Start moving api stuff to the inference module.

jedi/api/inference.py

@@ -0,0 +1,37 @@
+"""
+This module has helpers for doing type inference on strings. It is needed,
+because we still want to infer types where the syntax is invalid.
+"""
+from jedi.parser import Parser, ParseError
+from jedi.evaluate.cache import memoize_default
+
+
+def type_inference(evaluator, parser, user_context, position, dotted_path, is_completion=False):
+    pass
+
+
+@memoize_default(evaluator_is_first_arg=True)
+def get_under_cursor_stmt(evaluator, parser, cursor_txt, start_pos):
+    """
+    Create a syntax tree node from a string under the cursor. Directly taking
+    the node under the cursor (of the actual syntax tree) would disallow
+    invalid code to be understood.
+
+    The start_pos is typically the position of the current cursor, which may
+    not be the real starting position of that node, but it works perfectly well
+    (for both completions in docstrings and statements).
+    """
+    try:
+        stmt = Parser(evaluator.grammar, cursor_txt, 'eval_input').get_parsed_node()
+    except ParseError:
+        return None
+
+    user_stmt = parser.user_stmt()
+    if user_stmt is None:
+        pos = start_pos
+    else:
+        pos = user_stmt.start_pos
+
+    stmt.move(pos[0] - 1, pos[1])  # Moving the offset.
+    stmt.parent = parser.user_scope()
+    return stmt