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Java Predicate with SQL-like syntax support

There is a newer version: 2.1.2

package org.joo.libra;

import java.util.HashMap;
import java.util.Map;

import org.joo.libra.sql.ObjectUtils;
import org.joo.libra.support.exceptions.PredicateValueException;
import org.joo.libra.support.functions.MultiArgsFunction;

import lombok.Getter;

/**
 * Represents a predicate context. This is used to evaluate the predicate.
 * Generally the context itself is used by
 * {@link org.joo.libra.sql.node.VariableExpressionNode} to resolve the
 * variable. But it can also be used by any custom predicate to hold the value
 * they need while evaluating.
 * 
 * @author griever
 *
 */
public class PredicateContext implements Cloneable {

	@Getter
	private Object context;

	private Map cachedValues;

	private Map functionMappings;
	
	private Map tempVariables = new HashMap<>();

	public PredicateContext(final Object context) {
		this.context = context;
		this.cachedValues = new HashMap<>();
	}

	public PredicateContext(final Object context, Map functionMappings) {
		this.context = context;
		this.cachedValues = new HashMap<>();
		this.functionMappings = functionMappings;
	}
	
	public Object getVariableValue(final String name, final PredicateContext context) {
		Object value = cachedValues.get(name);
		if (value == null) {
			value = getValueNoCache(name, context);
			cachedValues.put(name, value);
		}
		return value;
	}

	private Object getValueNoCache(final String name, final PredicateContext context) {
		if (tempVariables.containsKey(name))
			return tempVariables.get(name);
		try {
			return ObjectUtils.getValue(context.getContext(), name);
		} catch (ReflectiveOperationException e) {
			throw new PredicateValueException(e);
		}
	}

	public boolean hasCachedValue(final String key) {
		return cachedValues.containsKey(key);
	}

	public MultiArgsFunction getRegisteredFunction(final String name) {
		return functionMappings != null ? functionMappings.get(name) : null;
	}
	
	public Object getTempVariable(String name) {
		return tempVariables.get(name);
	}
	
	public void setTempVariable(String name, Object value) {
		tempVariables.put(name, value);
	}

	@Override
	public PredicateContext clone() {
		return new PredicateContext(context, functionMappings);
	}
}