3.24.3 Predicates

[det]html_resource(+About, +Properties)

Register an HTML head resource. About is either an atom that specifies an HTTP location or a term Alias(Sub). This works similar to absolute_file_name/2. See http:location_path/2 for details. Recognised properties are:

requires(+Requirements)

Other required script and css files. If this is a plain file name, it is interpreted relative to the declared resource. Requirements can be a list, which is equivalent to multiple requires properties.

virtual(+Bool)

If true (default false), do not include About itself, but only its dependencies. This allows for defining an alias for one or more resources.

ordered(+Bool)

Defines that the list of requirements is ordered, which means that each requirement in the list depends on its predecessor.

aggregate(+List)

States that About is an aggregate of the resources in List. This means that if both About and one of the elements of List appears in the dependencies, About is kept and the smaller one is dropped. If there are a number of dependencies on the small members, these are replaced with dependency on the big (aggregate) one, for example, to specify that a big javascript is actually the composition of a number of smaller ones.

mime_type(-Mime)

May be specified for non-virtual resources to specify the mime-type of the resource. By default, the mime type is derived from the file name using file_mime_type/2.

Registering the same About multiple times extends the properties defined for About. In particular, this allows for adding additional dependencies to a (virtual) resource.

[nondet]html_current_resource(?About)

True when About is a currently known resource.

[det]html_requires(+ResourceOrList)//

Include ResourceOrList and all dependencies derived from it and add them to the HTML head using html_post/2. The actual dependencies are computed during the HTML output phase by html_insert_resource//1.

[det]html_insert_resource(+ResourceOrList)//

Actually include HTML head resources. Called through html_post//2 from html_requires//1 after rewrite by html_head_expansion/2. We are guaranteed we will only get one call that is passed a flat list of requested requirements. We have three jobs:

1. Figure out all indirect requirements
2. See whether we can use any‘aggregate’resources
3. Put required resources before their requiree.

[semidet,multifile]mime_include(+Mime, +Path)//

Hook called to include a link to an HTML resource of type Mime into the HTML head. The Mime type is computed from Path using file_mime_type/2. If the hook fails, two built-in rules for text/css and text/javascript are tried. For example, to include a =.pl= files as a Prolog script, use:

:- multifile
    html_head:mime_include//2.

html_head:mime_include(text/'x-prolog', Path) --> !,
    html(script([ type('text/x-prolog'),
                  src(Path)
                ],  [])).