Implements Hierarchical CONNECT_BY_ROOT Operator (#1282)

* Implements Hierarchical CONNECT_BY_ROOT Operator
Fixes Issue #1269
Resolves some Special Oracle Tests

* Improve Test Coverage

Co-authored-by: Tobias <t.warneke@gmx.net>

Author: manticore-projects

build.gradle

@@ -68,7 +68,7 @@ jacocoTestCoverageVerification {
     violationRules {
         rule {
             limit {
-                minimum = 0.837
+                minimum = 0.840
             }
         }
     }

src/main/java/net/sf/jsqlparser/expression/ConnectByRootOperator.java

@@ -0,0 +1,62 @@
+/*-
+ * #%L
+ * JSQLParser library
+ * %%
+ * Copyright (C) 2004 - 2021 JSQLParser
+ * %%
+ * Dual licensed under GNU LGPL 2.1 or Apache License 2.0
+ * #L%
+ */
+/*
+ * Copyright (C) 2021 JSQLParser.
+ *
+ * This library 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 library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License along with this library;
+ * if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+package net.sf.jsqlparser.expression;
+
+import java.util.Objects;
+import net.sf.jsqlparser.parser.ASTNodeAccessImpl;
+import net.sf.jsqlparser.schema.Column;
+
+/**
+ *
+ * @author are
+ */
+public class ConnectByRootOperator extends ASTNodeAccessImpl implements Expression {
+    private final Column column;
+
+    public ConnectByRootOperator(Column column) {
+        this.column = Objects.requireNonNull(column, "The COLUMN of the ConnectByRoot Operator must not be null");
+    }
+
+    public Column getColumn() {
+        return column;
+    }
+
+    @Override
+    public void accept(ExpressionVisitor expressionVisitor) {
+        expressionVisitor.visit(this);
+    }
+    
+    public StringBuilder appendTo(StringBuilder builder) {
+        builder.append("CONNECT_BY_ROOT ").append(column);
+        return builder;
+    }
+    
+    @Override
+    public String toString() {
+        return appendTo(new StringBuilder()).toString();
+    }
+
+}

src/main/java/net/sf/jsqlparser/expression/ExpressionVisitor.java

@@ -173,5 +173,6 @@ public interface ExpressionVisitor {
 
     void visit(JsonFunction aThis);
 
+    void visit(ConnectByRootOperator aThis);
     void visit(OracleNamedFunctionParameter aThis);
 }

src/main/java/net/sf/jsqlparser/expression/ExpressionVisitorAdapter.java

@@ -613,10 +613,16 @@ public void visit(JsonFunction expression) {
         }
     }
 
+    @Override
+    public void visit(ConnectByRootOperator connectByRootOperator) {
+        connectByRootOperator.getColumn().accept(this);
+    }
+    
     @Override
     public void visit(OracleNamedFunctionParameter oracleNamedFunctionParameter) {
         oracleNamedFunctionParameter.getExpression().accept(this);
     }
+    
     public void visit(ColumnDefinition columnDefinition) {
        columnDefinition.accept(this);
      }

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

@@ -21,6 +21,7 @@
 import net.sf.jsqlparser.expression.CaseExpression;
 import net.sf.jsqlparser.expression.CastExpression;
 import net.sf.jsqlparser.expression.CollateExpression;
+import net.sf.jsqlparser.expression.ConnectByRootOperator;
 import net.sf.jsqlparser.expression.DateTimeLiteralExpression;
 import net.sf.jsqlparser.expression.DateValue;
 import net.sf.jsqlparser.expression.DoubleValue;
@@ -1030,6 +1031,10 @@ public void visit(JsonFunction expression) {
     }
 
     @Override
+    public void visit(ConnectByRootOperator connectByRootOperator) {
+        connectByRootOperator.getColumn().accept(this);
+    }
+  
     public void visit(IfElseStatement ifElseStatement) {
         ifElseStatement.getIfStatement().accept(this);
         if (ifElseStatement.getElseStatement()!=null) {

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

@@ -22,6 +22,7 @@
 import net.sf.jsqlparser.expression.CaseExpression;
 import net.sf.jsqlparser.expression.CastExpression;
 import net.sf.jsqlparser.expression.CollateExpression;
+import net.sf.jsqlparser.expression.ConnectByRootOperator;
 import net.sf.jsqlparser.expression.DateTimeLiteralExpression;
 import net.sf.jsqlparser.expression.DateValue;
 import net.sf.jsqlparser.expression.DoubleValue;
@@ -1018,6 +1019,12 @@ public void visit(JsonAggregateFunction expression) {
     public void visit(JsonFunction expression) {
          expression.append(buffer);
     }
+    
+    @Override
+    public void visit(ConnectByRootOperator connectByRootOperator) {
+        buffer.append("CONNECT_BY_ROOT ");
+        connectByRootOperator.getColumn().accept(this);
+    }
 
     @Override
     public void visit(OracleNamedFunctionParameter oracleNamedFunctionParameter) {

src/main/java/net/sf/jsqlparser/util/validation/validator/ExpressionValidator.java

@@ -17,6 +17,7 @@
 import net.sf.jsqlparser.expression.CaseExpression;
 import net.sf.jsqlparser.expression.CastExpression;
 import net.sf.jsqlparser.expression.CollateExpression;
+import net.sf.jsqlparser.expression.ConnectByRootOperator;
 import net.sf.jsqlparser.expression.DateTimeLiteralExpression;
 import net.sf.jsqlparser.expression.DateValue;
 import net.sf.jsqlparser.expression.DoubleValue;
@@ -599,6 +600,11 @@ public void visit(JsonFunction expression) {
         // no idea what this is good for
     }
 
+    @Override
+    public void visit(ConnectByRootOperator connectByRootOperator) {
+        connectByRootOperator.getColumn().accept(this);
+    }
+    
     @Override
     public void visit(OracleNamedFunctionParameter oracleNamedFunctionParameter) {
         oracleNamedFunctionParameter.getExpression().accept(this);

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

@@ -167,6 +167,7 @@ TOKEN: /* SQL Keywords. prefixed with K_ to avoid name clashes */
 |   <K_COMMIT:"COMMIT">
 |   <K_COMMENT:"COMMENT">
 |   <K_CONNECT:"CONNECT">
+|   <K_CONNECT_BY_ROOT: "CONNECT_BY_ROOT"> 
 |   <K_CONSTRAINT:"CONSTRAINT">
 |   <K_COSTS: "COSTS">
 |   <K_CREATE:"CREATE">
@@ -3665,6 +3666,8 @@ Expression PrimaryExpression() #PrimaryExpression:
 
         | LOOKAHEAD(2) retval = NextValExpression()
 
+        | retval=ConnectByRootOperator()
+
         | retval=Column()
 
         | token=<S_CHAR_LITERAL> { retval = new StringValue(token.image); linkAST(retval,jjtThis); }
@@ -3745,6 +3748,16 @@ Expression PrimaryExpression() #PrimaryExpression:
     }
 }
 
+ConnectByRootOperator ConnectByRootOperator() #ConnectByRootOperator: {
+    Column column;
+}
+{
+    <K_CONNECT_BY_ROOT> column = Column()
+    {
+      return new ConnectByRootOperator(column);
+    }
+}
+
 NextValExpression NextValExpression() : {
     List<String> data = new ArrayList<String>();
     Token token;

src/test/java/net/sf/jsqlparser/expression/ExpressionVisitorAdapterTest.java

@@ -257,7 +257,15 @@ public void testJsonAggregateFunction() throws JSQLParserException {
           .accept(adapter);
     }
 
-     @Test
+    @Test
+    public void testConnectedByRootExpression() throws JSQLParserException {
+        ExpressionVisitorAdapter adapter = new ExpressionVisitorAdapter();
+        CCJSqlParserUtil
+          .parseExpression("CONNECT_BY_ROOT last_name as name")
+          .accept(adapter);
+    }
+    
+    @Test
     public void testRowConstructor() throws JSQLParserException {
         ExpressionVisitorAdapter adapter = new ExpressionVisitorAdapter();
         CCJSqlParserUtil

src/test/java/net/sf/jsqlparser/statement/select/SelectTest.java

@@ -4666,6 +4666,30 @@ public void testKeywordFilterIssue1255() throws JSQLParserException {
     }
 
     @Test
+    public void testConnectByRootIssue1255() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed(
+            "SELECT last_name \"Employee\", CONNECT_BY_ROOT last_name \"Manager\",\n" +
+            "   LEVEL-1 \"Pathlen\", SYS_CONNECT_BY_PATH(last_name, '/') \"Path\"\n" +
+            "   FROM employees\n" +
+            "   WHERE LEVEL > 1 and department_id = 110\n" +
+            "   CONNECT BY PRIOR employee_id = manager_id", true);
+
+        assertSqlCanBeParsedAndDeparsed(
+            "SELECT name, SUM(salary) \"Total_Salary\" FROM (\n" +
+            "   SELECT CONNECT_BY_ROOT last_name as name, Salary\n" +
+            "      FROM employees\n" +
+            "      WHERE department_id = 110\n" +
+            "      CONNECT BY PRIOR employee_id = manager_id)\n" +
+            "      GROUP BY name", true);
+        
+        assertSqlCanBeParsedAndDeparsed(
+            "SELECT CONNECT_BY_ROOT last_name as name"
+          + ", salary "
+          + "FROM employees "
+          + "WHERE department_id = 110 "
+          + "CONNECT BY PRIOR employee_id = manager_id", true);
+    }
+    
     public void testUnionLimitOrderByIssue1268() throws JSQLParserException {
         String sqlStr = "(SELECT __time FROM traffic_protocol_stat_log LIMIT 1) UNION ALL (SELECT __time FROM traffic_protocol_stat_log ORDER BY __time LIMIT 1)";
         assertSqlCanBeParsedAndDeparsed(sqlStr, true);