SPARK-2407: Added Parser of SQL SUBSTRING() #1442

Author: chutium

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/SqlParser.scala

@@ -121,6 +121,7 @@ class SqlParser extends StandardTokenParsers with PackratParsers {
   protected val INTERSECT = Keyword("INTERSECT")
   protected val EXCEPT = Keyword("EXCEPT")
   protected val SUBSTR = Keyword("SUBSTR")
+  protected val SUBSTRING = Keyword("SUBSTRING")
 
   // Use reflection to find the reserved words defined in this class.
   protected val reservedWords =
@@ -316,10 +317,10 @@ class SqlParser extends StandardTokenParsers with PackratParsers {
     IF ~> "(" ~> expression ~ "," ~ expression ~ "," ~ expression <~ ")" ^^ {
       case c ~ "," ~ t ~ "," ~ f => If(c,t,f)
     } |
-    SUBSTR ~> "(" ~> expression ~ "," ~ expression <~ ")" ^^ {
+    (SUBSTR | SUBSTRING) ~> "(" ~> expression ~ "," ~ expression <~ ")" ^^ {
       case s ~ "," ~ p => Substring(s,p,Literal(Integer.MAX_VALUE))
     } |
-    SUBSTR ~> "(" ~> expression ~ "," ~ expression ~ "," ~ expression <~ ")" ^^ {
+    (SUBSTR | SUBSTRING) ~> "(" ~> expression ~ "," ~ expression ~ "," ~ expression <~ ")" ^^ {
       case s ~ "," ~ p ~ "," ~ l => Substring(s,p,l)
     } |
     ident ~ "(" ~ repsep(expression, ",") <~ ")" ^^ {

sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala

@@ -43,6 +43,12 @@ class SQLQuerySuite extends QueryTest {
     checkAnswer(
       sql("SELECT substr(tableName, 3) FROM tableName"),
       "st")
+    checkAnswer(
+      sql("SELECT substring(tableName, 1, 2) FROM tableName"),
+      "te")
+    checkAnswer(
+      sql("SELECT substring(tableName, 3) FROM tableName"),
+      "st")
   }
 
   test("index into array") {