[SPARK-2182] Scalastyle rule blocking non ascii characters.

...erators.

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes #2358 from ScrapCodes/scalastyle-unicode and squashes the following commits:

12a20f2 [Prashant Sharma] [SPARK-2182] Scalastyle rule blocking (non keyboard typeable) unicode operators.

project/spark-style/src/main/scala/org/apache/spark/scalastyle/NonASCIICharacterChecker.scala

+/*
+ * 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.scalastyle
+
+import java.util.regex.Pattern
+
+import org.scalastyle.{PositionError, ScalariformChecker, ScalastyleError}
+
+import scalariform.lexer.Token
+import scalariform.parser.CompilationUnit
+
+class NonASCIICharacterChecker extends ScalariformChecker {
+  val errorKey: String = "non.ascii.character.disallowed"
+
+  override def verify(ast: CompilationUnit): List[ScalastyleError] = {
+    ast.tokens.filter(hasNonAsciiChars).map(x => PositionError(x.offset)).toList
+  }
+
+  private def hasNonAsciiChars(x: Token) =
+    x.rawText.trim.nonEmpty && !Pattern.compile( """\p{ASCII}+""", Pattern.DOTALL)
+    .matcher(x.text.trim).matches()
+
+}

scalastyle-config.xml

@@ -140,5 +140,6 @@
  <!-- <check level="error" class="org.scalastyle.scalariform.PublicMethodsHaveTypeChecker" enabled="true"></check> -->
  <check level="error" class="org.scalastyle.file.NewLineAtEofChecker" enabled="true"></check>
  <check level="error" class="org.scalastyle.file.NoNewLineAtEofChecker" enabled="false"></check>
+ <check level="error" class="org.apache.spark.scalastyle.NonASCIICharacterChecker" enabled="true"></check>
  <check level="error" class="org.apache.spark.scalastyle.SparkSpaceAfterCommentStartChecker" enabled="true"></check>
 </scalastyle>