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ARQ is a SPARQL 1.1 query engine for Apache Jena
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/*
 * 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.jena.sparql.graph;

import java.util.List ;

import javax.xml.crypto.dsig.Transform;

import org.apache.jena.graph.Node ;
import org.apache.jena.graph.Triple ;
import org.apache.jena.sparql.algebra.Op ;
import org.apache.jena.sparql.algebra.Table ;
import org.apache.jena.sparql.algebra.TransformCopy ;
import org.apache.jena.sparql.algebra.op.* ;
import org.apache.jena.sparql.algebra.table.TableUnit ;
import org.apache.jena.sparql.core.BasicPattern ;
import org.apache.jena.sparql.core.TriplePath ;
import org.apache.jena.sparql.core.Var ;
import org.apache.jena.sparql.core.VarExprList ;
import org.apache.jena.sparql.path.Path ;

/** A {@link Transform} that applies a {@link NodeTransform}
 * to graph patterns.
 * 
 * This does not transform expressions. That is done by {@link NodeTransformExpr}.
 * 
 * @see NodeTransformExpr  
 */
class NodeTransformOp extends TransformCopy
{
    // This finds everywhere that nodes can lurk in an algebra expression:
    //   BGPs, paths, triples, quads
    //   GRAPH, GRAPH{} (DatasetNames)
    //   OrderBy, GroupBy
    //   Extend, Assign
    //   Table
    //   Project
    
    private final NodeTransform transform ;
    NodeTransformOp(NodeTransform transform)
    {
        this.transform = transform ;
    }

    @Override
    public Op transform(OpTriple opTriple) {
        Triple t2 = NodeTransformLib.transform(transform, opTriple.getTriple());
        if ( t2 == opTriple.getTriple() )
            return super.transform(opTriple);
        return new OpTriple(t2);
    }

    @Override
    public Op transform(OpBGP opBGP) {
        BasicPattern bgp2 = NodeTransformLib.transform(transform, opBGP.getPattern());
        if ( bgp2 == opBGP.getPattern() )
            return super.transform(opBGP);
        return new OpBGP(bgp2);
    }

    @Override
    public Op transform(OpPath opPath) {
        TriplePath tp = opPath.getTriplePath();
        Node s = tp.getSubject();
        Node s1 = transform.apply(s);
        Node o = tp.getObject();
        Node o1 = transform.apply(o);

        if ( s1 == s && o1 == o )
            // No change.
            return super.transform(opPath);

        Path path = tp.getPath();
        TriplePath tp2;

        if ( path != null )
            tp2 = new TriplePath(s1, path, o1);
        else {
            Triple t = new Triple(s1, tp.getPredicate(), o1);
            tp2 = new TriplePath(t);
        }
        return new OpPath(tp2);
    }

    @Override
    public Op transform(OpQuadPattern opQuadPattern) {
        // The internal representation is (graph, BGP)
        BasicPattern bgp2 = NodeTransformLib.transform(transform, opQuadPattern.getBasicPattern());
        Node g2 = opQuadPattern.getGraphNode();
        g2 = transform.apply(g2);

        if ( g2 == opQuadPattern.getGraphNode() && bgp2 == opQuadPattern.getBasicPattern() )
            return super.transform(opQuadPattern);
        return new OpQuadPattern(g2, bgp2);
    }

    @Override
    public Op transform(OpGraph opGraph, Op subOp) {
        Node g2 = transform.apply(opGraph.getNode());
        if ( g2 == opGraph.getNode() )
            return super.transform(opGraph, subOp);
        return new OpGraph(g2, subOp);
    }

    @Override
    public Op transform(OpDatasetNames opDatasetNames) {
        Node g2 = transform.apply(opDatasetNames.getGraphNode());
        if ( g2 == opDatasetNames.getGraphNode() )
            return super.transform(opDatasetNames);
        return new OpDatasetNames(g2);
    }

    @Override
    public Op transform(OpTable opTable) {
        if ( opTable.isJoinIdentity() )
            return opTable;
        Table table = opTable.getTable();
        if ( table.isEmpty() )
            return opTable;
        if ( TableUnit.isTableUnit(table) )
            return opTable;
        if ( table.getVars().size() == 0 )
            return opTable;
        Table table2 = NodeTransformLib.transform(table, transform);
        return OpTable.create(table2);
    }

    @Override
    public Op transform(OpProject opProject, Op subOp) {
        List x = opProject.getVars();
        List x2 = NodeTransformLib.transformVars(transform, x);
        if ( x == x2 )
            return super.transform(opProject, subOp);
        return new OpProject(subOp, x2);
    }

    @Override
    public Op transform(OpAssign opAssign, Op subOp) {
        VarExprList varExprList = opAssign.getVarExprList();
        VarExprList varExprList2 = NodeTransformLib.transformVars(transform, varExprList);
        if ( varExprList == varExprList2 )
            return super.transform(opAssign, subOp);
        return OpAssign.assign(subOp, varExprList2);
    }

    @Override
    public Op transform(OpExtend opExtend, Op subOp) {
        VarExprList varExprList = opExtend.getVarExprList();
        VarExprList varExprList2 = NodeTransformLib.transformVars(transform, varExprList);
        if ( varExprList == varExprList2 )
            return super.transform(opExtend, subOp);
        return OpExtend.create(subOp, varExprList2);
    }

    @Override
    public Op transform(OpGroup opGroup, Op subOp) {
        VarExprList groupVars = opGroup.getGroupVars();
        VarExprList groupVars2 = NodeTransformLib.transformVars(transform, groupVars);
        if ( groupVars2 == groupVars )
            return super.transform(opGroup, subOp);
        return OpGroup.create(subOp, groupVars2, opGroup.getAggregators());
    }
}