[SPARK-15397][SQL] fix string udf locate as hive

## What changes were proposed in this pull request?

in hive, `locate("aa", "aaa", 0)` would yield 0, `locate("aa", "aaa", 1)` would yield 1 and `locate("aa", "aaa", 2)` would yield 2, while in Spark, `locate("aa", "aaa", 0)` would yield 1,  `locate("aa", "aaa", 1)` would yield 2 and  `locate("aa", "aaa", 2)` would yield 0. This results from the different understanding of the third parameter in udf `locate`. It means the starting index and starts from 1, so when we use 0, the return would always be 0.

## How was this patch tested?

tested with modified `StringExpressionsSuite` and `StringFunctionsSuite`

Author: Daoyuan Wang <daoyuan.wang@intel.com>

Closes #13186 from adrian-wang/locate.

6 files changed, 30 insertions, 21 deletions

diff --git a/R/pkg/R/functions.R b/R/pkg/R/functions.R
index 4a0bdf3315..2665d1d477 100644
--- a/R/pkg/R/functions.R
+++ b/R/pkg/R/functions.R
@@ -2226,7 +2226,7 @@ setMethod("window", signature(x = "Column"),
 #' @export
 #' @examples \dontrun{locate('b', df$c, 1)}
 setMethod("locate", signature(substr = "character", str = "Column"),
-          function(substr, str, pos = 0) {
+          function(substr, str, pos = 1) {
             jc <- callJStatic("org.apache.spark.sql.functions",
                               "locate",
                               substr, str@jc, as.integer(pos))
diff --git a/R/pkg/inst/tests/testthat/test_sparkSQL.R b/R/pkg/inst/tests/testthat/test_sparkSQL.R
index 6a99b43e5a..b2d769f2ac 100644
--- a/R/pkg/inst/tests/testthat/test_sparkSQL.R
+++ b/R/pkg/inst/tests/testthat/test_sparkSQL.R
@@ -1152,7 +1152,7 @@ test_that("string operators", {
   l2 <- list(list(a = "aaads"))
   df2 <- createDataFrame(sqlContext, l2)
   expect_equal(collect(select(df2, locate("aa", df2$a)))[1, 1], 1)
-  expect_equal(collect(select(df2, locate("aa", df2$a, 1)))[1, 1], 2)
+  expect_equal(collect(select(df2, locate("aa", df2$a, 2)))[1, 1], 2)
   expect_equal(collect(select(df2, lpad(df2$a, 8, "#")))[1, 1], "###aaads") # nolint
   expect_equal(collect(select(df2, rpad(df2$a, 8, "#")))[1, 1], "aaads###") # nolint
 
diff --git a/python/pyspark/sql/functions.py b/python/pyspark/sql/functions.py
index 1f15eec645..64b8bc442d 100644
--- a/python/pyspark/sql/functions.py
+++ b/python/pyspark/sql/functions.py
@@ -1359,7 +1359,7 @@ def levenshtein(left, right):
 
 
 @since(1.5)
-def locate(substr, str, pos=0):
+def locate(substr, str, pos=1):
     """
     Locate the position of the first occurrence of substr in a string column, after position pos.
 
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
index 78e846d3f5..44ff7fda8e 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
@@ -494,7 +494,7 @@ case class StringLocate(substr: Expression, str: Expression, start: Expression)
   extends TernaryExpression with ImplicitCastInputTypes {
 
   def this(substr: Expression, str: Expression) = {
-    this(substr, str, Literal(0))
+    this(substr, str, Literal(1))
   }
 
   override def children: Seq[Expression] = substr :: str :: start :: Nil
@@ -516,9 +516,14 @@ case class StringLocate(substr: Expression, str: Expression, start: Expression)
         if (l == null) {
           null
         } else {
-          l.asInstanceOf[UTF8String].indexOf(
-            r.asInstanceOf[UTF8String],
-            s.asInstanceOf[Int]) + 1
+          val sVal = s.asInstanceOf[Int]
+          if (sVal < 1) {
+            0
+          } else {
+            l.asInstanceOf[UTF8String].indexOf(
+              r.asInstanceOf[UTF8String],
+              s.asInstanceOf[Int] - 1) + 1
+          }
         }
       }
     }
@@ -537,8 +542,10 @@ case class StringLocate(substr: Expression, str: Expression, start: Expression)
         if (!${substrGen.isNull}) {
           ${strGen.code}
           if (!${strGen.isNull}) {
-            ${ev.value} = ${strGen.value}.indexOf(${substrGen.value},
-              ${startGen.value}) + 1;
+            if (${startGen.value} > 0) {
+              ${ev.value} = ${strGen.value}.indexOf(${substrGen.value},
+                ${startGen.value} - 1) + 1;
+            }
           } else {
             ${ev.isNull} = true;
           }
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/StringExpressionsSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/StringExpressionsSuite.scala
index c09c64fd6b..29bf15bf52 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/StringExpressionsSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/StringExpressionsSuite.scala
@@ -508,16 +508,18 @@ class StringExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {
     val s2 = 'b.string.at(1)
     val s3 = 'c.string.at(2)
     val s4 = 'd.int.at(3)
-    val row1 = create_row("aaads", "aa", "zz", 1)
-    val row2 = create_row(null, "aa", "zz", 0)
-    val row3 = create_row("aaads", null, "zz", 0)
-    val row4 = create_row(null, null, null, 0)
+    val row1 = create_row("aaads", "aa", "zz", 2)
+    val row2 = create_row(null, "aa", "zz", 1)
+    val row3 = create_row("aaads", null, "zz", 1)
+    val row4 = create_row(null, null, null, 1)
 
     checkEvaluation(new StringLocate(Literal("aa"), Literal("aaads")), 1, row1)
-    checkEvaluation(StringLocate(Literal("aa"), Literal("aaads"), Literal(1)), 2, row1)
-    checkEvaluation(StringLocate(Literal("aa"), Literal("aaads"), Literal(2)), 0, row1)
+    checkEvaluation(StringLocate(Literal("aa"), Literal("aaads"), Literal(0)), 0, row1)
+    checkEvaluation(StringLocate(Literal("aa"), Literal("aaads"), Literal(1)), 1, row1)
+    checkEvaluation(StringLocate(Literal("aa"), Literal("aaads"), Literal(2)), 2, row1)
+    checkEvaluation(StringLocate(Literal("aa"), Literal("aaads"), Literal(3)), 0, row1)
     checkEvaluation(new StringLocate(Literal("de"), Literal("aaads")), 0, row1)
-    checkEvaluation(StringLocate(Literal("de"), Literal("aaads"), 1), 0, row1)
+    checkEvaluation(StringLocate(Literal("de"), Literal("aaads"), 2), 0, row1)
 
     checkEvaluation(new StringLocate(s2, s1), 1, row1)
     checkEvaluation(StringLocate(s2, s1, s4), 2, row1)
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala
index c7b95c2683..1de2d9b5ad 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/StringFunctionsSuite.scala
@@ -189,15 +189,15 @@ class StringFunctionsSuite extends QueryTest with SharedSQLContext {
   }
 
   test("string locate function") {
-    val df = Seq(("aaads", "aa", "zz", 1)).toDF("a", "b", "c", "d")
+    val df = Seq(("aaads", "aa", "zz", 2)).toDF("a", "b", "c", "d")
 
     checkAnswer(
-      df.select(locate("aa", $"a"), locate("aa", $"a", 1)),
-      Row(1, 2))
+      df.select(locate("aa", $"a"), locate("aa", $"a", 2), locate("aa", $"a", 0)),
+      Row(1, 2, 0))
 
     checkAnswer(
-      df.selectExpr("locate(b, a)", "locate(b, a, d)"),
-      Row(1, 2))
+      df.selectExpr("locate(b, a)", "locate(b, a, d)", "locate(b, a, 3)"),
+      Row(1, 2, 0))
   }
 
   test("string padding functions") {