dart/third_party/pkg/route_hierarchical/lib/url_template.dart

library url_template;

import 'url_matcher.dart';

final _specialChars = new RegExp(r'[\\()$^.+[\]{}|]');
final _paramPattern = r'([^/?]+)';

/**
 * A reversible URL template class that can match/parse and reverse URL
 * templates like: /foo/:bar/baz
 */
class UrlTemplate implements UrlMatcher {
  List<String> _fields;
  RegExp _pattern;
  String _strPattern;
  List _chunks;

  String toString() => '$_pattern';

  int compareTo(UrlMatcher other) {
    final String tmpParamPattern = '\t';
    if (other is UrlTemplate) {
      String thisPattern = _strPattern.replaceAll(_paramPattern, tmpParamPattern);
      String otherPattern = other._strPattern.replaceAll(_paramPattern, tmpParamPattern);
      List<String> thisPatternParts = thisPattern.split('/');
      List<String> otherPatternParts = otherPattern.split('/');
      if (thisPatternParts.length == otherPatternParts.length) {
        for (int i = 0; i < thisPatternParts.length; i++) {
          String thisPart = thisPatternParts[i];
          String otherPart = otherPatternParts[i];
          if (thisPart == tmpParamPattern && otherPart != tmpParamPattern) {
            return 1;
          } else if (thisPart != tmpParamPattern && otherPart == tmpParamPattern) {
            return -1;
          }
        }
        return otherPattern.compareTo(thisPattern);
      } else {
        return otherPatternParts.length - thisPatternParts.length;
      }
    } else {
      return 0;
    }
  }

  UrlTemplate(String template) {
    _compileTemplate(template);
  }

  void _compileTemplate(String template) {
    template = template.
        replaceAllMapped(_specialChars, (m) => r'\' + m.group(0));
    _fields = <String>[];
    _chunks = [];
    var exp = new RegExp(r':(\w+)');
    StringBuffer sb = new StringBuffer('^');
    int start = 0;
    exp.allMatches(template).forEach((Match m) {
      var paramName = m.group(1);
      var txt = template.substring(start, m.start);
      _fields.add(paramName);
      _chunks.add(txt);
      _chunks.add((Map params) => params != null ? params[paramName] : null);
      sb.write(txt);
      sb.write(_paramPattern);
      start = m.end;
    });
    if (start != template.length) {
      var txt = template.substring(start, template.length);
      sb.write(txt);
      _chunks.add(txt);
    }
    _strPattern = sb.toString();
    _pattern = new RegExp(_strPattern);
  }

  UrlMatch match(String url) {
    var matches = _pattern.allMatches(url);
    if (matches.isEmpty) return null;
    var parameters = new Map();
    Match match = matches.first;
    for (var i = 0; i < match.groupCount; i++) {
      parameters[_fields[i]] = match.group(i + 1);
    }
    var tail = url.substring(match.group(0).length);
    return new UrlMatch(match.group(0), tail, parameters);
  }

  String reverse({Map parameters, String tail: ''}) =>
    _chunks.map((c) => c is Function ? c(parameters) : c).join() + tail;

  List<String> urlParameterNames() => _fields;
}