[GitHub] [spark] MaxGekk commented on a change in pull request #33919: [SPARK-36674][SQL] Support ILIKE - case insensitive LIKE

[GitBox <gi...@apache.org>]

MaxGekk commented on a change in pull request #33919:
URL: https://github.com/apache/spark/pull/33919#discussion_r704049052



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File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
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@@ -121,70 +187,73 @@ abstract class StringRegexExpression extends BinaryExpression
   since = "1.0.0",
   group = "predicate_funcs")
 // scalastyle:on line.contains.tab
-case class Like(left: Expression, right: Expression, escapeChar: Char)
-  extends StringRegexExpression {
+case class Like(left: Expression, right: Expression, escapeChar: Char) extends LikeBase {
 
   def this(left: Expression, right: Expression) = this(left, right, '\\')
 
-  override def escape(v: String): String = StringUtils.escapeLikeRegex(v, escapeChar)
+  override protected def likeName: String = "LIKE"
 
-  override def matches(regex: Pattern, str: String): Boolean = regex.matcher(str).matches()
+  override protected def withNewChildrenInternal(newLeft: Expression, newRight: Expression): Like =
+    copy(left = newLeft, right = newRight)
+}
 
-  final override val nodePatterns: Seq[TreePattern] = Seq(LIKE_FAMLIY)
+// scalastyle:off line.contains.tab
+/**
+ * Simple RegEx case-insensitive pattern matching function
+ */
+@ExpressionDescription(
+  usage = "str _FUNC_ pattern[ ESCAPE escape] - Returns true if str matches `pattern` with " +
+    "`escape` case-insensitively, null if any arguments are null, false otherwise.",
+  arguments = """
+    Arguments:
+      * str - a string expression
+      * pattern - a string expression. The pattern is a string which is matched literally and
+          case-insensitively, with exception to the following special symbols:
 
-  override def toString: String = escapeChar match {
-    case '\\' => s"$left LIKE $right"
-    case c => s"$left LIKE $right ESCAPE '$c'"
-  }
+          _ matches any one character in the input (similar to . in posix regular expressions)
 
-  override def sql: String = s"${left.sql} ${prettyName.toUpperCase(Locale.ROOT)} ${right.sql}"
+          % matches zero or more characters in the input (similar to .* in posix regular
+          expressions)
 
-  override protected def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
-    val patternClass = classOf[Pattern].getName
-    val escapeFunc = StringUtils.getClass.getName.stripSuffix("$") + ".escapeLikeRegex"
+          Since Spark 2.0, string literals are unescaped in our SQL parser. For example, in order
+          to match "\abc", the pattern should be "\\abc".
 
-    if (right.foldable) {
-      val rVal = right.eval()
-      if (rVal != null) {
-        val regexStr =
-          StringEscapeUtils.escapeJava(escape(rVal.asInstanceOf[UTF8String].toString()))
-        val pattern = ctx.addMutableState(patternClass, "patternLike",
-          v => s"""$v = $patternClass.compile("$regexStr");""")
+          When SQL config 'spark.sql.parser.escapedStringLiterals' is enabled, it falls back
+          to Spark 1.6 behavior regarding string literal parsing. For example, if the config is
+          enabled, the pattern to match "\abc" should be "\abc".
+      * escape - an character added since Spark 3.0. The default escape character is the '\'.
+          If an escape character precedes a special symbol or another escape character, the
+          following character is matched literally. It is invalid to escape any other character.
+  """,
+  examples = """
+    Examples:
+      > SELECT _FUNC_('Spark', '_Park');
+      true
+      > SET spark.sql.parser.escapedStringLiterals=true;

Review comment:
       The examples are executed in a test too. Or do you want to test something specifically to case-sensitivity?




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