http_help.pl -- Explore the running HTTP server

This module is part of the SWI-Prolog web-developent infrastructure. It documents the HTTP server using the reflexive capabilities of Prolog and the server infrastructure. Self-documentation is enabled by loading this module. The entry-point of this module is located at the HTTP location root(help/http), using the handler-identifier http_help.

In addition, this module provides the component page_documentation_link//1, which shows a small book linking from the displayed page to its documentation.

 page_documentation_link(+Request)// is det

Show a link to the documentation of the current page.

 http_help(Request)[private]

HTTP handler to explore the Prolog HTTP server

 help_page(Options)//[private]

Emit the tree and #http-help for holding the description. We need to include the requirements for PlDoc here as the scripts are not loaded through the innerHTML method.

Options:

location(Location)

Initially open Location.

 script(+Options)// is det[private]

Emit JavScript code that gets the help for the HTTP location associated with node and displays this information in #http-help.

 help_on_handler(+Request)[private]

Describe the HTTP handler for the given location.

To be done

- Include the output format by scanning for one of the defined output handlers.

 status(+How)//[private]

Emit HTTP code and comment for status.

To be done

- Use a clean interface from http_header.

 predicate_help(+Request, +Closure)// is det[private]

Provide the help-page of the implementing predicate.

 edit_options(+Request, -Options) is det[private]

Assume we can show and edit option if we are allowed to access the HTTP location pldoc(edit).

 dispatch_options(+Options, +Path)// is det[private]

Describe the dispatching options

 parameter_table(+Params)// is det[private]

Provide help on the parameters

 param_type(+Options)// is det[private]

Emit a description of the type in HTML.

 breaking_bar// is det[private]

Emits | followed by a zero-width white-space that allows the browser to insert a linebreak here.

 type_term(-Term) is nondet[private]

Enumerate the option-terms that are interpreted as types.

To be done

- provide a public interface from http_parameters.pl

 extracted_parameters(+Closure, -Declarations)[private]

Return a completely qualified list of parameters that are retrieved by calling Closure.

 extend_closure(:In, +Extra, -Out) is det[private]

Extend a possibly qualified closure with arguments from Extra.

 calls(:Goal, +MaxDepth, -Called) is det[private]

Called is the list of goals called by Goal obtained by unfolding the call-tree upto the given MaxDepth.

To be done

- Without MaxDepth not all programs terminate. Why?

 bind_vars(+Key, +Pairs) is det[private]

Pairs contains the variable bindings after scanning the alternative computation paths. Key are the initial variables.

To be done

- What we should do is find all bindings for a specific variable, compute the most specific generalization of this set and unify it with the variable in Key. For now, we only try to unify all of them with the input variable. That deals correctly with the case where no path binds the variable (this is typically the case for input variables and that is our biggest concern at the moment).

 evaluate_now(:Goal) is semidet[private]

If true, call Goal and propagate bindings that it produces instead of unfolding its call-tree. This was introduced to deal with extracted_parameters/2, which dynamically constructs option-lists for http_parameters/3.

See also

- The hook evaluate/1 extends the definition

 evaluate(:Goal) is semidet[multifile]

Multifile hook to extend the goals that are evaluated by evaluate_now/1.

 autocomplete(+HandlerID, +Options)// is det[private]

Insert a YUI autocomplete widget that obtains its alternatives from HandlerID. The following Options are supported:

width(+Width)

Specify the width of the box. Width must satisfy the CSS length syntax.

query_delay(+Seconds)

Wait until no more keys are typed for Seconds before sending the query to the server.

 ac_location(+Request)[private]

HTTP handler to for autocompletion on HTTP handlers.