org.hypergraphdb
Class HGQuery.hg

java.lang.Object
  org.hypergraphdb.HGQuery.hg

Enclosing class:

HGQuery<SearchResult>

public static final class HGQuery.hg
extends java.lang.Object

This class serves as a namespace to a set of syntactically concise functions for constructing HyperGraph query conditions and performing HyperGraph queries. With a Java 5+ compiler, you can import the class into your file's namespace and build HG condition with a much simpler syntax than constructing the expression tree explicitly. For example:

 ...other imports ...
 import org.hypergraphdb.HGQuery.hg;
 
 public void f(HyperGraph graph)
 {
     // find all link with weight > 1.5
     HGSearchResult rs = graph.find(hg.and(hg.type(MyLink.class), hg.gt("weight", 1.5)));    
 }
 

or, even more concisely, if there is no naming conflict, import all the function names directly:

 ...other imports ...
 import org.hypergraphdb.HGQuery.hg.*;
 
 public void f(HyperGraph graph)
 {
     // find all link with weight > 1.5 
     HGSearchResult rs = graph.find(and(type(MyLink.class), gt("weight", 1.5)));    
 }
 

In addition, several methods names get* and find* will execute queries and return their results in the form of individual objects or Java collections, thus saving you from the burden of paying attention to always properly close result sets.

Author:

Borislav Iordanov

Constructor Summary

HGQuery.hg()

Method Summary

static HGHandle	addUnique(HyperGraph graph, java.lang.Object instance, java.lang.Class javaClass, HGQueryCondition condition)
static HGHandle	addUnique(HyperGraph graph, java.lang.Object instance, HGHandle typeHandle, HGQueryCondition condition)
static HGHandle	addUnique(HyperGraph graph, java.lang.Object instance, HGQueryCondition condition)
static HGQueryCondition	all()
static And	and(HGQueryCondition... clauses)
static HGHandle	anyHandle()
static HGQueryCondition	apply(Mapping<?,?> m, HGQueryCondition c)
static ArityCondition	arity(int i)
static BFSCondition	bfs(HGHandle start)
static BFSCondition	bfs(HGHandle start, HGAtomPredicate lp, HGAtomPredicate sp)
static BFSCondition	bfs(HGHandle start, HGAtomPredicate lp, HGAtomPredicate sp, boolean returnPreceeding, boolean returnSucceeding)
static long	count(HGQuery<?> query) Count the result set from executing the given query.
static long	count(HyperGraph graph, HGQueryCondition cond) Count the number of atoms that match the query condition parameter.
static Mapping<HGHandle,java.lang.Object>	deref(HyperGraph graph)
static DFSCondition	dfs(HGHandle start)
static DFSCondition	dfs(HGHandle start, HGAtomPredicate lp, HGAtomPredicate sp)
static DFSCondition	dfs(HGHandle start, HGAtomPredicate lp, HGAtomPredicate sp, boolean returnPreceeding, boolean returnSucceeding)
static AtomValueCondition	eq(java.lang.Object x)
static AtomPartCondition	eq(java.lang.String path, java.lang.Object x)
static <T> java.util.List<T>	findAll(HGQuery<T> query)
static <T> java.util.List<T>	findAll(HyperGraph graph, HGQueryCondition condition) Run a query based on the specified condition and put all HGHandles from the result set into a java.util.List.
static <T> T	findOne(HyperGraph graph, HGQueryCondition condition) Run a query based on the passed in condition.
static <T> java.util.List<T>	getAll(HyperGraph graph, HGQueryCondition condition) Run a query based on the specified condition and put all atom instances from the result set into a java.util.List.
static <T> T	getOne(HyperGraph graph, HGQueryCondition condition) Run a query based on the passed in condition.
static AtomValueCondition	gt(java.lang.Object x)
static AtomPartCondition	gt(java.lang.String path, java.lang.Object x)
static AtomValueCondition	gte(java.lang.Object x)
static AtomPartCondition	gte(java.lang.String path, java.lang.Object x)
static IncidentCondition	incident(HGHandle h)
static LinkCondition	link(HGHandle... h)
static Mapping<HGLink,HGHandle>	linkProjection(int targetPosition)
static AtomValueCondition	lt(java.lang.Object x)
static AtomPartCondition	lt(java.lang.String path, java.lang.Object x)
static AtomValueCondition	lte(java.lang.Object x)
static AtomPartCondition	lte(java.lang.String path, java.lang.Object x)
static Not	not(HGAtomPredicate c)
static Or	or(HGQueryCondition... clauses)
static OrderedLinkCondition	orderedLink(HGHandle... h)
static AtomPartCondition	part(java.lang.String path, java.lang.Object value, ComparisonOperator op)
static SubsumedCondition	subsumed(HGHandle h)
static SubsumesCondition	subsumes(HGHandle h)
static TargetCondition	target(HGHandle h)
static Mapping<HGHandle,HGHandle>	targetAt(HyperGraph graph, int targetPosition)
static AtomTypeCondition	type(java.lang.Class<?> c)
static AtomTypeCondition	type(HGHandle h)
static TypePlusCondition	typePlus(java.lang.Class<?> c)
static TypePlusCondition	typePlus(HGHandle h)
static AtomValueCondition	value(java.lang.Object value, ComparisonOperator op)

Methods inherited from class java.lang.Object

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

Constructor Detail

HGQuery.hg

public HGQuery.hg()

Method Detail

addUnique

public static HGHandle addUnique(HyperGraph graph,
                                 java.lang.Object instance,
                                 HGQueryCondition condition)

addUnique

public static HGHandle addUnique(HyperGraph graph,
                                 java.lang.Object instance,
                                 HGHandle typeHandle,
                                 HGQueryCondition condition)

addUnique

public static HGHandle addUnique(HyperGraph graph,
                                 java.lang.Object instance,
                                 java.lang.Class javaClass,
                                 HGQueryCondition condition)

type

public static AtomTypeCondition type(HGHandle h)

type

public static AtomTypeCondition type(java.lang.Class<?> c)

typePlus

public static TypePlusCondition typePlus(HGHandle h)

typePlus

public static TypePlusCondition typePlus(java.lang.Class<?> c)

subsumes

public static SubsumesCondition subsumes(HGHandle h)

subsumed

public static SubsumedCondition subsumed(HGHandle h)

and

public static And and(HGQueryCondition... clauses)

or

public static Or or(HGQueryCondition... clauses)

not

public static Not not(HGAtomPredicate c)

target

public static TargetCondition target(HGHandle h)

incident

public static IncidentCondition incident(HGHandle h)

link

public static LinkCondition link(HGHandle... h)

orderedLink

public static OrderedLinkCondition orderedLink(HGHandle... h)

arity

public static ArityCondition arity(int i)

value

public static AtomValueCondition value(java.lang.Object value,
                                       ComparisonOperator op)

eq

public static AtomValueCondition eq(java.lang.Object x)

lt

public static AtomValueCondition lt(java.lang.Object x)

gt

public static AtomValueCondition gt(java.lang.Object x)

lte

public static AtomValueCondition lte(java.lang.Object x)

gte

public static AtomValueCondition gte(java.lang.Object x)

part

public static AtomPartCondition part(java.lang.String path,
                                     java.lang.Object value,
                                     ComparisonOperator op)

eq

public static AtomPartCondition eq(java.lang.String path,
                                   java.lang.Object x)

lt

public static AtomPartCondition lt(java.lang.String path,
                                   java.lang.Object x)

gt

public static AtomPartCondition gt(java.lang.String path,
                                   java.lang.Object x)

lte

public static AtomPartCondition lte(java.lang.String path,
                                    java.lang.Object x)

gte

public static AtomPartCondition gte(java.lang.String path,
                                    java.lang.Object x)

apply

public static HGQueryCondition apply(Mapping<?,?> m,
                                     HGQueryCondition c)

linkProjection

public static Mapping<HGLink,HGHandle> linkProjection(int targetPosition)

deref

public static Mapping<HGHandle,java.lang.Object> deref(HyperGraph graph)

targetAt

public static Mapping<HGHandle,HGHandle> targetAt(HyperGraph graph,
                                                  int targetPosition)

all

public static HGQueryCondition all()

bfs

public static BFSCondition bfs(HGHandle start)

bfs

public static BFSCondition bfs(HGHandle start,
                               HGAtomPredicate lp,
                               HGAtomPredicate sp)

bfs

public static BFSCondition bfs(HGHandle start,
                               HGAtomPredicate lp,
                               HGAtomPredicate sp,
                               boolean returnPreceeding,
                               boolean returnSucceeding)

dfs

public static DFSCondition dfs(HGHandle start)

dfs

public static DFSCondition dfs(HGHandle start,
                               HGAtomPredicate lp,
                               HGAtomPredicate sp)

dfs

public static DFSCondition dfs(HGHandle start,
                               HGAtomPredicate lp,
                               HGAtomPredicate sp,
                               boolean returnPreceeding,
                               boolean returnSucceeding)

anyHandle

public static HGHandle anyHandle()

count

public static long count(HyperGraph graph,
                         HGQueryCondition cond)

Count the number of atoms that match the query condition parameter. Retrieving the count might require performing the actual query traversing the result set. In cases where the condition is simple and the count is available directly from an index, it is returned right away. Otherwise, the operation may be expensive when the result set matching cond is large or it takes time to obtain it.

Parameters:

graph - The HyperGraph against which the counting is performed.

cond - The condition specifying the result set.

Returns:

The number of atoms satisfying the query condition.

count

public static long count(HGQuery<?> query)

Count the result set from executing the given query. The query is executed and the result set scanned completely.

Parameters:

query -

Returns:

getOne

public static <T> T getOne(HyperGraph graph,
                           HGQueryCondition condition)

Run a query based on the passed in condition. If the result set is not empty, get and return the atom instance of the first element. Otherwise, return null.

Parameters:

graph - The HyperGraph database to query.

condition - The query condition.

Returns:

findOne

public static <T> T findOne(HyperGraph graph,
                            HGQueryCondition condition)

Run a query based on the passed in condition. If the result set is not empty, return the first HGHandle element. Otherwise, return null.

Parameters:

graph -

condition -

Returns:

findAll

public static <T> java.util.List<T> findAll(HyperGraph graph,
                                            HGQueryCondition condition)

Run a query based on the specified condition and put all HGHandles from the result set into a java.util.List.

Parameters:

graph -

condition -

Returns:

getAll

public static <T> java.util.List<T> getAll(HyperGraph graph,
                                           HGQueryCondition condition)

Run a query based on the specified condition and put all atom instances from the result set into a java.util.List.

Parameters:

graph -

condition -

Returns:

findAll

public static <T> java.util.List<T> findAll(HGQuery<T> query)