Add more documentationWIP-SPARK-17647

2 files changed, 25 insertions, 6 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
index d25da3fd58..4147ace511 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
@@ -68,7 +68,14 @@ trait StringRegexExpression extends ImplicitCastInputTypes {
  * Simple RegEx pattern matching function
  */
 @ExpressionDescription(
-  usage = "str _FUNC_ pattern - Returns true if str matches pattern and false otherwise.")
+  usage = "str _FUNC_ pattern - Returns true if str matches pattern, null if any arguments are null, false otherwise.",
+  extended =
+    "The pattern is a string which is matched literally, with exception to the following symbols:\n" +
+    "    _ matches any one character in the input (similar to . in posix regular expressions)\n" +
+    "    % matches zero ore more characters in the input (similar to .* in posix regular expressions)\n" +
+    "The default escape character is '\\'. Any character after the escape character will be matched against literally. " +
+    "Ending a pattern in an escape character is invalid and will throw a ?? exception.\n" +
+    "Use RLIKE to match with standard regular expressions.")
 case class Like(left: Expression, right: Expression)
   extends BinaryExpression with StringRegexExpression {
 
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/RegexpExpressionsSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/RegexpExpressionsSuite.scala
index 9316f76190..9db3abacfa 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/RegexpExpressionsSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/RegexpExpressionsSuite.scala
@@ -19,7 +19,7 @@ package org.apache.spark.sql.catalyst.expressions
 
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.sql.catalyst.dsl.expressions._
-import org.apache.spark.sql.types.StringType
+import org.apache.spark.sql.types.{IntegerType, StringType}
 
 /**
  * Unit tests for regular expression (regexp) related SQL expressions.
@@ -54,6 +54,7 @@ class RegexpExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {
     checkEvaluation("ab" like "a%b", true)
     checkEvaluation("a\nb" like "a%b", true)
 
+    // SI-17647 double-escaping backslash
     checkEvaluation("""\\\\""" like """%\\%""", true) // triple quotes to avoid java string escaping
     checkEvaluation("""\_%""" like """%\\__""", true)
     checkEvaluation("""\_%""" like "%\\\\__", true)
@@ -63,12 +64,9 @@ class RegexpExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {
     checkEvaluation("\\\n\n%\\" like "\\\\___\\\\", true)
     checkEvaluation("""%%""" like """%%""", true)
     checkEvaluation("""\__""" like """\\\__""", true)
-
     checkEvaluation("""\\\__""" like """%\\%\%""", false)
-    checkEvaluation("""\_""" like """\_\_""", false)
     checkEvaluation("""_\\\%""" like """%\\""", false)
-    checkEvaluation("""_\\__""" like """_\___""", false)
-
+    
   }
 
   test("LIKE Non-literal Regular Expression") {
@@ -90,6 +88,20 @@ class RegexpExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {
     checkEvaluation("a\nb" like regEx, true, create_row("a%b"))
 
     checkEvaluation(Literal.create(null, StringType) like regEx, null, create_row("bc%"))
+
+
+    checkEvaluation("""\\\\""" like regEx, true, create_row("""%\\%"""))
+    checkEvaluation("""\_%""" like regEx, true, create_row("""%\\__"""))
+    checkEvaluation("""\_%""" like regEx, true, create_row("%\\\\__"))
+    checkEvaluation("""\_%""" like regEx, true, create_row("""%\\_%"""))
+    checkEvaluation("""\\\\%%""" like regEx, true, create_row("""\\%"""))
+    checkEvaluation("""\%\""" like regEx, true, create_row("""%\%%"""))
+    checkEvaluation("\\\n\n%\\" like regEx, true, create_row("\\\\___\\\\"))
+    checkEvaluation("""%%""" like regEx, true, create_row("""%%"""))
+    checkEvaluation("""\__""" like regEx, true, create_row("""\\\__"""))
+    checkEvaluation("""\\\__""" like regEx, false, create_row("""%\\%\%"""))
+    checkEvaluation("""_\\\%""" like regEx, false, create_row("""%\\"""))
+
   }
 
   test("RLIKE literal Regular Expression") {