/**
 * Class prototype field
 *
 *  Copyright (C) 2014 Free Software Foundation, Inc.
 *
 *  This file is part of GNU ease.js.
 *
 *  ease.js is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU 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 General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * Initializes field with a datum
 *
 * The ProtoField itself is immutable in the sense that its value cannot be
 * reassigned; but if DATUM references a mutable object, then that object is
 * not prohibited from changing; doing so is, however, not recommended and
 * such behavior is not defined, nor is it defined that DATUM's reference
 * will be maintained (e.g. the referenced object may be at some point
 * cloned).
 *
 * @type  {*}  datum  field datum (value)
 */
function ProtoField( datum )
{
    if ( !( this instanceof ProtoField ) ) {
        return new ProtoField( datum );
    }

    this._datum = datum;
}


ProtoField.prototype = {
    /**
     * Retrieve the datum assigned to the field during construction
     *
     * It is not defined whether this datum will be strictly equal to the
     * datum provided during construction (that is---reference the same
     * object), but it will be guaranteed to be recursively (deep)
     * equivalent.
     *
     * @return  {*}  field datum
     */
    getDatum: function()
    {
        return this._datum;
    },


    /**
     * Produce a representation of the field suitable for use in a class
     * prototype that contains, at a minimum, a datum that is recurisvely
     * equivalent to the datum provided during construction
     *
     * The produced datum is not guaranteed to be strictly equal to the one
     * provided during construction, or even to the one returned by the
     * getValue method. Further, the datum may contain metadata that was not
     * provided during construction.
     *
     * The produced datum should be treated as just that---a datum; opaque.
     * To decompose it for processing, use ProtoField.parse.
     *
     * @return  {*}  datum suitable for use in a class prototype
     */
    compile: function()
    {
        return this.getDatum();
    },
};


/**
 * Consume a previously compiled ProtoField, producing a new ProtoField that
 * is equivalent to the original ProtoField before compiling
 *
 * @param  {*}  compiled_field  datum produced with ProtoField#compile
 */
ProtoField.parse = function( compiled_field )
{
    return ProtoField( compiled_field );
};


module.exports = ProtoField;