[WIP] New SQL command DESCRIBE DATABASE

engine/src/main/grammar/SQLGrammar.jjt

@@ -125,6 +125,8 @@ TOKEN:
   |
   <DELETE: ("d"|"D")("e"|"E")("l"|"L")("e"|"E")("t"|"T")("e"|"E")>
   |
+  <DESCRIBE: ("d"|"D")("e"|"E")("s"|"S")("c"|"C")("r"|"R")("i"|"I")("b"|"B")("e"|"E")>
+  |
   <DOCUMENT: ("d"|"D")("o"|"O")("c"|"C")("u"|"U")("m"|"M")("e"|"E")("n"|"N")("t"|"T")>
   |
   <VERTEX: ("v"|"V")("e"|"E")("r"|"R")("t"|"T")("e"|"E")("x"|"X")>
@@ -1100,6 +1102,8 @@ Statement StatementInternal():
         result = CheckDatabaseStatement()
         |
         result = AlignDatabaseStatement()
+        |
+        result = DescribeDatabaseStatement()
       )
     )
     |
@@ -4293,6 +4297,13 @@ AlignDatabaseStatement AlignDatabaseStatement():
   {return jjtThis; }
 }
 
+DescribeDatabaseStatement DescribeDatabaseStatement():
+{ }
+{
+  <DESCRIBE> <DATABASE>
+  {return jjtThis; }
+}
+
 DefineFunctionStatement DefineFunctionStatement():
 {
   Token token;

engine/src/main/java/com/arcadedb/GlobalConfiguration.java

@@ -177,6 +177,9 @@ public Object call(final Object value) {
     return value;
   }),
 
+  DATABASE_DESCRIPTION("arcadedb.databaseDescription", SCOPE.DATABASE, "Message returned by the DESCRIBE DATABASE command", String.class,
+      "Welcome"),
+
   DATE_TIME_FORMAT("arcadedb.dateTimeFormat", SCOPE.DATABASE, "Default date time format using Java SimpleDateFormat syntax",
       String.class, "yyyy-MM-dd HH:mm:ss"),
 

engine/src/main/java/com/arcadedb/query/sql/parser/DescribeDatabaseStatement.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright © 2021-present Arcade Data Ltd (info@arcadedata.com)
+ *
+ * Licensed 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.
+ *
+ * SPDX-FileCopyrightText: 2021-present Arcade Data Ltd (info@arcadedata.com)
+ * SPDX-License-Identifier: Apache-2.0
+ */
+/* Generated By:JJTree: Do not edit this line. DescribeDatabaseStatement.java Version 4.3 */
+/* JavaCCOptions:MULTI=true,NODE_USES_PARSER=false,VISITOR=true,TRACK_TOKENS=true,NODE_PREFIX=O,NODE_EXTENDS=,NODE_FACTORY=,SUPPORT_USERTYPE_VISIBILITY_PUBLIC=true */
+package com.arcadedb.query.sql.parser;
+
+import com.arcadedb.GlobalConfiguration;
+
+import com.arcadedb.GlobalConfiguration;
+import com.arcadedb.database.DatabaseInternal;
+import com.arcadedb.query.sql.executor.CommandContext;
+import com.arcadedb.query.sql.executor.InternalResultSet;
+import com.arcadedb.query.sql.executor.ResultInternal;
+import com.arcadedb.query.sql.executor.ResultSet;
+
+import java.util.*;
+
+public class DescribeDatabaseStatement extends SimpleExecStatement {
+  public DescribeDatabaseStatement(final int id) {
+    super(id);
+  }
+
+  @Override
+  public ResultSet executeSimple(final CommandContext context) {
+
+    final GlobalConfiguration description = GlobalConfiguration.findByKey("arcadedb.databaseDescription");
+    final ResultInternal result = new ResultInternal();
+    result.setProperty("result", context.getDatabase().getConfiguration().getValue(description));
+
+    final InternalResultSet rs = new InternalResultSet();
+    rs.add(result);
+    return rs;
+  }
+
+  @Override
+  public void toString(final Map<String, Object> params, final StringBuilder builder) {
+    builder.append("DESCRIBE DATABASE");
+  }
+}