function UrlMatcher(pattern) {

  // Find all placeholders and create a compiled pattern, using either classic or curly syntax:
  //   '*' name
  //   ':' name
  //   '{' name '}'
  //   '{' name ':' regexp '}'
  // The regular expression is somewhat complicated due to the need to allow curly braces
  // inside the regular expression. The placeholder regexp breaks down as follows:
  //    ([:*])(\w+)               classic placeholder ($1 / $2)
  //    \{(\w+)(?:\:( ... ))?\}   curly brace placeholder ($3) with optional regexp ... ($4)
  //    (?: ... | ... | ... )+    the regexp consists of any number of atoms, an atom being either
  //    [^{}\\]+                  - anything other than curly braces or backslash
  //    \\.                       - a backslash escape
  //    \{(?:[^{}\\]+|\\.)*\}     - a matched set of curly braces containing other atoms
  var placeholder = /([:*])(\w+)|\{(\w+)(?:\:((?:[^{}\\]+|\\.|\{(?:[^{}\\]+|\\.)*\})+))?\}/g,
      names = {}, compiled = '^', last = 0, m,
      segments = this.segments = [],
      params = this.params = [];

  function addParameter(id) {
    if (!/^\w+(-+\w+)*$/.test(id)) throw new Error("Invalid parameter name '" + id + "' in pattern '" + pattern + "'");
    if (names[id]) throw new Error("Duplicate parameter name '" + id + "' in pattern '" + pattern + "'");
    names[id] = true;
    params.push(id);
  }

  function quoteRegExp(string) {
    return string.replace(/[\\\[\]\^$*+?.()|{}]/g, "\\$&");
  }

  this.source = pattern;

  // Split into static segments separated by path parameter placeholders.
  // The number of segments is always 1 more than the number of parameters.
  var id, regexp, segment;
  while ((m = placeholder.exec(pattern))) {
    id = m[2] || m[3]; // IE[78] returns '' for unmatched groups instead of null
    regexp = m[4] || (m[1] == '*' ? '.*' : '[^/]*');
    segment = pattern.substring(last, m.index);
    if (segment.indexOf('?') >= 0) break; // we're into the search part
    compiled += quoteRegExp(segment) + '(' + regexp + ')';
    addParameter(id);
    segments.push(segment);
    last = placeholder.lastIndex;
  }
  segment = pattern.substring(last);

  // Find any search parameter names and remove them from the last segment
  var i = segment.indexOf('?');
  if (i >= 0) {
    var search = this.sourceSearch = segment.substring(i);
    segment = segment.substring(0, i);
    this.sourcePath = pattern.substring(0, last+i);

    // Allow parameters to be separated by '?' as well as '&' to make concat() easier
    forEach(search.substring(1).split(/[&?]/), addParameter);
  } else {
    this.sourcePath = pattern;
    this.sourceSearch = '';
  }

  compiled += quoteRegExp(segment) + '$';
  segments.push(segment);
  this.regexp = new RegExp(compiled);
  this.prefix = segments[0];
}
Matches URLs against patterns and extracts named parameters from the path or the search
part of the URL. A URL pattern consists of a path pattern, optionally followed by '?' and a list
of search parameters. Multiple search parameter names are separated by '&'. Search parameters
do not influence whether or not a URL is matched, but their values are passed through into
the matched parameters returned by {@link UrlMatcher#exec exec}.

Path parameter placeholders can be specified using simple colon/catch-all syntax or curly brace
syntax, which optionally allows a regular expression for the parameter to be specified:

* ':' name - colon placeholder
* '*' name - catch-all placeholder
* '{' name '}' - curly placeholder
* '{' name ':' regexp '}' - curly placeholder with regexp. Should the regexp itself contain
  curly braces, they must be in matched pairs or escaped with a backslash.

Parameter names may contain only word characters (latin letters, digits, and underscore) and
must be unique within the pattern (across both path and search parameters). For colon 
placeholders or curly placeholders without an explicit regexp, a path parameter matches any
number of characters other than '/'. For catch-all placeholders the path parameter matches
any number of characters.

### Examples

* '/hello/' - Matches only if the path is exactly '/hello/'. There is no special treatment for
  trailing slashes, and patterns have to match the entire path, not just a prefix.
* '/user/:id' - Matches '/user/bob' or '/user/1234!!!' or even '/user/' but not '/user' or
  '/user/bob/details'. The second path segment will be captured as the parameter 'id'.
* '/user/{id}' - Same as the previous example, but using curly brace syntax.
* '/user/{id:[^/]*}' - Same as the previous example.
* '/user/{id:[0-9a-fA-F]{1,8}}' - Similar to the previous example, but only matches if the id
  parameter consists of 1 to 8 hex digits.
* '/files/{path:.*}' - Matches any URL starting with '/files/' and captures the rest of the
  path into the parameter 'path'.
* '/files/*path' - ditto.

@constructor
@param {string} pattern  the pattern to compile into a matcher.

@property {string} prefix  A static prefix of this pattern. The matcher guarantees that any
  URL matching this matcher (i.e. any string for which {@link UrlMatcher#exec exec()} returns
  non-null) will start with this prefix.