/* Part of SWI-Prolog
Author: Jan Wielemaker, Michiel Hildebrand
E-mail: J.Wielemaker@uva.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2010-2014, University of Amsterdam
VU University Amsterdam
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/
:- module(javascript,
[ js_script//1, % +Content
js_call//1, % +Function(Arg..)
js_new//2, % +Id, +Function(+Args)
js_expression//1, % +Expression
js_arg_list//1, % +ListOfExpressions
js_arg//1, % +Arg
js_args//1, % +Args
javascript/4 % Quasi Quotation handler
]).
:- use_module(library(http/html_write)).
:- use_module(library(http/json)).
:- use_module(library(apply)).
:- use_module(library(error)).
:- use_module(library(lists)).
:- use_module(library(debug)).
:- use_module(library(quasi_quotations)).
:- use_module(library(dcg/basics)).
:- use_module(js_grammar).
:- html_meta
js_script(html, ?, ?).
:- quasi_quotation_syntax(javascript).
/** <module> Utilities for including JavaScript
This library is a supplement to library(http/html_write) for producing
JavaScript fragments. Its main role is to be able to call JavaScript
functions with valid arguments constructed from Prolog data. For
example, suppose you want to call a JavaScript functions to process a
list of names represented as Prolog atoms. This can be done using the
call below, while without this library you would have to be careful to
properly escape special characters.
==
numbers_script(Names) -->
html(script(type('text/javascript'),
[ \js_call('ProcessNumbers'(Names)
]),
==
The accepted arguments are described with js_expression//1.
*/
%! js_script(+Content)// is det.
%
% Generate a JavaScript =script= element with the given content.
js_script(Content) -->
html(script(type('text/javascript'),
Content)).
/*******************************
* QUASI QUOTATION *
*******************************/
%! javascript(+Content, +Vars, +VarDict, -DOM) is det.
%
% Quasi quotation parser for JavaScript that allows for embedding
% Prolog variables to substitude _identifiers_ in the JavaScript
% snippet. Parameterizing a JavaScript string is achieved using
% the JavaScript `+` operator, which results in concatenation at
% the client side.
%
% ==
% ...,
% js_script({|javascript(Id, Config)||
% $(document).ready(function() {
% $("#"+Id).tagit(Config);
% });
% |}),
% ...
% ==
%
% The current implementation tokenizes the JavaScript input and
% yields syntax errors on unterminated comments, strings, etc. No
% further parsing is implemented, which makes it possible to
% produce syntactically incorrect and partial JavaScript. Future
% versions are likely to include a full parser, generating syntax
% errors.
%
% The parser produces a term `\List`, which is suitable for
% js_script//1 and html//1. Embedded variables are mapped to
% `\js_expression(Var)`, while the remaining text is mapped to
% atoms.
%
% @tbd Implement a full JavaScript parser. Users should _not_
% rely on the ability to generate partial JavaScript
% snippets.
javascript(Content, Vars, Dict, \Parts) :-
include(qq_var(Vars), Dict, QQDict),
phrase_from_quasi_quotation(
js(QQDict, Parts),
Content).
qq_var(Vars, _=Var) :-
member(V, Vars),
V == Var,
!.
js(Dict, [Pre, Subst|More]) -->
here(Here0),
js_tokens(_),
here(Here1),
js_token(identifier(Name)),
{ memberchk(Name=Var, Dict),
!,
Subst = \js_expression(Var),
diff_to_atom(Here0, Here1, Pre)
},
js(Dict, More).
js(_, [Last]) -->
string(Codes),
\+ [_],
!,
{ atom_codes(Last, Codes) }.
js_tokens([]) --> [].
js_tokens([H|T]) -->
js_token(H),
js_tokens(T).
% diff_to_atom(+Start, +End, -Atom)
%
% True when Atom is an atom that represents the characters between
% Start and End, where End must be in the tail of the list Start.
diff_to_atom(Start, End, Atom) :-
diff_list(Start, End, List),
atom_codes(Atom, List).
diff_list(Start, End, List) :-
Start == End,
!,
List = [].
diff_list([H|Start], End, [H|List]) :-
diff_list(Start, End, List).
here(Here, Here, Here).
/*******************************
* PROLOG --> JAVASCRIPT *
*******************************/
%! js_call(+Term)// is det.
%
% Emit a call to a Javascript function. The Prolog functor is the
% name of the function. The arguments are converted from Prolog to
% JavaScript using js_arg_list//1. Please not that Prolog functors can
% be quoted atom and thus the following is legal:
%
% ==
% ...
% html(script(type('text/javascript'),
% [ \js_call('x.y.z'(hello, 42))
% ]),
% ==
js_call(Term) -->
{ Term =.. [Function|Args] },
html(Function), js_arg_list(Args), [';\n'].
%! js_new(+Id, +Term)// is det.
%
% Emit a call to a Javascript object declaration. This is the same
% as:
%
% ==
% ['var ', Id, ' = new ', \js_call(Term)]
% ==
js_new(Id, Term) -->
{ Term =.. [Function|Args] },
html(['var ', Id, ' = new ', Function]), js_arg_list(Args), [';\n'].
%! js_arg_list(+Expressions:list)// is det.
%
% Write javascript (function) arguments. This writes "(", Arg,
% ..., ")". See js_expression//1 for valid argument values.
js_arg_list(Args) -->
['('], js_args(Args), [')'].
js_args([]) -->
[].
js_args([H|T]) -->
js_expression(H),
( { T == [] }
-> []
; html(', '),
js_args(T)
).
%! js_expression(+Expression)// is det.
%
% Emit a single JSON argument. Expression is one of:
%
% $ Variable :
% Emitted as Javascript =null=
% $ List :
% Produces a Javascript list, where each element is processed
% by this library.
% $ object(Attributes) :
% Where Attributes is a Key-Value list where each pair can be
% written as Key-Value, Key=Value or Key(Value), accomodating
% all common constructs for this used in Prolog.
% $ { K:V, ... }
% Same as object(Attributes), providing a more JavaScript-like
% syntax. This may be useful if the object appears literally
% in the source-code, but is generally less friendlyto produce
% as a result from a computation.
% $ Dict :
% Emit a dict as a JSON object using json_write_dict/3.
% $ json(Term) :
% Emits a term using json_write/3.
% $ @(Atom) :
% Emits these constants without quotes. Normally used for the
% symbols =true=, =false= and =null=, but can also be use for
% emitting JavaScript symbols (i.e. function- or variable
% names).
% $ Number :
% Emited literally
% $ symbol(Atom) :
% Synonym for @(Atom). Deprecated.
% $ Atom or String :
% Emitted as quoted JavaScript string.
js_expression(Expr) -->
js_arg(Expr),
!.
js_expression(Expr) -->
{ type_error(js(expression), Expr) }.
%! js_arg(+Expression)// is semidet.
%
% Same as js_expression//1, but fails if Expression is invalid,
% where js_expression//1 raises an error.
%
% @deprecated New code should use js_expression//1.
js_arg(H) -->
{ var(H) },
!,
[null].
js_arg(object(H)) -->
{ is_list(H) },
!,
html([ '{', \js_kv_list(H), '}' ]).
js_arg({}(Attrs)) -->
!,
html([ '{', \js_kv_cslist(Attrs), '}' ]).
js_arg(@(Id)) --> js_identifier(Id).
js_arg(symbol(Id)) --> js_identifier(Id).
js_arg(json(Term)) -->
{ json_to_string(json(Term), String),
debug(json_arg, '~w~n', String)
},
[ String ].
js_arg(Dict) -->
{ is_dict(Dict),
!,
with_output_to(string(String),
json_write_dict(current_output, Dict, [width(0)]))
},
[ String ].
js_arg(H) -->
{ is_list(H) },
!,
html([ '[', \js_args(H), ']' ]).
js_arg(H) -->
{ number(H) },
!,
[H].
js_arg(H) -->
{ atomic(H),
!,
js_quoted_string(H, Q)
},
[ '"', Q, '"'
].
js_kv_list([]) --> [].
js_kv_list([H|T]) -->
( js_kv(H)
-> ( { T == [] }
-> []
; html(', '),
js_kv_list(T)
)
; { type_error(javascript_key_value, H) }
).
js_kv(Key:Value) -->
!,
js_key(Key), [:], js_expression(Value).
js_kv(Key-Value) -->
!,
js_key(Key), [:], js_expression(Value).
js_kv(Key=Value) -->
!,
js_key(Key), [:], js_expression(Value).
js_kv(Term) -->
{ compound(Term),
Term =.. [Key,Value]
},
!,
js_key(Key), [:], js_expression(Value).
js_key(Key) -->
( { must_be(atom, Key),
js_identifier(Key)
}
-> [Key]
; { js_quoted_string(Key, QKey) },
html(['\'', QKey, '\''])
).
js_kv_cslist((A,B)) -->
!,
js_kv(A),
html(', '),
js_kv_cslist(B).
js_kv_cslist(A) -->
js_kv(A).
%! js_quoted_string(+Raw, -Quoted)
%
% Quote text for use in JavaScript. Quoted does _not_ include the
% leading and trailing quotes.
%
% @tbd Join with json stuff.
js_quoted_string(Raw, Quoted) :-
atom_codes(Raw, Codes),
phrase(js_quote_codes(Codes), QuotedCodes),
atom_codes(Quoted, QuotedCodes).
js_quote_codes([]) -->
[].
js_quote_codes([0'\r,0'\n|T]) -->
!,
"\\n",
js_quote_codes(T).
js_quote_codes([0'<,0'/|T]) --> % Avoid XSS scripting hacks
!,
"<\\/",
js_quote_codes(T).
js_quote_codes([H|T]) -->
js_quote_code(H),
js_quote_codes(T).
js_quote_code(0'') -->
!,
"\\'".
js_quote_code(0'") -->
!,
"\\\"".
js_quote_code(0'\\) -->
!,
"\\\\".
js_quote_code(0'\n) -->
!,
"\\n".
js_quote_code(0'\r) -->
!,
"\\r".
js_quote_code(0'\t) -->
!,
"\\t".
js_quote_code(C) -->
[C].
%! js_identifier(+Id:atom)// is det.
%
% Emit an identifier if it is a valid one
js_identifier(Id) -->
{ must_be(atom, Id),
js_identifier(Id)
},
!,
[ Id ].
js_identifier(Id) -->
{ domain_error(js(identifier), Id)
}.
%! js_identifier(+Id:atom) is semidet.
%
% True if Id is a valid identifier. In traditional JavaScript,
% this means it starts with [$_:letter:] and is followed by
% [$_:letter:digit:]
js_identifier(Id) :-
sub_atom(Id, 0, 1, _, First),
char_type(First, csymf),
forall(sub_atom(Id, _, 1, _, Char), char_type(Char, csym)).
%! json_to_string(+JSONTerm, -String)
%
% Write JSONTerm to String.
json_to_string(JSON, String) :-
with_output_to(string(String),
json_write(current_output,JSON,[width(0)])).