Fix off-by-one error in char-parallel string scalar replace (#7502)

Fixes #7500.

The filter for target replacement positions crossing a string boundary had an off-by-one error.  Target strings that were at the end of a string were incorrectly flagged as crossing a boundary.

Authors:
  - Jason Lowe (@jlowe)

Approvers:
  - David (@davidwendt)
  - Paul Taylor (@trxcllnt)

URL: #7502

cpp/src/strings/replace/replace.cu

@@ -315,7 +315,7 @@ size_type filter_false_target_positions(rmm::device_uvector<size_type>& target_p
                         // find the end of the string containing the start of this target
                         size_type const* offset_ptr = thrust::upper_bound(
                           thrust::seq, d_offsets_span.begin(), d_offsets_span.end(), target_pos);
-                        return target_pos + target_size >= *offset_ptr;
+                        return target_pos + target_size > *offset_ptr;
                       });
   auto const target_count = cudf::distance(d_target_positions, target_pos_end);
   if (target_count == 0) { return 0; }

cpp/tests/strings/replace_tests.cpp

@@ -200,6 +200,37 @@ TEST_F(StringsReplaceTest, ReplaceNullInput)
   CUDF_TEST_EXPECT_COLUMNS_EQUAL(*results, strings);
 }
 
+TEST_F(StringsReplaceTest, ReplaceEndOfString)
+{
+  auto strings      = build_corpus();
+  auto strings_view = cudf::strings_column_view(strings);
+  // replace all occurrences of 'in' with  ' '
+  std::vector<const char*> h_expected{"the quick brown fox jumps over the lazy dog",
+                                      "the fat cat lays next to the other accénted cat",
+                                      "a slow mov g turtlé cannot catch the bird",
+                                      "which can be composéd together to form a more complete",
+                                      "The result does not  clude the value   the sum  ",
+                                      "",
+                                      nullptr};
+
+  cudf::test::strings_column_wrapper expected(
+    h_expected.begin(),
+    h_expected.end(),
+    thrust::make_transform_iterator(h_expected.begin(), [](auto str) { return str != nullptr; }));
+
+  auto results =
+    cudf::strings::replace(strings_view, cudf::string_scalar("in"), cudf::string_scalar(" "));
+  cudf::test::expect_columns_equal(*results, expected);
+
+  results = cudf::strings::detail::replace<cudf::strings::detail::replace_algorithm::CHAR_PARALLEL>(
+    strings_view, cudf::string_scalar("in"), cudf::string_scalar(" "));
+  cudf::test::expect_columns_equal(*results, expected);
+
+  results = cudf::strings::detail::replace<cudf::strings::detail::replace_algorithm::ROW_PARALLEL>(
+    strings_view, cudf::string_scalar("in"), cudf::string_scalar(" "));
+  cudf::test::expect_columns_equal(*results, expected);
+}
+
 TEST_F(StringsReplaceTest, ReplaceSlice)
 {
   std::vector<const char*> h_strings{"Héllo", "thesé", nullptr, "ARE THE", "tést strings", ""};