/**
 * Polyfill for [Headers](https://developer.mozilla.org/en-US/docs/Web/API/Headers/Headers), as
 * specified in the [Fetch Spec](https://fetch.spec.whatwg.org/#headers-class).
 *
 * The only known difference between this `Headers` implementation and the spec is the
 * lack of an `entries` method.
 *
 * ### Example
 *
 * ```
 * import {Headers} from '\@angular/http';
 *
 * var firstHeaders = new Headers();
 * firstHeaders.append('Content-Type', 'image/jpeg');
 * console.log(firstHeaders.get('Content-Type')) //'image/jpeg'
 *
 * // Create headers from Plain Old JavaScript Object
 * var secondHeaders = new Headers({
 *   'X-My-Custom-Header': 'Angular'
 * });
 * console.log(secondHeaders.get('X-My-Custom-Header')); //'Angular'
 *
 * var thirdHeaders = new Headers(secondHeaders);
 * console.log(thirdHeaders.get('X-My-Custom-Header')); //'Angular'
 * ```
 *
 * \@experimental
 */
export var Headers = (function () {
    /**
     * @param {?=} headers
     */
    function Headers(headers) {
        var _this = this;
        /** @internal header names are lower case */
        this._headers = new Map();
        /** @internal map lower case names to actual names */
        this._normalizedNames = new Map();
        if (!headers) {
            return;
        }
        if (headers instanceof Headers) {
            headers.forEach(function (values, name) {
                values.forEach(function (value) { return _this.append(name, value); });
            });
            return;
        }
        Object.keys(headers).forEach(function (name) {
            var values = Array.isArray(headers[name]) ? headers[name] : [headers[name]];
            _this.delete(name);
            values.forEach(function (value) { return _this.append(name, value); });
        });
    }
    /**
     * Returns a new Headers instance from the given DOMString of Response Headers
     * @param {?} headersString
     * @return {?}
     */
    Headers.fromResponseHeaderString = function (headersString) {
        var /** @type {?} */ headers = new Headers();
        headersString.split('\n').forEach(function (line) {
            var /** @type {?} */ index = line.indexOf(':');
            if (index > 0) {
                var /** @type {?} */ name_1 = line.slice(0, index);
                var /** @type {?} */ value = line.slice(index + 1).trim();
                headers.set(name_1, value);
            }
        });
        return headers;
    };
    /**
     * Appends a header to existing list of header values for a given header name.
     * @param {?} name
     * @param {?} value
     * @return {?}
     */
    Headers.prototype.append = function (name, value) {
        var /** @type {?} */ values = this.getAll(name);
        if (values === null) {
            this.set(name, value);
        }
        else {
            values.push(value);
        }
    };
    /**
     * Deletes all header values for the given name.
     * @param {?} name
     * @return {?}
     */
    Headers.prototype.delete = function (name) {
        var /** @type {?} */ lcName = name.toLowerCase();
        this._normalizedNames.delete(lcName);
        this._headers.delete(lcName);
    };
    /**
     * @param {?} fn
     * @return {?}
     */
    Headers.prototype.forEach = function (fn) {
        var _this = this;
        this._headers.forEach(function (values, lcName) { return fn(values, _this._normalizedNames.get(lcName), _this._headers); });
    };
    /**
     * Returns first header that matches given name.
     * @param {?} name
     * @return {?}
     */
    Headers.prototype.get = function (name) {
        var /** @type {?} */ values = this.getAll(name);
        if (values === null) {
            return null;
        }
        return values.length > 0 ? values[0] : null;
    };
    /**
     * Checks for existence of header by given name.
     * @param {?} name
     * @return {?}
     */
    Headers.prototype.has = function (name) { return this._headers.has(name.toLowerCase()); };
    /**
     * Returns the names of the headers
     * @return {?}
     */
    Headers.prototype.keys = function () { return Array.from(this._normalizedNames.values()); };
    /**
     * Sets or overrides header value for given name.
     * @param {?} name
     * @param {?} value
     * @return {?}
     */
    Headers.prototype.set = function (name, value) {
        if (Array.isArray(value)) {
            if (value.length) {
                this._headers.set(name.toLowerCase(), [value.join(',')]);
            }
        }
        else {
            this._headers.set(name.toLowerCase(), [value]);
        }
        this.mayBeSetNormalizedName(name);
    };
    /**
     * Returns values of all headers.
     * @return {?}
     */
    Headers.prototype.values = function () { return Array.from(this._headers.values()); };
    /**
     * @return {?}
     */
    Headers.prototype.toJSON = function () {
        var _this = this;
        var /** @type {?} */ serialized = {};
        this._headers.forEach(function (values, name) {
            var /** @type {?} */ split = [];
            values.forEach(function (v) { return split.push.apply(split, v.split(',')); });
            serialized[_this._normalizedNames.get(name)] = split;
        });
        return serialized;
    };
    /**
     * Returns list of header values for a given name.
     * @param {?} name
     * @return {?}
     */
    Headers.prototype.getAll = function (name) {
        return this.has(name) ? this._headers.get(name.toLowerCase()) : null;
    };
    /**
     * This method is not implemented.
     * @return {?}
     */
    Headers.prototype.entries = function () { throw new Error('"entries" method is not implemented on Headers class'); };
    /**
     * @param {?} name
     * @return {?}
     */
    Headers.prototype.mayBeSetNormalizedName = function (name) {
        var /** @type {?} */ lcName = name.toLowerCase();
        if (!this._normalizedNames.has(lcName)) {
            this._normalizedNames.set(lcName, name);
        }
    };
    return Headers;
}());
function Headers_tsickle_Closure_declarations() {
    /**
     * \@internal header names are lower case
     * @type {?}
     */
    Headers.prototype._headers;
    /**
     * \@internal map lower case names to actual names
     * @type {?}
     */
    Headers.prototype._normalizedNames;
}
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