ARROW-18235: [C++][Gandiva] Fix the like function implementation for escape chars (apache#14579)

 The current implementation of optimisation for like function does a
 removal of the escape char, this causes errors in matching if the escape
 char is one of the pcre special chars or if the escape char is followed
 by itself.

 Fix this by only removing the '\\' escape char during optimisation.

Authored-by: Siddhant Rao <siddhant.rao@dremio.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>

Author: siddhantrao23

cpp/src/gandiva/regex_functions_holder.cc

@@ -27,14 +27,7 @@ RE2 LikeHolder::ends_with_regex_(R"(\.\*([^\.\*])*)");
 RE2 LikeHolder::is_substr_regex_(R"(\.\*([^\.\*])*\.\*)");
 
 std::string& RemovePatternEscapeChars(const FunctionNode& node, std::string& pattern) {
-  if (node.children().size() != 2) {
-    auto escape_char = dynamic_cast<LiteralNode*>(node.children().at(2).get());
-    pattern.erase(std::remove(pattern.begin(), pattern.end(),
-                              arrow::util::get<std::string>(escape_char->holder()).at(0)),
-                  pattern.end());  // remove escape chars
-  } else {
-    pattern.erase(std::remove(pattern.begin(), pattern.end(), '\\'), pattern.end());
-  }
+  pattern.erase(std::remove(pattern.begin(), pattern.end(), '\\'), pattern.end());
   return pattern;
 }
 

cpp/src/gandiva/regex_functions_holder_test.cc

@@ -39,7 +39,7 @@ class TestLikeHolder : public ::testing::Test {
     auto pattern_node =
         std::make_shared<LiteralNode>(arrow::utf8(), LiteralHolder(pattern), false);
     auto escape_char_node = std::make_shared<LiteralNode>(
-        arrow::int8(), LiteralHolder((int8_t)escape_char), false);
+        arrow::utf8(), LiteralHolder(std::string(1, escape_char)), false);
     return FunctionNode("like", {field, pattern_node, escape_char_node},
                         arrow::boolean());
   }
@@ -177,7 +177,16 @@ TEST_F(TestLikeHolder, TestOptimise) {
   fnode = LikeHolder::TryOptimize(BuildLike("\\%xyz", '\\'));
   EXPECT_EQ(fnode.descriptor()->name(), "like");
   EXPECT_EQ(fnode.ToString(),
-            "bool like((string) in, (const string) '\\%xyz', (const int8) \\)");
+            "bool like((string) in, (const string) '\\%xyz', (const string) '\\')");
+
+  // optimised for escape pattern that are pcre special chars.
+  fnode = LikeHolder::TryOptimize(BuildLike("%ab^_cd^_de%", '^'));
+  EXPECT_EQ(fnode.descriptor()->name(), "is_substr");
+  EXPECT_EQ(fnode.ToString(), "bool is_substr((string) in, (const string) 'ab_cd_de')");
+
+  fnode = LikeHolder::TryOptimize(BuildLike("%ab^^cd^^de%", '^'));
+  EXPECT_EQ(fnode.descriptor()->name(), "is_substr");
+  EXPECT_EQ(fnode.ToString(), "bool is_substr((string) in, (const string) 'ab^cd^de')");
 }
 
 TEST_F(TestLikeHolder, TestMatchOneEscape) {

cpp/src/gandiva/tests/filter_test.cc

@@ -414,6 +414,39 @@ TEST_F(TestFilter, TestLike) {
 
   // Validate results
   EXPECT_ARROW_ARRAY_EQUALS(exp, selection_vector->ToArray());
+
+  auto literal_escape_pattern =
+      TreeExprBuilder::MakeStringLiteral("%tu^_security^_freeze%");
+  auto escape_char = TreeExprBuilder::MakeStringLiteral("^");
+  like_func = TreeExprBuilder::MakeFunction(
+      "like", {node_f0, literal_escape_pattern, escape_char}, boolean());
+
+  condition = TreeExprBuilder::MakeCondition(like_func);
+
+  status = Filter::Make(schema, condition, TestConfiguration(), &filter);
+  EXPECT_TRUE(status.ok());
+
+  // Create a row-batch with some sample data
+  num_records = 5;
+  array0 = MakeArrowArrayUtf8(
+      {"AAAtu_security_freezeBBB", "hello", "bye", "abc-x", "AAAtusecurityfreezeBBB"},
+      {true, true, true, true, true});
+
+  // expected output (indices for which condition matches)
+  exp = MakeArrowArrayUint16({0});
+
+  // prepare input record batch
+  in_batch = arrow::RecordBatch::Make(schema, num_records, {array0});
+
+  status = SelectionVector::MakeInt16(num_records, pool_, &selection_vector);
+  EXPECT_TRUE(status.ok());
+
+  // Evaluate expression
+  status = filter->Evaluate(*in_batch, selection_vector);
+  EXPECT_TRUE(status.ok());
+
+  // Validate results
+  EXPECT_ARROW_ARRAY_EQUALS(exp, selection_vector->ToArray());
 }
 
 }  // namespace gandiva