Github user yhuai commented on a diff in the pull request:
https://github.com/apache/spark/pull/5350#discussion_r28013516
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/types/UTF8String.scala ---
@@ -0,0 +1,209 @@
+/*
+* Licensed to the Apache Software Foundation (ASF) under one or more
+* contributor license agreements. See the NOTICE file distributed with
+* this work for additional information regarding copyright ownership.
+* The ASF licenses this file to You under the Apache License, Version 2.0
+* (the "License"); you may not use this file except in compliance with
+* the License. You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+package org.apache.spark.sql.types
+
+import java.util.Arrays
+
+/**
+ * A UTF-8 String, as internal representation of StringType in SparkSQL
+ *
+ * A String encoded in UTF-8 as an Array[Byte], which can be used for
comparison,
+ * search, see http://en.wikipedia.org/wiki/UTF-8 for details.
+ *
+ * Note: This is not designed for general use cases, should not be used
outside SQL.
+ */
+
+final class UTF8String extends Ordered[UTF8String] with Serializable {
+
+ private[this] var bytes: Array[Byte] = _
+
+ /**
+ * Update the UTF8String with String.
+ */
+ def set(str: String): UTF8String = {
+ bytes = str.getBytes("utf-8")
+ this
+ }
+
+ /**
+ * Update the UTF8String with Array[Byte], which should be encoded in
UTF-8
+ */
+ def set(bytes: Array[Byte]): UTF8String = {
+ this.bytes = bytes
+ this
+ }
+
+ @inline
+ private[this] def numOfBytes(b: Byte): Int = {
+ val offset = (b & 0xFF) - 192
+ if (offset >= 0) UTF8String.tailBytesOfUTF8(offset) else 1
+ }
+
+ /**
+ * Return the number of code points in it.
+ *
+ * This is only used by Substring() when `start` is negative.
+ */
+ def length(): Int = {
+ var len = 0
+ var i: Int = 0
+ while (i < bytes.length) {
+ i += numOfBytes(bytes(i))
+ len += 1
+ }
+ len
+ }
+
+ def getBytes: Array[Byte] = {
+ bytes
+ }
+
+ /**
+ * Return a substring of this,
+ * @param start the position of first code point
+ * @param until the position after last code point
+ */
+ def slice(start: Int, until: Int): UTF8String = {
+ if (until <= start || start >= bytes.length || bytes == null) {
+ new UTF8String
+ }
+
+ var c = 0
+ var i: Int = 0
+ while (c < start && i < bytes.length) {
+ i += numOfBytes(bytes(i))
+ c += 1
+ }
+ var j = i
+ while (c < until && j < bytes.length) {
+ j += numOfBytes(bytes(j))
+ c += 1
+ }
+ UTF8String(Arrays.copyOfRange(bytes, i, j))
+ }
+
+ def contains(sub: UTF8String): Boolean = {
+ val b = sub.getBytes
+ if (b.length == 0) {
+ return true
+ }
+ var i: Int = 0
+ while (i <= bytes.length - b.length) {
+ // In worst case, it's O(N*K), but should works fine with SQL
+ if (bytes(i) == b(0) && Arrays.equals(Arrays.copyOfRange(bytes, i, i
+ b.length), b)) {
+ return true
+ }
+ i += 1
+ }
+ false
+ }
+
+ def startsWith(prefix: UTF8String): Boolean = {
+ val b = prefix.getBytes
+ if (b.length > bytes.length) {
+ return false
+ }
+ Arrays.equals(Arrays.copyOfRange(bytes, 0, b.length), b)
+ }
+
+ def endsWith(suffix: UTF8String): Boolean = {
+ val b = suffix.getBytes
+ if (b.length > bytes.length) {
+ return false
+ }
+ Arrays.equals(Arrays.copyOfRange(bytes, bytes.length - b.length,
bytes.length), b)
+ }
+
+ def toUpperCase(): UTF8String = {
+ // upper case depends on locale, fallback to String.
+ UTF8String(toString().toUpperCase)
+ }
+
+ def toLowerCase(): UTF8String = {
+ // lower case depends on locale, fallback to String.
+ UTF8String(toString().toLowerCase)
+ }
+
+ override def toString(): String = {
+ new String(bytes, "utf-8")
+ }
+
+ override def clone(): UTF8String = new UTF8String().set(this.bytes)
+
+ override def compare(other: UTF8String): Int = {
+ var i: Int = 0
+ val b = other.getBytes
+ while (i < bytes.length && i < b.length) {
+ val res = bytes(i).compareTo(b(i))
+ if (res != 0) return res
+ i += 1
+ }
+ bytes.length - b.length
+ }
+
+ override def compareTo(other: UTF8String): Int = {
+ compare(other)
+ }
+
+ override def equals(other: Any): Boolean = other match {
+ case s: UTF8String =>
+ Arrays.equals(bytes, s.getBytes)
+ case s: String =>
+ // fail fast
+ bytes.length >= s.length && length() == s.length && toString() == s
--- End diff --
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