Don't omit whitespace when the factor is not a math operator

Fixes #55

diff --git a/README.md b/README.md
index 20ab4be7e5b3c728d8cf6863563ac34e3d4fd22a..aba30ab2fb0483483e75bb32f28d7bd6185ae2ca 100644 (file)
--- a/README.md
+++ b/README.md
@@ -293,6 +293,11 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 
 ## Change Log
 
+### 18.3a4 (unreleased)
+
+* don't omit whitespace if the previous factor leaf wasn't a math
+  operator (#55)
+
 ### 18.3a3
 
 * don't remove single empty lines outside of bracketed expressions

diff --git a/black.py b/black.py
index 1c07de713fde713f5814275cc0a6e07f8c18db26..0dd763073622d2ec1d0234b46cf5cd4e42bfe607 100644 (file)
--- a/black.py
+++ b/black.py
@@ -340,6 +340,7 @@ MATH_OPERATORS = {
     token.AMPER,
     token.PERCENT,
     token.CIRCUMFLEX,
+    token.TILDE,
     token.LEFTSHIFT,
     token.RIGHTSHIFT,
     token.DOUBLESTAR,
@@ -888,7 +889,11 @@ def whitespace(leaf: Leaf) -> str:  # noqa C901
             if prevp.parent and prevp.parent.type in {syms.subscript, syms.sliceop}:
                 return NO
 
-        elif prevp.parent and prevp.parent.type in {syms.factor, syms.star_expr}:
+        elif (
+            prevp.parent
+            and prevp.parent.type in {syms.factor, syms.star_expr}
+            and prevp.type in MATH_OPERATORS
+        ):
             return NO
 
     elif prev.type in OPENING_BRACKETS:

diff --git a/tests/expression.py b/tests/expression.py
index dbb9303673eb2b98feb69ccdec018ecc28c5b09e..c18942ec3522f058dfd7f173d669bfb07385e932 100644 (file)
--- a/tests/expression.py
+++ b/tests/expression.py
@@ -63,6 +63,8 @@ str or None if (1 if True else 2) else str or bytes or None
 [((i ** 2) + j) for i in (1, 2, 3) for j in (1, 2, 3)]
 {i: 0 for i in (1, 2, 3)}
 {i: j for i, j in ((1, 'a'), (2, 'b'), (3, 'c'))}
+{a: b * 2 for a, b in dictionary.items()}
+{a: b * -2 for a, b in dictionary.items()}
 {k: v for k, v in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension}
 Python3 > Python2 > COBOL
 Life is Life
@@ -214,6 +216,8 @@ str or None if (1 if True else 2) else str or bytes or None
 [((i ** 2) + j) for i in (1, 2, 3) for j in (1, 2, 3)]
 {i: 0 for i in (1, 2, 3)}
 {i: j for i, j in ((1, 'a'), (2, 'b'), (3, 'c'))}
+{a: b * 2 for a, b in dictionary.items()}
+{a: b * -2 for a, b in dictionary.items()}
 {
     k: v
     for k, v in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension