documentation, pull-requests fixes

doc/UltiSnips.txt

@@ -653,6 +653,11 @@ The options currently supported are: >
        Without this option empty lines in snippets definition will have
        indentation too.
 
+   e   Context snippets - With this option expansion of snippet can be
+       controlled not only by previous characters in line, but by any given python
+       expression. This option can be specified along with other options,
+       like 'b'. See |UltiSnips-context-snippets| for more info.
+
 The end line is the 'endsnippet' keyword on a line by itself. >
 
    endsnippet
@@ -818,6 +823,7 @@ The variables automatically defined in python code are: >
    t    - The values of the placeholders, t[1] is the text of ${1}, and so on
    snip - UltiSnips.TextObjects.SnippetUtil object instance. Has methods that
           simplify indentation handling.
+   context - Result of context condition. See |UltiSnips-context-snippets|.
 
 The 'snip' object provides the following methods: >
 
@@ -1293,6 +1299,96 @@ clearsnippets trigger1 trigger2
 ------------------- SNAP -------------------
 
 
+4.9 Context snippets                            *UltiSnips-context-snippets*
+
+Context snippets can be enabled by using 'e' option in snippet definition.
+
+In that case snippet should be defined using this syntax: >
+
+    snippet tab_trigger "description" "expression" options
+
+'expression' can be any python expression. If 'expression' evaluates to
+'True', then this snippet will be chosen for expansion. 'expression' must be
+wrapped with double-quotes.
+
+Following python modules are automatically imported: 're', 'os', 'vim',
+'string', 'random'.
+
+Also, variables are declared in local scope for use in expression: >
+    'window' - alias for 'vim.current.window'
+    'buffer' - alias for 'vim.current.window.buffer'
+    'line' and 'column' - aliases for cursor position
+
+Keep in mind, that lines in vim numbered from 1, and lists in python starts
+from 0, so to access current line you need to use 'line-1' expression.
+
+------------------- SNIP -------------------
+snippet r "return" "re.match('^\s+if err ', buffer[line-2])" be
+return err
+endsnippet
+------------------- SNAP -------------------
+
+That snippet will expand to 'return err' only if previous line is starting
+from 'if err' prefix.
+
+Note: context snippets prioritized over non-context ones. So, if there are
+two snippets with the same trigger, and one of them is context snippet and
+it's expression evaluates to 'True', then context snippet will be used for
+expansion and first will be ignored.
+
+------------------- SNIP -------------------
+snippet i "if ..." b
+if $1 {
+    $2
+}
+endsnippet
+
+snippet i "if err != nil" "re.match('^\s+[^=]*err\s*:?=', buffer[line-2])" be
+if err != nil {
+    $1
+}
+endsnippet
+------------------- SNAP -------------------
+
+That snippet will expand into 'if err != nil' if previous line will
+match 'err :=' prefix, otherwise default 'if' snippet will be expanded.
+
+It's good idea to move context conditions to separate library, so it can be
+used with other UltiSnips user. In that case, library should be imported
+using 'global' keyword, like this:
+
+------------------- SNIP -------------------
+global !p
+import my_utils
+endglobal
+
+snippet , "return ..., nil/err" "my_utils.is_return_argument(buffer, line, column)" ie
+, `!p if my_utils.is_in_err_condition():
+    snip.rv = "err"
+else:
+    snip.rv = "nil"`
+endsnippet
+------------------- SNAP -------------------
+
+That snippet will expand only if cursor is located in the return statement,
+and then it will expand either to 'err' or to 'nil' depending in which 'if'
+statement it's located. 'is_return_argument' and 'is_in_err_condition' are
+part of custom python library which is called 'my_utils' in this example.
+
+Context condition can return any value which python can use as
+condition in it's 'if' statement, and if it's considired 'True', then snippet
+will be expanded. Moreover, result of condition will be accessed in the
+'context' variable:
+
+------------------- SNIP -------------------
+snippet + "var +=" "re.match('\s*(.*?)\s*:?=', buffer[line-2])" ie
+`!p snip.rv = context.group(1)` += $1
+endsnippet
+------------------- SNAP -------------------
+
+That snippet will expand to 'var1 +=' after line, which begins from 'var1 :='.
+
+
 ==============================================================================
 5. UltiSnips and Other Plugins                      *UltiSnips-other-plugins*
 

pythonx/UltiSnips/snippet/definition/_base.py

@@ -4,6 +4,7 @@
 """Snippet representation after parsing."""
 
 import re
+
 import vim
 
 from UltiSnips import _vim
@@ -44,7 +45,7 @@ class SnippetDefinition(object):
     _TABS = re.compile(r"^\t*")
 
     def __init__(self, priority, trigger, value, description,
-                 options, globals, location, context=None):
+                 options, globals, location, context):
         self._priority = int(priority)
         self._trigger = as_unicode(trigger)
         self._value = as_unicode(value)
@@ -90,17 +91,17 @@ class SnippetDefinition(object):
         code = "\n".join([
             'import re, os, vim, string, random',
             '\n'.join(self._globals.get('!p', [])).replace('\r\n', '\n'),
-            'ctx["match"] = ' + self._context_code,
+            'context["match"] = ' + self._context_code,
             ''
         ])
 
         context = {'match': False}
         locals = {
-            'ctx': context,
+            'context': context,
-            'w': current.window,
+            'window': current.window,
-            'b': current.buffer,
+            'buffer': current.buffer,
-            'l': current.window.cursor[0],
+            'line': current.window.cursor[0],
-            'c': current.window.cursor[1],
+            'column': current.window.cursor[1],
         }
 
         exec(code, locals)

pythonx/UltiSnips/snippet/definition/snipmate.py

@@ -15,7 +15,8 @@ class SnipMateSnippetDefinition(SnippetDefinition):
 
     def __init__(self, trigger, value, description, location):
         SnippetDefinition.__init__(self, self.SNIPMATE_SNIPPET_PRIORITY,
-                                   trigger, value, description, '', {}, location)
+                                   trigger, value, description, '', {}, location,
+                                   None)
 
     def instantiate(self, snippet_instance, initial_text, indent):
         parse_and_instantiate(snippet_instance, initial_text, indent)

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

@@ -72,12 +72,11 @@ def _handle_snippet_or_global(filename, line, lines, python_globals, priority):
             opts = words[-1]
             remain = remain[:-len(opts) - 1].rstrip()
 
-    if 'x' in opts:
+    context = None
+    if 'e' in opts:
         left = remain[:-1].rfind('"')
         if left != -1 and left != 0:
             context, remain = remain[left:].strip('"'), remain[:left]
-    else:
-        context = None
 
     # Get and strip description if it exists
     remain = remain.strip()
@@ -111,10 +110,12 @@ def _handle_snippet_or_global(filename, line, lines, python_globals, priority):
     if snip == 'global':
         python_globals[trig].append(content)
     elif snip == 'snippet':
-        return 'snippet', (UltiSnipsSnippetDefinition(priority, trig, content,
+        definition = UltiSnipsSnippetDefinition(
-                                                      descr, opts, python_globals,
+            priority, trig, content,
-                                                      '%s:%i' % (filename, start_line_index),
+            descr, opts, python_globals,
-                                                      context),)
+            '%s:%i' % (filename, start_line_index),
+            context)
+        return 'snippet', (definition,)
     else:
         return 'error', ("Invalid snippet type: '%s'" % snip, lines.line_index)