org.datanucleus.query.evaluator

Class JavaQueryEvaluator

java.lang.Object

org.datanucleus.query.evaluator.JavaQueryEvaluator

Direct Known Subclasses:

JDOQLEvaluator, JPQLEvaluator

public abstract class JavaQueryEvaluator
extends Object

Class to evaluate a Java "string-based" query in whole or part. Takes in a list of instances and applies the required restrictions to the input giving a final result. Typically extended for JDOQL, JPQL, SQL specifics.

Field Summary

Fields

Modifier and Type	Field and Description
protected String	candidateAlias
protected Collection	candidates Candidates objects to evaluate.
protected ClassLoaderResolver	clr
protected QueryCompilation	compilation Compilation of the underlying query, that we are evaluating.
protected InMemoryExpressionEvaluator	evaluator The evaluator.
protected String	language
protected Map	parameterValues Map of input parameter values, keyed by the parameter name.
protected Query	query Underlying "string-based" query.
static String	RESULTS_SET Name under which any set of results are stored in the state map.
protected Map<String,Object>	state Map of state symbols for the query evaluation.

Constructor Summary

Constructors

Constructor and Description
JavaQueryEvaluator(String language, Query query, QueryCompilation compilation, Map parameterValues, ClassLoaderResolver clr, Collection candidates) Constructor for the evaluator of a query in the specified language.

Method Summary

Modifier and Type	Method and Description
protected abstract Collection	evaluateSubquery(Query subquery, QueryCompilation compilation, Collection candidates, Object outerCandidate) Method to evaluate a subquery of the query being evaluated.
Collection	execute(boolean applyFilter, boolean applyOrdering, boolean applyResult, boolean applyResultClass, boolean applyRange) Method to perform the evaluation, applying the query restrictions that are required.

Methods inherited from class java.lang.Object

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

Field Detail

RESULTS_SET

public static final String RESULTS_SET

Name under which any set of results are stored in the state map. Used for aggregation.

See Also:

Constant Field Values

language

protected final String language

candidateAlias

protected String candidateAlias

candidates

protected Collection candidates

Candidates objects to evaluate.

query

protected Query query

Underlying "string-based" query.

compilation

protected QueryCompilation compilation

Compilation of the underlying query, that we are evaluating.

parameterValues

protected Map parameterValues

Map of input parameter values, keyed by the parameter name.

evaluator

protected InMemoryExpressionEvaluator evaluator

The evaluator.

state

protected Map<String,Object> state

Map of state symbols for the query evaluation.

clr

protected ClassLoaderResolver clr

Constructor Detail

JavaQueryEvaluator

public JavaQueryEvaluator(String language,
                          Query query,
                          QueryCompilation compilation,
                          Map parameterValues,
                          ClassLoaderResolver clr,
                          Collection candidates)

Constructor for the evaluator of a query in the specified language.

Parameters:

language - Name of the language

query - The underlying query

compilation - Query compilation

parameterValues - Input parameter values

clr - ClassLoader resolver

candidates - Candidate objects

Method Detail

evaluateSubquery

protected abstract Collection evaluateSubquery(Query subquery,
                                               QueryCompilation compilation,
                                               Collection candidates,
                                               Object outerCandidate)

Method to evaluate a subquery of the query being evaluated.

Parameters:

subquery - The subquery

compilation - The subquery compilation

candidates - The candidates for the subquery

outerCandidate - The current outer candidate (for use when linking back to outer query)

Returns:

The result

execute

public Collection execute(boolean applyFilter,
                          boolean applyOrdering,
                          boolean applyResult,
                          boolean applyResultClass,
                          boolean applyRange)

Method to perform the evaluation, applying the query restrictions that are required.

Parameters:

applyFilter - Whether to apply any filter constraints on the results

applyOrdering - Whether to apply any order constraints on the results

applyResult - Whether to apply any result/grouping/having on the results

applyResultClass - Whether to apply any resultClass constraint on the results

applyRange - Whether to apply any range constraint on the results

Returns:

The results after evaluation.