autotrigger: make snippets expand without <tab>

autoload/UltiSnips.vim

@@ -151,3 +151,8 @@ endf
 function! UltiSnips#LeavingInsertMode()
     exec g:_uspy "UltiSnips_Manager._leaving_insert_mode()"
 endfunction
+
+function! UltiSnips#TrackChange()
+    exec g:_uspy "UltiSnips_Manager._track_change()"
+endfunction
+" }}}

doc/UltiSnips.txt

@@ -42,6 +42,7 @@ UltiSnips                                      *snippet* *snippets* *UltiSnips*
       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|
+   4.11 Autotrigger                             |UltiSnips-autotrigger|
 5. UltiSnips and Other Plugins                  |UltiSnips-other-plugins|
    5.1 Existing Integrations                    |UltiSnips-integrations|
    5.2 Extending UltiSnips                      |UltiSnips-extending|
@@ -690,6 +691,9 @@ The options currently supported are: >
        python expression. This option can be specified along with other
        options, like 'b'. See |UltiSnips-context-snippets| for more info.
 
+   A   Snippet will be triggered automatically, when condition matches.
+       See |UltiSnips-autotrigger| for more info.
+
 The end line is the 'endsnippet' keyword on a line by itself. >
 
    endsnippet
@@ -1599,6 +1603,41 @@ def $1():
 endsnippet
 ------------------- SNAP -------------------
 
+4.11 Autotrigger                                       *UltiSnips-autotrigger*
+----------------
+
+Note: vim should be newer than 7.4.214 to support this feature.
+
+Many language constructs can occur only at specific places, so it's
+possible to use snippets without manually triggering them.
+
+Snippet can be marked as autotriggered by specifying 'A' option in the snippet
+definition.
+
+After snippet is defined as being autotriggered, snippet condition will be
+checked on every typed character and if condition matches, then snippet will
+be triggered.
+
+*Warning:* using of this feature can lead to significant vim slowdown. If you
+discovered that, report an issue to the github.com/SirVer/UltiSnips.
+
+Consider following snippets, that can be usefull in Go programming:
+------------------- SNIP -------------------
+snippet "^p" "package" rbA
+package ${1:main}
+endsnippet
+
+snippet "^m" "func main" rbA
+func main() {
+	$1
+}
+endsnippet
+------------------- SNAP -------------------
+
+When "p" character will occur in the beginning of the line, it will be
+automatically expanded into "package main". Same with "m" character. There is
+no need to press trigger key after "m""
+
 ==============================================================================
 5. UltiSnips and Other Plugins                      *UltiSnips-other-plugins*
 

plugin/UltiSnips.vim

@@ -46,6 +46,12 @@ command! -bang -nargs=? -complete=customlist,UltiSnips#FileTypeComplete UltiSnip
 
 command! -nargs=1 UltiSnipsAddFiletypes :call UltiSnips#AddFiletypes(<q-args>)
 
+augroup UltiSnips_AutoTrigger
+    au!
+    au InsertCharPre * call UltiSnips#TrackChange()
+    au TextChangedI * call UltiSnips#TrackChange()
+augroup END
+
 call UltiSnips#map_keys#MapKeys()
 
 " vim: ts=8 sts=4 sw=4

pythonx/UltiSnips/snippet/source/_base.py

@@ -23,12 +23,15 @@ class SnippetSource(object):
 
         """
 
+    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)
         return [ft for ft in deep_extends if ft in self._snippets]
 
-    def get_snippets(self, filetypes, before, possible):
+    def get_snippets(self, filetypes, before, possible, autotrigger_only):
         """Returns the snippets for all 'filetypes' (in order) and their
         parents matching the text 'before'. If 'possible' is true, a partial
         match is enough. Base classes can override this method to provide means
@@ -40,7 +43,8 @@ class SnippetSource(object):
         result = []
         for ft in self._get_existing_deep_extends(filetypes):
             snips = self._snippets[ft]
-            result.extend(snips.get_matching_snippets(before, possible))
+            result.extend(snips.get_matching_snippets(before, possible,
+                                                      autotrigger_only))
         return result
 
     def get_clear_priority(self, filetypes):

pythonx/UltiSnips/snippet/source/_snippet_dictionary.py

@@ -16,13 +16,23 @@ class SnippetDictionary(object):
         """Add 'snippet' to this dictionary."""
         self._snippets.append(snippet)
 
-    def get_matching_snippets(self, trigger, potentially):
+    def get_matching_snippets(self, trigger, potentially, autotrigger_only):
         """Returns all snippets matching the given trigger.
 
         If 'potentially' is true, returns all that could_match().
 
+        If 'autotrigger_only' is true, function will return only snippets which
+        are marked with flag 'A' (should be automatically expanded without
+        trigger key press).
+        It's handled specially to avoid walking down the list of all snippets,
+        which can be very slow, because function will be called on each change
+        made in insert mode.
+
         """
         all_snippets = self._snippets
+        if autotrigger_only:
+            all_snippets = [s for s in all_snippets if s.has_option('A')]
+
         if not potentially:
             return [s for s in all_snippets if s.matches(trigger)]
         else:
@@ -43,3 +53,6 @@ class SnippetDictionary(object):
                 if (trigger not in self._cleared or
                         priority > self._cleared[trigger]):
                     self._cleared[trigger] = priority
+
+    def __len__(self):
+        return len(self._snippets)

pythonx/UltiSnips/snippet_manager.py

@@ -100,6 +100,8 @@ class SnippetManager(object):
         self._snip_expanded_in_action = False
         self._inside_action = False
 
+        self._last_inserted_char = ''
+
         self._added_snippets_source = AddedSnippetsSource()
         self.register_snippet_source('ultisnips_files', UltiSnipsFileSource())
         self.register_snippet_source('added', self._added_snippets_source)
@@ -541,7 +543,7 @@ class SnippetManager(object):
         elif feedkey:
             _vim.command('return %s' % _vim.escape(feedkey))
 
-    def _snips(self, before, partial):
+    def _snips(self, before, partial, autotrigger_only=False):
         """Returns all the snippets for the given text before the cursor.
 
         If partial is True, then get also return partial matches.
@@ -552,6 +554,7 @@ class SnippetManager(object):
         clear_priority = None
         cleared = {}
         for _, source in self._snippet_sources:
+            if not autotrigger_only or not source.loaded(filetypes):
                 source.ensure(filetypes)
 
         # Collect cleared information from sources.
@@ -565,7 +568,14 @@ class SnippetManager(object):
                     cleared[key] = value
 
         for _, source in self._snippet_sources:
-            for snippet in source.get_snippets(filetypes, before, partial):
+            possible_snippets = source.get_snippets(
+                filetypes,
+                before,
+                partial,
+                autotrigger_only
+            )
+
+            for snippet in possible_snippets:
                 if ((clear_priority is None or snippet.priority > clear_priority)
                         and (snippet.trigger not in cleared or
                              snippet.priority > cleared[snippet.trigger])):
@@ -667,10 +677,10 @@ class SnippetManager(object):
                 self._snip_expanded_in_action = True
 
 
-    def _try_expand(self):
+    def _try_expand(self, autotrigger_only=False):
         """Try to expand a snippet in the current place."""
         before = _vim.buf.line_till_cursor
-        snippets = self._snips(before, False)
+        snippets = self._snips(before, False, autotrigger_only)
         if snippets:
             # prefer snippets with context if any
             snippets_with_context = [s for s in snippets if s.context]
@@ -765,6 +775,18 @@ class SnippetManager(object):
         finally:
             self._inside_action = old_flag
 
+    @err_to_scratch_buffer
+    def _track_change(self):
+        inserted_char = _vim.eval('v:char')
+        try:
+            if inserted_char == '':
+                before = _vim.buf.line_till_cursor
+                if before and before[-1] == self._last_inserted_char:
+                    self._try_expand(autotrigger_only=True)
+        finally:
+            self._last_inserted_char = inserted_char
+
+
 UltiSnips_Manager = SnippetManager(  # pylint:disable=invalid-name
     vim.eval('g:UltiSnipsExpandTrigger'),
     vim.eval('g:UltiSnipsJumpForwardTrigger'),

test/test_Autotrigger.py

@@ -0,0 +1,69 @@
+from test.vim_test_case import VimTestCase as _VimTest
+from test.constant import *
+
+import subprocess
+
+
+def has_patch(version, executable):
+    output = subprocess.check_output([executable, "--version"])
+    patch = 1
+    for line in output.decode('utf-8').split("\n"):
+        if line.startswith("Included patches:"):
+            patch = line.split('-')[1]
+
+    return int(patch) >= version
+
+
+def check_required_vim_version(test):
+    if test.vim_flavor == 'neovim':
+        return None
+    if not has_patch(214, test.vim._vim_executable):
+        return 'Vim newer than 7.4.214 is required'
+    else:
+        return None
+
+
+class Autotrigger_CanMatchSimpleTrigger(_VimTest):
+    skip_if = check_required_vim_version
+    files = { 'us/all.snippets': r"""
+        snippet a "desc" A
+        autotriggered
+        endsnippet
+        """}
+    keys = 'a'
+    wanted = 'autotriggered'
+
+
+class Autotrigger_CanMatchContext(_VimTest):
+    skip_if = check_required_vim_version
+    files = { 'us/all.snippets': r"""
+        snippet a "desc" "snip.line == 2" Ae
+        autotriggered
+        endsnippet
+        """}
+    keys = 'a\na'
+    wanted = 'autotriggered\na'
+
+
+class Autotrigger_CanExpandOnTriggerWithLengthMoreThanOne(_VimTest):
+    skip_if = check_required_vim_version
+    files = { 'us/all.snippets': r"""
+        snippet abc "desc" A
+        autotriggered
+        endsnippet
+        """}
+    keys = 'abc'
+    wanted = 'autotriggered'
+
+
+class Autotrigger_WillProduceNoExceptionWithVimLowerThan214(_VimTest):
+    skip_if = lambda self: 'Vim older than 7.4.214 is required' \
+        if has_patch(214, self.vim._vim_executable) else None
+
+    files = { 'us/all.snippets': r"""
+        snippet abc "desc" A
+        autotriggered
+        endsnippet
+        """}
+    keys = 'abc'
+    wanted = 'abc'

test/test_UltiSnipFunc.py

@@ -154,8 +154,8 @@ from UltiSnips.snippet.source import SnippetSource
 from UltiSnips.snippet.definition import UltiSnipsSnippetDefinition
 
 class MySnippetSource(SnippetSource):
-  def get_snippets(self, filetypes, before, possible):
+  def get_snippets(self, filetypes, before, possible, autotrigger_only):
-    if before.endswith('blumba'):
+    if before.endswith('blumba') and autotrigger_only == False:
       return [
           UltiSnipsSnippetDefinition(
               -100, "blumba", "this is a dynamic snippet", "", "", {}, "blub",