implemented explain select

src/main/java/net/sf/jsqlparser/statement/ExplainStatement.java

@@ -0,0 +1,55 @@
+/*
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2019 JSQLParser
+ * %%
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 2.1 of the
+ * License, or (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Lesser Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Lesser Public
+ * License along with this program.  If not, see
+ * <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ * #L%
+ */
+package net.sf.jsqlparser.statement;
+
+import net.sf.jsqlparser.statement.select.Select;
+
+/**
+ *
+ * @author tw
+ */
+public class ExplainStatement implements Statement {
+
+    private Select select;
+
+    public ExplainStatement(Select select) {
+        this.select = select;
+    }
+
+    public Select getStatement() {
+        return select;
+    }
+
+    public void setStatement(Select select) {
+        this.select = select;
+    }
+
+    @Override
+    public String toString() {
+        return "EXPLAIN " + select.toString();
+    }
+
+    @Override
+    public void accept(StatementVisitor statementVisitor) {
+        statementVisitor.visit(this);
+    }
+}

src/main/java/net/sf/jsqlparser/statement/StatementVisitor.java

@@ -88,4 +88,6 @@ public interface StatementVisitor {
     void visit(ValuesStatement values);
 
     void visit(DescribeStatement describe);
+
+    public void visit(ExplainStatement aThis);
 }

src/main/java/net/sf/jsqlparser/statement/StatementVisitorAdapter.java

@@ -155,4 +155,8 @@ public void visit(ValuesStatement values) {
     @Override
     public void visit(DescribeStatement describe) {
     }
+
+    @Override
+    public void visit(ExplainStatement aThis) {
+    }
 }

src/main/java/net/sf/jsqlparser/util/TablesNamesFinder.java

@@ -96,6 +96,7 @@
 import net.sf.jsqlparser.statement.Block;
 import net.sf.jsqlparser.statement.Commit;
 import net.sf.jsqlparser.statement.DescribeStatement;
+import net.sf.jsqlparser.statement.ExplainStatement;
 import net.sf.jsqlparser.statement.SetStatement;
 import net.sf.jsqlparser.statement.ShowStatement;
 import net.sf.jsqlparser.statement.Statement;
@@ -853,4 +854,9 @@ public void visit(ValuesStatement values) {
     public void visit(DescribeStatement describe) {
         describe.getTable().accept(this);
     }
+
+    @Override
+    public void visit(ExplainStatement explain) {
+        explain.getStatement().accept(this);
+    }
 }

src/main/java/net/sf/jsqlparser/util/deparser/StatementDeParser.java

@@ -25,6 +25,7 @@
 import net.sf.jsqlparser.statement.Block;
 import net.sf.jsqlparser.statement.Commit;
 import net.sf.jsqlparser.statement.DescribeStatement;
+import net.sf.jsqlparser.statement.ExplainStatement;
 import net.sf.jsqlparser.statement.SetStatement;
 import net.sf.jsqlparser.statement.ShowStatement;
 import net.sf.jsqlparser.statement.Statement;
@@ -266,4 +267,10 @@ public void visit(DescribeStatement describe) {
         buffer.append("DESCRIBE ");
         buffer.append(describe.getTable());
     }
+
+    @Override
+    public void visit(ExplainStatement explain) {
+        buffer.append("EXPLAIN ");
+        explain.getStatement().accept(this);
+    }
 }

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -190,6 +190,7 @@ TOKEN: /* SQL Keywords. prefixed with K_ to avoid name clashes */
 |   <K_EXEC: "EXEC">
 |   <K_EXECUTE: "EXECUTE">
 |   <K_EXISTS:"EXISTS">
+|   <K_EXPLAIN:"EXPLAIN">
 |   <K_EXTRACT:"EXTRACT">
 |   <K_FETCH:"FETCH">
 |   <K_FIRST: "FIRST">
@@ -436,6 +437,8 @@ Statement SingleStatement() :
         stm = Comment() 
         |
         stm = Describe()
+        |
+        stm = Explain()
         )
 		{ return stm; }
     } catch (ParseException e) {
@@ -534,6 +537,14 @@ DescribeStatement Describe(): {
     }
 }
 
+ExplainStatement Explain(): {
+    Select select;
+} {
+    <K_EXPLAIN> select = Select()
+    {
+        return new ExplainStatement(select);
+    }
+}
 
 UseStatement Use(): {
     String name;

src/test/java/net/sf/jsqlparser/statement/ExplainTest.java

@@ -0,0 +1,17 @@
+package net.sf.jsqlparser.statement;
+
+import net.sf.jsqlparser.JSQLParserException;
+import static net.sf.jsqlparser.test.TestUtils.*;
+import org.junit.Test;
+
+/**
+ *
+ * @author tw
+ */
+public class ExplainTest {
+
+    @Test
+    public void testDescribe() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("EXPLAIN SELECT * FROM mytable");
+    }
+}