com.conwet.silbops.model.Constraint.java Source code

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Here is the source code for com.conwet.silbops.model.Constraint.java

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package com.conwet.silbops.model;

/*
 * #%L
 * SilboPS API
 * %%
 * Copyright (C) 2011 - 2014 CoNWeT Lab., Universidad Politcnica de Madrid
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * #L%
 */

import java.util.Map;
import java.util.Map.Entry;
import java.util.Objects;
import java.util.Set;

import org.json.simple.JSONObject;

import com.conwet.silbops.model.basic.Operator;
import com.conwet.silbops.model.basic.Value;
import com.conwet.silbops.util.JSONizable;

/**
 * Represents a single constraint for an attribute. This class is not meant to
 * be used directly but as part of subscriptions.
 * 
 *
 * <p>Immutable class.</p>
 *
 * @author sergio
 * @apiviz.owns com.conwet.silbops.model.basic.Operator
 * @apiviz.owns com.conwet.silbops.model.basic.Value
 */
public class Constraint implements JSONizable {

    /**
     * Constraint object representing Exist restriction   
     */
    public static final Constraint EXIST = new Constraint(Operator.EXISTS, null);

    /**
     * Constraint operator.
     */
    private final Operator operator;

    /**
     * Value to compare with.
     */
    private final Value value;

    /**
     * Create a new constraint with the given operator.
     *
     * @param operator Operator
     * @param value Operand whose operator must match the operator
     */
    public Constraint(Operator operator, Value value) {

        operator = Objects.requireNonNull(operator, "Operator is null");

        if (!operator.isValidOperand(value)) {

            throw new IllegalArgumentException("Operator " + operator + " isn't compatible with value " + value);
        }

        this.operator = operator; // EXISTS doesn't need a value
        this.value = operator == Operator.EXISTS ? null : value;
    }

    public Operator getOperator() {

        return operator;
    }

    public Value getValue() {

        return value;
    }

    /**
     * True if the constraint is satisfied by the value
     *
     * @param value Value to compare to
     * @return Whether the constraint is satisfied
     */
    public boolean match(Value value) {

        return operator.compare(value, this.value);
    }

    @Override
    public boolean equals(Object obj) {

        if (this == obj) {
            return true;
        }

        if (obj instanceof Constraint) {

            Constraint other = (Constraint) obj;
            return operator == other.operator && Objects.equals(value, other.value);
        }

        return false;
    }

    @Override
    public int hashCode() {

        return 41 * operator.hashCode() + Objects.hashCode(value);
    }

    @Override
    public String toString() {

        return "[operator=" + operator + ", value=" + value + "]";
    }

    /**
     * Deserialize from a JSON representation
     *
     * @param json JSON representation
     * @return A new constraint
     */
    public static Constraint fromJSON(JSONObject json) {

        @SuppressWarnings("unchecked")
        Set<Map.Entry<String, Object>> entries = json.entrySet();

        if (entries.size() != 1) {

            throw new IllegalArgumentException("Malformed object: " + json);
        }

        Entry<String, Object> entry = entries.iterator().next();
        Operator operator = Operator.fromJSON(entry.getKey());
        return (operator == Operator.EXISTS) ? EXIST : new Constraint(operator, Value.fromJSON(entry.getValue()));
    }

    @Override
    @SuppressWarnings("unchecked")
    public JSONObject toJSON() {

        Object val = operator == Operator.EXISTS ? "" : value.toJSON();
        JSONObject json = new JSONObject();
        json.put(operator.toJSON(), val);

        return json;
    }

    @Override
    public String toJSONString() {

        return this.toJSON().toJSONString();
    }
}