Consider in, not in, is, is not operators

README.md

@@ -628,6 +628,9 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 
 * fixed crash on dealing with optional parentheses (#193)
 
+* fixed "is", "is not", "in", and "not in" not considered operators for
+  splitting purposes
+
 * fixed crash when dead symlinks where encountered
 
 

black.py

@@ -1746,31 +1746,54 @@ def is_split_before_delimiter(leaf: Leaf, previous: Leaf = None) -> int:
     ):
         return STRING_PRIORITY
 
+    if leaf.type != token.NAME:
+        return 0
+
     if (
-        leaf.type == token.NAME
+        leaf.value == "for"
-        and leaf.value == "for"
         and leaf.parent
         and leaf.parent.type in {syms.comp_for, syms.old_comp_for}
     ):
         return COMPREHENSION_PRIORITY
 
     if (
-        leaf.type == token.NAME
+        leaf.value == "if"
-        and leaf.value == "if"
         and leaf.parent
         and leaf.parent.type in {syms.comp_if, syms.old_comp_if}
     ):
         return COMPREHENSION_PRIORITY
 
-    if (
+    if leaf.value in {"if", "else"} and leaf.parent and leaf.parent.type == syms.test:
-        leaf.type == token.NAME
-        and leaf.value in {"if", "else"}
-        and leaf.parent
-        and leaf.parent.type == syms.test
-    ):
         return TERNARY_PRIORITY
 
-    if leaf.type == token.NAME and leaf.value in LOGIC_OPERATORS and leaf.parent:
+    if leaf.value == "is":
+        return COMPARATOR_PRIORITY
+
+    if (
+        leaf.value == "in"
+        and leaf.parent
+        and leaf.parent.type in {syms.comp_op, syms.comparison}
+        and not (
+            previous is not None
+            and previous.type == token.NAME
+            and previous.value == "not"
+        )
+    ):
+        return COMPARATOR_PRIORITY
+
+    if (
+        leaf.value == "not"
+        and leaf.parent
+        and leaf.parent.type == syms.comp_op
+        and not (
+            previous is not None
+            and previous.type == token.NAME
+            and previous.value == "is"
+        )
+    ):
+        return COMPARATOR_PRIORITY
+
+    if leaf.value in LOGIC_OPERATORS and leaf.parent:
         return LOGIC_PRIORITY
 
     return 0

tests/expression.diff

@@ -128,7 +128,7 @@
  ]
  slice[0]
  slice[0:1]
-@@ -124,103 +144,138 @@
+@@ -124,107 +144,154 @@
  numpy[-(c + 1) :, d]
  numpy[:, l[-2]]
  numpy[:, ::-1]
@@ -208,6 +208,10 @@
 -for i in (call()): ...
 -for j in (1 + (2 + 3)): ...
 -while(this and that): ...
+-a = aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp in qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
+-a = aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp not in qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
+-a = aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp is qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
+-a = aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp is not qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
 -if (
 -    threading.current_thread() != threading.main_thread() and
 -    threading.current_thread() != threading.main_thread() or
@@ -272,6 +276,22 @@
 +    ...
 +while this and that:
 +    ...
++a = (
++    aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp
++    in qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
++)
++a = (
++    aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp
++    not in qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
++)
++a = (
++    aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp
++    is qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
++)
++a = (
++    aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp
++    is not qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
++)
 +if (
 +    threading.current_thread() != threading.main_thread()
 +    and threading.current_thread() != threading.main_thread()

tests/expression.py

@@ -173,6 +173,10 @@ async def f():
 for i in (call()): ...
 for j in (1 + (2 + 3)): ...
 while(this and that): ...
+a = aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp in qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
+a = aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp not in qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
+a = aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp is qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
+a = aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp is not qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
 if (
     threading.current_thread() != threading.main_thread() and
     threading.current_thread() != threading.main_thread() or
@@ -449,6 +453,22 @@ async def f():
     ...
 while this and that:
     ...
+a = (
+    aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp
+    in qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
+)
+a = (
+    aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp
+    not in qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
+)
+a = (
+    aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp
+    is qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
+)
+a = (
+    aaaa.bbbb.cccc.dddd.eeee.ffff.gggg.hhhh.iiii.jjjj.kkkk.llll.mmmm.nnnn.oooo.pppp
+    is not qqqq.rrrr.ssss.tttt.uuuu.vvvv.xxxx.yyyy.zzzz
+)
 if (
     threading.current_thread() != threading.main_thread()
     and threading.current_thread() != threading.main_thread()