NoIssue - Detect redundant comparisons

flake8-eyeo/flake8_eyeo.py

Index: flake8-eyeo/flake8_eyeo.py
===================================================================
--- a/flake8-eyeo/flake8_eyeo.py
+++ b/flake8-eyeo/flake8_eyeo.py
@@ -287,6 +287,36 @@
 
         self.generic_visit(node)
 
+    def visit_BoolOp(self, node):
+        if isinstance(node.op, ast.Or):
+            left = node.values[0]
+            right = node.values[1]

[Sebastian Noack, 2017/12/10 23:19:57]

What if there is another condition in between? E.g: x == 1 or y or x == 2

+            if (isinstance(left, ast.Compare) and
+                    isinstance(right, ast.Compare)):
+                if (isinstance(left.ops[0], ast.Eq) and
+                   isinstance(left.ops[0], ast.Eq) or

[Sebastian Noack, 2017/12/10 23:19:57]

This expression is the same as the left-hand side of the and-operator.

+                    (isinstance(left.ops[0], ast.NotEq) and
+                        isinstance(left.ops[0], ast.NotEq))):
+                    value1names = []
+                    value2names = []
+                    # Gather variable names from the left comparison
+                    if isinstance(left.left, ast.Name):

[Sebastian Noack, 2017/12/10 23:19:57]

What if it is an Attribute node? E.g: x.a == 1 or x.a == 2

+                        value1names.append(left.left.id)
+                    if isinstance(left.comparators[0], ast.Name):
+                        value1names.append(left.comparators[0].id)
+                    # Gather variable names from the right comparison
+                    if isinstance(right.left, ast.Name):
+                        value2names.append(right.left.id)
+                    if isinstance(right.comparators[0], ast.Name):
+                        value2names.append(right.comparators[0].id)
+                    # Check for duplicates
+                    for i in value1names:
+                        if i in value2names:
+                            self.errors.append((node, 'A208 `{} == x or {} == '
+                                                      'y` should be `{} in {{x'
+                                                      ', y}}`'.format(i, i,
+                                                                      i)))
+
     def _check_deprecated(self, node, name):
         substitute = DISCOURAGED_APIS.get(name)
         if substitute:
@@ -391,7 +421,7 @@
         checker_state['has_unicode_literals'] = True
 
     for kind, token, start, end, _ in tokens:
-        if kind == tokenize.INDENT or kind == tokenize.DEDENT:
+        if kind in {tokenize.INDENT, tokenize.DEDENT}:
             continue
 
         if kind == tokenize.STRING: