com.bigdata.rdf.sail.sparql

Class GroupGraphPatternBuilder

java.lang.Object

com.bigdata.rdf.sail.sparql.ASTVisitorBase

com.bigdata.rdf.sail.sparql.BigdataASTVisitorBase

com.bigdata.rdf.sail.sparql.ValueExprBuilder

com.bigdata.rdf.sail.sparql.TriplePatternExprBuilder

com.bigdata.rdf.sail.sparql.GroupGraphPatternBuilder

All Implemented Interfaces:

SyntaxTreeBuilderVisitor

Direct Known Subclasses:

BigdataExprBuilder

public class GroupGraphPatternBuilder
extends TriplePatternExprBuilder

Visitor handles the GroupGraphPattern production (aka the "WHERE" clause). This includes SubSelect and GraphPatternNotTriples. ASTWhereClause has GroupGraphPattern child which is a (SelectQuery (aka subquery)), GraphPattern (BasicGraphPattern aka JoinGroup or GraphPatternNotTriples). The TriplesBlock is handled by the TriplePatternExprBuilder.

Version:

$Id: GroupGraphPatternBuilder.java 5064 2011-08-21 22:50:55Z thompsonbry $

Author:

Bryan Thompson

Field Summary

Fields inherited from class com.bigdata.rdf.sail.sparql.ValueExprBuilder

graphPattern

Fields inherited from class com.bigdata.rdf.sail.sparql.BigdataASTVisitorBase

context

Constructor Summary

Constructors

Constructor and Description
GroupGraphPatternBuilder(BigdataASTContext context)

Method Summary

Methods

Modifier and Type	Method and Description
Object	visit(ASTBind node, Object data) A BIND (or FILTER) can appear in an ASTBasicGraphPattern.
ValueExpressionNode	visit(ASTConstraint node, Object data) A FILTER.
ConstructNode	visit(ASTConstruct node, Object data) CONSTRUCT (handled as a TriplesBlock).
Void	visit(ASTGraphGraphPattern node, Object data)
GroupNodeBase<?>	visit(ASTGraphPatternGroup node, Object data) ( SelectQuery | GraphPattern ) - this is the common path for SubSelect and graph patterns.
BindingsClause	visit(ASTInlineData node, Object data)
AssignmentNode	visit(ASTLet node, Object data) A LET is just an alternative syntax for BIND
Object	visit(ASTMinusGraphPattern node, Object data) MINUS is modeled very much like OPTIONAL in the bigdata AST.
Void	visit(ASTNamedSubqueryInclude node, Object data) INCLUDE for a named subquery result set.
Void	visit(ASTOptionalGraphPattern node, Object data) Note: while openrdf lifts the filters out of the optional, we do not need to do this per MikeP.
Void	visit(ASTServiceGraphPattern node, Object data) SPARQL 1.1 SERVICE.
Void	visit(ASTUnionGraphPattern node, Object data) Given

Methods inherited from class com.bigdata.rdf.sail.sparql.TriplePatternExprBuilder

visit, visit, visit, visit, visit, visit, visit, visit, visit, visit

Methods inherited from class com.bigdata.rdf.sail.sparql.ValueExprBuilder

aggregate, binary, left, nary, noneary, quadary, right, ternary, unary, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit

Methods inherited from class com.bigdata.rdf.sail.sparql.BigdataASTVisitorBase

depth, firstASTGraphGraphAncestor, indent, indent, scopedGroupGraphPattern, visit, visit, visit, visit, visit, visit, visit, visit, visit

Methods inherited from class com.bigdata.rdf.sail.sparql.ASTVisitorBase

visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GroupGraphPatternBuilder

public GroupGraphPatternBuilder(BigdataASTContext context)

Method Detail

visit

public final ConstructNode visit(ASTConstruct node,
                  Object data)
                          throws VisitorException

CONSTRUCT (handled as a TriplesBlock).

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public final GroupNodeBase<?> visit(ASTGraphPatternGroup node,
                     Object data)
                             throws VisitorException

( SelectQuery | GraphPattern ) - this is the common path for SubSelect and graph patterns.

Note: (NOT) EXISTS uses a temporary graph pattern in order to avoid the side-effect on the parent's graph pattern. Other value functions with inner graph patterns should do this as well.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Returns:

The GroupNodeBase. This return value is used by the visitor method for the ASTWhereClause and also in SPARQL UPDATE.

Throws:

VisitorException

See Also:

Sub-select in INSERT cause NPE in UpdateExprBuilder

visit

public final Void visit(ASTOptionalGraphPattern node,
         Object data)
                 throws VisitorException

Note: while openrdf lifts the filters out of the optional, we do not need to do this per MikeP.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public Object visit(ASTMinusGraphPattern node,
           Object data)
             throws VisitorException

MINUS is modeled very much like OPTIONAL in the bigdata AST. It is a JoinGroupNode which is annotated to indicate the negation semantics.

Note: The grammar file treats OPTIONAL somewhat differently than MINUS due to the scope of the filters. For OPTIONAL, the child group can see the variable bindings in the parent group. That is not true for MINUS. Therefore the code in this method only sets the MINUS attribute on the group and does not need to create a new group.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public final Void visit(ASTGraphGraphPattern node,
         Object data)
                 throws VisitorException

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public final Void visit(ASTUnionGraphPattern node,
         Object data)
                 throws VisitorException

Given

 select ?s where { { ?s ?p1 ?o } UNION  { ?s ?p2 ?o } UNION  { ?s ?p3 ?o } }
 

The parse tree looks like:

 QueryContainer
  SelectQuery
   Select
    ProjectionElem
     Var (s)
   WhereClause
    GraphPatternGroup
     UnionGraphPattern
      GraphPatternGroup
       BasicGraphPattern
        TriplesSameSubjectPath
         Var (s)
         PropertyListPath
          Var (p1)
          ObjectList
           Var (o)
      UnionGraphPattern
       GraphPatternGroup
        BasicGraphPattern
         TriplesSameSubjectPath
          Var (s)
          PropertyListPath
           Var (p2)
           ObjectList
            Var (o)
       GraphPatternGroup
        BasicGraphPattern
         TriplesSameSubjectPath
          Var (s)
          PropertyListPath
           Var (p3)
           ObjectList
            Var (o)
 

That is, UNION in a binary operator in the parse tree. If the right hand argument is also a UNION, then you are looking at a sequence of UNIONs at the same level. Such sequences should be turned into a single UnionNode in the bigdata AST. In contrast, this is a UNION of two groups with another UNION embedded in the 2nd group.

 select ?s where { { ?s ?p1 ?o } UNION  { { ?s ?p2 ?o } UNION  { ?s ?p3 ?o } }  }
 

The 2nd child of the first union is a GraphPatternGroup, not a UnionGraphPattern.

 QueryContainer
  SelectQuery
   Select
    ProjectionElem
     Var (s)
   WhereClause
    GraphPatternGroup
     UnionGraphPattern
      GraphPatternGroup
       BasicGraphPattern
        TriplesSameSubjectPath
         Var (s)
         PropertyListPath
          Var (p1)
          ObjectList
           Var (o)
      GraphPatternGroup
       UnionGraphPattern
        GraphPatternGroup
         BasicGraphPattern
          TriplesSameSubjectPath
           Var (s)
           PropertyListPath
            Var (p2)
            ObjectList
             Var (o)
        GraphPatternGroup
         BasicGraphPattern
          TriplesSameSubjectPath
           Var (s)
           PropertyListPath
            Var (p3)
            ObjectList
             Var (o)
 

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public final Object visit(ASTBind node,
           Object data)
                   throws VisitorException

A BIND (or FILTER) can appear in an ASTBasicGraphPattern.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Returns:

The AssignmentNode for the BIND -or- the null if this is BIND(tripleRef AS var).

Throws:

VisitorException

visit

public final BindingsClause visit(ASTInlineData node,
                   Object data)
                           throws VisitorException

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Returns:

An object which encapsulates both the ordered set of variables for which bindings exist and the set of binding sets. The bindings are BigdataValues. They must be translated into IV through a batch resolution process before they can be passed into the query engine.

Throws:

VisitorException

visit

public final AssignmentNode visit(ASTLet node,
                   Object data)
                           throws VisitorException

A LET is just an alternative syntax for BIND

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Returns:

The AssignmentNode.

Throws:

VisitorException

visit

public final ValueExpressionNode visit(ASTConstraint node,
                        Object data)
                                throws VisitorException

A FILTER. The filter is attached to the ValueExprBuilder.graphPattern. However, it is also returned from this method. The ASTHavingClause uses the return value.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Returns:

The constraint.

Throws:

VisitorException

visit

public final Void visit(ASTNamedSubqueryInclude node,
         Object data)
                 throws VisitorException

INCLUDE for a named subquery result set.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public final Void visit(ASTServiceGraphPattern node,
         Object data)
                 throws VisitorException

SPARQL 1.1 SERVICE.

Note: The prefix declarations are attached to the ASTServiceGraphPattern by the PrefixDeclProcessor.

TODO Do we need to pass through the baseURI? Can this be used to abbreviate serialized IRIs? (I would think that we would use the prefix declarations for that.)

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException