From 698485055b57016f190d716040eeda5f96d1aaa3 Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Sat, 19 May 2018 14:36:17 +0200
Subject: [PATCH] Fix, test order of operations in shift stringification
 (closes #6 on gitlab)

---
 pymbolic/mapper/stringifier.py | 12 ++++++++----
 test/test_pymbolic.py          | 13 +++++++++----
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/pymbolic/mapper/stringifier.py b/pymbolic/mapper/stringifier.py
index 6e1519e..44057df 100644
--- a/pymbolic/mapper/stringifier.py
+++ b/pymbolic/mapper/stringifier.py
@@ -225,16 +225,20 @@ class StringifyMapper(pymbolic.mapper.Mapper):
 
     def map_left_shift(self, expr, enclosing_prec, *args, **kwargs):
         return self.parenthesize_if_needed(
+                # +1 to address
+                # https://gitlab.tiker.net/inducer/pymbolic/issues/6
                 self.format("%s << %s",
-                    self.rec(expr.shiftee, PREC_SHIFT, *args, **kwargs),
-                    self.rec(expr.shift, PREC_SHIFT, *args, **kwargs)),
+                    self.rec(expr.shiftee, PREC_SHIFT+1, *args, **kwargs),
+                    self.rec(expr.shift, PREC_SHIFT+1, *args, **kwargs)),
                 enclosing_prec, PREC_SHIFT)
 
     def map_right_shift(self, expr, enclosing_prec, *args, **kwargs):
         return self.parenthesize_if_needed(
+                # +1 to address
+                # https://gitlab.tiker.net/inducer/pymbolic/issues/6
                 self.format("%s >> %s",
-                    self.rec(expr.shiftee, PREC_SHIFT, *args, **kwargs),
-                    self.rec(expr.shift, PREC_SHIFT, *args, **kwargs)),
+                    self.rec(expr.shiftee, PREC_SHIFT+1, *args, **kwargs),
+                    self.rec(expr.shift, PREC_SHIFT+1, *args, **kwargs)),
                 enclosing_prec, PREC_SHIFT)
 
     def map_bitwise_not(self, expr, enclosing_prec, *args, **kwargs):
diff --git a/test/test_pymbolic.py b/test/test_pymbolic.py
index 44cd8cd..f6b8733 100644
--- a/test/test_pymbolic.py
+++ b/test/test_pymbolic.py
@@ -22,9 +22,9 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 """
 
-import pymbolic
 import pymbolic.primitives as prim
 import pytest
+from pymbolic import parse
 
 
 from pymbolic.mapper import IdentityMapper
@@ -35,9 +35,6 @@ except NameError:
     from functools import reduce
 
 
-pymbolic.disable_subscript_by_getitem()
-
-
 def test_integer_power():
     from pymbolic.algorithm import integer_power
 
@@ -487,6 +484,14 @@ def test_long_sympy_mapping():
     SympyToPymbolicMapper()(sp.sympify(int(10)))
 
 
+def test_stringifier_preserve_shift_order():
+    for expr in [
+            parse("(a << b) >> 2"),
+            parse("a << (b >> 2)")
+            ]:
+        assert parse(str(expr)) == expr
+
+
 if __name__ == "__main__":
     import sys
     if len(sys.argv) > 1:
-- 
GitLab