A QR code is a machine-readable two-dimensional barcode. They might contain data for a identifier or a URL to a website.

This example shows how to construct and modify URLs to consume a third party API to generate QR Codes.

This example shows how to classify URLs according to a set of rules. It is inspired by Finicky application.

The URLs are classified and redirected to a browser according to their category. See the example config.json file.

mailto is a URL scheme for email addresses. mailto URL are used on websites to allow users to send an email to a specific address directly from an HTML document.

This example parses a mailto URL into a new view type and prints its components to standard output.

magnet is a URL scheme for identifying files by their content. These files are usually identified by cryptographic hash value.

Magnet links are useful in peer-to-peer file sharing networks because they allow resources to be referred to without the need for a continuously available host..

This example parses a magnet link into a new view type and prints its components to standard output.

This example defines a router that associates URL paths to a directory in the filesystem. If the specified route matches and the file exists, the example prints its contents to standard output.

This example defines a router for URL paths. If the specified route matches one of the existing routes, the example executes the underlying callback function.

This example parses a non-strict or invalid URL into path components according to its delimiters. This pattern can be adapted to the requirements of other applications.

Once the non-strict components are determined, a new URL is created and its parts are set with the set_encoded_X functions, which will encode any invalid chars accordingly.

This sort of transformation is useful in applications that are extremely loose in what kinds of URLs they accept, such as browsers. The sanitized URL can later be used for machine-to-machine communication.

Using non-strict URLs directly is a security concern in machine-to-machine communication, is ambiguous, and also involve an extra cost for the transformations.

Different transformations are required by different applications to construct a valid URL appropriate for machine-to-machine communication. For instance, if an invalid relative reference includes something that looks like a host in the first path segment, browsers usually interpret that as the host with an implicit "https" scheme. Other applications also have other implicit schemes.

The example also identifies whether the input url is already valid. It includes diagnostics that can be used to help the user determine if a URL is invalid and why it’s invalid.

Once all transformations are applied, the result is a URL appropriate for machine-to-machine communication.