Disable auto detecting changes to snippet files on expansion (#967)

Instead, trigger an auto command whenever a .snippets file is saved that will reload the snippets. This is a performance improvement with a loss of functionality: externally (i.e. outside of the current Vim instance) generated snippet files will not be picked up until UltiSnips#RefreshSnippets is called.

I decided to not expose a command for this, since I assume it is rarely useful. I think the command would add confusion of when it was supposed to be ran.

Fixes #932.

autoload/UltiSnips.vim

@@ -131,7 +131,6 @@ function! UltiSnips#Anon(value, ...)
     return ""
 endfunction
 
-
 function! UltiSnips#CursorMoved()
     exec g:_uspy "UltiSnips_Manager._cursor_moved()"
 endf
@@ -147,4 +146,8 @@ endfunction
 function! UltiSnips#TrackChange()
     exec g:_uspy "UltiSnips_Manager._track_change()"
 endfunction
+
+function! UltiSnips#RefreshSnippets()
+    exec g:_uspy "UltiSnips_Manager._refresh_snippets()"
+endfunction
 " }}}

doc/UltiSnips.txt

@@ -751,8 +751,9 @@ with a backslash, '\'.
 To illustrate plaintext snippets, let's begin with a simple example. You can
 try the examples yourself. Simply edit a new file with Vim. Example snippets
 will be added to the 'all.snippets' file, so you'll want to open it in Vim for
-editing as well. >
-   ~/.vim/UltiSnips/all.snippets
+editing as well in the same Vim instance. You can use |UltiSnipsEdit| for this,
+but you can also just run >
+   :tabedit ~/.vim/UltiSnips/all.snippets
 
 Add this snippet to 'all.snippets' and save the file.
 

ftplugin/snippets.vim

@@ -17,6 +17,15 @@ setlocal commentstring=#%s
 setlocal noexpandtab
 setlocal autoindent nosmartindent nocindent
 
+" Whenever a snippets file is written, we ask UltiSnips to reload all snippet
+" files. This feels like auto-updating, but is of course just an
+" approximation: If files change outside of the current Vim instance, we will
+" not notice.
+augroup ultisnips_snippets.vim
+autocmd!
+autocmd BufWritePost <buffer> call UltiSnips#RefreshSnippets()
+augroup END
+
 " Define match words for use with matchit plugin
 " http://www.vim.org/scripts/script.php?script_id=39
 if exists("loaded_matchit") && !exists("b:match_words")

pythonx/UltiSnips/snippet/source/_base.py

@@ -16,16 +16,14 @@ class SnippetSource(object):
         self._snippets = defaultdict(SnippetDictionary)
         self._extends = defaultdict(set)
 
-    def ensure(self, filetypes, cached):
-        """Update/reload the snippets in the source when needed.
-
-        It makes sure that the snippets are not outdated.
+    def ensure(self, filetypes):
+        """Ensures that snippets are loaded."""
 
+    def refresh(self):
+        """Resets all snippets, so that they are reloaded on the next call to
+        ensure.
         """
 
-    def loaded(self, filetypes):
-        return len(self._snippets) > 0
-
     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)

pythonx/UltiSnips/snippet/source/file/_base.py

@@ -4,7 +4,6 @@
 """Code to provide access to UltiSnips files from disk."""
 
 from collections import defaultdict
-import hashlib
 import os
 
 from UltiSnips import _vim
@@ -12,13 +11,6 @@ from UltiSnips import compatibility
 from UltiSnips.snippet.source._base import SnippetSource
 
 
-def _hash_file(path):
-    """Returns a hashdigest of 'path'."""
-    if not os.path.isfile(path):
-        return False
-    return hashlib.sha1(open(path, 'rb').read()).hexdigest()
-
-
 class SnippetSyntaxError(RuntimeError):
 
     """Thrown when a syntax error is found in a file."""
@@ -29,24 +21,18 @@ class SnippetSyntaxError(RuntimeError):
 
 
 class SnippetFileSource(SnippetSource):
-
     """Base class that abstracts away 'extends' info and file hashes."""
 
     def __init__(self):
         SnippetSource.__init__(self)
-        self._files_for_ft = defaultdict(set)
-        self._file_hashes = defaultdict(lambda: None)
-        self._ensure_cached = False
-
-    def ensure(self, filetypes, cached):
-        if cached and self._ensure_cached:
-            return
 
+    def ensure(self, filetypes):
         for ft in self.get_deep_extends(filetypes):
             if self._needs_update(ft):
                 self._load_snippets_for(ft)
 
-        self._ensure_cached = True
+    def refresh(self):
+        self.__init__()
 
     def _get_all_snippet_files_for(self, ft):
         """Returns a set of all files that define snippets for 'ft'."""
@@ -59,38 +45,22 @@ class SnippetFileSource(SnippetSource):
     def _needs_update(self, ft):
         """Returns true if any files for 'ft' have changed and must be
         reloaded."""
-        existing_files = self._get_all_snippet_files_for(ft)
-        if existing_files != self._files_for_ft[ft]:
-            self._files_for_ft[ft] = existing_files
-            return True
-
-        for filename in self._files_for_ft[ft]:
-            if _hash_file(filename) != self._file_hashes[filename]:
-                return True
-
-        return False
+        return not (ft in self._snippets)
 
     def _load_snippets_for(self, ft):
         """Load all snippets for the given 'ft'."""
-        if ft in self._snippets:
-            del self._snippets[ft]
-            del self._extends[ft]
-        try:
-            for fn in self._files_for_ft[ft]:
+        assert(ft not in self._snippets)
+        for fn in self._get_all_snippet_files_for(ft):
             self._parse_snippets(ft, fn)
-        except:
-            del self._files_for_ft[ft]
-            raise
         # Now load for the parents
         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):
-        """Parse the 'filename' for the given 'ft' and watch it for changes in
-        the future."""
-        self._file_hashes[filename] = _hash_file(filename)
+        """Parse the 'filename' for the given 'ft'."""
         file_data = compatibility.open_ascii_file(filename, 'r').read()
+        self._snippets[ft]  # Make sure the dictionary exists
         for event, data in self._parse_snippet_file(file_data, filename):
             if event == 'error':
                 msg, line_index = data

pythonx/UltiSnips/snippet_manager.py

@@ -569,7 +569,7 @@ class SnippetManager(object):
         clear_priority = None
         cleared = {}
         for _, source in self._snippet_sources:
-            source.ensure(filetypes, cached=autotrigger_only)
+            source.ensure(filetypes)
 
         # Collect cleared information from sources.
         for _, source in self._snippet_sources:
@@ -859,6 +859,10 @@ class SnippetManager(object):
 
         self._should_reset_visual = True
 
+    @err_to_scratch_buffer.wrap
+    def _refresh_snippets(self):
+        for _, source in self._snippet_sources:
+            source.refresh()
 
 UltiSnips_Manager = SnippetManager(  # pylint:disable=invalid-name
     vim.eval('g:UltiSnipsExpandTrigger'),