/*
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								  Copyright (C) 2015 Yusuke Suzuki <utatane.tea@gmail.com>
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								  Redistribution and use in source and binary forms, with or without
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								  modification, are permitted provided that the following conditions are met:
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								    * Redistributions of source code must retain the above copyright
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								      notice, this list of conditions and the following disclaimer.
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								    * Redistributions in binary form must reproduce the above copyright
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								      notice, this list of conditions and the following disclaimer in the
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								      documentation and/or other materials provided with the distribution.
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								  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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								  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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								  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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								  ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
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								  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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								  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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								  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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								  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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								  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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								  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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								*/
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								const READ = 0x1;
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								const WRITE = 0x2;
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								const RW = READ | WRITE;
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								/**
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								 * A Reference represents a single occurrence of an identifier in code.
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								 * @constructor Reference
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								 */
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								class Reference {
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								    constructor(ident, scope, flag, writeExpr, maybeImplicitGlobal, partial, init) {
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								        /**
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								         * Identifier syntax node.
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								         * @member {espreeIdentifier} Reference#identifier
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								         */
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								        this.identifier = ident;
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								        /**
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								         * Reference to the enclosing Scope.
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								         * @member {Scope} Reference#from
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								         */
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								        this.from = scope;
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								        /**
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								         * Whether the reference comes from a dynamic scope (such as 'eval',
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								         * 'with', etc.), and may be trapped by dynamic scopes.
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								         * @member {boolean} Reference#tainted
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								         */
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								        this.tainted = false;
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								        /**
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								         * The variable this reference is resolved with.
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								         * @member {Variable} Reference#resolved
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								         */
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								        this.resolved = null;
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								        /**
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								         * The read-write mode of the reference. (Value is one of {@link
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								         * Reference.READ}, {@link Reference.RW}, {@link Reference.WRITE}).
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								         * @member {number} Reference#flag
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								         * @private
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								         */
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								        this.flag = flag;
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								        if (this.isWrite()) {
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								            /**
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								             * If reference is writeable, this is the tree being written to it.
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								             * @member {espreeNode} Reference#writeExpr
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								             */
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								            this.writeExpr = writeExpr;
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								            /**
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								             * Whether the Reference might refer to a partial value of writeExpr.
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								             * @member {boolean} Reference#partial
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								             */
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								            this.partial = partial;
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								            /**
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								             * Whether the Reference is to write of initialization.
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								             * @member {boolean} Reference#init
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								             */
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								            this.init = init;
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								        }
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								        this.__maybeImplicitGlobal = maybeImplicitGlobal;
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								    }
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								    /**
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								     * Whether the reference is static.
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								     * @function Reference#isStatic
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								     * @returns {boolean} static
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								     */
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								    isStatic() {
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								        return !this.tainted && this.resolved && this.resolved.scope.isStatic();
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								    }
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								    /**
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								     * Whether the reference is writeable.
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								     * @function Reference#isWrite
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								     * @returns {boolean} write
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								     */
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								    isWrite() {
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								        return !!(this.flag & Reference.WRITE);
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								    }
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								    /**
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								     * Whether the reference is readable.
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								     * @function Reference#isRead
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								     * @returns {boolean} read
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								     */
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								    isRead() {
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								        return !!(this.flag & Reference.READ);
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								    }
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								    /**
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								     * Whether the reference is read-only.
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								     * @function Reference#isReadOnly
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								     * @returns {boolean} read only
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								     */
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								    isReadOnly() {
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								        return this.flag === Reference.READ;
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								    }
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								    /**
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								     * Whether the reference is write-only.
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								     * @function Reference#isWriteOnly
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								     * @returns {boolean} write only
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								     */
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								    isWriteOnly() {
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								        return this.flag === Reference.WRITE;
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								    }
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								    /**
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								     * Whether the reference is read-write.
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								     * @function Reference#isReadWrite
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								     * @returns {boolean} read write
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								     */
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								    isReadWrite() {
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								        return this.flag === Reference.RW;
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								    }
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								}
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								/**
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								 * @constant Reference.READ
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								 * @private
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								 */
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								Reference.READ = READ;
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								/**
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								 * @constant Reference.WRITE
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								 * @private
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								 */
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								Reference.WRITE = WRITE;
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								/**
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								 * @constant Reference.RW
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								 * @private
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								 */
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								Reference.RW = RW;
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								export default Reference;
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								/* vim: set sw=4 ts=4 et tw=80 : */
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