+    if removefiles:
+        for f in sorted(status.unknown + status.ignored):
+            if not noop:
+                repo.ui.note(_('removing file %s\n') % f)
+                remove(util.unlink, f)
+            yield f
+
+    if removeemptydirs:
+        for f in sorted(directories, reverse=True):
+            if match(f) and not os.listdir(repo.wvfs.join(f)):
+                if not noop:
+                    repo.ui.note(_('removing directory %s\n') % f)
+                    remove(os.rmdir, f)
+                yield f