[SPARK-3654][SQL] Unifies SQL and HiveQL parsers

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

@@ -0,0 +1,186 @@
+/*
+ * 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.catalyst
+
+import scala.language.implicitConversions
+import scala.util.parsing.combinator.lexical.StdLexical
+import scala.util.parsing.combinator.syntactical.StandardTokenParsers
+import scala.util.parsing.combinator.{PackratParsers, RegexParsers}
+import scala.util.parsing.input.CharArrayReader.EofCh
+
+import org.apache.spark.sql.catalyst.plans.logical._
+
+private[sql] abstract class AbstractSparkSQLParser
+  extends StandardTokenParsers with PackratParsers {
+
+  def apply(input: String): LogicalPlan = phrase(start)(new lexical.Scanner(input)) match {
+    case Success(plan, _) => plan
+    case failureOrError => sys.error(failureOrError.toString)
+  }
+
+  protected case class Keyword(str: String)
+
+  protected def start: Parser[LogicalPlan]
+
+  // Returns the whole input string
+  protected lazy val wholeInput: Parser[String] = new Parser[String] {
+    def apply(in: Input): ParseResult[String] =
+      Success(in.source.toString, in.drop(in.source.length()))
+  }
+
+  // Returns the rest of the input string that are not parsed yet
+  protected lazy val restInput: Parser[String] = new Parser[String] {
+    def apply(in: Input): ParseResult[String] =
+      Success(
+        in.source.subSequence(in.offset, in.source.length()).toString,
+        in.drop(in.source.length()))
+  }
+}
+
+class SqlLexical(val keywords: Seq[String]) extends StdLexical {
+  case class FloatLit(chars: String) extends Token {
+    override def toString = chars
+  }
+
+  reserved ++= keywords.flatMap(w => allCaseVersions(w))
+
+  delimiters += (
+    "@", "*", "+", "-", "<", "=", "<>", "!=", "<=", ">=", ">", "/", "(", ")",
+    ",", ";", "%", "{", "}", ":", "[", "]", "."
+  )
+
+  override lazy val token: Parser[Token] =
+    ( identChar ~ (identChar | digit).* ^^
+      { case first ~ rest => processIdent((first :: rest).mkString) }
+    | rep1(digit) ~ ('.' ~> digit.*).? ^^ {
+        case i ~ None    => NumericLit(i.mkString)
+        case i ~ Some(d) => FloatLit(i.mkString + "." + d.mkString)
+      }
+    | '\'' ~> chrExcept('\'', '\n', EofCh).* <~ '\'' ^^
+      { case chars => StringLit(chars mkString "") }
+    | '"' ~> chrExcept('"', '\n', EofCh).* <~ '"' ^^
+      { case chars => StringLit(chars mkString "") }
+    | EofCh ^^^ EOF
+    | '\'' ~> failure("unclosed string literal")
+    | '"' ~> failure("unclosed string literal")
+    | delim
+    | failure("illegal character")
+    )
+
+  override def identChar = letter | elem('_')
+
+  override def whitespace: Parser[Any] =
+    ( whitespaceChar
+    | '/' ~ '*' ~ comment
+    | '/' ~ '/' ~ chrExcept(EofCh, '\n').*
+    | '#' ~ chrExcept(EofCh, '\n').*
+    | '-' ~ '-' ~ chrExcept(EofCh, '\n').*
+    | '/' ~ '*' ~ failure("unclosed comment")
+    ).*
+
+  /** Generate all variations of upper and lower case of a given string */
+  def allCaseVersions(s: String, prefix: String = ""): Stream[String] = {
+    if (s == "") {
+      Stream(prefix)
+    } else {
+      allCaseVersions(s.tail, prefix + s.head.toLower) ++
+        allCaseVersions(s.tail, prefix + s.head.toUpper)
+    }
+  }
+}
+
+/**
+ * The top level Spark SQL parser. This parser recognizes syntaxes that are available for all SQL
+ * dialects supported by Spark SQL, and delegates all the other syntaxes to the `fallback` parser.
+ *
+ * @param fallback A function that parses an input string to a logical plan
+ */
+private[sql] class SparkSQLParser(fallback: String => LogicalPlan) extends AbstractSparkSQLParser {
+
+  // A parser for the key-value part of the "SET [key = [value ]]" syntax
+  private object SetCommandParser extends RegexParsers {
+    private val key: Parser[String] = "(?m)[^=]+".r
+
+    private val value: Parser[String] = "(?m).*$".r
+
+    private val pair: Parser[LogicalPlan] =
+      (key ~ ("=".r ~> value).?).? ^^ {
+        case None => SetCommand(None)
+        case Some(k ~ v) => SetCommand(Some(k.trim -> v.map(_.trim)))
+      }
+
+    def apply(input: String): LogicalPlan = parseAll(pair, input) match {
+      case Success(plan, _) => plan
+      case x => sys.error(x.toString)
+    }
+  }
+
+  protected val AS      = Keyword("AS")
+  protected val CACHE   = Keyword("CACHE")
+  protected val LAZY    = Keyword("LAZY")
+  protected val SET     = Keyword("SET")
+  protected val TABLE   = Keyword("TABLE")
+  protected val SOURCE  = Keyword("SOURCE")
+  protected val UNCACHE = Keyword("UNCACHE")
+
+  protected implicit def asParser(k: Keyword): Parser[String] =
+    lexical.allCaseVersions(k.str).map(x => x : Parser[String]).reduce(_ | _)
+
+  private val reservedWords: Seq[String] =
+    this
+      .getClass
+      .getMethods
+      .filter(_.getReturnType == classOf[Keyword])
+      .map(_.invoke(this).asInstanceOf[Keyword].str)
+
+  override val lexical = new SqlLexical(reservedWords)
+
+  override protected lazy val start: Parser[LogicalPlan] =
+    cache | uncache | set | shell | source | others
+
+  private lazy val cache: Parser[LogicalPlan] =
+    CACHE ~> LAZY.? ~ (TABLE ~> ident) ~ (AS ~> restInput).? ^^ {
+      case isLazy ~ tableName ~ plan =>
+        CacheTableCommand(tableName, plan.map(fallback), isLazy.isDefined)
+    }
+
+  private lazy val uncache: Parser[LogicalPlan] =
+    UNCACHE ~ TABLE ~> ident ^^ {
+      case tableName => UncacheTableCommand(tableName)
+    }
+
+  private lazy val set: Parser[LogicalPlan] =
+    SET ~> restInput ^^ {
+      case input => SetCommandParser(input)
+    }
+
+  private lazy val shell: Parser[LogicalPlan] =
+    "!" ~> restInput ^^ {
+      case input => ShellCommand(input.trim)
+    }
+
+  private lazy val source: Parser[LogicalPlan] =
+    SOURCE ~> restInput ^^ {
+      case input => SourceCommand(input.trim)
+    }
+
+  private lazy val others: Parser[LogicalPlan] =
+    wholeInput ^^ {
+      case input => fallback(input)
+    }
+}