com.bigdata.rdf.sail.sparql

Class BigdataExprBuilder

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

com.bigdata.rdf.sail.sparql.BigdataExprBuilder

All Implemented Interfaces:

SyntaxTreeBuilderVisitor

Direct Known Subclasses:

UpdateExprBuilder

public class BigdataExprBuilder
extends GroupGraphPatternBuilder

Top-level expression builder for SPARQL.

Version:

$Id$

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
BigdataExprBuilder(BigdataASTContext context)

Method Summary

Methods

Modifier and Type	Method and Description
protected void	handleSelect(ASTSelect select, IProjectionDecl queryRoot) Handle a SELECT clause.
static void	verifyAggregate(QueryBase queryBase) Verify the various conditions that must be met when a query uses GROUP BY or when a query uses aggregates in a PROJECTION.
QueryBase	visit(ASTAskQuery node, Object data) ASK query.
BindingsClause	visit(ASTBindingsClause node, Object data)
IBindingSet	visit(ASTBindingSet node, Object data) Note: BigdataValues have already been resolved to IVs.
ValueExpressionNode	visit(ASTBindingValue node, Object data)
QueryBase	visit(ASTConstructQuery node, Object data) Handle a CONSTRUCT query.
Void	visit(ASTDescribe node, Object data) This is the "projection" part of the DESCRIBE query.
QueryBase	visit(ASTDescribeQuery node, Object data) DESCRIBE query.
GroupByNode	visit(ASTGroupClause node, Object data)
Long	visit(ASTLimit node, Object data)
Long	visit(ASTOffset node, Object data)
List<OrderByExpr>	visit(ASTOrderClause node, Object data)
OrderByExpr	visit(ASTOrderCondition node, Object data) Note: Delegate to the ValueExprBuilder.
QueryRoot	visit(ASTQueryContainer node, Object data) This is the top-level entry point for a SPARQL query.
QueryBase	visit(ASTSelectQuery astQuery, Object data) This is the entry point for both a top-level SELECT and a SubSelect.

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

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

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

Methods inherited from class java.lang.Object

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

Constructor Detail

BigdataExprBuilder

public BigdataExprBuilder(BigdataASTContext context)

Method Detail

visit

public QueryRoot visit(ASTQueryContainer node,
              Object data)
                throws VisitorException

This is the top-level entry point for a SPARQL query.

Note: ASTBaseDecl and ASTPrefixDecls are available from the ASTQueryContainer node. They are being ignored here as they should have been processed before running the BigdataExprBuilder.

Note: ASTQuery is an abstract type. The concrete classes are: ASTAskQuery, ASTConstructQuery, ASTDescribeQuery, and ASTSelectQuery. This method will wind up delegating to the visitor method for the appropriate concrete ASTQuery instance.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public QueryBase visit(ASTSelectQuery astQuery,
              Object data)
                throws VisitorException

This is the entry point for both a top-level SELECT and a SubSelect.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Returns:

The method returns either a QueryRoot or a SubqueryRoot depending on whether or not the ASTSelectQuery appears as a top-level query or a subquery.

Throws:

VisitorException

visit

public QueryBase visit(ASTAskQuery node,
              Object data)
                throws VisitorException

ASK query.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public QueryBase visit(ASTDescribeQuery node,
              Object data)
                throws VisitorException

DESCRIBE query.

Note: The openrdf parser has a "Describe" production which is not in the SPARQL 1.1 grammar (it is an equivalent grammar in that it accepts the same inputs). This means that the "projection" part of the DESCRIBE query is visited on the ASTDescribe node.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public Void visit(ASTDescribe node,
         Object data)
           throws VisitorException

This is the "projection" part of the DESCRIBE query. This code marks the query as a "DESCRIBE" and generates and attaches a ProjectionNode to the QueryBase. The ProjectionNode uses an assignment node to bind an anonymous variable for a IRI. Variables are projected normally. * is projected as the variable named "*".

Note: This ProjectionNode models the "DESCRIBE" but does not provide a query plan. The QueryBase MUST be further rewritten in order to supply an appropriate query plan. This should be done using the appropriate IASTOptimizer.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Parameters:

data - The QueryBase.

Throws:

VisitorException

visit

public QueryBase visit(ASTConstructQuery node,
              Object data)
                throws VisitorException

Handle a CONSTRUCT query.

This builds a ConstructNode which is a model of the statement patterns in the construct template and attaches the where clause and solution modifiers. However, this is NOT a complete description of the semantics of the query. An IASTOptimizer will intercept the CONSTRUCT query and rewrite it before it is executed in order to provide an appropriate ProjectionNode.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public final GroupByNode visit(ASTGroupClause node,
                Object data)
                        throws VisitorException

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public final List<OrderByExpr> visit(ASTOrderClause node,
                      Object data)
                              throws VisitorException

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public final OrderByExpr visit(ASTOrderCondition node,
                Object data)
                        throws VisitorException

Note: Delegate to the ValueExprBuilder.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public final Long visit(ASTLimit node,
         Object data)
                 throws VisitorException

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

visit

public final Long visit(ASTOffset node,
         Object data)
                 throws VisitorException

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

handleSelect

protected void handleSelect(ASTSelect select,
                IProjectionDecl queryRoot)
                     throws VisitorException

Handle a SELECT clause. The ProjectionNode will be attached to the IProjectionDecl.

Parameters:

select - The ASTSelect node.

queryRoot - The QueryBase.

Throws:

VisitorException

visit

public final BindingsClause visit(ASTBindingsClause 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 IBindingSet visit(ASTBindingSet node,
                Object data)
                  throws VisitorException

Note: BigdataValues have already been resolved to IVs.

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Parameters:

data - The ordered variables for which bindings must be given.

Returns:

The binding set. Variables will be bound unless UNDEF was specified at the index corresponding to a given variable.

Throws:

VisitorException

visit

public ValueExpressionNode visit(ASTBindingValue node,
                        Object data)
                          throws VisitorException

Specified by:

visit in interface SyntaxTreeBuilderVisitor

Overrides:

visit in class ASTVisitorBase

Throws:

VisitorException

verifyAggregate

public static void verifyAggregate(QueryBase queryBase)
                            throws VisitorException

Verify the various conditions that must be met when a query uses GROUP BY or when a query uses aggregates in a PROJECTION.

Parameters:

queryBase - The query.

Throws:

VisitorException