/*
* 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.core.sqlnode;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import org.apache.jena.sdb.core.* ;
import org.apache.jena.sdb.core.sqlexpr.SqlColumn ;
import org.apache.jena.sdb.core.sqlexpr.SqlExpr ;
import org.apache.jena.sdb.core.sqlexpr.SqlExprList ;
import org.apache.jena.sdb.shared.SDBInternalError ;
import org.apache.jena.sparql.core.Var ;
/** A unit that generates an SQL SELECT Statement.
* The SQL generation process is a pass over the SqlNdoe structure to generate SelectBlocks,
* then to generate the SQL strings.
*/
public class SqlSelectBlock extends SqlNodeBase1
{
// Need: code to take an SqlNode and produce a rename map.
// Already in SqlRename. Use SqlRename.view.
// SqlRename is currently unused.
// Is SqlRename > SqlProject?
// with Map<Var, String> = List<VarCol>
// Mapping of names
// projection
// Joins (inner and left)
// Restriction.
// Group
// aggregrate
// order
// limit/offset
private List<ColAlias> cols = new ArrayList<ColAlias>() ;
private SqlExprList exprs = new SqlExprList() ;
private static final int NOT_SET = -9 ;
private long start = NOT_SET ;
private long length = NOT_SET ;
private boolean distinct = false ;
private SqlTable vTable ; // Naming base for renamed columns
private Scope idScope = null ; // Scopes are as the wrapped SqlNode unless explicitly changed.
private Scope nodeScope = null ;
static public SqlNode distinct(SDBRequest request, SqlNode sqlNode)
{
SqlSelectBlock block = blockWithView(request, sqlNode) ;
block.setDistinct(true) ;
return block ;
}
static public SqlNode project(SDBRequest request, SqlNode sqlNode)
{ return project(request, sqlNode, (ColAlias)null) ; }
static public SqlNode project(SDBRequest request, SqlNode sqlNode, Collection<ColAlias> cols)
{
// If already a view, not via a project, - think harder
SqlSelectBlock block = blockNoView(request, sqlNode) ;
if ( block.idScope != null || block.nodeScope != null )
System.err.println("SqlSelectBlock.project : already a view") ;
if ( cols != null )
block.addAll(cols) ;
return block ;
}
static public SqlNode project(SDBRequest request, SqlNode sqlNode, ColAlias col)
{
SqlSelectBlock block = blockNoView(request, sqlNode) ;
if ( col != null )
block.add(col) ;
return block ;
}
static public SqlNode slice(SDBRequest request, SqlNode sqlNode, long start, long length)
{
SqlSelectBlock block = blockWithView(request, sqlNode) ;
if ( start >= 0 )
{
if ( block.getStart() > 0 )
start = start + block.getStart() ;
block.setStart(start) ;
}
if ( length >= 0 )
{
if ( block.getLength() >= 0 )
length = Math.min(length, block.getLength()) ;
block.setLength(length) ;
}
return block ;
}
static public SqlNode view(SDBRequest request, SqlNode sqlNode)
{
SqlSelectBlock block = blockWithView(request, sqlNode) ;
return block ;
}
static public SqlNode restrict(SDBRequest request, SqlNode sqlNode, SqlExprList exprs)
{
if ( exprs.size() == 0 )
return sqlNode ;
// Single table does not need renaming of columns
SqlSelectBlock block = (sqlNode.isTable() ? blockPlain(request, sqlNode) : blockWithView(request, sqlNode)) ;
block.getConditions().addAll(exprs) ;
return block ;
}
static public SqlNode restrict(SDBRequest request, SqlNode sqlNode, SqlExpr expr)
{
SqlSelectBlock block = (sqlNode.isTable() ? blockPlain(request, sqlNode) : blockWithView(request, sqlNode)) ;
block.getConditions().add(expr) ;
return block ;
}
/**
* @param aliasName
* @param sqlNode
*/
private SqlSelectBlock(String aliasName, SqlNode sqlNode)
{
super(aliasName, sqlNode) ;
if ( aliasName != null )
vTable = new SqlTable(aliasName) ;
}
@Override
public boolean isSelectBlock() { return true ; }
@Override
public SqlSelectBlock asSelectBlock() { return this ; }
public void setBlockAlias(String alias) { super.aliasName = alias ; }
public List<ColAlias> getCols() { return cols ; }
public void add(ColAlias c) { _add(c) ; }
public void addAll(Collection<ColAlias> vc)
{
for ( ColAlias c : vc )
_add(c) ;
}
private void _add(ColAlias c)
{
SqlColumn col = c.getColumn() ;
SqlColumn aliasCol = c.getAlias() ;
c.check(getAliasName()) ;
//
// if ( aliasCol.getTable() != null && aliasCol.getTable().getAliasName().equals(getAliasName()) )
// throw new SDBInternalError("Attempt to project to a column with different alias: "+col+" -> "+aliasCol) ;
cols.add(c) ;
}
/** Prepare the SelectBlock for use as a top level element - may discard the block */
public SqlNode clearView()
{
idScope = null ;
nodeScope = null ;
cols.clear() ;
if ( !distinct && ! hasConditions() && ! hasSlice() )
return getSubNode() ;
return this ;
}
public SqlExprList getConditions() { return exprs ; }
public boolean hasSlice() { return (start != NOT_SET ) || ( length != NOT_SET ) ; }
public boolean hasConditions() { return exprs.size() > 0 ; }
public long getStart() { return start ; }
private void setStart(long start) { this.start = start ; }
public long getLength() { return length ; }
private void setLength(long length) { this.length = length ; }
@Override
public Scope getIdScope() { return idScope != null ? idScope : super.getIdScope() ; }
@Override
public Scope getNodeScope() { return nodeScope != null ? nodeScope : super.getNodeScope() ; }
@Override
public SqlNode apply(SqlTransform transform, SqlNode newSubNode)
{ return transform.transform(this, newSubNode) ; }
@Override
public SqlNode copy(SqlNode subNode)
{ return new SqlSelectBlock(this.getAliasName(), subNode) ; }
@Override
public void visit(SqlNodeVisitor visitor)
{ visitor.visit(this) ; }
// Not "isDistinct"
public boolean getDistinct()
{
return distinct ;
}
private void setDistinct(boolean isDistinct)
{
this.distinct = isDistinct ;
}
private static SqlSelectBlock blockWithView(SDBRequest request,SqlNode sqlNode)
{
if ( sqlNode instanceof SqlSelectBlock )
{
SqlSelectBlock block = (SqlSelectBlock)sqlNode ;
if ( block.cols.size() == 0 )
{
// Didn't have a column view - force it
calcView(block) ;
}
return (SqlSelectBlock)sqlNode ;
}
SqlSelectBlock block = _create(request, sqlNode) ;
if ( block.getCols().size() != 0 )
throw new SDBInternalError("Can't set a view on Select block which is already had columns set") ;
calcView(block) ;
return block ;
}
private static SqlSelectBlock blockPlain(SDBRequest request,SqlNode sqlNode)
{
if ( sqlNode instanceof SqlSelectBlock )
return (SqlSelectBlock)sqlNode ;
// Same alias (typically, sqlNode is a table or view and this is the table name)
SqlSelectBlock block = new SqlSelectBlock(sqlNode.getAliasName(), sqlNode) ;
//addNotes(block, sqlNode) ;
return block ;
}
private static SqlSelectBlock blockNoView(SDBRequest request, SqlNode sqlNode)
{
if ( sqlNode instanceof SqlSelectBlock )
return (SqlSelectBlock)sqlNode ;
return _create(request, sqlNode) ;
}
private static SqlSelectBlock _create(SDBRequest request,SqlNode sqlNode)
{
String alias = sqlNode.getAliasName() ;
//if ( ! sqlNode.isTable() )
alias = request.generator(AliasesSql.SelectBlock).next() ;
SqlSelectBlock block = new SqlSelectBlock(alias, sqlNode) ;
addNotes(block, sqlNode) ;
return block ;
}
private static void addNotes(SqlSelectBlock block, SqlNode sqlNode)
{
block.addNotes(sqlNode.getNotes()) ;
}
static private void calcView(SqlSelectBlock block)
{
SqlNode sqlNode = block.getSubNode() ;
ScopeBase idScopeRename = new ScopeBase() ;
ScopeBase nodeScopeRename = new ScopeBase() ;
Generator gen = Gensym.create("X") ; // Column names. Not global.
block.merge(sqlNode.getIdScope(), idScopeRename, gen) ;
block.merge(sqlNode.getNodeScope(), nodeScopeRename, gen) ;
block.nodeScope = nodeScopeRename ;
block.idScope = idScopeRename ;
}
// Calculate renames
// Map all vars in the scope to names in the rename.
private void merge(Scope scope, ScopeBase newScope, Generator gen)
{
String x = "" ;
String sep = "" ;
for ( ScopeEntry e : scope.findScopes() )
{
SqlColumn oldCol = e.getColumn() ;
Var v = e.getVar() ;
String colName = gen.next() ;
SqlColumn newCol = new SqlColumn(vTable, colName) ;
this.add(new ColAlias(oldCol, newCol)) ;
newScope.setColumnForVar(v, newCol) ;
// Annotations
x = String.format("%s%s%s:(%s=>%s)", x, sep, v, oldCol, newCol) ;
sep = " " ;
}
if ( x.length() > 0 )
addNote(x) ;
}
}