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// Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
/// A library for broadly-useful functions and regular expressions for scanning
/// HTTP entities.
/// Many of the regular expressions come from [section 2.2 of the HTTP
/// spec][spec].
/// [spec]:
import 'package:string_scanner/string_scanner.dart';
/// An HTTP token.
final token = new RegExp(r'[^()<>@,;:"\\/[\]?={} \t\x00-\x1F\x7F]+');
/// Linear whitespace.
final _lws = new RegExp(r"(?:\r\n)?[ \t]+");
/// A quoted string.
final _quotedString = new RegExp(r'"(?:[^"\x00-\x1F\x7F]|\\.)*"');
/// A quoted pair.
final _quotedPair = new RegExp(r'\\(.)');
/// A character that is *not* a valid HTTP token.
final nonToken = new RegExp(r'[()<>@,;:"\\/\[\]?={} \t\x00-\x1F\x7F]');
/// A regular expression matching any number of [_lws] productions in a row.
final whitespace = new RegExp("(?:${_lws.pattern})*");
/// Parses a list of elements, as in `1#element` in the HTTP spec.
/// [scanner] is used to parse the elements, and [parseElement] is used to parse
/// each one individually. The values returned by [parseElement] are collected
/// in a list and returned.
/// Once this is finished, [scanner] will be at the next non-LWS character in
/// the string, or the end of the string.
List/*<T>*/ parseList/*<T>*/(StringScanner scanner, /*=T*/ parseElement()) {
var result = /*<T>*/[];
// Consume initial empty values.
while (scanner.scan(",")) {
while (scanner.scan(",")) {
// Empty elements are allowed, but excluded from the results.
if (scanner.matches(",") || scanner.isDone) continue;
return result;
/// Parses a single quoted string, and returns its contents.
/// If [name] is passed, it's used to describe the expected value if it's not
/// found.
String expectQuotedString(StringScanner scanner, {String name}) {
if (name == null) name = "quoted string";
scanner.expect(_quotedString, name: name);
var string = scanner.lastMatch[0];
return string
.substring(1, string.length - 1)
.replaceAllMapped(_quotedPair, (match) => match[1]);