/*
* 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.sdb.compiler;
import static org.apache.jena.sdb.compiler.OpLibSDB.asProject ;
import static org.apache.jena.sdb.compiler.OpLibSDB.sub ;
import java.util.ArrayList ;
import java.util.Collection ;
import java.util.List ;
import org.apache.jena.sdb.SDB ;
import org.apache.jena.sdb.compiler.rewrite.QuadBlockRewriteCompiler ;
import org.apache.jena.sdb.core.SDBRequest ;
import org.apache.jena.sdb.core.sqlnode.SqlNode ;
import org.apache.jena.sdb.core.sqlnode.SqlSelectBlock ;
import org.apache.jena.sdb.store.SQLBridge ;
import org.apache.jena.sdb.store.SQLBridgeFactory ;
import org.apache.jena.sparql.algebra.* ;
import org.apache.jena.sparql.algebra.op.* ;
import org.apache.jena.sparql.core.Var ;
public abstract class QueryCompilerMain implements QueryCompiler
{
protected SDBRequest request ;
public QueryCompilerMain(SDBRequest request)
{
this.request = request ;
}
@Override
public Op compile(final Op op)
{
QuadBlockCompiler quadCompiler = createQuadBlockCompiler() ;
if ( request.getContext().isTrue(SDB.useQuadRewrite) )
quadCompiler = new QuadBlockRewriteCompiler(request, quadCompiler) ;
// XXX Turn off Limit/Offset processing - do later so as to enable filter processing.
boolean b = request.LimitOffsetTranslation ;
request.LimitOffsetTranslation = false ;
Transform t = new TransformSDB(request, quadCompiler) ;
Op op2 = Transformer.transform(t, op) ;
// Modifiers: the structure is:
// slice
// distinct/reduced
// project
// order
// [toList]
// Find the first non-modifier. WRONG with SqlSelectBlocks.
Op patternOp = op2 ;
while ( patternOp instanceof OpModifier )
patternOp = ((OpModifier)patternOp).getSubOp() ;
boolean patternIsOneSQLStatement = SDB_QC.isOpSQL(patternOp) ;
// Find all OpSQL nodes and put a bridge round them.
OpWalker.walk(op2, new SqlNodesFinisher(patternIsOneSQLStatement)) ;
request.LimitOffsetTranslation = b ;
// At this point, we have converted what we can into OpSQL.
// Some changes can still be made now w have the whole SQL expression.
Op op3 = postProcessSQL(op2) ;
return op3 ;
}
protected abstract Op postProcessSQL(Op op) ;
/*
// This rewrite can be done in all layouts but for layout2, it needs to be
// done after other changes so QueryCompiler2 overrides this method
// and does things in the right order.
// (slice (distinct ....))
op = rewriteDistinct(op, request) ;
op = rewriteLimitOffset(op, request) ;
return op ;
*/
public abstract QuadBlockCompiler createQuadBlockCompiler() ;
@Override
public ConditionCompiler getConditionCompiler()
{
return null ;
}
// Add the "bridge" that gets the lexical forms etc for the projected, or all, variables.
private class SqlNodesFinisher extends OpVisitorBase
{
private boolean justProjectVars ;
SqlNodesFinisher(boolean justProjectVars)
{ this.justProjectVars = justProjectVars ; }
@Override
public void visit(OpExt op)
{
if ( ! ( op instanceof OpSQL ) )
{
super.visit(op) ;
return ;
}
OpSQL opSQL = (OpSQL)op ;
List<Var> projectVars = null ;
if ( justProjectVars && request.getQuery() != null )
// Need project vars and also the ORDER BY (for external sorting)
projectVars = SDB_QC.queryOutVars(request.getQuery()) ;
else
{
// All variables.
Collection<Var> tmp = OpVars.visibleVars(opSQL.getOriginal()) ;
projectVars = new ArrayList<Var>(tmp) ;
}
SqlNode sqlNode = opSQL.getSqlNode() ;
SQLBridgeFactory f = request.getStore().getSQLBridgeFactory() ;
SQLBridge bridge = f.create(request, sqlNode, projectVars) ;
bridge.build();
sqlNode = bridge.getSqlNode() ;
opSQL.setBridge(bridge) ;
opSQL.resetSqlNode(sqlNode) ;
}
}
// -- Library of possible operations that can be applied to all layouts.
protected static Op rewriteLimitOffset(Op op, SDBRequest request)
{
Transform t = new LimitOffsetOptimizer(request) ;
return Transformer.transform(t, op) ;
}
private static class LimitOffsetOptimizer extends TransformCopy
{
private final SDBRequest request ;
public LimitOffsetOptimizer(SDBRequest request)
{
this.request = request ;
}
// From TransformSDB
@Override
public Op transform(OpSlice opSlice, Op subOp)
{
if ( ! request.LimitOffsetTranslation )
return super.transform(opSlice, subOp) ;
// Two cases are currently handled:
// (slice (sql expression))
// (slice (project ... (sql expression)))
boolean canHandle = false ;
// Relies on the fact that isOpSQL(null) is false.
if ( SDB_QC.isOpSQL(subOp) )
canHandle = true ;
else if ( SDB_QC.isOpSQL(sub(asProject(subOp))) )
{
return transformSliceProject(opSlice, (OpProject)subOp) ;
}
// Simple slice
if ( ! SDB_QC.isOpSQL(subOp) )
return super.transform(opSlice, subOp) ;
return transformSlice(opSlice, ((OpSQL)subOp)) ;
}
private Op transformSlice(OpSlice opSlice, OpSQL opSQL)
{
// (slice X)
SqlNode sqlSubOp = opSQL.getSqlNode() ;
SqlNode n = SqlSelectBlock.slice(request, sqlSubOp, opSlice.getStart(), opSlice.getLength()) ;
OpSQL x = new OpSQL(n, opSlice, request) ;
x.setBridge(opSQL.getBridge()) ;
return x ;
}
public Op transformSliceProject(OpSlice opSlice, OpProject opProject)
{
// (slice (project X))
Op subOp = opProject.getSubOp() ;
if ( ! SDB_QC.isOpSQL(subOp) )
// Can't cope - just pass the slice to the general superclass.
return super.transform(opSlice, opProject) ;
OpSQL opSQL = (OpSQL)subOp ;
SqlNode sqlSubOp = opSQL.getSqlNode() ;
List<Var> pv = opProject.getVars() ;
// Do as (slice X)
SqlNode n = SqlSelectBlock.slice(request, sqlSubOp, opSlice.getStart(), opSlice.getLength()) ;
// Put back project - as an OpProject to leave for the bridge.
OpSQL x = new OpSQL(n, opProject, request) ;
x.setBridge(opSQL.getBridge()) ;
// Bridge will be set later.
// Is OpProject needed?
return new OpProject(x, pv) ;
}
}
protected static Op rewriteDistinct(Op op, SDBRequest request)
{
Transform t = new DistinctOptimizer(request) ;
return Transformer.transform(t, op) ;
}
private static class DistinctOptimizer extends TransformCopy
{
private final SDBRequest request ;
public DistinctOptimizer(SDBRequest request)
{
this.request = request ;
}
@Override
public Op transform(OpDistinct opDistinct, Op subOp)
{
if ( ! request.DistinctTranslation )
return super.transform(opDistinct, subOp) ;
if ( ! SDB_QC.isOpSQL(subOp) )
return super.transform(opDistinct, subOp) ;
SqlNode sqlSubOp = ((OpSQL)subOp).getSqlNode() ;
SqlNode n = SqlSelectBlock.distinct(request, sqlSubOp) ;
return new OpSQL(n, opDistinct, request) ;
}
}
}