Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/9202#discussion_r42743817
--- Diff:
sql/catalyst/src/main/java/org/apache/spark/sql/SqlIdentifierUtil.java ---
@@ -0,0 +1,322 @@
+/*
+ * 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;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.util.Locale;
+import java.util.Vector;
+import org.apache.spark.SparkException;
+
+/**
+ * Methods for handling SQL identifiers. These methods were cribbed
+ * from org.apache.derby.iapi.util.IdUtil and
+ * org.apache.derby.iapi.util.StringUtil.
+ */
+public class SqlIdentifierUtil {
+
+ /**
+ * Quote a string so that it can be used as an identifier or a string
+ * literal in SQL statements. Identifiers are surrounded by double quotes
+ * and string literals are surrounded by single quotes. If the string
+ * contains quote characters, they are escaped.
+ *
+ * @param source the string to quote
+ * @param quote the character to quote the string with (' or ")
+ * @return a string quoted with the specified quote character
+ */
+ public static String quoteString(String source, char quote) {
+ // Normally, the quoted string is two characters longer than the source
+ // string (because of start quote and end quote).
+ StringBuffer quoted = new StringBuffer(source.length() + 2);
+ quoted.append(quote);
+ for (int i = 0; i < source.length(); i++) {
+ char c = source.charAt(i);
+ // if the character is a quote, escape it with an extra quote
+ if (c == quote) quoted.append(quote);
+ quoted.append(c);
+ }
+ quoted.append(quote);
+ return quoted.toString();
+ }
+
+ /**
+ * Parse a multi-part (dot separated) SQL identifier from the
+ * String provided. Raise an excepion
+ * if the string does not contain valid SQL indentifiers.
+ * The returned String array contains the normalized form of the
+ * identifiers.
+ *
+ * @param s The string to be parsed
+ * @param quoteCharacter The character which frames a delimited id
(e.g., " or `)
+ * @param upperCaseIdentifiers True if SQL ids are normalized to upper
case.
+ * @return An array of strings made by breaking the input string at its
dots, '.'.
+ * @throws SparkException Invalid SQL identifier.
+ */
+ public static String[] parseMultiPartSQLIdentifier(
+ String s,
+ char quoteCharacter,
+ boolean upperCaseIdentifiers)
+ throws SparkException {
+ StringReader r = new StringReader(s);
+ String[] qName = parseMultiPartSQLIdentifier(
+ s,
+ r,
+ quoteCharacter,
+ upperCaseIdentifiers);
+ verifyEmpty(s, r);
+ return qName;
+ }
+
+ /**
+ * Parse a multi-part (dot separated) SQL identifier from the
+ * String provided. Raise an excepion
+ * if the string does not contain valid SQL indentifiers.
+ * The returned String array contains the normalized form of the
+ * identifiers.
+ *
+ * @param orig The full text being parsed
+ * @param r The multi-part identifier to be parsed
+ * @param quoteCharacter The character which frames a delimited id
(e.g., " or `)
+ * @param upperCaseIdentifiers True if SQL ids are normalized to upper
case.
+ * @return An array of strings made by breaking the input string at its
dots, '.'.
+ * @throws SparkException Invalid SQL identifier.
+ */
+ private static String[] parseMultiPartSQLIdentifier(
--- End diff --
A lot of this looks accomplishable more simply with regexes. Is that not
feasible?
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