diff --git a/doc/UltiSnips.txt b/doc/UltiSnips.txt
index 2c8e5e4..9d6f88a 100644
--- a/doc/UltiSnips.txt
+++ b/doc/UltiSnips.txt
@@ -38,6 +38,10 @@ UltiSnips                                      *snippet* *snippets* *UltiSnips*
       4.7.2 Demos                               |UltiSnips-demos|
    4.8 Clearing snippets                        |UltiSnips-clearing-snippets|
    4.9 Context snippets                         |UltiSnips-context-snippets|
+   4.10 Snippet actions                         |UltiSnips-snippet-actions|
+      4.10.1 Pre-expand actions                 |UltiSnips-pre-expand-actions|
+      4.10.2 Post-expand actions                |UltiSnips-post-expand-actions|
+      4.10.3 Post-jump actions                  |UltiSnips-post-jump-actions|
 5. UltiSnips and Other Plugins                  |UltiSnips-other-plugins|
    5.1 Existing Integrations                    |UltiSnips-integrations|
    5.2 Extending UltiSnips                      |UltiSnips-extending|
@@ -1417,6 +1421,179 @@ endsnippet
 That snippet will expand to 'var1 +=' after line, which begins from 'var1 :='.
 
 
+4.10 Snippets actions                             *UltiSnips-snippets-actions*
+---------------------
+
+Snippet actions is an arbitrary python code which can be executed at specific
+points in lifetime of the snippet.
+
+There are three types of actions:
+
+* Pre-expand - invoked just after trigger condition was matched, but before
+  snippet actually expanded;
+* Post-expand - invoked after snippet was expanded and interpolations
+  was applied for the first time, but before jump on the first placeholder.
+* Jump - invoked just after jump to the next/prev placeholder.
+
+Specified code will be evaluated at stages defined above and same global
+variables and modules will be available that are stated in
+the *UltiSnips-context-snippets* section.
+
+Note: special variable called 'buffer' should be used for all buffer
+modifications. Not 'vim.current.buffer' and not 'vim.command("...")', because
+of in that case UltiSnips will not be able to track changes buffer from
+actions.
+
+4.10.1 Pre-expand actions                       *UltiSnips-pre-expand-actions*
+
+Pre-expand actions can be used to match snippet in one location and then
+expand it in the different location. Some useful cases are: correcting
+indentation for snippet; expanding snippet for function declaration in another
+function body with moving expansion point beyond initial function; performing
+extract method refactoring via expanding snippet in different place.
+
+Pre-expand action declared as follows: >
+    pre_expand "python code here"
+    snippet ...
+    endsnippet
+
+Buffer can be modified in pre-expand action code through variable called
+'buffer', snippet expansion position will be automatically adjusted.
+
+If cursor line (where trigger was matched) need to be modified, then special
+variable named 'new_cursor' must be set to the desired cursor position. In
+that case UltiSnips will not remove any matched trigger text and it should
+be done manually in action code.
+
+To addition to the scope variables defined above 'visual_content' will be also
+declared and will contain text that was selected before snippet expansion
+(similar to $VISUAL placeholder).
+
+Following snippet will be expanded at 4 spaces indentation level no matter
+where it was triggered.
+
+------------------- SNIP -------------------
+pre_expand "buffer[line] = ' '*4; new_cursor = (line, 4)"
+snippet d
+def $1():
+    $0
+endsnippet
+------------------- SNAP -------------------
+
+Following snippet will move the selected code to the end of file and create
+new method definition for it:
+
+------------------- SNIP -------------------
+pre_expand "del buffer[line]; buffer.append(''); new_cursor = (len(buffer)-1, 0)"
+snippet x
+def $1():
+	${2:${VISUAL}}
+endsnippet
+------------------- SNAP -------------------
+
+4.10.2 Post-expand actions                     *UltiSnips-post-expand-actions*
+
+Post-expand actions can be used to perform some actions based on the expanded
+snippet text. Some cases are: code style formatting (e.g. inserting newlines
+before and after method declaration), apply actions depending on python
+interpolation result.
+
+Post-expand action declared as follows: >
+    post_expand "python code here"
+    snippet ...
+    endsnippet
+
+Buffer can be modified in post-expand action code through variable called
+'buffer', snippet expansion position will be automatically adjusted.
+
+Variables 'snippet_start' and 'snippet_end' will be defined at the action code
+scope and will point to positions of the start and end of expanded snippet
+accordingly in the form '(line, column)'.
+
+Note: 'snippet_start' and 'snippet_end' will automatically adjust to the
+correct positions if post-action will insert or delete lines before expansion.
+
+Following snippet will expand to method definition and automatically insert
+additional newline after end of the snippet. It's very useful to create a
+function that will insert as many newlines as required in specific context.
+
+------------------- SNIP -------------------
+post_expand "buffer[snippet_end[0]+1:snippet_end[0]+1] = ['']"
+snippet d "Description" b
+def $1():
+	$2
+endsnippet
+------------------- SNAP -------------------
+
+4.10.3 Post-jump actions                         *UltiSnips-post-jump-actions*
+
+Post-jump actions can be used to trigger some code based on user input into
+the placeholders. Notable use cases: expand another snippet after jump or
+anonymous snippet after last jump (e.g. perform move method refactoring and
+then insert new method invokation); insert heading into TOC after last jump.
+
+Jump-expand action declared as follows: >
+    post_jump "python code here"
+    snippet ...
+    endsnippet
+
+Buffer can be modified in post-expand action code through variable called
+'buffer', snippet expansion position will be automatically adjusted.
+
+Next variables will be also defined in the action code scope:
+* 'tabstop' - number of tabstop jumped onto;
+* 'jump_direction' - '1' if jumped forward and '-1' otherwise;
+* 'tabstops' - list with tabstop objects, see above;
+* 'snippet_start' - (line, column) of start of the expanded snippet;
+* 'snippet_end' - (line, column) of end of the expanded snippet;
+
+Tabstop object has several useful properties:
+* 'start' - (line, column) of the starting position of the tabstop (also
+  accessible as 'tabstop.line' and 'tabstop.col').
+* 'end' - (line, column) of the ending position;
+* 'current_text' - text inside the tabstop.
+
+Following snippet will insert section in the Table of Contents in the vim-help
+file:
+
+------------------- SNIP -------------------
+post_jump "if tabstop == 0: insert_toc_item(tabstops[1], buffer)"
+snippet s "section" b
+`!p insert_delimiter_0(snip, t)`$1`!p insert_section_title(snip, t)`
+`!p insert_delimiter_1(snip, t)`
+$0
+endsnippet
+------------------- SNAP -------------------
+
+'insert_toc_item' will be called after first jump and will add newly entered
+section into the TOC for current file.
+
+Note: It is also possible to trigger snippet expansion from the jump action.
+In that case 'new_cursor' should be set to special value named '"keep"', so
+UltiSnips will know that cursor is already at the required position.
+
+Following example will insert method call at the end of file after user jump
+out of method declaration snippet.
+
+------------------- SNIP -------------------
+global !p
+from UltiSnips import UltiSnips_Manager
+
+def insert_method_call(name):
+	global new_cursor
+
+	vim.command('normal G')
+	UltiSnips_Manager.expand_anon(name + '($1)\n')
+	new_cursor = 'keep'
+endglobal
+
+post_jump "if tabstop == 0: insert_method_call(tabstops[1].current_text)"
+snippet d "method declaration" b
+def $1():
+	$2
+endsnippet
+------------------- SNAP -------------------
+
 ==============================================================================
 5. UltiSnips and Other Plugins                      *UltiSnips-other-plugins*
 
diff --git a/pythonx/UltiSnips/_vim.py b/pythonx/UltiSnips/_vim.py
index 9665a2b..09cc32b 100644
--- a/pythonx/UltiSnips/_vim.py
+++ b/pythonx/UltiSnips/_vim.py
@@ -108,7 +108,18 @@ def feedkeys(keys, mode='n'):
     Mainly for convenience.
 
     """
-    command(as_unicode(r'call feedkeys("%s", "%s")') % (keys, mode))
+    if eval('mode()') == 'n':
+        if keys == 'a':
+            cursor_pos = get_cursor_pos()
+            cursor_pos[2] = int(cursor_pos[2]) + 1
+            set_cursor_from_pos(cursor_pos)
+        if keys in 'ai':
+            keys = 'startinsert'
+
+    if keys == 'startinsert':
+        command('startinsert')
+    else:
+        command(as_unicode(r'call feedkeys("%s", "%s")') % (keys, mode))
 
 
 def new_scratch_buffer(text):
@@ -137,13 +148,15 @@ def select(start, end):
     col = col2byte(start.line + 1, start.col)
     vim.current.window.cursor = start.line + 1, col
 
+    mode = eval('mode()')
+
     move_cmd = ''
-    if eval('mode()') != 'n':
+    if mode != 'n':
         move_cmd += r"\<Esc>"
 
     if start == end:
         # Zero Length Tabstops, use 'i' or 'a'.
-        if col == 0 or eval('mode()') not in 'i' and \
+        if col == 0 or mode not in 'i' and \
                 col < len(buf[start.line]):
             move_cmd += 'i'
         else:
@@ -164,6 +177,32 @@ def select(start, end):
             start.line + 1, start.col + 1)
     feedkeys(move_cmd)
 
+def set_mark_from_pos(name, pos):
+    return _set_pos("'" + name, pos)
+
+def get_mark_pos(name):
+    return _get_pos("'" + name)
+
+def set_cursor_from_pos(pos):
+    return _set_pos('.', pos)
+
+def get_cursor_pos():
+    return _get_pos('.')
+
+def delete_mark(name):
+    try:
+        return command('delma ' + name)
+    except:
+        return False
+
+def _set_pos(name, pos):
+    return eval("setpos(\"{}\", {})".format(name, pos))
+
+def _get_pos(name):
+    return eval("getpos(\"{}\")".format(name))
+
+def _is_pos_zero(pos):
+    return ['0'] * 4 == pos or [0] == pos
 
 def _unmap_select_mode_mapping():
     """This function unmaps select mode mappings if so wished by the user.
diff --git a/pythonx/UltiSnips/buffer_helper.py b/pythonx/UltiSnips/buffer_helper.py
new file mode 100644
index 0000000..3c114f2
--- /dev/null
+++ b/pythonx/UltiSnips/buffer_helper.py
@@ -0,0 +1,100 @@
+# coding=utf8
+
+import vim
+from UltiSnips.position import Position
+from UltiSnips._diff import diff
+
+class VimBufferHelper:
+    def __init__(self, snippets_stack):
+        self._snippets_stack = snippets_stack
+        self._buffer = vim.current.buffer
+        self._buffer_copy = self._buffer[:]
+
+    def is_buffer_changed_outside(self):
+        if len(self._buffer) != len(self._buffer_copy):
+            return True
+
+        for line_number in range(0, len(self._buffer_copy)):
+            if self._buffer[line_number] != self._buffer_copy[line_number]:
+                return True
+
+        return False
+
+    def validate_buffer(self):
+        if self.is_buffer_changed_outside():
+            raise RuntimeError('buffer was modified using vim.command or ' +
+            'vim.current.buffer; that changes are untrackable and leads to' +
+            'errors in snippet expansion; use special variable `buffer` for' +
+            'buffer modifications')
+
+    def __setitem__(self, key, value):
+        if isinstance(key, slice):
+            changes = list(self._get_diff(key.start, key.stop, value))
+            self._buffer[key.start:key.stop] = value
+            self._buffer_copy[key.start:key.stop] = map(
+                lambda line: line.strip('\n'),
+                value
+            )
+            map(self._apply_change, changes)
+        else:
+            changes = list(self._get_line_diff(key, self._buffer[key], value))
+            self._buffer[key] = value
+            self._buffer_copy[key] = value
+            map(self._apply_change, changes)
+
+    def __getitem__(self, key):
+        if isinstance(key, slice):
+            return self._buffer[key.start:key.stop]
+        else:
+            return self._buffer[key]
+
+    def __len__(self):
+        return len(self._buffer)
+
+    def append(self, line, line_number=-1):
+        if line_number < 0:
+            line_number = len(self)
+        if not isinstance(line, list):
+            line = [line]
+        self[line_number:line_number] = line
+
+    def __delitem__(self, key):
+        if isinstance(key, slice):
+            self.__setitem__(key, [])
+        else:
+            self.__setitem__(slice(key, key+1), [])
+
+    def _get_diff(self, start, end, new_value):
+        for line_number in range(start, end):
+            yield ('D', line_number, 0, self._buffer[line_number])
+
+        for line_number in range(0, len(new_value)):
+            yield ('I', start+line_number, 0, new_value[line_number])
+
+    def _get_line_diff(self, line_number, before, after):
+        if before == '':
+            for change in self._get_diff(line_number, line_number+1, [after]):
+                yield change
+        else:
+            for change in diff(before, after):
+                yield (change[0], line_number, change[2], change[3])
+
+    def _apply_change(self, change):
+        if not self._snippets_stack:
+            return
+
+        line_number = change[1]
+        column_number = change[2]
+        line_before = line_number <= self._snippets_stack[0]._start.line
+        column_before = column_number <= self._snippets_stack[0]._start.col
+        if line_before and column_before:
+            direction = 1
+            if change[0] == 'D':
+                direction = -1
+
+            self._snippets_stack[0]._move(
+                Position(line_number, 0),
+                Position(direction, 0)
+            )
+        else:
+            self._snippets_stack[0]._do_edit(change)
diff --git a/pythonx/UltiSnips/position.py b/pythonx/UltiSnips/position.py
index c2a68f4..3c9d2a5 100644
--- a/pythonx/UltiSnips/position.py
+++ b/pythonx/UltiSnips/position.py
@@ -65,3 +65,13 @@ class Position(object):
 
     def __repr__(self):
         return '(%i,%i)' % (self.line, self.col)
+
+    def __getitem__(self, index):
+        if index > 1:
+            raise IndexError(
+                'position can be indexed only 0 (line) and 1 (column)'
+            )
+        if index == 0:
+            return self.line
+        else:
+            return self.col
diff --git a/pythonx/UltiSnips/snippet/definition/_base.py b/pythonx/UltiSnips/snippet/definition/_base.py
index 225807a..8a9b563 100644
--- a/pythonx/UltiSnips/snippet/definition/_base.py
+++ b/pythonx/UltiSnips/snippet/definition/_base.py
@@ -12,6 +12,8 @@ from UltiSnips.compatibility import as_unicode
 from UltiSnips.indent_util import IndentUtil
 from UltiSnips.text import escape
 from UltiSnips.text_objects import SnippetInstance
+from UltiSnips.position import Position
+from UltiSnips.buffer_helper import VimBufferHelper
 
 __WHITESPACE_SPLIT = re.compile(r"\s")
 def split_at_whitespace(string):
@@ -46,7 +48,7 @@ class SnippetDefinition(object):
     _TABS = re.compile(r"^\t*")
 
     def __init__(self, priority, trigger, value, description,
-                 options, globals, location, context):
+                 options, globals, location, context, actions):
         self._priority = int(priority)
         self._trigger = as_unicode(trigger)
         self._value = as_unicode(value)
@@ -58,6 +60,7 @@ class SnippetDefinition(object):
         self._location = location
         self._context_code = context
         self._context = None
+        self._actions = actions
 
         # Make sure that we actually match our trigger in case we are
         # immediately expanded.
@@ -84,29 +87,93 @@ class SnippetDefinition(object):
         return False
 
     def _context_match(self):
-        current = vim.current
         # skip on empty buffer
-        if len(current.buffer) == 1 and current.buffer[0] == "":
+        if len(vim.current.buffer) == 1 and vim.current.buffer[0] == "":
             return
 
+        return self._eval_code('holder["result"] = ' + self._context_code)
+
+    def _eval_code(self, code, additional_locals={}):
         code = "\n".join([
             'import re, os, vim, string, random',
             '\n'.join(self._globals.get('!p', [])).replace('\r\n', '\n'),
-            'context["match"] = ' + self._context_code,
-            ''
+            code
         ])
 
-        context = {'match': False}
+        current = vim.current
+
+        holder = {'result': False}
+
         locals = {
-            'context': context,
+            'holder': holder,
             'window': current.window,
             'buffer': current.buffer,
-            'line': current.window.cursor[0],
-            'column': current.window.cursor[1],
-            'cursor': current.window.cursor,
+            'line': current.window.cursor[0]-1,
+            'column': current.window.cursor[1]-1,
+            'cursor': (current.window.cursor[0]-1, current.window.cursor[1]-1)
         }
+
+        locals.update(additional_locals)
+
         exec(code, locals)
-        return context["match"]
+
+        return holder["result"]
+
+    def _execute_action(
+        self,
+        action,
+        context,
+        additional_locals={}
+    ):
+        mark_to_use = '`'
+        mark_pos = _vim.get_mark_pos(mark_to_use)
+
+        _vim.set_mark_from_pos(mark_to_use, _vim.get_cursor_pos())
+
+        cursor_line_before = _vim.buf.line_till_cursor
+
+        locals = {
+            'new_cursor': None,
+            'context': context,
+        }
+
+        locals.update(additional_locals)
+
+        new_cursor, new_context = self._eval_code(
+            action + "\nholder['result'] = (new_cursor, context)",
+            locals
+        )
+
+        cursor_set_in_action = False
+        if new_cursor:
+            if new_cursor != 'keep':
+                vim.current.window.cursor = (new_cursor[0]+1, new_cursor[1])
+            cursor_set_in_action = True
+        else:
+            new_mark_pos = _vim.get_mark_pos(mark_to_use)
+
+            cursor_invalid = False
+
+            if _vim._is_pos_zero(new_mark_pos):
+                cursor_invalid = True
+            else:
+                _vim.set_cursor_from_pos(new_mark_pos)
+                if cursor_line_before != _vim.buf.line_till_cursor:
+                    cursor_invalid = True
+
+            if cursor_invalid:
+                raise RuntimeError(
+                    'line under the cursor was modified, but "new_cursor" ' +
+                    'variable is not set; either set set "new_cursor" to ' +
+                    'new cursor position, or do not modify cursor line'
+                )
+
+            # restore original mark position
+            if _vim._is_pos_zero(mark_pos):
+                _vim.delete_mark(mark_to_use)
+            else:
+                _vim.set_mark_from_pos(mark_to_use, mark_pos)
+        return cursor_set_in_action, new_context
 
     def has_option(self, opt):
         """Check if the named option is set."""
@@ -243,6 +310,67 @@ class SnippetDefinition(object):
         objects alive inside of Vim."""
         raise NotImplementedError()
 
+    def do_pre_expand(self, visual_content, snippets_stack):
+        buffer = VimBufferHelper(snippets_stack)
+        if 'pre_expand' in self._actions:
+            locals = {'buffer': buffer, 'visual_content': visual_content}
+
+            cursor_set_in_action, new_context = self._execute_action(
+                self._actions['pre_expand'], self._context, locals
+            )
+
+            self._context = new_context
+
+            return buffer, cursor_set_in_action
+        else:
+            return buffer, False
+
+    def do_post_expand(self, start, end, snippets_stack):
+        buffer = VimBufferHelper(snippets_stack)
+        if 'post_expand' in self._actions:
+            locals = {
+                'snippet_start': start,
+                'snippet_end': end,
+                'buffer': buffer
+            }
+
+            cursor_set_in_action, new_context = self._execute_action(
+                self._actions['post_expand'], snippets_stack[0].context, locals
+            )
+
+            snippets_stack[0].context = new_context
+
+            return buffer, cursor_set_in_action
+        else:
+            return buffer, False
+
+    def do_post_jump(
+        self, tabstop_number, jump_direction, snippets_stack
+    ):
+        buffer = VimBufferHelper(snippets_stack)
+        if 'post_jump' in self._actions:
+            start = snippets_stack[0].start
+            end = snippets_stack[0].end
+            locals = {
+                'tabstop': tabstop_number,
+                'jump_direction': jump_direction,
+                'tabstops': snippets_stack[0].get_tabstops(),
+                'snippet_start': start,
+                'snippet_end': end,
+                'buffer': buffer
+            }
+
+            cursor_set_in_action, new_context = self._execute_action(
+                self._actions['post_jump'], snippets_stack[0].context, locals
+            )
+
+            snippets_stack[0].context = new_context
+
+            return buffer, cursor_set_in_action
+        else:
+            return buffer, (False, None)
+
+
     def launch(self, text_before, visual_content, parent, start, end):
         """Launch this snippet, overwriting the text 'start' to 'end' and
         keeping the 'text_before' on the launch line.
diff --git a/pythonx/UltiSnips/snippet/definition/snipmate.py b/pythonx/UltiSnips/snippet/definition/snipmate.py
index a77046b..8ab1e2a 100644
--- a/pythonx/UltiSnips/snippet/definition/snipmate.py
+++ b/pythonx/UltiSnips/snippet/definition/snipmate.py
@@ -16,7 +16,7 @@ class SnipMateSnippetDefinition(SnippetDefinition):
     def __init__(self, trigger, value, description, location):
         SnippetDefinition.__init__(self, self.SNIPMATE_SNIPPET_PRIORITY,
                                    trigger, value, description, '', {}, location,
-                                   None)
+                                   None, {})
 
     def instantiate(self, snippet_instance, initial_text, indent):
         parse_and_instantiate(snippet_instance, initial_text, indent)
diff --git a/pythonx/UltiSnips/snippet/source/file/_common.py b/pythonx/UltiSnips/snippet/source/file/_common.py
index 82ba603..ec4be60 100644
--- a/pythonx/UltiSnips/snippet/source/file/_common.py
+++ b/pythonx/UltiSnips/snippet/source/file/_common.py
@@ -10,3 +10,12 @@ def handle_extends(tail, line_index):
         return 'extends', ([p.strip() for p in tail.split(',')],)
     else:
         return 'error', ("'extends' without file types", line_index)
+
+
+def handle_action(head, tail, line_index):
+    if tail:
+        action = tail.strip('"').replace(r'\"', '"').replace(r'\\\\', r'\\')
+        return head, (action,)
+    else:
+        return 'error', ("'{}' without specified action".format(head),
+            line_index)
diff --git a/pythonx/UltiSnips/snippet/source/file/ultisnips.py b/pythonx/UltiSnips/snippet/source/file/ultisnips.py
index 0383997..2005ebd 100644
--- a/pythonx/UltiSnips/snippet/source/file/ultisnips.py
+++ b/pythonx/UltiSnips/snippet/source/file/ultisnips.py
@@ -10,7 +10,8 @@ import os
 from UltiSnips import _vim
 from UltiSnips.snippet.definition import UltiSnipsSnippetDefinition
 from UltiSnips.snippet.source.file._base import SnippetFileSource
-from UltiSnips.snippet.source.file._common import handle_extends
+from UltiSnips.snippet.source.file._common import handle_extends, \
+    handle_action
 from UltiSnips.text import LineIterator, head_tail
 
 
@@ -53,7 +54,9 @@ def find_all_snippet_files(ft):
     return ret
 
 
-def _handle_snippet_or_global(filename, line, lines, python_globals, priority):
+def _handle_snippet_or_global(
+    filename, line, lines, python_globals, priority, pre_expand
+):
     """Parses the snippet that begins at the current line."""
     start_line_index = lines.line_index
     descr = ''
@@ -114,7 +117,7 @@ def _handle_snippet_or_global(filename, line, lines, python_globals, priority):
             priority, trig, content,
             descr, opts, python_globals,
             '%s:%i' % (filename, start_line_index),
-            context)
+            context, pre_expand)
         return 'snippet', (definition,)
     else:
         return 'error', ("Invalid snippet type: '%s'" % snip, lines.line_index)
@@ -130,14 +133,21 @@ def _parse_snippets_file(data, filename):
     python_globals = defaultdict(list)
     lines = LineIterator(data)
     current_priority = 0
+    actions = {}
     for line in lines:
         if not line.strip():
             continue
 
         head, tail = head_tail(line)
         if head in ('snippet', 'global'):
-            snippet = _handle_snippet_or_global(filename, line, lines,
-                                                python_globals, current_priority)
+            snippet = _handle_snippet_or_global(
+                filename, line, lines,
+                python_globals,
+                current_priority,
+                actions
+            )
+
+            actions = {}
             if snippet is not None:
                 yield snippet
         elif head == 'extends':
@@ -149,6 +159,12 @@ def _parse_snippets_file(data, filename):
                 current_priority = int(tail.split()[0])
             except (ValueError, IndexError):
                 yield 'error', ('Invalid priority %r' % tail, lines.line_index)
+        elif head in ['pre_expand', 'post_expand', 'post_jump']:
+            head, tail = handle_action(head, tail, lines.line_index)
+            if head == 'error':
+                yield (head, tail)
+            else:
+                actions[head], = tail
         elif head and not head.startswith('#'):
             yield 'error', ('Invalid line %r' % line.rstrip(), lines.line_index)
 
diff --git a/pythonx/UltiSnips/snippet_manager.py b/pythonx/UltiSnips/snippet_manager.py
index 69ef69b..7112f44 100644
--- a/pythonx/UltiSnips/snippet_manager.py
+++ b/pythonx/UltiSnips/snippet_manager.py
@@ -205,19 +205,22 @@ class SnippetManager(object):
 
     @err_to_scratch_buffer
     def add_snippet(self, trigger, value, description,
-                    options, ft='all', priority=0, context=None):
+                    options, ft='all', priority=0, context=None, actions={}):
         """Add a snippet to the list of known snippets of the given 'ft'."""
         self._added_snippets_source.add_snippet(ft,
-                                                UltiSnipsSnippetDefinition(priority, trigger, value,
-                                                                           description, options, {}, 'added',
-                                                                           context))
+            UltiSnipsSnippetDefinition(priority, trigger, value,
+                                       description, options, {}, 'added',
+                                       context, actions))
 
     @err_to_scratch_buffer
-    def expand_anon(self, value, trigger='', description='', options='', context=None):
+    def expand_anon(
+        self, value, trigger='', description='', options='',
+        context=None, actions={}
+    ):
         """Expand an anonymous snippet right here."""
         before = _vim.buf.line_till_cursor
         snip = UltiSnipsSnippetDefinition(0, trigger, value, description,
-                                          options, {}, '', context)
+                                          options, {}, '', context, actions)
 
         if not trigger or snip.matches(before):
             self._do_snippet(snip, before)
@@ -275,6 +278,7 @@ class SnippetManager(object):
         if _vim.eval('mode()') not in 'in':
             return
 
+
         if self._ignore_movements:
             self._ignore_movements = False
             return
@@ -432,6 +436,18 @@ class SnippetManager(object):
     def _jump(self, backwards=False):
         """Helper method that does the actual jump."""
         jumped = False
+
+        # We need to remember current snippets stack here because of
+        # post-jump action on the last tabstop should be able to access
+        # snippet instance which is ended just now.
+        stack_for_post_jump = self._csnippets[:]
+
+        # we need to set 'onemore' there, because of limitations of the vim
+        # API regarding cursor movements; without that test
+        # 'CanExpandAnonSnippetInJumpActionWhileSelected' will fail
+        old_virtualedit = _vim.eval('&ve')
+        _vim.command('set ve=onemore')
+
         # If next tab has length 1 and the distance between itself and
         # self._ctab is 1 then there is 1 less CursorMove events.  We
         # cannot ignore next movement in such case.
@@ -450,18 +466,28 @@ class SnippetManager(object):
                     ntab_short_and_near = True
                 if ntab.number == 0:
                     self._current_snippet_is_done()
+                self._ctab = ntab
             else:
                 # This really shouldn't happen, because a snippet should
                 # have been popped when its final tabstop was used.
                 # Cleanup by removing current snippet and recursing.
                 self._current_snippet_is_done()
                 jumped = self._jump(backwards)
-            self._ctab = ntab
         if jumped:
             self._vstate.remember_position()
             self._vstate.remember_unnamed_register(self._ctab.current_text)
             if not ntab_short_and_near:
                 self._ignore_movements = True
+
+        if len(stack_for_post_jump) > 0 and ntab is not None:
+            stack_for_post_jump[0].snippet.do_post_jump(
+                ntab.number,
+                -1 if backwards else 1,
+                stack_for_post_jump
+            )
+
+        _vim.command('set ve=' + old_virtualedit)
+
         return jumped
 
     def _leaving_insert_mode(self):
@@ -562,6 +588,17 @@ class SnippetManager(object):
         if snippet.matched:
             text_before = before[:-len(snippet.matched)]
 
+        new_buffer, cursor_set_in_action = snippet.do_pre_expand(
+            self._visual_content.text,
+            self._csnippets
+        )
+
+        new_buffer.validate_buffer()
+
+        if cursor_set_in_action:
+            text_before = _vim.buf.line_till_cursor
+            before = _vim.buf.line_till_cursor
+
         if self._cs:
             start = Position(_vim.buf.cursor.line, len(text_before))
             end = Position(_vim.buf.cursor.line, len(before))
@@ -590,6 +627,12 @@ class SnippetManager(object):
 
         si.update_textobjects()
 
+        new_buffer, _ = snippet.do_post_expand(
+            si._start, si._end, self._csnippets
+        )
+
+        new_buffer.validate_buffer()
+
         self._vstate.remember_buffer(self._csnippets[0])
 
         self._jump()
diff --git a/pythonx/UltiSnips/text_objects/_snippet_instance.py b/pythonx/UltiSnips/text_objects/_snippet_instance.py
index 8b8e222..e3e3158 100644
--- a/pythonx/UltiSnips/text_objects/_snippet_instance.py
+++ b/pythonx/UltiSnips/text_objects/_snippet_instance.py
@@ -30,6 +30,7 @@ class SnippetInstance(EditableTextObject):
         self.snippet = snippet
         self._cts = 0
 
+        self.context = context
         self.locals = {'match': last_re, 'context': context}
         self.globals = globals
         self.visual_content = visual_content
@@ -130,6 +131,9 @@ class SnippetInstance(EditableTextObject):
         self._parent = cached_parent
         return rv
 
+    def get_tabstops(self):
+        return self._tabstops
+
 
 class _VimCursor(NoneditableTextObject):
 
diff --git a/syntax/snippets.vim b/syntax/snippets.vim
index 94e1458..3a044ce 100644
--- a/syntax/snippets.vim
+++ b/syntax/snippets.vim
@@ -151,6 +151,12 @@ syn match snipPriority "^priority\%(\s.*\|$\)" contains=snipPriorityKeyword disp
 syn match snipPriorityKeyword "^priority" contained nextgroup=snipPriorityValue skipwhite display
 syn match snipPriorityValue "-\?\d\+" contained display
 
+" Actions {{{3
+
+syn match snipAction "^\(pre_expand\|post_expand\|post_jump\)\%(\s.*\|$\)" contains=snipActionKeyword display
+syn match snipActionKeyword "^\(pre_expand\|post_expand\|post_jump\)" contained nextgroup=snipActionValue skipwhite display
+syn match snipActionValue '".*"' contained display
+
 " Snippt Clearing {{{2
 
 syn match snipClear "^clearsnippets\%(\s.*\|$\)" contains=snipClearKeyword display
@@ -201,6 +207,9 @@ hi def link snipTransformationOptions      Operator
 hi def link snipPriorityKeyword  Keyword
 hi def link snipPriorityValue    Number
 
+hi def link snipActionKeyword  Keyword
+hi def link snipActionValue    String
+
 hi def link snipClearKeyword     Keyword
 
 " }}}1
diff --git a/test/test_ContextSnippets.py b/test/test_ContextSnippets.py
index fc4fe9d..8d35a77 100644
--- a/test/test_ContextSnippets.py
+++ b/test/test_ContextSnippets.py
@@ -49,7 +49,7 @@ class ContextSnippets_UseContext(_VimTest):
             return "< " + ins + " >"
         endglobal
 
-        snippet a "desc" "wrap(buffer[line-1])" e
+        snippet a "desc" "wrap(buffer[line])" e
         { `!p snip.rv = context` }
         endsnippet
         """}
@@ -59,7 +59,7 @@ class ContextSnippets_UseContext(_VimTest):
 
 class ContextSnippets_SnippetPriority(_VimTest):
     files = { 'us/all.snippets': r"""
-        snippet i "desc" "re.search('err :=', buffer[line-2])" e
+        snippet i "desc" "re.search('err :=', buffer[line-1])" e
         if err != nil {
             ${1:// pass}
         }
@@ -127,3 +127,14 @@ class ContextSnippets_ReportErrorOnIndexOutOfRange(_VimTest):
     keys = 'e' + EX
     wanted = 'e' + EX
     expected_error = r"IndexError: line number out of range"
+
+
+class ContextSnippets_CursorIsZeroBased(_VimTest):
+    files = { 'us/all.snippets': r"""
+        snippet e "desc" "cursor" e
+        `!p snip.rv = str(context)`
+        endsnippet
+        """}
+
+    keys = "e" + EX
+    wanted = "(2, 0)"
diff --git a/test/test_Editing.py b/test/test_Editing.py
index 518a9ec..06f4a7a 100644
--- a/test/test_Editing.py
+++ b/test/test_Editing.py
@@ -69,6 +69,11 @@ class DeleteSnippetInsertion1(_VimTest):
     snippets = ('test', r"$1${1/(.*)/(?0::.)/}")
     keys = 'test' + EX + ESC + 'u'
     wanted = 'test'
+
+class DoNotCrashOnUndoAndJumpInNestedSnippet(_VimTest):
+    snippets = ('test', r"if $1: $2")
+    keys = 'test' + EX + 'a' + JF + 'test' + EX + ESC + 'u' + JF
+    wanted = 'if a: test'
 # End: Undo of Snippet insertion  #}}}
 
 # Normal mode editing  {{{#
diff --git a/test/test_SnippetActions.py b/test/test_SnippetActions.py
new file mode 100644
index 0000000..2bf5609
--- /dev/null
+++ b/test/test_SnippetActions.py
@@ -0,0 +1,287 @@
+from test.vim_test_case import VimTestCase as _VimTest
+from test.constant import *
+
+
+class SnippetActions_PreActionModifiesBuffer(_VimTest):
+    files = { 'us/all.snippets': r"""
+        pre_expand "buffer[line:line] = ['\n']"
+        snippet a "desc" "True" e
+        abc
+        endsnippet
+        """}
+    keys = 'a' + EX
+    wanted = '\nabc'
+
+
+class SnippetActions_PostActionModifiesBuffer(_VimTest):
+    files = { 'us/all.snippets': r"""
+        post_expand "buffer[line+1:line+1] = ['\n']"
+        snippet a "desc" "True" e
+        abc
+        endsnippet
+        """}
+    keys = 'a' + EX
+    wanted = 'abc\n'
+
+class SnippetActions_ErrorOnBufferModificationThroughCommand(_VimTest):
+    files = { 'us/all.snippets': r"""
+        pre_expand "vim.command('normal O')"
+        snippet a "desc" "True" e
+        abc
+        endsnippet
+        """}
+    keys = 'a' + EX
+    expected_error = 'changes are untrackable'
+
+
+class SnippetActions_ErrorOnModificationSnippetLine(_VimTest):
+    files = { 'us/all.snippets': r"""
+        post_expand "vim.command('normal dd')"
+        snippet i "desc" "True" e
+        if:
+            $1
+        endsnippet
+        """}
+    keys = 'i' + EX
+    expected_error = 'line under the cursor was modified'
+
+
+class SnippetActions_EnsureIndent(_VimTest):
+    files = { 'us/all.snippets': r"""
+        pre_expand "buffer[line] = ' '*4; new_cursor = (cursor[0], 4)"
+        snippet i "desc" "True" e
+        if:
+            $1
+        endsnippet
+        """}
+    keys = '\ni' + EX + 'i' + EX + 'x'
+    wanted = """
+    if:
+    if:
+        x"""
+
+
+class SnippetActions_PostActionCanUseSnippetRange(_VimTest):
+    files = { 'us/all.snippets': r"""
+        global !p
+        def ensure_newlines(start, end):
+            buffer[start[0]:start[0]] = ['\n'] * 2
+            buffer[end[0]+1:end[0]+1] = ['\n'] * 1
+        endglobal
+
+        post_expand "ensure_newlines(snippet_start, snippet_end)"
+        snippet i "desc"
+        if
+            $1
+        else
+            $2
+        end
+        endsnippet
+        """}
+    keys = '\ni' + EX + 'x' + JF + 'y'
+    wanted = """
+
+
+if
+    x
+else
+    y
+end
+"""
+
+
+class SnippetActions_CanModifyParentBody(_VimTest):
+    files = { 'us/all.snippets': r"""
+        global !p
+        def ensure_newlines(start, end):
+            buffer[start[0]:start[0]] = ['\n'] * 2
+        endglobal
+
+        post_expand "ensure_newlines(snippet_start, snippet_end)"
+        snippet i "desc"
+        if
+            $1
+        else
+            $2
+        end
+        endsnippet
+        """}
+    keys = '\ni' + EX + 'i' + EX + 'x' + JF + 'y' + JF + JF + 'z'
+    wanted = """
+
+
+if
+
+
+    if
+        x
+    else
+        y
+    end
+else
+    z
+end"""
+
+
+class SnippetActions_MoveParentSnippetFromChildInPreAction(_VimTest):
+    files = { 'us/all.snippets': r"""
+        global !p
+        def insert_import():
+            buffer[2:2] = ['import smthing', '']
+        endglobal
+
+        pre_expand "insert_import()"
+        snippet p "desc"
+        print(smthing.traceback())
+        endsnippet
+
+        snippet i "desc"
+        if
+            $1
+        else
+            $2
+        end
+        endsnippet
+        """}
+    keys = 'i' + EX + 'p' + EX + JF + 'z'
+    wanted = """import smthing
+
+if
+    print(smthing.traceback())
+else
+    z
+end"""
+
+
+class SnippetActions_CanExpandSnippetInDifferentPlace(_VimTest):
+    files = { 'us/all.snippets': r"""
+        global !p
+        def expand_after_if():
+            global new_cursor
+            buffer[line] = buffer[line][:column] + buffer[line][column+1:]
+            new_cursor = (line, buffer[line].index('if ')+3)
+        endglobal
+
+        pre_expand "expand_after_if()"
+        snippet n "append not to if" w
+        not $0
+        endsnippet
+
+        snippet i "if cond" w
+        if $1: $2
+        endsnippet
+        """}
+    keys = 'i' + EX + 'blah' + JF + 'n' + EX + JF + 'pass'
+    wanted = """if not blah: pass"""
+
+
+class SnippetActions_MoveVisual(_VimTest):
+    files = { 'us/all.snippets': r"""
+        global !p
+        def extract_method():
+            global new_cursor
+            del buffer[line]
+            buffer[len(buffer)-1:len(buffer)-1] = ['']
+            new_cursor = (len(buffer)-2, 0)
+        endglobal
+
+        pre_expand "extract_method()"
+        snippet n "append not to if" w
+        def $1:
+            ${VISUAL}
+
+        endsnippet
+        """}
+
+    keys = """
+def a:
+    x()
+    y()
+    z()""" + ESC + 'kVk' + EX + 'n' + EX + 'b'
+
+    wanted = """
+def a:
+    z()
+
+def b:
+    x()
+    y()"""
+
+
+class SnippetActions_CanMirrorTabStopsOutsideOfSnippet(_VimTest):
+    files = { 'us/all.snippets': r"""
+        post_jump "buffer[2] = 'debug({})'.format(tabstops[1].current_text)"
+        snippet i "desc"
+        if $1:
+            $2
+        endsnippet
+        """}
+    keys = """
+---
+i""" + EX + "test(some(complex(cond(a))))" + JF + "x"
+    wanted = """debug(test(some(complex(cond(a)))))
+---
+if test(some(complex(cond(a)))):
+    x"""
+
+
+class SnippetActions_CanExpandAnonSnippetInJumpAction(_VimTest):
+    files = { 'us/all.snippets': r"""
+        global !p
+        def expand_anon():
+            if tabstop == 0:
+                from UltiSnips import UltiSnips_Manager
+                UltiSnips_Manager.expand_anon("a($2, $1)")
+                return 'keep'
+        endglobal
+
+        post_jump "new_cursor = expand_anon()"
+        snippet i "desc"
+        if ${1:cond}:
+            $0
+        endsnippet
+        """}
+    keys = "i" + EX + "x" + JF + "1" + JF + "2" + JF + ";"
+    wanted = """if x:
+    a(2, 1);"""
+
+
+class SnippetActions_CanExpandAnonSnippetInJumpActionWhileSelected(_VimTest):
+    files = { 'us/all.snippets': r"""
+        global !p
+        def expand_anon():
+            if tabstop == 0:
+                from UltiSnips import UltiSnips_Manager
+                UltiSnips_Manager.expand_anon(" // a($2, $1)")
+                return 'keep'
+        endglobal
+
+        post_jump "new_cursor = expand_anon()"
+        snippet i "desc"
+        if ${1:cond}:
+            ${2:pass}
+        endsnippet
+        """}
+    keys = "i" + EX + "x" + JF + JF + "1" + JF + "2" + JF + ";"
+    wanted = """if x:
+    pass // a(2, 1);"""
+
+
+class SnippetActions_CanUseContextFromContextMatch(_VimTest):
+    files = { 'us/all.snippets': r"""
+        global !p
+        def expand_anon():
+            if tabstop == 0:
+                from UltiSnips import UltiSnips_Manager
+                UltiSnips_Manager.expand_anon(" // a($2, $1)")
+                return 'keep'
+        endglobal
+
+        pre_expand "buffer[line:line] = [context]"
+        snippet i "desc" "'some context'" e
+        body
+        endsnippet
+        """}
+    keys = "i" + EX
+    wanted = """some context
+body"""
diff --git a/test/test_UltiSnipFunc.py b/test/test_UltiSnipFunc.py
index 6568c54..6e6a06e 100644
--- a/test/test_UltiSnipFunc.py
+++ b/test/test_UltiSnipFunc.py
@@ -159,7 +159,7 @@ class MySnippetSource(SnippetSource):
       return [
           UltiSnipsSnippetDefinition(
               -100, "blumba", "this is a dynamic snippet", "", "", {}, "blub",
-              None)
+              None, {})
         ]
     return []
 """)
diff --git a/test/vim_test_case.py b/test/vim_test_case.py
index ec888f4..6caa78b 100644
--- a/test/vim_test_case.py
+++ b/test/vim_test_case.py
@@ -46,16 +46,16 @@ class VimTestCase(unittest.TestCase, TempFileManager):
 
         # Only checks the output. All work is done in setUp().
         wanted = self.text_before + self.wanted + self.text_after
-        if self.expected_error:
-            self.assertRegexpMatches(self.output, self.expected_error)
-            return
         for i in range(self.retries):
-            if self.output != wanted:
+            if self.output and self.expected_error:
+                self.assertRegexpMatches(self.output, self.expected_error)
+                return
+            if self.output != wanted or self.output is None:
                 # Redo this, but slower
                 self.sleeptime += 0.15
                 self.tearDown()
                 self.setUp()
-        self.assertEqual(self.output, wanted)
+        self.assertMultiLineEqual(self.output, wanted)
 
     def _extra_vim_config(self, vim_config):
         """Adds extra lines to the vim_config list."""
@@ -128,6 +128,7 @@ class VimTestCase(unittest.TestCase, TempFileManager):
         vim_config.append('set fileencoding=utf-8')
         vim_config.append('set buftype=nofile')
         vim_config.append('set shortmess=at')
+        vim_config.append('set cmdheight=10')
         vim_config.append('let @" = ""')
         assert EX == "\t"  # Otherwise you need to change the next line
         vim_config.append('let g:UltiSnipsExpandTrigger="<tab>"')