/usr/share/Yap/http/http_json.pl is in yap 6.2.2-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 | /* $Id$
Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: wielemak@science.uva.nl
WWW: http://www.swi-prolog.org
Copyright (C): 1985-2007, University of Amsterdam
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
As a special exception, if you link this library with other files,
compiled with a Free Software compiler, to produce an executable, this
library does not by itself cause the resulting executable to be covered
by the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License.
*/
:- module(http_json,
[ reply_json/1, % +JSON
reply_json/2, % +JSON, Options
http_read_json/2, % +Request, -JSON
http_read_json/3 % +Request, -JSON, +Options
]).
:- use_module(http_client).
:- use_module(http_header).
:- use_module(http_stream).
:- use_module(json).
:- use_module(library(option)).
:- use_module(library(error)).
:- use_module(library(lists)).
:- use_module(library(memfile)).
:- multifile
http_client:http_convert_data/4,
http_client:post_data_hook/3,
json_type/1.
/** <module> HTTP JSON Plugin module
This module inserts the JSON parser for documents of MIME type
=|application/jsonrequest|= and =|application/json|= requested through
the http_client.pl library.
Typically JSON is used by Prolog HTTP servers. Below is a skeleton for
handling a JSON request, answering in JSON.
==
handle(Request) :-
http_read_json(Request, JSONIn),
json_to_prolog(JSONIn, PrologIn),
<compute>(PrologIn, PrologOut), % application body
prolog_to_json(PrologOut, JSONOut),
reply_json(JSONOut).
==
This module also integrates JSON support into the http client provided
by http_client.pl. Posting a JSON query and processing the JSON reply
(or any other reply understood by http_read_data/3) is as simple as
below, where Term is a JSON term as described in json.pl and reply is
of the same format if the server replies with JSON.
==
...,
http_post(URL, json(Term), Reply, [])
==
@see JSON Requests are discussed in http://json.org/JSONRequest.html
@see json.pl describes how JSON objects are represented in Prolog terms.
@see json_convert.pl converts between more natural Prolog terms and json
terms.
*/
http_client:http_convert_data(In, Fields, Data, Options) :-
memberchk(content_type(Type), Fields),
is_json_type(Type), !,
( memberchk(content_length(Bytes), Fields)
-> stream_range_open(In, Range, [size(Bytes)]),
set_stream(Range, encoding(utf8)),
call_cleanup(json_read(Range, Data, Options), close(Range))
; set_stream(In, encoding(utf8)),
json_read(In, Data, Options)
).
is_json_type(Type) :-
json_type(Type), !.
is_json_type(ContentType) :-
json_type(Type),
sub_atom(ContentType, 0, _, _, Type), !,
strip_utf8(ContentType, Plain),
json_type(Plain).
%% strip_utf8(+ContentTypeIn, -ContentType) is det.
%
% Strip an optional =|; charset=UTF-8|=. JSON data is always
% UTF-8, but some clients seem to insist in sending this.
strip_utf8(ContentType, Plain) :-
sub_atom(ContentType, B, _, A, ;),
sub_atom(ContentType, _, A, 0, Ext),
normalize_space(atom('charset=UTF-8'), Ext), !,
sub_atom(ContentType, 0, B, _, CT),
normalize_space(atom(Plain), CT).
strip_utf8(ContentType, ContentType).
%% json_type(?MIMEType:atom) is semidet.
%
% True if MIMEType is a JSON mimetype. http_json:json_type/1 is a
% multifile predicate and may be extended to facilitate
% non-conforming clients.
json_type('application/jsonrequest').
json_type('application/json').
% http_client:post_data_hook(+Data, +Out:stream, +HdrExtra) is semidet.
%
% Hook into http_post_data/3 that allows for
%
% ==
% http_post(URL, json(Term), Reply, Options)
% ==
%
% @tbd avoid creation of intermediate data using chunked output.
http_client:post_data_hook(json(Term), Out, HdrExtra) :-
http_client:post_data_hook(json(Term, []), Out, HdrExtra).
http_client:post_data_hook(json(Term, Options), Out, HdrExtra) :-
option(content_type(Type), HdrExtra, 'application/json'),
new_memory_file(MemFile),
open_memory_file(MemFile, write, Handle),
format(Handle, 'Content-type: ~w~n~n', [Type]),
json_write(Handle, Term, Options),
close(Handle),
open_memory_file(MemFile, read, RdHandle),
call_cleanup(http_post_data(cgi_stream(RdHandle), Out, HdrExtra),
( close(RdHandle),
free_memory_file(MemFile))).
%% http_read_json(+Request, -JSON) is det.
%% http_read_json(+Request, -JSON, +Options) is det.
%
% Extract JSON data posted to this HTTP request.
%
% @error domain_error(mimetype, Found) if the mimetype is
% not known (see json_type/1).
% @error domain_error(method, Method) if the request is not
% a POST request.
http_read_json(Request, JSON) :-
http_read_json(Request, JSON, []).
http_read_json(Request, JSON, Options) :-
select_option(content_type(Type), Options, Rest), !,
delete(Request, content_type(_), Request2),
request_to_json([content_type(Type)|Request2], JSON, Rest).
http_read_json(Request, JSON, Options) :-
request_to_json(Request, JSON, Options).
request_to_json(Request, JSON, Options) :-
memberchk(method(Method), Request),
memberchk(content_type(Type), Request),
( Method == post
-> true
; domain_error(method, Method)
),
( is_json_type(Type)
-> true
; domain_error(mimetype, Type)
),
http_read_data(Request, JSON, Options).
%% reply_json(+JSONTerm) is det.
%% reply_json(+JSONTerm, +Options) is det.
%
% Formulate a JSON HTTP reply. See json_write/2 for details.
% Options accepts content_type(+Type) and options accepted by
% json_write/3.
reply_json(Term) :-
format('Content-type: application/json~n~n'),
json_write(current_output, Term).
reply_json(Term, Options) :-
select_option(content_type(Type), Options, Rest, 'application/json'),
format('Content-type: ~w~n~n', [Type]),
json_write(current_output, Term, Rest).
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