simplify implementation

hypothesis-python/src/hypothesis/internal/compat.py

@@ -12,7 +12,6 @@
 import copy
 import dataclasses
 import inspect
-import itertools
 import platform
 import sys
 import sysconfig
@@ -252,20 +251,6 @@ def bad_django_TestCase(runner):
         return not isinstance(runner, HypothesisTestCase)
 
 
-if sys.version_info[:2] < (3, 10):
-
-    # copied straight from
-    # https://docs.python.org/3/library/itertools.html#itertools.pairwise
-    def pairwise(iterable):
-        iterator = iter(iterable)
-        a = next(iterator, None)
-        for b in iterator:
-            yield a, b
-            a = b
-
-else:
-    pairwise = itertools.pairwise
-
 # see issue #3812
 if sys.version_info[:2] < (3, 12):
 

hypothesis-python/src/hypothesis/internal/conjecture/junkdrawer.py

@@ -15,7 +15,6 @@
 import array
 import sys
 import warnings
-from itertools import chain
 from random import Random
 from typing import (
     Callable,
@@ -35,7 +34,6 @@
 from sortedcontainers import SortedList
 
 from hypothesis.errors import HypothesisWarning
-from hypothesis.internal.compat import pairwise
 
 ARRAY_CODES = ["B", "H", "I", "L", "Q", "O"]
 
@@ -254,38 +252,22 @@ def __underlying_index(self, i: int) -> int:
         assert 0 <= i < n
 
         if self.__popped_indices is not None:
-            i = self.__underlying_index_for_pops(i)
-
+            # given an index i in the popped representation of the list, compute
+            # its corresponding index in the underlying list. given
+            #   l = [1, 4, 2, 10, 188]
+            #   l.pop(3)
+            #   l.pop(1)
+            #   assert l == [1, 2, 188]
+            #
+            # we want l[i] == self.__values[f(i)], where f is this function.
+            assert len(self.__popped_indices) <= len(self.__values)
+
+            for idx in self.__popped_indices:
+                if idx > i:
+                    break
+                i += 1
         return i
 
-    def __underlying_index_for_pops(self, i):
-        # given an index i in the popped representation of the list, compute
-        # its corresponding index in the underlying list. given
-        #   l = [1, 4, 2, 10, 188]
-        #   l.pop(3)
-        #   l.pop(1)
-        #   assert l == [1, 2, 188]
-        #
-        # we want l[i] == self.__values[f(i)], where f is this function.
-        assert len(self.__popped_indices) <= len(self.__values)
-
-        # we know what indices have been popped. count the total gap (number of
-        # "free indices") between these these, which is the elements remaining.
-        # stop whenever the gap is bigger than we need it to be and compute
-        # exactly where in the gap the expected index would be.
-        #
-        # This relies on popped_indices being sorted.
-        gap = 0
-        for n1, n2 in pairwise(
-            chain([-1], self.__popped_indices, [len(self.__values)])
-        ):
-            prev_gap = gap
-            gap += n2 - n1 - 1
-            if gap > i:
-                return n1 + (i - prev_gap) + 1
-
-        raise NotImplementedError("unreachable")
-
 
 def clamp(lower: float, value: float, upper: float) -> float:
     """Given a value and lower/upper bounds, 'clamp' the value so that