Disable vims auto-wrapping inside snippets

- Disable autowrapping inside of snippets
- renable it when the snippet has been completely handled
- added snippet option 'f' to avoid disabling text wrapping
- added docs and tests

doc/UltiSnips.txt

@@ -201,7 +201,7 @@ will not unmap any mapping that contains the string "somePlugin" or
 3.5 Functions                                           *UltiSnips-functions*
 -------------
 
-Ultisnips provides two functions for extending core functionality.
+UltiSnips provides two functions for extending core functionality.
 
  3.5.1 UltiSnips_AddSnippet                            *UltiSnips_AddSnippet*
 
@@ -309,6 +309,11 @@ snippet on. The options currently supported are >
        option is set, UltiSnips will not try to do this expansion, and will
        leave the tabs alone. This can be useful for snippets dealing with
        tab delimited formats, etc.
+   f   Do not turn 'formatoptions' off when expanding the snippet. Normally,
+       UltiSnips will disable the 'c' and the 't' option of 'formatoptions'
+       because otherwise, Vim might break a line without UltiSnips noticing
+       and this might mess up the snippet completely. This is useful for
+       snippets that need paragraphs in their tabstops.
 <
 
  4.1.1 Character Escaping:                             *UltiSnips-character-escaping*

plugin/UltiSnips/__init__.py

@@ -357,6 +357,10 @@ class Snippet(object):
 
         return match
 
+    def keep_formatoptions_unchanged(self):
+        return "f" in self._opts
+    keep_formatoptions_unchanged = property(keep_formatoptions_unchanged)
+
     def overwrites_previous(self):
         return "!" in self._opts
     overwrites_previous = property(overwrites_previous)
@@ -587,6 +591,8 @@ class SnippetManager(object):
     def __init__(self):
         self._vstate = VimState()
         self._supertab_keys = None
+        self._csnippets = []
+        self._cached_offending_vim_options = {}
 
         self.reset()
 
@@ -594,7 +600,10 @@ class SnippetManager(object):
     def reset(self, test_error=False):
         self._test_error = test_error
         self._snippets = {}
-        self._csnippets = []
+
+        while len(self._csnippets):
+            self._current_snippet_is_done()
+
         self._reinit()
 
     @err_to_scratch_buffer
@@ -763,8 +772,9 @@ class SnippetManager(object):
     def entered_insert_mode(self):
         self._vstate.update()
         if self._cs and self._vstate.has_moved:
+            while len(self._csnippets):
+                self._current_snippet_is_done()
             self._reinit()
-            self._csnippets = []
 
     ###################################
     # Private/Protect Functions Below #
@@ -795,12 +805,18 @@ class SnippetManager(object):
 
         # Did we leave the snippet with this movement?
         if self._cs and not (self._vstate.pos in self._cs.abs_span):
-            self._csnippets.pop()
+            self._current_snippet_is_done()
 
             self._reinit()
 
             self._check_if_still_inside_snippet()
 
+    def _current_snippet_is_done(self):
+        self._csnippets.pop()
+
+        if not len(self._csnippets):
+            self._reset_offending_vim_options()
+
     def _jump(self, backwards = False):
         jumped = False
         if self._cs:
@@ -812,13 +828,13 @@ class SnippetManager(object):
                 jumped = True
                 if self._ctab.no == 0:
                     self._ctab = None
-                    self._csnippets.pop()
+                    self._current_snippet_is_done()
                 self._vstate.update()
             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._csnippets.pop()
+                self._current_snippet_is_done()
                 jumped = self._jump(backwards)
         return jumped
 
@@ -929,6 +945,8 @@ class SnippetManager(object):
         if snippet.matched:
             text_before = before[:-len(snippet.matched)]
 
+        self._unset_offending_vim_options(snippet)
+
         self._expect_move_wo_change = True
         if self._cs:
             # Determine position
@@ -981,6 +999,19 @@ class SnippetManager(object):
 
         return True
 
+    # Handling of offending vim options
+    def _unset_offending_vim_options(self, snippet):
+        # Care for textwrapping
+        if not snippet.keep_formatoptions_unchanged:
+            self._cached_offending_vim_options["fo"] = ''.join(
+                c for c in vim.eval("&fo") if c in "ct"
+            )
+            for c in "ct": vim.command("set fo-=%s" % c)
+
+    def _reset_offending_vim_options(self):
+        # Textwrapping
+        for c in self._cached_offending_vim_options.pop("fo", []):
+            vim.command("set fo+=%s" % c)
 
     # Input Handling
     def _chars_entered(self, chars, del_more_lines = 0):

test.py

@@ -342,13 +342,26 @@ class _FormatoptionsBase(_VimTest):
     def _options_off(self):
         self.send(":set tw=0\n")
 
-class FOSimple_ExceptCorrectResult(_FormatoptionsBase):
+class FOSimple_WithoutBreak_ExceptCorrectResult(_FormatoptionsBase):
     snippets = ("test", "${1:longer expand}\n$0")
+    keys = "test" + EX + "This is a longer text that should not wrap as formatoptions are disabled"
+    wanted = "This is a longer text that should not wrap as formatoptions are disabled\n"
+
+class FO_WithoutBreakEnableAfterSnippet_ExceptCorrectResult(_FormatoptionsBase):
+    snippets = ("test", "${1:longer expand}\n")
+    keys = "test" + EX + "This is a longer text that should not wrap as formatoptions are disabled" \
+            + JF + "This is a longer text that should wrap"
+    wanted = "This is a longer text that should not wrap as formatoptions are disabled\n" + \
+            "This is a longer\ntext that should\nwrap"
+
+
+class FOSimple_WithBreak_ExceptCorrectResult(_FormatoptionsBase):
+    snippets = ("test", "${1:longer expand}\n$0", "", "f")
     keys = "test" + EX + "This is a longer text that should wrap"
     wanted = "This is a longer\ntext that should\nwrap\n"
 
 class FOTextBeforeAndAfter_ExceptCorrectResult(_FormatoptionsBase):
-    snippets = ("test", "Before${1:longer expand}After\nstart$1end")
+    snippets = ("test", "Before${1:longer expand}After\nstart$1end", "", "f")
     keys = "test" + EX + "This is a longer text that should wrap"
     wanted = \
 """BeforeThis is a
@@ -361,7 +374,7 @@ should wrapend"""
 
 class FOTextAfter_ExceptCorrectResult(_FormatoptionsBase):
     """Testcase for lp:719998"""
-    snippets = ("test", "${1:longer expand}after\nstart$1end")
+    snippets = ("test", "${1:longer expand}after\nstart$1end", "", "f")
     keys = ("test" + EX + "This is a longer snippet that should wrap properly "
             "and the mirror below should work as well")
     wanted = \
@@ -378,7 +391,7 @@ should work as wellend"""
 
 class FOWrapOnLongWord_ExceptCorrectResult(_FormatoptionsBase):
     """Testcase for lp:719998"""
-    snippets = ("test", "${1:longer expand}after\nstart$1end")
+    snippets = ("test", "${1:longer expand}after\nstart$1end", "", "f")
     keys = ("test" + EX + "This is a longersnippet that should wrap properly")
     wanted = \
 """This is a