Matchers¶

Cripts supports most common comparisons, ==, !=, etc. for many of the strings and variables that it provides. However, this is sometimes not adequate for all use cases, so Cripts provides a way to define custom matchers. There are currently three types of matchers:

Matcher	Description
`cripts::Matcher::Range`	Matching IP addresses against one or many IP ranges.
`cripts::Matcher::PCRE`	Matching strings against one or many regular expressions.
`cripts::Matcher::List::Method`	Match a request method against a list of methods.

Often you will declare these ranges once, and then use them over and over again. For this purpose, Cripts allows ranges to be declared static, which means it can optimize the code around the matches.

Here’s an example using the regular expression matcher:

do_remap()
{
  static cripts::Matcher::PCRE pcre({"^/([^/]+)/(.*)$", "^(.*)$"}); // Nonsensical ...

  borrow url = cripts::Client::URL::Get();

  if (pcre.Match(url.path)) {
    // Do something with the match
  }
}

Note

For the IP-range and regular expression matcher, you can specify a single range or regular expression, it does not have to be declared as a list with the {} syntax. For both, the single or list arguments are strings within "".

Matcher Functions¶

All matchers have the following functions:

Function	Description
`Match()`	Match the given string against the matcher.
`Contains()`	Another name for `Match()`
`Add()`	Add another element to the matcher (can not be used with `static`)

Matcher::PCRE¶

The PCRE matcher is used to match strings against one or many regular expressions. When a match is found, a cripts::Matcher::PCRE::Result object is returned. This object has the following functions to deal with the matched results and the capture groups:

Function	Description
`Matched()`	A boolean indicating if a regex was matched.
`Count()`	Returns the number of regex capture groups that are matched.
`MatchIX()`	Returns the index of the matched regex capture group.
[] Index	Retrieves the matched string for the given capture group index.

Lets show an example:

do_remap()
{
  static cripts::Matcher::PCRE allow({"^([a-c][^/]*)/?(.*)", "^([g-h][^/]*)/?(.*)"});

  borrow url = cripts::Client::URL::Get();

  auto res = allow.Match(url.path);

  if (res.Matched()) {
    CDebug("Matched: {}", res[1]);
    CDebug("Matched: {}", res[2]);
    // Now do something with these URLs matching these paths
  }
}