URL patterns

This document describes the URL patterns allowed in a url rule property.

A url property can be either a valid URL (RFC 3986) or a URL pattern as a valid URI Template (RFC 6570, Level 3).

This implementation imposes two types of expression for convenience: segment expressions and pair expressions.

Segment expressions

A segment expression is any expression that can be applied by position instead of by name. This is: simple string expressions {var}, plus operator {+var}, multiple variables {var,x,y}, {+x,y}, dot operator {.x,y} and path segments {/path,x}.

Caveats

• Currently the crosshatch (#) is not handled as URL fragments are dropped.

Example: Simple

A rule like:

url: http://example.org/{var}

Will catch URLs like:

http://example.org/alfa
http://example.org/foobar
http://example.org/x
http://example.org/

Example: Simple sequence

A rule like:

url: http://example.org/{x}/{y}/

Will catch URLs like:

http://example.org/foo/bar/
http://example.org/x/y/

Example: Multiple sequence

A rule like:

url: http://example.org{/x,y,z}

Warning: something like http://example.org/{/x,y} would create two slashes//`.

Will catch URLs like:

http://example.org/foo/bar/baz
http://example.org/foo/bar
http://example.org/foo

Pair expressions

A pair expression is any expression that can be applied by name. This is form-style query {?x} and query continuation {&x} with multiple variables allowed {?x,y}.

Caveats

• Path-style parameters {;x} is not handled so it will be treated as part of a segment.

Example: Simple query

A rule like:

url: http://example.org{?q}

Will catch URLs like:

http://example.org?q=1
http://example.org

Example: Multiple query

A rule like:

url: http://example.org{?q,p}

Will catch URLs like:

http://example.org?q=1&p=2
http://example.org?q=1
http://example.org?p=2
http://example.org

Combined expressions

Segment and pair expressions can be combined as the RFC states. Some examples below.

Example: Query with continuation

A rule like:

url: http://example.org?q={x}{&p}

Will catch URLs like:

http://example.org?q=1&p=2
http://example.org?q=1

Example: Query with continuation

A rule like:

url: http://example.org/{+var}?q={var}{&p,x}

Note: notice segment names are ignored so the same can be used many times.

Will catch URLs like:

http://example.org/hello%20world?q=1&p=2&x=3
http://example.org/hello%20world?q=1&p=2
http://example.org/hello%20world?q=1&x=3
http://example.org/hello%20world?q=1
http://example.org/?q=1