/*
* 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.core.JoinType.INNER ;
import static org.apache.jena.sdb.core.JoinType.LEFT ;
import java.util.Collection;
import java.util.Set;
import org.apache.jena.sdb.core.JoinType ;
import org.apache.jena.sdb.core.SDBRequest ;
import org.apache.jena.sdb.core.ScopeEntry ;
import org.apache.jena.sdb.core.sqlexpr.* ;
import org.apache.jena.sdb.core.sqlnode.* ;
import org.apache.jena.sdb.shared.SDBInternalError ;
import org.apache.jena.sparql.core.Var ;
public class SqlBuilder
{
static public SqlNode distinct(SDBRequest request, SqlNode sqlNode)
{ return SqlSelectBlock.distinct(request, sqlNode) ; }
static public SqlNode slice(SDBRequest request, SqlNode sqlNode, long start, long length)
{ return SqlSelectBlock.slice(request, sqlNode, start, length) ; }
static public SqlNode project(SDBRequest request, SqlNode sqlNode, Collection<ColAlias> cols)
{ return SqlSelectBlock.project(request, sqlNode, cols) ; }
static public SqlNode project(SDBRequest request, SqlNode sqlNode, ColAlias col)
{ return SqlSelectBlock.project(request, sqlNode, col) ; }
static public SqlNode view(SDBRequest request, SqlNode sqlNode)
{ return SqlSelectBlock.view(request, sqlNode) ; }
static public SqlNode restrict(SDBRequest request, SqlNode sqlNode, SqlExprList conditions)
{
for ( SqlExpr e : conditions )
sqlNode = SqlSelectBlock.restrict(request, sqlNode, e) ;
return sqlNode ;
}
static public SqlNode restrict(SDBRequest request, SqlNode sqlNode, SqlExpr expr)
{
if ( sqlNode.isInnerJoin() )
{
sqlNode.asInnerJoin().addCondition(expr) ;
return sqlNode ;
}
return SqlSelectBlock.restrict(request, sqlNode, expr) ;
}
// ----- Making join nodes
public static SqlNode innerJoin(SDBRequest request, SqlNode left, SqlNode right)
{
if ( left == null )
return right ;
return join(request, INNER, left, right, null) ;
}
public static SqlNode leftJoin(SDBRequest request, SqlNode left, SqlNode right, SqlExpr expr)
{
if ( left == null )
throw new SDBInternalError("Attempt to leftJoin to null") ;
SqlJoin j = join(request, LEFT, left, right, null) ;
if ( expr != null )
j.addCondition(expr) ;
return j ;
}
public static SqlNode leftJoinCoalesce(SDBRequest request, String alias,
SqlNode left, SqlNode right,
Set<Var> coalesceVars)
{
SqlJoin sqlJoin = join(request, LEFT, left, right, coalesceVars) ;
return SqlCoalesce.create(request, alias, sqlJoin, coalesceVars) ;
}
// private static String sqlNodeName(SqlNode sNode)
// {
// if ( sNode == null ) return "<null>" ;
// if ( sNode.isProject() ) return "Project" ;
// if ( sNode.isRestrict() ) return "Restrict/"+sqlNodeName(sNode.asRestrict().getSubNode()) ;
// if ( sNode.isTable() ) return "Table" ;
// if ( sNode.isInnerJoin() ) return "JoinInner" ;
// if ( sNode.isLeftJoin() ) return "Joinleft" ;
// if ( sNode.isCoalesce() ) return "Coalesce" ;
// return "<unknown>" ;
// }
// Join/LeftJoin two subexpressions, calculating the join conditions in the process
// If a coalesce (LeftJoin) then don't equate left and right vars of the same name.
// A SqlCoalesce is a special case of LeftJoin where ignoreVars!=null
private static SqlJoin join(SDBRequest request,
JoinType joinType,
SqlNode left, SqlNode right,
Set<Var> ignoreVars)
{
SqlExprList conditions = new SqlExprList() ;
if ( joinType == INNER )
// Put any left filter into the join conditions.
// Does not apply to LEFT because the LHS filter does not apply to the right in the same way.
left = extractRestrict(left, conditions) ;
right = extractRestrict(right, conditions) ;
for ( Var v : left.getIdScope().getVars() )
{
if ( right.getIdScope().hasColumnForVar(v) )
{
ScopeEntry sLeft = left.getIdScope().findScopeForVar(v) ;
ScopeEntry sRight = right.getIdScope().findScopeForVar(v) ;
SqlExpr c = joinCondition(joinType, sLeft, sRight) ;
conditions.add(c) ;
c.addNote("Join var: "+v) ;
}
}
SqlJoin join = SqlJoin.create(joinType, left, right) ;
join.addConditions(conditions) ;
return join ;
}
private static SqlExpr joinCondition(JoinType joinType, ScopeEntry sLeft, ScopeEntry sRight)
{
SqlExpr c = null ;
SqlColumn leftCol = sLeft.getColumn() ;
SqlColumn rightCol = sRight.getColumn() ;
// SPARQL join condition is join if "undef or same"
// Soft null handling : need to insert "IsNull OR"
// if the column can be a null.
// The order of the OR conditions matters.
if ( sLeft.isOptional() )
c = makeOr(c, new S_IsNull(leftCol)) ;
if ( sRight.isOptional() )
c = makeOr(c, new S_IsNull(rightCol)) ;
c = makeOr(c, new S_Equal(leftCol, rightCol)) ;
return c ;
}
// ---- Expressions
private static SqlExpr makeOr(SqlExpr c, SqlExpr expr)
{
if ( c == null )
return expr ;
return new S_Or(c, expr) ;
}
private static SqlExpr makeAnd(SqlExpr c, SqlExpr expr)
{
if ( c == null )
return expr ;
return new S_And(c, expr) ;
}
private static SqlNode extractRestrict(SqlNode sqlNode, SqlExprList conditions)
{
// SqlSelectBlocks as simple restrictions.
if ( sqlNode.isSelectBlock() )
{
SqlSelectBlock block = sqlNode.asSelectBlock() ;
if ( block.getDistinct() )
return sqlNode ;
if ( block.hasSlice() )
return sqlNode ;
// If a restriction of a table.
if ( block.getSubNode().isTable() )
{
SqlTable t = block.getSubNode().asTable() ;
conditions.addAll(block.getConditions()) ;
return t ;
}
}
return sqlNode ;
// if ( ! sqlNode.isRestrict() )
// return sqlNode ;
//
// SqlRestrict restrict = sqlNode.asRestrict() ;
// SqlNode subNode = restrict.getSubNode() ;
// if ( ! subNode.isTable() && ! subNode.isInnerJoin() )
// return sqlNode ;
// conditions.addAll(restrict.getConditions()) ;
// subNode.addNotes(restrict.getNotes()) ;
// return subNode ;
}
}