Infinite loop if this lambda is parsed in Jupyter (#111)

* Found bug if a "word" wasn't at the end of the line, which was a bit of a dumb bug and a bit embarassing that none of my tests had covered it.

Fixes #110

Author: gordonwatts

func_adl/util_ast.py

@@ -64,7 +64,7 @@ def function_call(function_name: str, args: List[ast.AST]) -> ast.Call:
 
 
 def lambda_unwrap(lam: ast.AST) -> ast.Lambda:
-    """Given an AST of a lambda node, return the lambda node. If it is burried in a module, then
+    """Given an AST of a lambda node, return the lambda node. If it is buried in a module, then
     unwrap it first Python, when it parses an module, returns the lambda wrapped in a `Module` AST
     node. This gets rid of it, but is also flexible.
 
@@ -557,7 +557,7 @@ def previous_word(self) -> Optional[str]:
         carrot = self._carrot
         while line_no >= 0:
             while carrot >= 0:
-                m = re.match(r".*\W(\w+)\s*$", self._lines[line_no][:carrot])
+                m = re.match(r".*\b(\w+)\b[\s|\W]*$", self._lines[line_no][:carrot])
                 if m:
                     return m.group(1)
             line_no -= 1

tests/test_util_ast.py

@@ -612,6 +612,42 @@ def do_it(self, x: Callable):
     assert "20" in ast.dump(found[0])
 
 
+def test_parse_multiline_lambda_blank_lines_no_infinite_loop():
+    "Make sure we can properly parse a multi-line lambda - using parens as delimiters"
+
+    found = []
+
+    class my_obj:
+        def Where(self, x: Callable):
+            found.append(parse_as_ast(x))
+            return self
+
+        def Select(self, x: Callable):
+            found.append(parse_as_ast(x))
+            return self
+
+        def AsAwkwardArray(self, stuff: str):
+            return self
+
+        def value(self):
+            return self
+
+    jets_pflow_name = "hi"
+    ds_dijet = my_obj()
+
+    # fmt: off
+    jets_pflow = (
+        ds_dijet.Select(lambda e: e.Jets(uncalibrated_collection=jets_pflow_name))
+        .Select(lambda e: e.Where(lambda j: (j.pt() / 1000) > 30))
+        .Select(lambda e: e.Select(lambda j: (j.pt() / 1000)))
+        .AsAwkwardArray("JetPt")
+        .value()
+    )
+    # fmt: on
+    assert jets_pflow is not None  # Just to keep flake8 happy without adding a noqa above.
+    assert "uncalibrated_collection" in ast.dump(found[0])
+
+
 def test_parse_multiline_lambda_ok_with_one_as_arg():
     "Make sure we can properly parse a multi-line lambda - but now with argument"