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JSimpleDB classes for parsing Java expressions.

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/*
 * Copyright (C) 2015 Archie L. Cobbs. All rights reserved.
 */

package org.jsimpledb.parse.expr;

import com.google.common.base.Preconditions;

import org.jsimpledb.JField;
import org.jsimpledb.JObject;
import org.jsimpledb.parse.ParseSession;

/**
 * {@link Value} that reflects a {@link JField} in some {@link JObject}.
 *
 * @see FieldValue
 */
public class JFieldValue extends AbstractValue {

    protected final JObject jobj;
    protected final JField jfield;

    /**
     * Constructor.
     *
     * @param jobj database object
     * @param jfield database field
     * @throws IllegalArgumentException if {@code jobj} is null
     * @throws IllegalArgumentException if {@code jfield} is null
     */
    public JFieldValue(JObject jobj, JField jfield) {
        Preconditions.checkArgument(jobj != null, "null jobj");
        Preconditions.checkArgument(jfield != null, "null jfield");
        this.jobj = jobj;
        this.jfield = jfield;
    }

    @Override
    public Object get(ParseSession session) {
        try {
            return this.jfield.getValue(MethodUtil.refresh(this.jobj));
        } catch (Exception e) {
            throw new EvalException("error reading field `" + this.jfield.getName() + "' from object " + this.jobj.getObjId()
              + ": " + (e.getMessage() != null ? e.getMessage() : e));
        }
    }

    @Override
    public Class getType(ParseSession session) {
        return this.jfield.getGetter().getReturnType();
    }
}