org.nsdl.mptstore.query.lang.spo
Class SPOQueryCompiler

java.lang.Object
  org.nsdl.mptstore.query.lang.spo.SPOQueryCompiler

All Implemented Interfaces:

QueryCompiler

public class SPOQueryCompiler
extends java.lang.Object
implements QueryCompiler

Compiler for SPO queries.

SPO is a simple query language that returns triples (subject, predicate, object) given a single triple pattern where an asterisk in any position acts as a wildcard.

The grammar for SPO queries is the same as the N-Triples "triple" production, except it allows an asterisk in any node position and is not terminated with a dot.

Author:

cwilper@cs.cornell.edu

See Also:

N-Triples "triple" syntax specification

Field Summary

static java.util.List<java.lang.String>

SPO_TARGETS The targets are always "s", "p", "o".

Constructor Summary

SPOQueryCompiler(TableManager tableManager, boolean backslashIsEscape)
Instantiate an SPOQueryCompiler.

Method Summary

SQLProvider

compile(java.lang.String query) Compile the given query.

Methods inherited from class java.lang.Object

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

Field Detail

SPO_TARGETS

public static final java.util.List<java.lang.String> SPO_TARGETS

The targets are always "s", "p", "o".

Constructor Detail

SPOQueryCompiler

public SPOQueryCompiler(TableManager tableManager,
                        boolean backslashIsEscape)

Instantiate an SPOQueryCompiler.

Parameters:

tableManager - The table manager to be used to look up table names for predicates.

backslashIsEscape - Whether the backslash character should be escaped in the output SQL.

Method Detail

compile

public SQLProvider compile(java.lang.String query)
                    throws QueryException

Compile the given query.

Specified by:

compile in interface QueryCompiler

Parameters:

query - the RDF query.

Returns:

SQLProvider provides the SQL and result column names.

Throws:

QueryException - if there's an error querying.