/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */
import { Injectable } from '@angular/core';
import * as i0 from "@angular/core";
/** Injectable that ensures only the most recently enabled FocusTrap is active. */
import * as ɵngcc0 from '@angular/core';
export class FocusTrapManager {
    constructor() {
        // A stack of the FocusTraps on the page. Only the FocusTrap at the
        // top of the stack is active.
        this._focusTrapStack = [];
    }
    /**
     * Disables the FocusTrap at the top of the stack, and then pushes
     * the new FocusTrap onto the stack.
     */
    register(focusTrap) {
        // Dedupe focusTraps that register multiple times.
        this._focusTrapStack = this._focusTrapStack.filter((ft) => ft !== focusTrap);
        let stack = this._focusTrapStack;
        if (stack.length) {
            stack[stack.length - 1]._disable();
        }
        stack.push(focusTrap);
        focusTrap._enable();
    }
    /**
     * Removes the FocusTrap from the stack, and activates the
     * FocusTrap that is the new top of the stack.
     */
    deregister(focusTrap) {
        focusTrap._disable();
        const stack = this._focusTrapStack;
        const i = stack.indexOf(focusTrap);
        if (i !== -1) {
            stack.splice(i, 1);
            if (stack.length) {
                stack[stack.length - 1]._enable();
            }
        }
    }
}
FocusTrapManager.ɵfac = function FocusTrapManager_Factory(t) { return new (t || FocusTrapManager)(); };
FocusTrapManager.ɵprov = i0.ɵɵdefineInjectable({ factory: function FocusTrapManager_Factory() { return new FocusTrapManager(); }, token: FocusTrapManager, providedIn: "root" });
(function () { (typeof ngDevMode === "undefined" || ngDevMode) && ɵngcc0.ɵsetClassMetadata(FocusTrapManager, [{
        type: Injectable,
        args: [{ providedIn: 'root' }]
    }], function () { return []; }, null); })();

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