From 72438d8a480f9158d0c6a1e5d8db119bb1550200 Mon Sep 17 00:00:00 2001
From: Jason Lowe <jlowe@nvidia.com>
Date: Thu, 4 Mar 2021 06:40:45 -0600
Subject: [PATCH] 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: https://github.com/rapidsai/cudf/pull/7502
---
 cpp/src/strings/replace/replace.cu  |  2 +-
 cpp/tests/strings/replace_tests.cpp | 31 +++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/cpp/src/strings/replace/replace.cu b/cpp/src/strings/replace/replace.cu
index 0955c217526..ea474644d06 100644
--- a/cpp/src/strings/replace/replace.cu
+++ b/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; }
diff --git a/cpp/tests/strings/replace_tests.cpp b/cpp/tests/strings/replace_tests.cpp
index 98175674a3a..359b31177bf 100644
--- a/cpp/tests/strings/replace_tests.cpp
+++ b/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", ""};