From 5c87806d7b2b32837f5ea11a9952343d8b27868b Mon Sep 17 00:00:00 2001
From: cwahbong <cw.ahbong@gmail.com>
Date: Wed, 16 Jul 2014 19:42:03 +0800
Subject: [PATCH 1/5] Implement priority-based clearsnippets.

---
 pythonx/UltiSnips/snippet/source/_base.py     | 42 +++++++++++++++++++
 .../snippet/source/_snippet_dictionary.py     | 21 ++++++----
 .../UltiSnips/snippet/source/file/_base.py    |  7 ++--
 .../snippet/source/file/ultisnips.py          |  2 +-
 pythonx/UltiSnips/snippet_manager.py          | 18 +++++++-
 5 files changed, 75 insertions(+), 15 deletions(-)

diff --git a/pythonx/UltiSnips/snippet/source/_base.py b/pythonx/UltiSnips/snippet/source/_base.py
index 6c5fdf0..03de530 100644
--- a/pythonx/UltiSnips/snippet/source/_base.py
+++ b/pythonx/UltiSnips/snippet/source/_base.py
@@ -13,6 +13,9 @@ class SnippetSource(object):
     def __init__(self):
         self._snippets = defaultdict(SnippetDictionary)
 
+    def ensure(self, filetypes):
+        pass
+
     def get_snippets(self, filetypes, before, possible):
         """Returns the snippets for all 'filetypes' (in order) and their parents
         matching the text 'before'. If 'possible' is true, a partial match is
@@ -26,6 +29,45 @@ class SnippetSource(object):
             found_snippets += self._find_snippets(ft, before, possible)
         return found_snippets
 
+    def get_clear_priority(self, filetypes, seen=None):
+        priority = None
+        if not seen:
+            seen = set()
+        for ft in filetypes:
+            seen.add(ft)
+            snippets = self._snippets[ft]
+            if priority is None or snippets._clear_priority > priority:
+                priority = snippets._clear_priority
+        todo_parent_fts = []
+        for ft in filetypes:
+            extends = self._snippets[ft].extends
+            havnt_seen = filter(lambda ft: ft not in seen, extends)
+            seen.update(havnt_seen)
+            todo_parent_fts.extend(havnt_seen)
+        if todo_parent_fts:
+            return max(priority, self.get_clear_priority(todo_parent_fts, seen))
+        return priority
+
+    def get_cleared(self, filetypes, seen=None):
+        cleared = {}
+        if not seen:
+            seen = set()
+        for ft in filetypes:
+            seen.add(ft)
+            snippets = self._snippets[ft]
+            for key, value in snippets._cleared.items():
+                if key not in cleared or value > cleared[key]:
+                    cleared[key] = value
+        todo_parent_fts = []
+        for ft in filetypes:
+            extends = self._snippets[ft].extends
+            havnt_seen = filter(lambda ft: ft not in seen, extends)
+            seen.update(havnt_seen)
+            todo_parent_fts.extend(havnt_seen)
+        if todo_parent_fts:
+            cleared.update(self.get_cleared(todo_parent_fts, seen))
+        return cleared
+
     def _find_snippets(self, ft, trigger, potentially=False, seen=None):
         """Find snippets matching 'trigger' for 'ft'. If 'potentially' is True,
         partial matches are enough."""
diff --git a/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py b/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
index 5be6775..b075333 100644
--- a/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
+++ b/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
@@ -10,6 +10,8 @@ class SnippetDictionary(object):
     def __init__(self):
         self._snippets = []
         self._extends = []
+        self._cleared = {}
+        self._clear_priority = None
 
     def add_snippet(self, snippet):
         """Add 'snippet' to this dictionary."""
@@ -24,16 +26,17 @@ class SnippetDictionary(object):
         else:
             return [s for s in all_snippets if s.could_match(trigger)]
 
-    def clear_snippets(self, triggers):
-        """Remove all snippets that match each trigger in 'triggers'. When
-        'triggers' is None, empties this dictionary completely."""
+    def clear_snippets(self, priority, triggers):
+        """Mark snippets as cleared with priority.  When 'triggers' is
+        None, then it updated the clear_priority."""
         if not triggers:
-            self._snippets = []
-            return
-        for trigger in triggers:
-            for snippet in self.get_matching_snippets(trigger, False):
-                if snippet in self._snippets:
-                    self._snippets.remove(snippet)
+          if self._clear_priority is None or priority > self._clear_priority:
+            self._clear_priority = priority
+        else:
+          for trigger in triggers:
+            if (trigger not in self._cleared or
+                priority > self._cleared[trigger]):
+              self._cleared[trigger] = priority
 
     @property
     def extends(self):
diff --git a/pythonx/UltiSnips/snippet/source/file/_base.py b/pythonx/UltiSnips/snippet/source/file/_base.py
index 425e3dd..1ec325e 100644
--- a/pythonx/UltiSnips/snippet/source/file/_base.py
+++ b/pythonx/UltiSnips/snippet/source/file/_base.py
@@ -31,10 +31,9 @@ class SnippetFileSource(SnippetSource):
         self._files_for_ft = defaultdict(set)
         self._file_hashes = defaultdict(lambda: None)
 
-    def get_snippets(self, filetypes, before, possible):
+    def ensure(self, filetypes):
         for ft in filetypes:
             self._ensure_loaded(ft, set())
-        return SnippetSource.get_snippets(self, filetypes, before, possible)
 
     def _get_all_snippet_files_for(self, ft):
         """Returns a set of all files that define snippets for 'ft'."""
@@ -94,8 +93,8 @@ class SnippetFileSource(SnippetSource):
                         _vim.escape(filename))
                 raise SnippetSyntaxError(filename, line_index, msg)
             elif event == "clearsnippets":
-                triggers, = data
-                self._snippets[ft].clear_snippets(triggers)
+                priority, triggers = data
+                self._snippets[ft].clear_snippets(priority, triggers)
             elif event == "extends":
                 # TODO(sirver): extends information is more global
                 # than one snippet source.
diff --git a/pythonx/UltiSnips/snippet/source/file/ultisnips.py b/pythonx/UltiSnips/snippet/source/file/ultisnips.py
index de0ae96..81878a0 100644
--- a/pythonx/UltiSnips/snippet/source/file/ultisnips.py
+++ b/pythonx/UltiSnips/snippet/source/file/ultisnips.py
@@ -122,7 +122,7 @@ def _parse_snippets_file(data, filename):
         elif head == "extends":
             yield handle_extends(tail, lines.line_index)
         elif head == "clearsnippets":
-            yield "clearsnippets", (tail.split(),)
+            yield "clearsnippets", (current_priority, tail.split())
         elif head == "priority":
             try:
                 current_priority = int(tail.split()[0])
diff --git a/pythonx/UltiSnips/snippet_manager.py b/pythonx/UltiSnips/snippet_manager.py
index 22c28e7..c649029 100644
--- a/pythonx/UltiSnips/snippet_manager.py
+++ b/pythonx/UltiSnips/snippet_manager.py
@@ -445,9 +445,25 @@ class SnippetManager(object):
         partial is True, then get also return partial matches. """
         filetypes = self._buffer_filetypes[_vim.buf.number][::-1]
         matching_snippets = defaultdict(list)
+        clear_priority = None
+        cleared = {}
+        # Collect cleared information fomr sources.
+        for _, source in self._snippet_sources:
+            source.ensure(filetypes)
+            sclear_priority = source.get_clear_priority(filetypes)
+            if sclear_priority is not None and (clear_priority is None
+                    or sclear_priority > clear_priority):
+                clear_priority = sclear_priority
+            for key, value in source.get_cleared(filetypes).items():
+                if key not in cleared or value > cleared[key]:
+                    cleared[key] = value
+
         for _, source in self._snippet_sources:
             for snippet in source.get_snippets(filetypes, before, partial):
-                matching_snippets[snippet.trigger].append(snippet)
+                if ((clear_priority is None or snippet.priority > clear_priority)
+                        and (snippet.trigger not in cleared or
+                        snippet.priority > cleared[snippet.trigger])):
+                    matching_snippets[snippet.trigger].append(snippet)
         if not matching_snippets:
             return []
 

From 20f3832ffa3a477007d3c09914f0ee8bc0118510 Mon Sep 17 00:00:00 2001
From: cwahbong <cw.ahbong@gmail.com>
Date: Wed, 16 Jul 2014 22:57:24 +0800
Subject: [PATCH 2/5] Code cleanup.

Full tested and does not break and old tests.
---
 pythonx/UltiSnips/snippet/source/_base.py     | 113 ++++++++----------
 .../snippet/source/_snippet_dictionary.py     |  12 +-
 2 files changed, 58 insertions(+), 67 deletions(-)

diff --git a/pythonx/UltiSnips/snippet/source/_base.py b/pythonx/UltiSnips/snippet/source/_base.py
index 03de530..d051b46 100644
--- a/pythonx/UltiSnips/snippet/source/_base.py
+++ b/pythonx/UltiSnips/snippet/source/_base.py
@@ -24,66 +24,57 @@ class SnippetSource(object):
 
         Returns a list of SnippetDefinition s.
         """
-        found_snippets = []
-        for ft in filetypes:
-            found_snippets += self._find_snippets(ft, before, possible)
-        return found_snippets
+        def __inner(fts):
+            result = []
+            existing_fts = filter(lambda ft: ft in self._snippets, fts)
+            for ft in existing_fts:
+                snips = self._snippets[ft]
+                result.extend(snips.get_matching_snippets(before, possible))
+            return result
+        return __inner(filetypes) + __inner(self._extends_all(filetypes))
 
-    def get_clear_priority(self, filetypes, seen=None):
-        priority = None
-        if not seen:
-            seen = set()
-        for ft in filetypes:
-            seen.add(ft)
-            snippets = self._snippets[ft]
-            if priority is None or snippets._clear_priority > priority:
-                priority = snippets._clear_priority
-        todo_parent_fts = []
-        for ft in filetypes:
-            extends = self._snippets[ft].extends
-            havnt_seen = filter(lambda ft: ft not in seen, extends)
+    def get_clear_priority(self, filetypes):
+        def __inner(fts):
+            pri = None
+            existing_fts = filter(lambda ft: ft in self._snippets, fts)
+            for ft in existing_fts:
+                snippets = self._snippets[ft]
+                if pri is None or snippets._clear_priority > pri:
+                    pri = snippets._clear_priority
+            return pri
+        priority = __inner(filetypes)
+        deep_clear_priority = __inner(self._extends_all(filetypes))
+        if deep_clear_priority is None:
+            return priority
+        elif priority is None:
+            return deep_clear_priority
+        else:
+            return max(priority, deep_clear_priority)
+
+    def get_cleared(self, filetypes):
+        def __inner(fts):
+            cleared = {}
+            existing_fts = filter(lambda ft: ft in self._snippets, fts)
+            for ft in existing_fts:
+                snippets = self._snippets[ft]
+                for key, value in snippets._cleared.items():
+                    if key not in cleared or value > cleared[key]:
+                        cleared[key] = value
+            return cleared
+        return dict(__inner(filetypes).items() + __inner(self._extends_all(filetypes)).items())
+
+    def _extends_all(self, filetypes, seen=None):
+        """Return deep extends dependency, excluding the filetype itself
+        """
+        if seen is None:
+            seen = set(filetypes)
+
+        shallow_extends = set()
+        for filetype in filetypes:
+            ft_extends = self._snippets[filetype].extends
+            havnt_seen = set(filter(lambda ft: ft not in seen, ft_extends))
             seen.update(havnt_seen)
-            todo_parent_fts.extend(havnt_seen)
-        if todo_parent_fts:
-            return max(priority, self.get_clear_priority(todo_parent_fts, seen))
-        return priority
-
-    def get_cleared(self, filetypes, seen=None):
-        cleared = {}
-        if not seen:
-            seen = set()
-        for ft in filetypes:
-            seen.add(ft)
-            snippets = self._snippets[ft]
-            for key, value in snippets._cleared.items():
-                if key not in cleared or value > cleared[key]:
-                    cleared[key] = value
-        todo_parent_fts = []
-        for ft in filetypes:
-            extends = self._snippets[ft].extends
-            havnt_seen = filter(lambda ft: ft not in seen, extends)
-            seen.update(havnt_seen)
-            todo_parent_fts.extend(havnt_seen)
-        if todo_parent_fts:
-            cleared.update(self.get_cleared(todo_parent_fts, seen))
-        return cleared
-
-    def _find_snippets(self, ft, trigger, potentially=False, seen=None):
-        """Find snippets matching 'trigger' for 'ft'. If 'potentially' is True,
-        partial matches are enough."""
-        snips = self._snippets.get(ft, None)
-        if not snips:
-            return []
-        if not seen:
-            seen = set()
-        seen.add(ft)
-        parent_results = []
-        # TODO(sirver): extends information is not bound to one
-        # source. It should be tracked further up.
-        for parent_ft in snips.extends:
-            if parent_ft not in seen:
-                seen.add(parent_ft)
-                parent_results += self._find_snippets(parent_ft, trigger,
-                        potentially, seen)
-        return parent_results + snips.get_matching_snippets(
-            trigger, potentially)
+            shallow_extends.update(havnt_seen)
+        if not shallow_extends:
+            return shallow_extends
+        return shallow_extends | self._extends_all(shallow_extends, seen)
diff --git a/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py b/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
index b075333..89b92cf 100644
--- a/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
+++ b/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
@@ -30,13 +30,13 @@ class SnippetDictionary(object):
         """Mark snippets as cleared with priority.  When 'triggers' is
         None, then it updated the clear_priority."""
         if not triggers:
-          if self._clear_priority is None or priority > self._clear_priority:
-            self._clear_priority = priority
+            if self._clear_priority is None or priority > self._clear_priority:
+                self._clear_priority = priority
         else:
-          for trigger in triggers:
-            if (trigger not in self._cleared or
-                priority > self._cleared[trigger]):
-              self._cleared[trigger] = priority
+            for trigger in triggers:
+                if (trigger not in self._cleared or
+                        priority > self._cleared[trigger]):
+                    self._cleared[trigger] = priority
 
     @property
     def extends(self):

From 4784a9e1262c8cc04669dbbdd8fc99684fb9dbe7 Mon Sep 17 00:00:00 2001
From: cwahbong <cw.ahbong@gmail.com>
Date: Tue, 22 Jul 2014 15:06:13 +0800
Subject: [PATCH 3/5] Refactor: snippet dictionary does not keep the extend
 info now.

---
 .../UltiSnips/snippet/definition/snipmate.py  |  0
 pythonx/UltiSnips/snippet/parsing/_base.py    |  0
 pythonx/UltiSnips/snippet/source/_base.py     | 40 ++++++++-----------
 .../snippet/source/_snippet_dictionary.py     |  7 ----
 .../UltiSnips/snippet/source/file/_base.py    | 33 ++++-----------
 .../UltiSnips/snippet/source/file/_common.py  |  0
 pythonx/UltiSnips/snippet_manager.py          |  4 +-
 7 files changed, 26 insertions(+), 58 deletions(-)
 mode change 100755 => 100644 pythonx/UltiSnips/snippet/definition/snipmate.py
 mode change 100755 => 100644 pythonx/UltiSnips/snippet/parsing/_base.py
 mode change 100755 => 100644 pythonx/UltiSnips/snippet/source/file/_common.py

diff --git a/pythonx/UltiSnips/snippet/definition/snipmate.py b/pythonx/UltiSnips/snippet/definition/snipmate.py
old mode 100755
new mode 100644
diff --git a/pythonx/UltiSnips/snippet/parsing/_base.py b/pythonx/UltiSnips/snippet/parsing/_base.py
old mode 100755
new mode 100644
diff --git a/pythonx/UltiSnips/snippet/source/_base.py b/pythonx/UltiSnips/snippet/source/_base.py
index d051b46..b795d46 100644
--- a/pythonx/UltiSnips/snippet/source/_base.py
+++ b/pythonx/UltiSnips/snippet/source/_base.py
@@ -12,6 +12,7 @@ class SnippetSource(object):
 
     def __init__(self):
         self._snippets = defaultdict(SnippetDictionary)
+        self._extends = defaultdict(set)
 
     def ensure(self, filetypes):
         pass
@@ -31,7 +32,7 @@ class SnippetSource(object):
                 snips = self._snippets[ft]
                 result.extend(snips.get_matching_snippets(before, possible))
             return result
-        return __inner(filetypes) + __inner(self._extends_all(filetypes))
+        return __inner(self.get_deep_extends(filetypes))
 
     def get_clear_priority(self, filetypes):
         def __inner(fts):
@@ -42,14 +43,7 @@ class SnippetSource(object):
                 if pri is None or snippets._clear_priority > pri:
                     pri = snippets._clear_priority
             return pri
-        priority = __inner(filetypes)
-        deep_clear_priority = __inner(self._extends_all(filetypes))
-        if deep_clear_priority is None:
-            return priority
-        elif priority is None:
-            return deep_clear_priority
-        else:
-            return max(priority, deep_clear_priority)
+        return __inner(self.get_deep_extends(filetypes))
 
     def get_cleared(self, filetypes):
         def __inner(fts):
@@ -61,20 +55,18 @@ class SnippetSource(object):
                     if key not in cleared or value > cleared[key]:
                         cleared[key] = value
             return cleared
-        return dict(__inner(filetypes).items() + __inner(self._extends_all(filetypes)).items())
+        return __inner(self.get_deep_extends(filetypes))
 
-    def _extends_all(self, filetypes, seen=None):
-        """Return deep extends dependency, excluding the filetype itself
-        """
-        if seen is None:
-            seen = set(filetypes)
+    def update_extends(self, child_ft, parent_fts):
+        self._extends[child_ft].update(parent_fts)
 
-        shallow_extends = set()
-        for filetype in filetypes:
-            ft_extends = self._snippets[filetype].extends
-            havnt_seen = set(filter(lambda ft: ft not in seen, ft_extends))
-            seen.update(havnt_seen)
-            shallow_extends.update(havnt_seen)
-        if not shallow_extends:
-            return shallow_extends
-        return shallow_extends | self._extends_all(shallow_extends, seen)
+    def get_deep_extends(self, root_filetypes):
+        seen = set(root_filetypes)
+        l = list(set(root_filetypes))
+        while l:
+            top = l.pop()
+            for ft in self._extends[top]:
+                if ft not in seen:
+                    seen.add(ft)
+                    l.append(ft)
+        return seen
diff --git a/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py b/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
index 89b92cf..351ba68 100644
--- a/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
+++ b/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
@@ -3,13 +3,11 @@
 
 """Implements a container for parsed snippets."""
 
-# TODO(sirver): This class should not keep track of extends.
 class SnippetDictionary(object):
     """See module docstring."""
 
     def __init__(self):
         self._snippets = []
-        self._extends = []
         self._cleared = {}
         self._clear_priority = None
 
@@ -37,8 +35,3 @@ class SnippetDictionary(object):
                 if (trigger not in self._cleared or
                         priority > self._cleared[trigger]):
                     self._cleared[trigger] = priority
-
-    @property
-    def extends(self):
-        """The list of filetypes this filetype extends."""
-        return self._extends
diff --git a/pythonx/UltiSnips/snippet/source/file/_base.py b/pythonx/UltiSnips/snippet/source/file/_base.py
index 1ec325e..20f67e8 100644
--- a/pythonx/UltiSnips/snippet/source/file/_base.py
+++ b/pythonx/UltiSnips/snippet/source/file/_base.py
@@ -32,8 +32,9 @@ class SnippetFileSource(SnippetSource):
         self._file_hashes = defaultdict(lambda: None)
 
     def ensure(self, filetypes):
-        for ft in filetypes:
-            self._ensure_loaded(ft, set())
+        for ft in self.get_deep_extends(filetypes):
+            if self._needs_update(ft):
+                self._load_snippets_for(ft)
 
     def _get_all_snippet_files_for(self, ft):
         """Returns a set of all files that define snippets for 'ft'."""
@@ -43,19 +44,6 @@ class SnippetFileSource(SnippetSource):
         """Parses 'filedata' as a snippet file and yields events."""
         raise NotImplementedError()
 
-    def _ensure_loaded(self, ft, already_loaded):
-        """Make sure that the snippets for 'ft' and everything it extends are
-        loaded."""
-        if ft in already_loaded:
-            return
-        already_loaded.add(ft)
-
-        if self._needs_update(ft):
-            self._load_snippets_for(ft)
-
-        for parent in self._snippets[ft].extends:
-            self._ensure_loaded(parent, already_loaded)
-
     def _needs_update(self, ft):
         """Returns true if any files for 'ft' have changed and must be
         reloaded."""
@@ -74,11 +62,12 @@ class SnippetFileSource(SnippetSource):
         """Load all snippets for the given 'ft'."""
         if ft in self._snippets:
             del self._snippets[ft]
+            del self._extends[ft]
         for fn in self._files_for_ft[ft]:
             self._parse_snippets(ft, fn)
         # Now load for the parents
-        for parent_ft in self._snippets[ft].extends:
-            if parent_ft not in self._snippets:
+        for parent_ft in self.get_deep_extends([ft]):
+            if parent_ft != ft and self._needs_update(parent_ft):
                 self._load_snippets_for(parent_ft)
 
     def _parse_snippets(self, ft, filename):
@@ -99,17 +88,9 @@ class SnippetFileSource(SnippetSource):
                 # TODO(sirver): extends information is more global
                 # than one snippet source.
                 filetypes, = data
-                self._add_extending_info(ft, filetypes)
+                self.update_extends(ft, filetypes)
             elif event == "snippet":
                 snippet, = data
                 self._snippets[ft].add_snippet(snippet)
             else:
                 assert False, "Unhandled %s: %r" % (event, data)
-
-    def _add_extending_info(self, ft, parents):
-        """Add the list of 'parents' as being extended by the 'ft'."""
-        sd = self._snippets[ft]
-        for parent in parents:
-            if parent in sd.extends:
-                continue
-            sd.extends.append(parent)
diff --git a/pythonx/UltiSnips/snippet/source/file/_common.py b/pythonx/UltiSnips/snippet/source/file/_common.py
old mode 100755
new mode 100644
diff --git a/pythonx/UltiSnips/snippet_manager.py b/pythonx/UltiSnips/snippet_manager.py
index c649029..8dcbcb8 100644
--- a/pythonx/UltiSnips/snippet_manager.py
+++ b/pythonx/UltiSnips/snippet_manager.py
@@ -447,9 +447,11 @@ class SnippetManager(object):
         matching_snippets = defaultdict(list)
         clear_priority = None
         cleared = {}
-        # Collect cleared information fomr sources.
         for _, source in self._snippet_sources:
             source.ensure(filetypes)
+
+        # Collect cleared information from sources.
+        for _, source in self._snippet_sources:
             sclear_priority = source.get_clear_priority(filetypes)
             if sclear_priority is not None and (clear_priority is None
                     or sclear_priority > clear_priority):

From 63f65ea87421b63617692a29e0dfb4820b264e84 Mon Sep 17 00:00:00 2001
From: cwahbong <cw.ahbong@gmail.com>
Date: Sat, 26 Jul 2014 16:10:22 +0800
Subject: [PATCH 4/5] Add/modify test cases for priority-based clearsnippets.

---
 test/test_ParseSnippets.py     |  8 ++---
 test/test_SnippetPriorities.py | 65 ++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/test/test_ParseSnippets.py b/test/test_ParseSnippets.py
index 072f0e0..4a870a5 100644
--- a/test/test_ParseSnippets.py
+++ b/test/test_ParseSnippets.py
@@ -64,6 +64,8 @@ class ParseSnippets_ClearAll(_VimTest):
 
 class ParseSnippets_ClearOne(_VimTest):
     files = { "us/all.snippets": r"""
+        clearsnippets toclear
+
         snippet testsnip "Test snippet"
         This is a test.
         endsnippet
@@ -71,14 +73,14 @@ class ParseSnippets_ClearOne(_VimTest):
         snippet toclear "Snippet to clear"
         Do not expand.
         endsnippet
-
-        clearsnippets toclear
         """}
     keys = "toclear" + EX + "\n" + "testsnip" + EX
     wanted = "toclear" + EX + "\n" + "This is a test."
 
 class ParseSnippets_ClearTwo(_VimTest):
     files = { "us/all.snippets": r"""
+        clearsnippets testsnip toclear
+
         snippet testsnip "Test snippet"
         This is a test.
         endsnippet
@@ -86,8 +88,6 @@ class ParseSnippets_ClearTwo(_VimTest):
         snippet toclear "Snippet to clear"
         Do not expand.
         endsnippet
-
-        clearsnippets testsnip toclear
         """}
     keys = "toclear" + EX + "\n" + "testsnip" + EX
     wanted = "toclear" + EX + "\n" + "testsnip" + EX
diff --git a/test/test_SnippetPriorities.py b/test/test_SnippetPriorities.py
index ae2ea8c..a43a3ea 100644
--- a/test/test_SnippetPriorities.py
+++ b/test/test_SnippetPriorities.py
@@ -10,6 +10,7 @@ class SnippetPriorities_MultiWordTriggerOverwriteExisting(_VimTest):
     )
     keys = "test me" + EX
     wanted = "We overwrite"
+
 class SnippetPriorities_DoNotCareAboutNonMatchings(_VimTest):
     snippets = (
      ("test1", "Hallo", "Types Hallo"),
@@ -17,6 +18,7 @@ class SnippetPriorities_DoNotCareAboutNonMatchings(_VimTest):
     )
     keys = "test1" + EX
     wanted = "Hallo"
+
 class SnippetPriorities_OverwriteExisting(_VimTest):
     snippets = (
      ("test", "${1:Hallo}", "Types Hallo"),
@@ -25,6 +27,7 @@ class SnippetPriorities_OverwriteExisting(_VimTest):
     )
     keys = "test" + EX
     wanted = "We overwrite"
+
 class SnippetPriorities_OverwriteTwice_ECR(_VimTest):
     snippets = (
         ("test", "${1:Hallo}", "Types Hallo"),
@@ -34,6 +37,7 @@ class SnippetPriorities_OverwriteTwice_ECR(_VimTest):
     )
     keys = "test" + EX
     wanted = "again"
+
 class SnippetPriorities_OverwriteThenChoose_ECR(_VimTest):
     snippets = (
         ("test", "${1:Hallo}", "Types Hallo"),
@@ -43,6 +47,7 @@ class SnippetPriorities_OverwriteThenChoose_ECR(_VimTest):
     )
     keys = "test" + EX + "1\n\n" + "test" + EX + "2\n"
     wanted = "We overwrite\nNo overwrite"
+
 class SnippetPriorities_AddedHasHigherThanFile(_VimTest):
     files = { "us/all.snippets": r"""
         snippet test "Test Snippet" b
@@ -54,6 +59,7 @@ class SnippetPriorities_AddedHasHigherThanFile(_VimTest):
     )
     keys = "test" + EX
     wanted = "We overwrite"
+
 class SnippetPriorities_FileHasHigherThanAdded(_VimTest):
     files = { "us/all.snippets": r"""
         snippet test "Test Snippet" b
@@ -65,6 +71,7 @@ class SnippetPriorities_FileHasHigherThanAdded(_VimTest):
     )
     keys = "test" + EX
     wanted = "This is a test snippet"
+
 class SnippetPriorities_FileHasHigherThanAdded(_VimTest):
     files = { "us/all.snippets": r"""
         priority -3
@@ -77,4 +84,62 @@ class SnippetPriorities_FileHasHigherThanAdded(_VimTest):
     )
     keys = "test" + EX
     wanted = "This is a test snippet"
+
+class SnippetPriorities_SimpleClear(_VimTest):
+    files = {
+        "us/all.snippets": r"""
+        priority 1
+        clearsnippets
+        priority -1
+        snippet test "Test Snippet"
+        Should not expand to this.
+        endsnippet
+        """
+    }
+    keys = "test" + EX
+    wanted = "test" + EX
+
+class SnippetPriorities_SimpleClear2(_VimTest):
+    files = {
+        "us/all.snippets": r"""
+        clearsnippets
+        snippet test "Test snippet"
+        Should not expand to this.
+        endsnippet
+        """
+    }
+    keys = "test" + EX
+    wanted = "test" + EX
+
+class SnippetPriorities_ClearedByParent(_VimTest):
+    files = {
+        "us/p.snippets": r"""
+        clearsnippets
+        """,
+        "us/c.snippets": r"""
+        extends p
+        snippet test "Test snippets"
+        Should not expand to this.
+        endsnippet
+        """
+    }
+    keys = ESC + ":set ft=c\n" + "itest" + EX
+    wanted = "test" + EX
+
+class SnippetPriorities_ClearedByChild(_VimTest):
+    files = {
+        "us/p.snippets": r"""
+        snippet test "Test snippets"
+        Should only expand in p.
+        endsnippet
+        """,
+        "us/c.snippets": r"""
+        extends p
+        clearsnippets
+        """
+    }
+    keys = (ESC + ":set ft=p\n" + "itest" + EX + "\n" +
+            ESC + ":set ft=c\n" + "itest" + EX + ESC + ":set ft=p")
+    wanted = "Should only expand in p.\ntest" + EX
+
 # End: Snippet Priority  #}}}

From 0abfc3bececa47eeec6fcdbaac0318fd92f98c76 Mon Sep 17 00:00:00 2001
From: cwahbong <cw.ahbong@gmail.com>
Date: Thu, 31 Jul 2014 21:50:43 +0800
Subject: [PATCH 5/5] Some refinements.

1. Add docstrings.
2. Re-implement get_deep_extends().
3. Remove all inners.
---
 pythonx/UltiSnips/snippet/source/_base.py     | 85 +++++++++++--------
 .../snippet/source/_snippet_dictionary.py     |  4 +-
 2 files changed, 51 insertions(+), 38 deletions(-)

diff --git a/pythonx/UltiSnips/snippet/source/_base.py b/pythonx/UltiSnips/snippet/source/_base.py
index b795d46..bca5079 100644
--- a/pythonx/UltiSnips/snippet/source/_base.py
+++ b/pythonx/UltiSnips/snippet/source/_base.py
@@ -15,8 +15,18 @@ class SnippetSource(object):
         self._extends = defaultdict(set)
 
     def ensure(self, filetypes):
+        """Update/reload the snippets in the source when needed.  It makes sure
+        that the snippets are not outdated.
+        """
         pass
 
+    def _get_existing_deep_extends(self, base_filetypes):
+        """Helper for get all existing filetypes extended by base
+        filetypes.
+        """
+        deep_extends = self.get_deep_extends(base_filetypes)
+        return [ft for ft in deep_extends if ft in self._snippets]
+
     def get_snippets(self, filetypes, before, possible):
         """Returns the snippets for all 'filetypes' (in order) and their parents
         matching the text 'before'. If 'possible' is true, a partial match is
@@ -25,48 +35,51 @@ class SnippetSource(object):
 
         Returns a list of SnippetDefinition s.
         """
-        def __inner(fts):
-            result = []
-            existing_fts = filter(lambda ft: ft in self._snippets, fts)
-            for ft in existing_fts:
-                snips = self._snippets[ft]
-                result.extend(snips.get_matching_snippets(before, possible))
-            return result
-        return __inner(self.get_deep_extends(filetypes))
+        result = []
+        for ft in self._get_existing_deep_extends(filetypes):
+            snips = self._snippets[ft]
+            result.extend(snips.get_matching_snippets(before, possible))
+        return result
 
     def get_clear_priority(self, filetypes):
-        def __inner(fts):
-            pri = None
-            existing_fts = filter(lambda ft: ft in self._snippets, fts)
-            for ft in existing_fts:
-                snippets = self._snippets[ft]
-                if pri is None or snippets._clear_priority > pri:
-                    pri = snippets._clear_priority
-            return pri
-        return __inner(self.get_deep_extends(filetypes))
+        """Get maximum clearsnippets priority without arguments for specified
+        filetypes, if any.  It returns None if there are no clearsnippets.
+        """
+        pri = None
+        for ft in self._get_existing_deep_extends(filetypes):
+            snippets = self._snippets[ft]
+            if pri is None or snippets._clear_priority > pri:
+                pri = snippets._clear_priority
+        return pri
 
     def get_cleared(self, filetypes):
-        def __inner(fts):
-            cleared = {}
-            existing_fts = filter(lambda ft: ft in self._snippets, fts)
-            for ft in existing_fts:
-                snippets = self._snippets[ft]
-                for key, value in snippets._cleared.items():
-                    if key not in cleared or value > cleared[key]:
-                        cleared[key] = value
-            return cleared
-        return __inner(self.get_deep_extends(filetypes))
+        """Get a set of cleared snippets marked by clearsnippets with arguments
+        for specified filetypes.
+        """
+        cleared = {}
+        for ft in self._get_existing_deep_extends(filetypes):
+            snippets = self._snippets[ft]
+            for key, value in snippets._cleared.items():
+                if key not in cleared or value > cleared[key]:
+                    cleared[key] = value
+        return cleared
 
     def update_extends(self, child_ft, parent_fts):
+        """Update the extending relation by given child filetype and
+        its parent filetypes.
+        """
         self._extends[child_ft].update(parent_fts)
 
-    def get_deep_extends(self, root_filetypes):
-        seen = set(root_filetypes)
-        l = list(set(root_filetypes))
-        while l:
-            top = l.pop()
-            for ft in self._extends[top]:
-                if ft not in seen:
-                    seen.add(ft)
-                    l.append(ft)
+    def get_deep_extends(self, base_filetypes):
+        """Get a list of filetypes that is either directed or indirected
+        extended by given base filetypes.  Note that the returned list
+        include the root filetype itself.
+        """
+        seen = set(base_filetypes)
+        todo_fts = list(set(base_filetypes))
+        while todo_fts:
+            todo_ft = todo_fts.pop()
+            unseen_extends = set(ft for ft in self._extends[todo_ft] if ft not in seen)
+            seen.update(unseen_extends)
+            todo_fts.extend(unseen_extends)
         return seen
diff --git a/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py b/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
index 351ba68..5b23a32 100644
--- a/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
+++ b/pythonx/UltiSnips/snippet/source/_snippet_dictionary.py
@@ -25,8 +25,8 @@ class SnippetDictionary(object):
             return [s for s in all_snippets if s.could_match(trigger)]
 
     def clear_snippets(self, priority, triggers):
-        """Mark snippets as cleared with priority.  When 'triggers' is
-        None, then it updated the clear_priority."""
+        """Clear the snippets by mark them as cleared.  If trigger is
+        None, it updates the value of clear priority instead."""
         if not triggers:
             if self._clear_priority is None or priority > self._clear_priority:
                 self._clear_priority = priority