| // Copyright 2013 The Flutter Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| final RegExp _parameterRegExp = RegExp(r':(\w+)(\((?:\\.|[^\\()])+\))?'); |
| |
| /// Converts a [pattern] such as `/user/:id` into [RegExp]. |
| /// |
| /// The path parameters can be specified by prefixing them with `:`. The |
| /// `parameters` are used for storing path parameter names. |
| /// |
| /// |
| /// For example: |
| /// |
| /// `pattern` = `/user/:id/book/:bookId` |
| /// |
| /// The `parameters` would contain `['id', 'bookId']` as a result of calling |
| /// this method. |
| /// |
| /// To extract the path parameter values from a [RegExpMatch], pass the |
| /// [RegExpMatch] into [extractPathParameters] with the `parameters` that are |
| /// used for generating the [RegExp]. |
| RegExp patternToRegExp(String pattern, List<String> parameters) { |
| final StringBuffer buffer = StringBuffer('^'); |
| int start = 0; |
| for (final RegExpMatch match in _parameterRegExp.allMatches(pattern)) { |
| if (match.start > start) { |
| buffer.write(RegExp.escape(pattern.substring(start, match.start))); |
| } |
| final String name = match[1]!; |
| final String? optionalPattern = match[2]; |
| final String regex = optionalPattern != null |
| ? _escapeGroup(optionalPattern, name) |
| : '(?<$name>[^/]+)'; |
| buffer.write(regex); |
| parameters.add(name); |
| start = match.end; |
| } |
| |
| if (start < pattern.length) { |
| buffer.write(RegExp.escape(pattern.substring(start))); |
| } |
| |
| if (!pattern.endsWith('/')) { |
| buffer.write(r'(?=/|$)'); |
| } |
| return RegExp(buffer.toString(), caseSensitive: false); |
| } |
| |
| String _escapeGroup(String group, [String? name]) { |
| final String escapedGroup = group.replaceFirstMapped( |
| RegExp(r'[:=!]'), (Match match) => '\\${match[0]}'); |
| if (name != null) { |
| return '(?<$name>$escapedGroup)'; |
| } |
| return escapedGroup; |
| } |
| |
| /// Reconstructs the full path from a [pattern] and path parameters. |
| /// |
| /// This is useful for restoring the original path from a [RegExpMatch]. |
| /// |
| /// For example, A path matched a [RegExp] returned from [patternToRegExp] and |
| /// produced a [RegExpMatch]. To reconstruct the path from the match, one |
| /// can follow these steps: |
| /// |
| /// 1. Get the `pathParameters` by calling [extractPathParameters] with the |
| /// [RegExpMatch] and the parameters used for generating the [RegExp]. |
| /// 2. Call [patternToPath] with the `pathParameters` from the first step and |
| /// the original `pattern` used for generating the [RegExp]. |
| String patternToPath(String pattern, Map<String, String> pathParameters) { |
| final StringBuffer buffer = StringBuffer(); |
| int start = 0; |
| for (final RegExpMatch match in _parameterRegExp.allMatches(pattern)) { |
| if (match.start > start) { |
| buffer.write(pattern.substring(start, match.start)); |
| } |
| final String name = match[1]!; |
| buffer.write(pathParameters[name]); |
| start = match.end; |
| } |
| |
| if (start < pattern.length) { |
| buffer.write(pattern.substring(start)); |
| } |
| return buffer.toString(); |
| } |
| |
| /// Extracts arguments from the `match` and maps them by parameter name. |
| /// |
| /// The [parameters] should originate from the call to [patternToRegExp] that |
| /// creates the [RegExp]. |
| Map<String, String> extractPathParameters( |
| List<String> parameters, RegExpMatch match) { |
| return <String, String>{ |
| for (int i = 0; i < parameters.length; ++i) |
| parameters[i]: match.namedGroup(parameters[i])! |
| }; |
| } |
| |
| /// Concatenates two paths. |
| /// |
| /// e.g: pathA = /a, pathB = c/d, concatenatePaths(pathA, pathB) = /a/c/d. |
| String concatenatePaths(String parentPath, String childPath) { |
| // at the root, just return the path |
| if (parentPath.isEmpty) { |
| assert(childPath.startsWith('/')); |
| assert(childPath == '/' || !childPath.endsWith('/')); |
| return childPath; |
| } |
| |
| // not at the root, so append the parent path |
| assert(childPath.isNotEmpty); |
| assert(!childPath.startsWith('/')); |
| assert(!childPath.endsWith('/')); |
| return '${parentPath == '/' ? '' : parentPath}/$childPath'; |
| } |
| |
| /// Normalizes the location string. |
| String canonicalUri(String loc) { |
| String canon = Uri.parse(loc).toString(); |
| canon = canon.endsWith('?') ? canon.substring(0, canon.length - 1) : canon; |
| |
| // remove trailing slash except for when you shouldn't, e.g. |
| // /profile/ => /profile |
| // / => / |
| // /login?from=/ => login?from=/ |
| canon = canon.endsWith('/') && canon != '/' && !canon.contains('?') |
| ? canon.substring(0, canon.length - 1) |
| : canon; |
| |
| // /login/?from=/ => /login?from=/ |
| // /?from=/ => /?from=/ |
| canon = canon.replaceFirst('/?', '?', 1); |
| |
| return canon; |
| } |