2.6, 2.7 Parse if else inside list comprehension

Fixes #171

test/simple_source/bug26/01_ifelse_listcomp.py

@@ -0,0 +1,4 @@
+# Bug from issue #171:  parsing "if x if a else y" inside a list comprehension on 2.7
+# This is RUNNABLE!
+assert [False, True, True, True, True] == [False if not a else True for a in range(5)]
+assert [True, False, False, False, False] == [False if a else True for a in range(5)]

uncompyle6/parsers/parse26.py

@@ -264,6 +264,9 @@ class Python26Parser(Python2Parser):
         dict ::= BUILD_MAP kvlist
         kvlist ::= kvlist kv3
 
+        expr ::= conditional_not
+        conditional_not ::= expr jmp_true expr _jump COME_FROM POP_TOP expr COME_FROM
+
         conditional  ::= expr jmp_false expr jf_cf_pop expr come_from_opt
         and          ::= expr JUMP_IF_FALSE POP_TOP expr JUMP_IF_FALSE POP_TOP
 

uncompyle6/parsers/parse27.py

@@ -165,6 +165,9 @@ class Python27Parser(Python2Parser):
                            ::= expr jmp_true expr return_if_lambda
                                return_stmt_lambda LAMBDA_MARKER
 
+        expr ::= conditional_not
+        conditional_not ::= expr jmp_true expr _jump expr COME_FROM
+
         kv3 ::= expr expr STORE_MAP
         """
 
@@ -172,12 +175,17 @@ class Python27Parser(Python2Parser):
         # 2.7 changes COME_FROM to COME_FROM_FINALLY
         self.remove_rules("""
         while1elsestmt ::= SETUP_LOOP l_stmts JUMP_BACK else_suite COME_FROM
-        tryfinallystmt ::= SETUP_FINALLY suite_stmts_opt POP_BLOCK LOAD_CONST COME_FROM suite_stmts_opt END_FINALLY
+        tryfinallystmt ::= SETUP_FINALLY suite_stmts_opt
+                           POP_BLOCK LOAD_CONST COME_FROM suite_stmts_opt
+                           END_FINALLY
         """)
         super(Python27Parser, self).customize_grammar_rules(tokens, customize)
         self.check_reduce['and'] = 'AST'
+        # self.check_reduce['or'] = 'AST'
         self.check_reduce['raise_stmt1'] = 'AST'
-        # self.check_reduce['conditional_true'] = 'AST'
+        self.check_reduce['list_if_not'] = 'AST'
+        self.check_reduce['list_if'] = 'AST'
+        self.check_reduce['conditional_true'] = 'AST'
         return
 
     def reduce_is_invalid(self, rule, ast, tokens, first, last):
@@ -195,6 +203,21 @@ class Python27Parser(Python2Parser):
                         tokens[last].pattr == jmp_false.pattr)
         elif rule[0] == ('raise_stmt1'):
             return ast[0] == 'expr' and ast[0][0] == 'or'
+        elif rule == ('list_if_not', ('expr', 'jmp_true', 'list_iter')):
+            jump_inst = ast[1][0]
+            jump_offset = jump_inst.attr
+            return jump_offset > jump_inst.offset and jump_offset < tokens[last].offset
+        elif rule == ('list_if', ('expr', 'jmp_false', 'list_iter')):
+            jump_inst = ast[1][0]
+            jump_offset = jump_inst.attr
+            return jump_offset > jump_inst.offset and jump_offset < tokens[last].offset
+        elif rule == ('or', ('expr', 'jmp_true', 'expr', '\\e_come_from_opt')):
+            # Test that jmp_true doesn't jump inside the middle the "or"
+            # or that it jumps to the same place as the end of "and"
+            jmp_true = ast[1][0]
+            jmp_target = jmp_true.offset + jmp_true.attr + 3
+            return not (jmp_target == tokens[last].offset or
+                        tokens[last].pattr == jmp_true.pattr)
         # elif rule[0] == ('conditional_true'):
         #     # FIXME: the below is a hack: we check expr for
         #     # nodes that could have possibly been a been a Boolean.

uncompyle6/semantics/consts.py

@@ -207,7 +207,7 @@ TABLE_DIRECT = {
     'conditional':      ( '%p if %p else %p', (2, 27), (0, 27), (4, 27) ),
     'conditional_true': ( '%p if 1 else %p', (0, 27), (2, 27) ),
     'ret_cond':         ( '%p if %p else %p', (2, 27), (0, 27), (-1, 27) ),
-    'conditionalnot':   ( '%p if not %p else %p', (2, 27), (0, 22), (4, 27) ),
+    'conditional_not':  ( '%p if not %p else %p', (2, 27), (0, 22), (4, 27) ),
     'ret_cond_not':     ( '%p if not %p else %p', (2, 27), (0, 22), (-1, 27) ),
     'conditional_lambda':
                         ( '%c if %c else %c',

uncompyle6/semantics/pysource.py

@@ -784,7 +784,7 @@ class SourceWalker(GenericASTTraversal, object):
     def n_list_comp(self, node):
         """List comprehensions"""
         p = self.prec
-        self.prec = 27
+        self.prec = 100
         if self.version >= 2.7:
             if self.is_pypy:
                 self.n_list_comp_pypy27(node)