/*
* 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.serializer;
import java.io.OutputStream ;
import java.util.List ;
import org.apache.jena.atlas.io.IndentedWriter ;
import org.apache.jena.graph.Node ;
import org.apache.jena.query.Query ;
import org.apache.jena.query.QueryVisitor ;
import org.apache.jena.query.SortCondition ;
import org.apache.jena.sparql.core.Prologue ;
import org.apache.jena.sparql.core.Var ;
import org.apache.jena.sparql.core.VarExprList ;
import org.apache.jena.sparql.engine.binding.Binding ;
import org.apache.jena.sparql.expr.Expr ;
import org.apache.jena.sparql.syntax.Element ;
import org.apache.jena.sparql.syntax.Template ;
import org.apache.jena.sparql.util.FmtUtils ;
/**
* Serialize a query into SPARQL or ARQ formats
*/
public class QuerySerializer implements QueryVisitor
{
static final int BLOCK_INDENT = 2 ;
protected FormatterTemplate fmtTemplate ;
protected FormatterElement fmtElement ;
protected FmtExprSPARQL fmtExpr ;
protected IndentedWriter out = null ;
QuerySerializer(OutputStream _out,
FormatterElement formatterElement,
FmtExprSPARQL formatterExpr,
FormatterTemplate formatterTemplate)
{
this(new IndentedWriter(_out),
formatterElement, formatterExpr, formatterTemplate) ;
}
QuerySerializer(IndentedWriter iwriter,
FormatterElement formatterElement,
FmtExprSPARQL formatterExpr,
FormatterTemplate formatterTemplate)
{
out = iwriter ;
fmtTemplate = formatterTemplate ;
fmtElement = formatterElement ;
fmtExpr = formatterExpr ;
}
@Override
public void startVisit(Query query) {}
@Override
public void visitResultForm(Query query) {}
@Override
public void visitPrologue(Prologue prologue)
{
int row1 = out.getRow() ;
PrologueSerializer.output(out, prologue) ;
int row2 = out.getRow() ;
if ( row1 != row2 )
out.newline() ;
}
@Override
public void visitSelectResultForm(Query query)
{
out.print("SELECT ") ;
if ( query.isDistinct() )
out.print("DISTINCT ") ;
if ( query.isReduced() )
out.print("REDUCED ") ;
out.print(" ") ; //Padding
if ( query.isQueryResultStar() )
out.print("*") ;
else
appendNamedExprList(query, out, query.getProject()) ;
out.newline() ;
}
@Override
public void visitConstructResultForm(Query query)
{
out.print("CONSTRUCT ") ;
// if ( query.isQueryResultStar() )
// {
// out.print("*") ;
// out.newline() ;
// }
// else
{
out.incIndent(BLOCK_INDENT) ;
out.newline() ;
Template t = query.getConstructTemplate() ;
fmtTemplate.format(t) ;
out.decIndent(BLOCK_INDENT) ;
}
}
@Override
public void visitDescribeResultForm(Query query)
{
out.print("DESCRIBE ") ;
if ( query.isQueryResultStar() )
out.print("*") ;
else
{
appendVarList(query, out, query.getResultVars()) ;
if ( query.getResultVars().size() > 0 &&
query.getResultURIs().size() > 0 )
out.print(" ") ;
appendURIList(query, out, query.getResultURIs()) ;
}
out.newline() ;
}
@Override
public void visitAskResultForm(Query query)
{
out.print("ASK") ;
out.newline() ;
}
@Override
public void visitDatasetDecl(Query query)
{
if ( query.getGraphURIs() != null && query.getGraphURIs().size() != 0 )
{
for ( String uri : query.getGraphURIs() )
{
out.print("FROM ") ;
out.print(FmtUtils.stringForURI(uri, query)) ;
out.newline() ;
}
}
if ( query.getNamedGraphURIs() != null && query.getNamedGraphURIs().size() != 0 )
{
for ( String uri : query.getNamedGraphURIs() )
{
// One per line
out.print("FROM NAMED ") ;
out.print(FmtUtils.stringForURI(uri, query)) ;
out.newline() ;
}
}
}
@Override
public void visitQueryPattern(Query query)
{
if ( query.getQueryPattern() != null )
{
out.print("WHERE") ;
out.incIndent(BLOCK_INDENT) ;
out.newline() ;
Element el = query.getQueryPattern() ;
fmtElement.visitAsGroup(el) ;
//el.visit(fmtElement) ;
out.decIndent(BLOCK_INDENT) ;
out.newline() ;
}
}
@Override
public void visitGroupBy(Query query)
{
if ( query.hasGroupBy() )
{
// Can have an empty GROUP BY list if the groupin gis implicit
// by use of an aggregate in the SELECT clause.
if ( ! query.getGroupBy().isEmpty() )
{
out.print("GROUP BY ") ;
appendNamedExprList(query, out, query.getGroupBy()) ;
out.println();
}
}
}
@Override
public void visitHaving(Query query)
{
if ( query.hasHaving() )
{
out.print("HAVING") ;
for (Expr expr : query.getHavingExprs())
{
out.print(" ") ;
fmtExpr.format(expr) ;
}
out.println() ;
}
}
@Override
public void visitOrderBy(Query query)
{
if ( query.hasOrderBy() )
{
out.print("ORDER BY ") ;
boolean first = true ;
for (SortCondition sc : query.getOrderBy())
{
if ( ! first )
out.print(" ") ;
sc.format(fmtExpr, out) ;
first = false ;
}
out.println() ;
}
}
@Override
public void visitLimit(Query query)
{
if ( query.hasLimit() )
{
out.print("LIMIT "+query.getLimit()) ;
out.newline() ;
}
}
@Override
public void visitOffset(Query query)
{
if ( query.hasOffset() )
{
out.print("OFFSET "+query.getOffset()) ;
out.newline() ;
}
}
@Override
public void visitValues(Query query)
{
if ( query.hasValues() )
{
outputDataBlock(out, query.getValuesVariables(), query.getValuesData(), fmtElement.context) ;
out.newline() ;
}
}
public static void outputDataBlock(IndentedWriter out, List<Var> variables, List<Binding> values, SerializationContext cxt)
{
out.print("VALUES ") ;
if ( variables.size() == 1 )
{
// Short form.
out.print("?") ;
out.print(variables.get(0).getVarName()) ;
out.print(" {") ;
out.incIndent() ;
for ( Binding valueRow : values )
outputValuesOneRow(out, variables, valueRow, cxt);
out.decIndent() ;
out.print(" }") ;
return ;
}
// Long form.
out.print("(") ;
for ( Var v : variables )
{
out.print(" ") ;
out.print(v.toString()) ;
}
out.print(" )") ;
out.print(" {") ;
out.incIndent() ;
for ( Binding valueRow : values )
{
out.println() ;
out.print("(") ;
outputValuesOneRow(out, variables, valueRow, cxt);
out.print(" )") ;
}
out.decIndent() ;
out.ensureStartOfLine() ;
out.print("}") ;
}
private static void outputValuesOneRow(IndentedWriter out, List<Var> variables, Binding row, SerializationContext cxt) {
// A value may be null for UNDEF
for ( Var var : variables )
{
out.print(" ") ;
Node value = row.get(var) ;
if ( value == null )
out.print("UNDEF") ;
else {
// Context for bnodes.
// Bnodes don't occur in legal syntax but a rewritten query may
// have them. The output will not be legal SPARQL.
// ARQ (SPARQL with extensions) does parse blankd nodes in VALUES.
out.print(FmtUtils.stringForNode(value, cxt)) ;
}
}
}
@Override
public void finishVisit(Query query)
{
out.flush() ;
}
// ----
void appendVarList(Query query, IndentedWriter sb, List<String> vars)
{
boolean first = true ;
for ( String varName : vars )
{
Var var = Var.alloc(varName) ;
if ( ! first )
sb.print(" ") ;
sb.print(var.toString()) ;
first = false ;
}
}
void appendNamedExprList(Query query, IndentedWriter sb, VarExprList namedExprs)
{
boolean first = true ;
for ( Var var : namedExprs.getVars() )
{
Expr expr = namedExprs.getExpr(var) ;
if ( ! first )
sb.print(" ") ;
if ( expr != null )
{
// The following are safe to write without ()
// Compare/merge with fmtExpr.format
boolean needParens = true ;
if ( expr.isFunction() )
needParens = false ;
// else if ( expr instanceof E_Aggregator )
// // Aggregators are variables (the function maps to an internal variable
// // that is accesses by the E_Aggregator
// needParens = false ;
else if ( expr.isVariable() )
needParens = false ;
if ( ! Var.isAllocVar(var) )
// AS ==> need parens
needParens = true ;
if ( needParens )
out.print("(") ;
fmtExpr.format(expr) ;
if ( ! Var.isAllocVar(var) )
{
sb.print(" AS ") ;
sb.print(var.toString()) ;
}
if ( needParens )
out.print(")") ;
}
else
{
sb.print(var.toString()) ;
}
first = false ;
}
}
static void appendURIList(Query query, IndentedWriter sb, List<Node> vars)
{
SerializationContext cxt = new SerializationContext(query) ;
boolean first = true ;
for ( Node node : vars )
{
if ( ! first )
sb.print(" ") ;
sb.print(FmtUtils.stringForNode(node, cxt)) ;
first = false ;
}
}
}