Files
scryer-prolog/src/lib/http/http_open.pl
2022-03-28 20:38:55 +02:00

68 lines
2.7 KiB
Prolog

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Written 2022 by Adrián Arroyo Calle (adrian.arroyocalle@gmail.com)
Part of Scryer Prolog.
http_open(+Address, -Stream, +Options)
======================================
Yields Stream to read the body of an HTTP reply from Address.
Address is a list of characters, and includes the method. Both HTTP
and HTTPS are supported.
Options supported:
* method(+Method): Sets the HTTP method of the call. Method can be get (default), head, delete, post, put or patch.
* data(+Data): Data to be sent in the request. Useful for POST, PUT and PATCH operations.
* size(-Size): Unifies with the value of the Content-Length header
* request_headers(+RequestHeaders): Headers to be used in the request
* headers(-ListHeaders): Unifies with a list with all headers returned in the response
* status_code(-Code): Unifies with the status code of the request (200, 201, 404, ...)
Example:
?- http_open("https://github.com/mthom/scryer-prolog", S, []).
%@ S = '$stream'(0x7fcfc9e00f00).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
:- module(http_open, [http_open/3]).
:- use_module(library(lists)).
http_open(Address, Response, Options) :-
parse_http_options(Options, OptionValues),
( member(method(Method), OptionValues) -> true; Method = get),
( member(data(Data), OptionValues) -> true; Data = []),
( member(request_headers(RequestHeaders), OptionValues) -> true; RequestHeaders = ['user-agent'("Scryer Prolog")]),
( member(status_code(Code), OptionValues) -> true; true),
( member(headers(Headers), OptionValues) -> true; true),
( member(size(Size), OptionValues) -> member('content-length'(Size), Headers); true),
'$http_open'(Address, Response, Method, Code, Data, Headers, RequestHeaders).
parse_http_options(Options, OptionValues) :-
maplist(parse_http_options_, Options, OptionValues).
parse_http_options_(method(Method), method(Method)) :-
( var(Method) ->
throw(error(instantiation_error, http_open/3))
;
member(Method, [get, post, put, delete, patch, head]) -> true
;
throw(error(domain_error(http_option, method(Method)), _))
).
parse_http_options_(data(Data), data(Data)) :-
( var(Data) ->
throw(error(instantiation_error, http_open/3))
; true
).
parse_http_options_(request_headers(Headers), request_headers(Headers)) :-
( var(Headers) ->
throw(error(instantiation_error, http_open/3))
; true
).
parse_http_options_(size(Size), size(Size)).
parse_http_options_(status_code(Code), status_code(Code)).
parse_http_options_(headers(Headers), headers(Headers)).