/* Part of SWI-Prolog Author: Jan Wielemaker and Anjo Anjewierden E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (c) 2002-2020, 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(html_write, [ reply_html_page/2, % :Head, :Body reply_html_page/3, % +Style, :Head, :Body % Basic output routines page//1, % :Content page//2, % :Head, :Body page//3, % +Style, :Head, :Body html//1, % :Content % Option processing html_set_options/1, % +OptionList html_current_option/1, % ?Option % repositioning HTML elements html_post//2, % +Id, :Content html_receive//1, % +Id html_receive//2, % +Id, :Handler xhtml_ns//2, % +Id, +Value html_root_attribute//2, % +Name, +Value html/4, % {|html||quasi quotations|} % Useful primitives for expanding html_begin//1, % +EnvName[(Attribute...)] html_end//1, % +EnvName html_quoted//1, % +Text html_quoted_attribute//1, % +Attribute % Emitting the HTML code print_html/1, % +List print_html/2, % +Stream, +List html_print_length/2, % +List, -Length % Extension support (html_meta)/1, % +Spec op(1150, fx, html_meta) ]). :- use_module(html_quasiquotations, [html/4]). :- autoload(library(apply),[maplist/3,maplist/4]). :- autoload(library(debug),[debug/3]). :- autoload(library(error), [must_be/2,domain_error/2,instantiation_error/1]). :- autoload(library(lists), [permutation/2,selectchk/3,append/3,select/4,list_to_set/2]). :- autoload(library(option),[option/2]). :- autoload(library(pairs),[group_pairs_by_key/2]). :- autoload(library(sgml),[xml_quote_cdata/3,xml_quote_attribute/3]). :- autoload(library(uri),[uri_encoded/3]). :- autoload(library(url),[www_form_encode/2]). :- if(exists_source(library(http/http_dispatch))). :- autoload(library(http/http_dispatch), [http_location_by_id/2]). :- endif. % Quote output :- set_prolog_flag(generate_debug_info, false). :- meta_predicate reply_html_page(+, :, :), reply_html_page(:, :), html(:, -, +), page(:, -, +), page(:, :, -, +), pagehead(+, :, -, +), pagebody(+, :, -, +), html_receive(+, 3, -, +), html_post(+, :, -, +). :- multifile expand//1, % +HTMLElement expand_attribute_value//1, % +HTMLAttributeValue html_header_hook/1. % +Style /** Write HTML text Most code doesn't need to use this directly; instead use library(http/http_server), which combines this library with the typical HTTP libraries that most servers need. The purpose of this library is to simplify writing HTML pages. Of course, it is possible to use format/3 to write to the HTML stream directly, but this is generally not very satisfactory: * It is a lot of typing * It does not guarantee proper HTML syntax. You have to deal with HTML quoting, proper nesting and reasonable layout. * It is hard to use satisfactory abstraction This module tries to remedy these problems. The idea is to translate a Prolog term into an HTML document. We use DCG for most of the generation. ---++ International documents The library supports the generation of international documents, but this is currently limited to using UTF-8 encoded HTML or XHTML documents. It is strongly recommended to use the following mime-type. == Content-type: text/html; charset=UTF-8 == When generating XHTML documents, the output stream must be in UTF-8 encoding. */ /******************************* * SETTINGS * *******************************/ %! html_set_options(+Options) is det. % % Set options for the HTML output. Options are stored in prolog % flags to ensure proper multi-threaded behaviour where setting an % option is local to the thread and new threads start with the % options from the parent thread. Defined options are: % % * dialect(Dialect) % One of =html4=, =xhtml= or =html5= (default). For % compatibility reasons, =html= is accepted as an % alias for =html4=. % % * doctype(+DocType) % Set the =|<|DOCTYPE|= DocType =|>|= line for page//1 and % page//2. % % * content_type(+ContentType) % Set the =|Content-type|= for reply_html_page/3 % % Note that the doctype and content_type flags are covered by % distinct prolog flags: =html4_doctype=, =xhtml_doctype= and % =html5_doctype= and similar for the content type. The Dialect % must be switched before doctype and content type. html_set_options(Options) :- must_be(list, Options), set_options(Options). set_options([]). set_options([H|T]) :- html_set_option(H), set_options(T). html_set_option(dialect(Dialect0)) :- !, must_be(oneof([html,html4,xhtml,html5]), Dialect0), ( html_version_alias(Dialect0, Dialect) -> true ; Dialect = Dialect0 ), set_prolog_flag(html_dialect, Dialect). html_set_option(doctype(Atom)) :- !, must_be(atom, Atom), current_prolog_flag(html_dialect, Dialect), dialect_doctype_flag(Dialect, Flag), set_prolog_flag(Flag, Atom). html_set_option(content_type(Atom)) :- !, must_be(atom, Atom), current_prolog_flag(html_dialect, Dialect), dialect_content_type_flag(Dialect, Flag), set_prolog_flag(Flag, Atom). html_set_option(O) :- domain_error(html_option, O). html_version_alias(html, html4). %! html_current_option(?Option) is nondet. % % True if Option is an active option for the HTML generator. html_current_option(dialect(Dialect)) :- current_prolog_flag(html_dialect, Dialect). html_current_option(doctype(DocType)) :- current_prolog_flag(html_dialect, Dialect), dialect_doctype_flag(Dialect, Flag), current_prolog_flag(Flag, DocType). html_current_option(content_type(ContentType)) :- current_prolog_flag(html_dialect, Dialect), dialect_content_type_flag(Dialect, Flag), current_prolog_flag(Flag, ContentType). dialect_doctype_flag(html4, html4_doctype). dialect_doctype_flag(html5, html5_doctype). dialect_doctype_flag(xhtml, xhtml_doctype). dialect_content_type_flag(html4, html4_content_type). dialect_content_type_flag(html5, html5_content_type). dialect_content_type_flag(xhtml, xhtml_content_type). option_default(html_dialect, html5). option_default(html4_doctype, 'HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" \c "http://www.w3.org/TR/html4/loose.dtd"'). option_default(html5_doctype, 'html'). option_default(xhtml_doctype, 'html PUBLIC "-//W3C//DTD XHTML 1.0 \c Transitional//EN" \c "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"'). option_default(html4_content_type, 'text/html; charset=UTF-8'). option_default(html5_content_type, 'text/html; charset=UTF-8'). option_default(xhtml_content_type, 'application/xhtml+xml; charset=UTF-8'). %! init_options is det. % % Initialise the HTML processing options. init_options :- ( option_default(Name, Value), ( current_prolog_flag(Name, _) -> true ; create_prolog_flag(Name, Value, []) ), fail ; true ). :- init_options. %! xml_header(-Header) % % First line of XHTML document. Added by print_html/1. xml_header(''). %! ns(?Which, ?Atom) % % Namespace declarations ns(xhtml, 'http://www.w3.org/1999/xhtml'). /******************************* * PAGE * *******************************/ %! page(+Content:dom)// is det. %! page(+Head:dom, +Body:dom)// is det. % % Generate a page including the HTML =||= header. The % actual doctype is read from the option =doctype= as defined by % html_set_options/1. page(Content) --> doctype, html(html(Content)). page(Head, Body) --> page(default, Head, Body). page(Style, Head, Body) --> doctype, content_type, html_begin(html), pagehead(Style, Head), pagebody(Style, Body), html_end(html). %! doctype// % % Emit the =| { html_current_option(doctype(DocType)), DocType \== '' }, !, [ '' ]. doctype --> []. content_type --> { html_current_option(content_type(Type)) }, !, html_post(head, meta([ 'http-equiv'('content-type'), content(Type) ], [])). content_type --> { html_current_option(dialect(html5)) }, !, html_post(head, meta('charset=UTF-8')). content_type --> []. pagehead(_, Head) --> { functor(Head, head, _) }, !, html(Head). pagehead(Style, Head) --> { strip_module(Head, M, _), hook_module(M, HM, head//2) }, HM:head(Style, Head), !. pagehead(_, Head) --> { strip_module(Head, M, _), hook_module(M, HM, head//1) }, HM:head(Head), !. pagehead(_, Head) --> html(head(Head)). pagebody(_, Body) --> { functor(Body, body, _) }, !, html(Body). pagebody(Style, Body) --> { strip_module(Body, M, _), hook_module(M, HM, body//2) }, HM:body(Style, Body), !. pagebody(_, Body) --> { strip_module(Body, M, _), hook_module(M, HM, body//1) }, HM:body(Body), !. pagebody(_, Body) --> html(body(Body)). hook_module(M, M, PI) :- current_predicate(M:PI), !. hook_module(_, user, PI) :- current_predicate(user:PI). %! html(+Content:dom)// is det % % Generate HTML from Content. Generates a token sequence for % print_html/2. html(Spec) --> { strip_module(Spec, M, T) }, qhtml(T, M). qhtml(Var, _) --> { var(Var), !, instantiation_error(Var) }. qhtml([], _) --> !, []. qhtml([H|T], M) --> !, html_expand(H, M), qhtml(T, M). qhtml(X, M) --> html_expand(X, M). html_expand(Var, _) --> { var(Var), !, instantiation_error(Var) }. html_expand(Term, Module) --> do_expand(Term, Module), !. html_expand(Term, _Module) --> { print_message(error, html(expand_failed(Term))) }. do_expand(Token, _) --> % call user hooks expand(Token), !. do_expand(Fmt-Args, _) --> !, { format(string(String), Fmt, Args) }, html_quoted(String). do_expand(\List, Module) --> { is_list(List) }, !, raw(List, Module). do_expand(\Term, Module, In, Rest) :- !, call(Module:Term, In, Rest). do_expand(Module:Term, _) --> !, qhtml(Term, Module). do_expand(&(Entity), _) --> !, { integer(Entity) -> format(string(String), '&#~d;', [Entity]) ; format(string(String), '&~w;', [Entity]) }, [ String ]. do_expand(Token, _) --> { atomic(Token) }, !, html_quoted(Token). do_expand(element(Env, Attributes, Contents), M) --> !, ( { Contents == [], html_current_option(dialect(xhtml)) } -> xhtml_empty(Env, Attributes) ; html_begin(Env, Attributes), qhtml(Env, Contents, M), html_end(Env) ). do_expand(Term, M) --> { Term =.. [Env, Contents] }, !, ( { layout(Env, _, empty) } -> html_begin(Env, Contents) ; ( { Contents == [], html_current_option(dialect(xhtml)) } -> xhtml_empty(Env, []) ; html_begin(Env), qhtml(Env, Contents, M), html_end(Env) ) ). do_expand(Term, M) --> { Term =.. [Env, Attributes, Contents], check_non_empty(Contents, Env, Term) }, !, ( { Contents == [], html_current_option(dialect(xhtml)) } -> xhtml_empty(Env, Attributes) ; html_begin(Env, Attributes), qhtml(Env, Contents, M), html_end(Env) ). qhtml(Env, Contents, M) --> { cdata_element(Env), phrase(cdata(Contents, M), Tokens) }, !, [ cdata(Env, Tokens) ]. qhtml(_, Contents, M) --> qhtml(Contents, M). check_non_empty([], _, _) :- !. check_non_empty(_, Tag, Term) :- layout(Tag, _, empty), !, print_message(warning, format('Using empty element with content: ~p', [Term])). check_non_empty(_, _, _). cdata(List, M) --> { is_list(List) }, !, raw(List, M). cdata(One, M) --> raw_element(One, M). %! raw(+List, +Module)// is det. % % Emit unquoted (raw) output used for scripts, etc. raw([], _) --> []. raw([H|T], Module) --> raw_element(H, Module), raw(T, Module). raw_element(Var, _) --> { var(Var), !, instantiation_error(Var) }. raw_element(\List, Module) --> { is_list(List) }, !, raw(List, Module). raw_element(\Term, Module, In, Rest) :- !, call(Module:Term, In, Rest). raw_element(Module:Term, _) --> !, raw_element(Term, Module). raw_element(Fmt-Args, _) --> !, { format(string(S), Fmt, Args) }, [S]. raw_element(Value, _) --> { must_be(atomic, Value) }, [Value]. %! html_begin(+Env)// is det. %! html_end(+End)// is det % % For html_begin//1, Env is a term Env(Attributes); for % html_end//1 it is the plain environment name. Used for % exceptional cases. Normal applications use html//1. The % following two fragments are identical, where we prefer the first % as it is more concise and less error-prone. % % == % html(table(border=1, \table_content)) % == % == % html_begin(table(border=1) % table_content, % html_end(table) % == html_begin(Env) --> { Env =.. [Name|Attributes] }, html_begin(Name, Attributes). html_begin(Env, Attributes) --> pre_open(Env), [<], [Env], attributes(Env, Attributes), ( { layout(Env, _, empty), html_current_option(dialect(xhtml)) } -> ['/>'] ; [>] ), post_open(Env). html_end(Env) --> % empty element or omited close { layout(Env, _, -), html_current_option(dialect(html)) ; layout(Env, _, empty) }, !, []. html_end(Env) --> pre_close(Env), [''], post_close(Env). %! xhtml_empty(+Env, +Attributes)// is det. % % Emit element in xhtml mode with empty content. xhtml_empty(Env, Attributes) --> pre_open(Env), [<], [Env], attributes(Attributes), ['/>']. %! xhtml_ns(+Id, +Value)// % % Demand an xmlns:id=Value in the outer html tag. This uses the % html_post/2 mechanism to post to the =xmlns= channel. Rdfa % (http://www.w3.org/2006/07/SWD/RDFa/syntax/), embedding RDF in % (x)html provides a typical usage scenario where we want to % publish the required namespaces in the header. We can define: % % == % rdf_ns(Id) --> % { rdf_global_id(Id:'', Value) }, % xhtml_ns(Id, Value). % == % % After which we can use rdf_ns//1 as a normal rule in html//1 to % publish namespaces from library(semweb/rdf_db). Note that this % macro only has effect if the dialect is set to =xhtml=. In % =html= mode it is silently ignored. % % The required =xmlns= receiver is installed by html_begin//1 % using the =html= tag and thus is present in any document that % opens the outer =html= environment through this library. xhtml_ns(Id, Value) --> { html_current_option(dialect(xhtml)) }, !, html_post(xmlns, \attribute(xmlns:Id=Value)). xhtml_ns(_, _) --> []. %! html_root_attribute(+Name, +Value)// % % Add an attribute to the HTML root element of the page. For % example: % % == % html(div(...)), % html_root_attribute(lang, en), % ... % == html_root_attribute(Name, Value) --> html_post(html_begin, \attribute(Name=Value)). %! attributes(+Env, +Attributes)// is det. % % Emit attributes for Env. Adds XHTML namespace declaration to the % html tag if not provided by the caller. attributes(html, L) --> !, ( { html_current_option(dialect(xhtml)) } -> ( { option(xmlns(_), L) } -> attributes(L) ; { ns(xhtml, NS) }, attributes([xmlns(NS)|L]) ), html_receive(xmlns) ; attributes(L), html_noreceive(xmlns) ), html_receive(html_begin). attributes(_, L) --> attributes(L). attributes([]) --> !, []. attributes([H|T]) --> !, attribute(H), attributes(T). attributes(One) --> attribute(One). attribute(Name=Value) --> !, [' '], name(Name), [ '="' ], attribute_value(Value), ['"']. attribute(NS:Term) --> !, { Term =.. [Name, Value] }, !, attribute((NS:Name)=Value). attribute(Term) --> { Term =.. [Name, Value] }, !, attribute(Name=Value). attribute(Atom) --> % Value-abbreviated attribute { atom(Atom) }, [ ' ', Atom ]. name(NS:Name) --> !, [NS, :, Name]. name(Name) --> [ Name ]. %! attribute_value(+Value) is det. % % Print an attribute value. Value is either atomic or one of the % following terms: % % * A+B % Concatenation of A and B % * encode(V) % Emit URL-encoded version of V. See www_form_encode/2. % * An option list % Emit ?Name1=encode(Value1)&Name2=encode(Value2) ... % * A term Format-Arguments % Use format/3 and emit the result as quoted value. % % The hook html_write:expand_attribute_value//1 can be defined to % provide additional `function like' translations. For example, % http_dispatch.pl defines location_by_id(ID) to refer to a % location on the current server based on the handler id. See % http_location_by_id/2. attribute_value(List) --> { is_list(List) }, !, attribute_value_m(List). attribute_value(Value) --> attribute_value_s(Value). % emit a single attribute value attribute_value_s(Var) --> { var(Var), !, instantiation_error(Var) }. attribute_value_s(A+B) --> !, attribute_value(A), ( { is_list(B) } -> ( { B == [] } -> [] ; [?], search_parameters(B) ) ; attribute_value(B) ). attribute_value_s(encode(Value)) --> !, { uri_encoded(query_value, Value, Encoded) }, [ Encoded ]. attribute_value_s(Value) --> expand_attribute_value(Value), !. attribute_value_s(Fmt-Args) --> !, { format(string(Value), Fmt, Args) }, html_quoted_attribute(Value). attribute_value_s(Value) --> html_quoted_attribute(Value). search_parameters([H|T]) --> search_parameter(H), ( {T == []} -> [] ; ['&'], search_parameters(T) ). search_parameter(Var) --> { var(Var), !, instantiation_error(Var) }. search_parameter(Name=Value) --> { www_form_encode(Value, Encoded) }, [Name, =, Encoded]. search_parameter(Term) --> { Term =.. [Name, Value], !, www_form_encode(Value, Encoded) }, [Name, =, Encoded]. search_parameter(Term) --> { domain_error(search_parameter, Term) }. %! attribute_value_m(+List)// % % Used for multi-valued attributes, such as class-lists. E.g., % % == % body(class([c1, c2]), Body) % == % % Emits =| ...|= attribute_value_m([]) --> []. attribute_value_m([H|T]) --> attribute_value_s(H), ( { T == [] } -> [] ; [' '], attribute_value_m(T) ). /******************************* * QUOTING RULES * *******************************/ %! html_quoted(Text)// is det. % % Quote the value for normal (CDATA) text. Note that text % appearing in the document structure is normally quoted using % these rules. I.e. the following emits properly quoted bold text % regardless of the content of Text: % % == % html(b(Text)) % == % % @tbd Assumes UTF-8 encoding of the output. html_quoted(Text) --> { xml_quote_cdata(Text, Quoted, utf8) }, [ Quoted ]. %! html_quoted_attribute(+Text)// is det. % % Quote the value according to the rules for tag-attributes % included in double-quotes. Note that -like html_quoted//1-, % attributed values printed through html//1 are quoted % atomatically. % % @tbd Assumes UTF-8 encoding of the output. html_quoted_attribute(Text) --> { xml_quote_attribute(Text, Quoted, utf8) }, [ Quoted ]. %! cdata_element(?Element) % % True when Element contains declared CDATA and thus only =| % html_post(css, % link([ type('text/css'), % rel('stylesheet'), % href(URL) % ])). % == % % Next we insert the _unique_ CSS links, in the pagehead using the % following call to reply_html_page/2: % % == % reply_html_page([ title(...), % \html_receive(css) % ], % ...) % == html_post(Id, Content) --> { strip_module(Content, M, C) }, [ mailbox(Id, post(M, C)) ]. %! html_receive(+Id)// is det. % % Receive posted HTML tokens. Unique sequences of tokens posted % with html_post//2 are inserted at the location where % html_receive//1 appears. % % @see The local predicate sorted_html//1 handles the output of % html_receive//1. % @see html_receive//2 allows for post-processing the posted % material. html_receive(Id) --> html_receive(Id, sorted_html). %! html_receive(+Id, :Handler)// is det. % % This extended version of html_receive//1 causes Handler to be % called to process all messages posted to the channal at the time % output is generated. Handler is called as below, where % `PostedTerms` is a list of Module:Term created from calls to % html_post//2. Module is the context module of html_post and Term % is the unmodified term. Members in `PostedTerms` are in the % order posted and may contain duplicates. % % == % phrase(Handler, PostedTerms, HtmlTerms, Rest) % == % % Typically, Handler collects the posted terms, creating a term % suitable for html//1 and finally calls html//1. html_receive(Id, Handler) --> { strip_module(Handler, M, P) }, [ mailbox(Id, accept(M:P, _)) ]. %! html_noreceive(+Id)// is det. % % As html_receive//1, but discard posted messages. html_noreceive(Id) --> [ mailbox(Id, ignore(_,_)) ]. %! mailman(+Tokens) is det. % % Collect posted tokens and copy them into the receiving % mailboxes. Mailboxes may produce output for each other, but not % cyclic. The current scheme to resolve this is rather naive: It % simply permutates the mailbox resolution order until it found a % working one. Before that, it puts =head= and =script= boxes at % the end. mailman(Tokens) :- ( html_token(mailbox(_, accept(_, Accepted)), Tokens) -> true ), var(Accepted), % not yet executed !, mailboxes(Tokens, Boxes), keysort(Boxes, Keyed), group_pairs_by_key(Keyed, PerKey), move_last(PerKey, script, PerKey1), move_last(PerKey1, head, PerKey2), ( permutation(PerKey2, PerKeyPerm), ( mail_ids(PerKeyPerm) -> ! ; debug(html(mailman), 'Failed mail delivery order; retrying', []), fail ) -> true ; print_message(error, html(cyclic_mailboxes)) ). mailman(_). move_last(Box0, Id, Box) :- selectchk(Id-List, Box0, Box1), !, append(Box1, [Id-List], Box). move_last(Box, _, Box). %! html_token(?Token, +Tokens) is nondet. % % True if Token is a token in the token set. This is like member, % but the toplevel list may contain cdata(Elem, Tokens). html_token(Token, [H|T]) :- html_token_(T, H, Token). html_token_(_, Token, Token) :- !. html_token_(_, cdata(_,Tokens), Token) :- html_token(Token, Tokens). html_token_([H|T], _, Token) :- html_token_(T, H, Token). %! mailboxes(+Tokens, -MailBoxes) is det. % % Get all mailboxes from the token set. mailboxes(Tokens, MailBoxes) :- mailboxes(Tokens, MailBoxes, []). mailboxes([], List, List). mailboxes([mailbox(Id, Value)|T0], [Id-Value|T], Tail) :- !, mailboxes(T0, T, Tail). mailboxes([cdata(_Type, Tokens)|T0], Boxes, Tail) :- !, mailboxes(Tokens, Boxes, Tail0), mailboxes(T0, Tail0, Tail). mailboxes([_|T0], T, Tail) :- mailboxes(T0, T, Tail). mail_ids([]). mail_ids([H|T0]) :- mail_id(H, NewPosts), add_new_posts(NewPosts, T0, T), mail_ids(T). mail_id(Id-List, NewPosts) :- mail_handlers(List, Boxes, Content), ( Boxes = [accept(MH:Handler, In)] -> extend_args(Handler, Content, Goal), phrase(MH:Goal, In), mailboxes(In, NewBoxes), keysort(NewBoxes, Keyed), group_pairs_by_key(Keyed, NewPosts) ; Boxes = [ignore(_, _)|_] -> NewPosts = [] ; Boxes = [accept(_,_),accept(_,_)|_] -> print_message(error, html(multiple_receivers(Id))), NewPosts = [] ; print_message(error, html(no_receiver(Id))), NewPosts = [] ). add_new_posts([], T, T). add_new_posts([Id-Posts|NewT], T0, T) :- ( select(Id-List0, T0, Id-List, T1) -> append(List0, Posts, List) ; debug(html(mailman), 'Stuck with new posts on ~q', [Id]), fail ), add_new_posts(NewT, T1, T). %! mail_handlers(+Boxes, -Handlers, -Posters) is det. % % Collect all post(Module,HTML) into Posters and the remainder in % Handlers. Handlers consists of accept(Handler, Tokens) and % ignore(_,_). mail_handlers([], [], []). mail_handlers([post(Module,HTML)|T0], H, [Module:HTML|T]) :- !, mail_handlers(T0, H, T). mail_handlers([H|T0], [H|T], C) :- mail_handlers(T0, T, C). extend_args(Term, Extra, NewTerm) :- Term =.. [Name|Args], append(Args, [Extra], NewArgs), NewTerm =.. [Name|NewArgs]. %! sorted_html(+Content:list)// is det. % % Default handlers for html_receive//1. It sorts the posted % objects to create a unique list. % % @bug Elements can differ just on the module. Ideally we % should phrase all members, sort the list of list of % tokens and emit the result. Can we do better? sorted_html(List) --> { sort(List, Unique) }, html(Unique). %! head_html(+Content:list)// is det. % % Handler for html_receive(head). Unlike sorted_html//1, it calls % a user hook html_write:html_head_expansion/2 to process the % collected head material into a term suitable for html//1. % % @tbd This has been added to facilitate html_head.pl, an % experimental library for dealing with css and javascript % resources. It feels a bit like a hack, but for now I do not know % a better solution. head_html(List) --> { list_to_set(List, Unique), html_expand_head(Unique, NewList) }, html(NewList). :- multifile html_head_expansion/2. html_expand_head(List0, List) :- html_head_expansion(List0, List1), List0 \== List1, !, html_expand_head(List1, List). html_expand_head(List, List). /******************************* * LAYOUT * *******************************/ pre_open(Env) --> { layout(Env, N-_, _) }, !, [ nl(N) ]. pre_open(_) --> []. post_open(Env) --> { layout(Env, _-N, _) }, !, [ nl(N) ]. post_open(_) --> []. pre_close(head) --> !, html_receive(head, head_html), { layout(head, _, N-_) }, [ nl(N) ]. pre_close(Env) --> { layout(Env, _, N-_) }, !, [ nl(N) ]. pre_close(_) --> []. post_close(Env) --> { layout(Env, _, _-N) }, !, [ nl(N) ]. post_close(_) --> []. %! layout(+Tag, -Open, -Close) is det. % % Define required newlines before and after tags. This table is % rather incomplete. New rules can be added to this multifile % predicate. % % @param Tag Name of the tag % @param Open Tuple M-N, where M is the number of lines before % the tag and N after. % @param Close Either as Open, or the atom - (minus) to omit the % close-tag or =empty= to indicate the element has % no content model. % % @tbd Complete table :- multifile layout/3. layout(table, 2-1, 1-2). layout(blockquote, 2-1, 1-2). layout(pre, 2-1, 0-2). layout(textarea, 1-1, 0-1). layout(center, 2-1, 1-2). layout(dl, 2-1, 1-2). layout(ul, 1-1, 1-1). layout(ol, 2-1, 1-2). layout(form, 2-1, 1-2). layout(frameset, 2-1, 1-2). layout(address, 2-1, 1-2). layout(head, 1-1, 1-1). layout(body, 1-1, 1-1). layout(script, 1-1, 1-1). layout(style, 1-1, 1-1). layout(select, 1-1, 1-1). layout(map, 1-1, 1-1). layout(html, 1-1, 1-1). layout(caption, 1-1, 1-1). layout(applet, 1-1, 1-1). layout(tr, 1-0, 0-1). layout(option, 1-0, 0-1). layout(li, 1-0, 0-1). layout(dt, 1-0, -). layout(dd, 0-0, -). layout(title, 1-0, 0-1). layout(h1, 2-0, 0-2). layout(h2, 2-0, 0-2). layout(h3, 2-0, 0-2). layout(h4, 2-0, 0-2). layout(iframe, 1-1, 1-1). layout(area, 1-0, empty). layout(base, 1-1, empty). layout(br, 0-1, empty). layout(col, 0-0, empty). layout(embed, 1-1, empty). layout(hr, 1-1, empty). % empty elements layout(img, 0-0, empty). layout(input, 1-0, empty). layout(link, 1-1, empty). layout(meta, 1-1, empty). layout(param, 1-0, empty). layout(source, 1-0, empty). layout(track, 1-0, empty). layout(wbr, 0-0, empty). layout(p, 2-1, -). % omited close layout(td, 0-0, 0-0). layout(div, 1-0, 0-1). /******************************* * PRINTING * *******************************/ %! print_html(+List) is det. %! print_html(+Out:stream, +List) is det. % % Print list of atoms and layout instructions. Currently used layout % instructions: % % * nl(N) % Use at minimum N newlines here. % % * mailbox(Id, Box) % Repositioned tokens (see html_post//2 and % html_receive//2) print_html(List) :- current_output(Out), mailman(List), write_html(List, Out). print_html(Out, List) :- ( html_current_option(dialect(xhtml)) -> stream_property(Out, encoding(Enc)), ( Enc == utf8 -> true ; print_message(warning, html(wrong_encoding(Out, Enc))) ), xml_header(Hdr), write(Out, Hdr), nl(Out) ; true ), mailman(List), write_html(List, Out), flush_output(Out). write_html([], _). write_html([nl(N)|T], Out) :- !, join_nl(T, N, Lines, T2), write_nl(Lines, Out), write_html(T2, Out). write_html([mailbox(_, Box)|T], Out) :- !, ( Box = accept(_, Accepted), nonvar(Accepted) -> write_html(Accepted, Out) ; true ), write_html(T, Out). write_html([cdata(Env, Tokens)|T], Out) :- !, with_output_to(string(CDATA), write_html(Tokens, current_output)), valid_cdata(Env, CDATA), write(Out, CDATA), write_html(T, Out). write_html([H|T], Out) :- write(Out, H), write_html(T, Out). join_nl([nl(N0)|T0], N1, N, T) :- !, N2 is max(N0, N1), join_nl(T0, N2, N, T). join_nl(L, N, N, L). write_nl(0, _) :- !. write_nl(N, Out) :- nl(Out), N1 is N - 1, write_nl(N1, Out). %! valid_cdata(+Env, +String) is det. % % True when String is valid content for a CDATA element such as % =|" can be written as % "<\/script>". % % @see write_json/2, js_arg//1. % @error domain_error(cdata, String) valid_cdata(Env, String) :- atomics_to_string([''], End), sub_atom_icasechk(String, _, End), !, domain_error(cdata, String). valid_cdata(_, _). %! html_print_length(+List, -Len) is det. % % Determine the content length of a token list produced using % html//1. Here is an example on how this is used to output an % HTML compatible to HTTP: % % == % phrase(html(DOM), Tokens), % html_print_length(Tokens, Len), % format('Content-type: text/html; charset=UTF-8~n'), % format('Content-length: ~d~n~n', [Len]), % print_html(Tokens) % == html_print_length(List, Len) :- mailman(List), ( html_current_option(dialect(xhtml)) -> xml_header(Hdr), atom_length(Hdr, L0), L1 is L0+1 % one for newline ; L1 = 0 ), html_print_length(List, L1, Len). html_print_length([], L, L). html_print_length([nl(N)|T], L0, L) :- !, join_nl(T, N, Lines, T1), L1 is L0 + Lines, % assume only \n! html_print_length(T1, L1, L). html_print_length([mailbox(_, Box)|T], L0, L) :- !, ( Box = accept(_, Accepted) -> html_print_length(Accepted, L0, L1) ; L1 = L0 ), html_print_length(T, L1, L). html_print_length([cdata(_, CDATA)|T], L0, L) :- !, html_print_length(CDATA, L0, L1), html_print_length(T, L1, L). html_print_length([H|T], L0, L) :- atom_length(H, Hlen), L1 is L0+Hlen, html_print_length(T, L1, L). %! reply_html_page(:Head, :Body) is det. %! reply_html_page(+Style, :Head, :Body) is det. % % Provide the complete reply as required by http_wrapper.pl for a % page constructed from Head and Body. The HTTP =|Content-type|= % is provided by html_current_option/1. reply_html_page(Head, Body) :- reply_html_page(default, Head, Body). reply_html_page(Style, Head, Body) :- html_current_option(content_type(Type)), phrase(page(Style, Head, Body), HTML), forall(html_header_hook(Style), true), format('Content-type: ~w~n~n', [Type]), print_html(HTML). %! html_header_hook(+Style) is nondet. % % This multifile hook is called just before the ``Content-type`` % header is emitted. It allows for emitting additional headers % depending on the first argument of reply_html_page/3. /******************************* * META-PREDICATE SUPPORT * *******************************/ %! html_meta(+Heads) is det. % % This directive can be used to declare that an HTML rendering % rule takes HTML content as argument. It has two effects. It % emits the appropriate meta_predicate/1 and instructs the % built-in editor (PceEmacs) to provide proper colouring for the % arguments. The arguments in Head are the same as for % meta_predicate or can be constant =html=. For example: % % == % :- html_meta % page(html,html,?,?). % == html_meta(Spec) :- throw(error(context_error(nodirective, html_meta(Spec)), _)). html_meta_decls(Var, _, _) :- var(Var), !, instantiation_error(Var). html_meta_decls((A,B), (MA,MB), [MH|T]) :- !, html_meta_decl(A, MA, MH), html_meta_decls(B, MB, T). html_meta_decls(A, MA, [MH]) :- html_meta_decl(A, MA, MH). html_meta_decl(Head, MetaHead, html_write:html_meta_head(GenHead, Module, Head)) :- functor(Head, Name, Arity), functor(GenHead, Name, Arity), prolog_load_context(module, Module), Head =.. [Name|HArgs], maplist(html_meta_decl, HArgs, MArgs), MetaHead =.. [Name|MArgs]. html_meta_decl(html, :) :- !. html_meta_decl(Meta, Meta). system:term_expansion((:- html_meta(Heads)), [ (:- meta_predicate(Meta)) | MetaHeads ]) :- html_meta_decls(Heads, Meta, MetaHeads). :- multifile html_meta_head/3. html_meta_colours(Head, Goal, built_in-Colours) :- Head =.. [_|MArgs], Goal =.. [_|Args], maplist(meta_colours, MArgs, Args, Colours). meta_colours(html, HTML, Colours) :- !, html_colours(HTML, Colours). meta_colours(I, _, Colours) :- integer(I), I>=0, !, Colours = meta(I). meta_colours(_, _, classify). html_meta_called(Head, Goal, Called) :- Head =.. [_|MArgs], Goal =.. [_|Args], meta_called(MArgs, Args, Called, []). meta_called([], [], Called, Called). meta_called([html|MT], [A|AT], Called, Tail) :- !, phrase(called_by(A), Called, Tail1), meta_called(MT, AT, Tail1, Tail). meta_called([0|MT], [A|AT], [A|CT0], CT) :- !, meta_called(MT, AT, CT0, CT). meta_called([I|MT], [A|AT], [A+I|CT0], CT) :- integer(I), I>0, !, meta_called(MT, AT, CT0, CT). meta_called([_|MT], [_|AT], Called, Tail) :- !, meta_called(MT, AT, Called, Tail). :- html_meta html(html,?,?), page(html,?,?), page(html,html,?,?), page(+,html,html,?,?), pagehead(+,html,?,?), pagebody(+,html,?,?), reply_html_page(html,html), reply_html_page(+,html,html), html_post(+,html,?,?). /******************************* * PCE EMACS SUPPORT * *******************************/ :- multifile prolog_colour:goal_colours/2, prolog_colour:style/2, prolog_colour:message//1, prolog:called_by/2. prolog_colour:goal_colours(Goal, Colours) :- html_meta_head(Goal, _Module, Head), html_meta_colours(Head, Goal, Colours). prolog_colour:goal_colours(html_meta(_), built_in-[meta_declarations([html])]). % TBD: Check with do_expand! html_colours(Var, classify) :- var(Var), !. html_colours(\List, html_raw-[list-Colours]) :- is_list(List), !, list_colours(List, Colours). html_colours(\_, html_call-[dcg]) :- !. html_colours(_:Term, built_in-[classify,Colours]) :- !, html_colours(Term, Colours). html_colours(&(Entity), functor-[entity(Entity)]) :- !. html_colours(List, list-ListColours) :- List = [_|_], !, list_colours(List, ListColours). html_colours(Format-Args, functor-[FormatColor,ArgsColors]) :- !, format_colours(Format, FormatColor), format_arg_colours(Args, Format, ArgsColors). html_colours(Term, TermColours) :- compound(Term), compound_name_arguments(Term, Name, Args), Name \== '.', !, ( Args = [One] -> TermColours = html(Name)-ArgColours, ( layout(Name, _, empty) -> attr_colours(One, ArgColours) ; html_colours(One, Colours), ArgColours = [Colours] ) ; Args = [AList,Content] -> TermColours = html(Name)-[AColours, Colours], attr_colours(AList, AColours), html_colours(Content, Colours) ; TermColours = error ). html_colours(_, classify). list_colours(Var, classify) :- var(Var), !. list_colours([], []). list_colours([H0|T0], [H|T]) :- !, html_colours(H0, H), list_colours(T0, T). list_colours(Last, Colours) :- % improper list html_colours(Last, Colours). attr_colours(Var, classify) :- var(Var), !. attr_colours([], classify) :- !. attr_colours(Term, list-Elements) :- Term = [_|_], !, attr_list_colours(Term, Elements). attr_colours(Name=Value, built_in-[html_attribute(Name), VColour]) :- !, attr_value_colour(Value, VColour). attr_colours(NS:Term, built_in-[ html_xmlns(NS), html_attribute(Name)-[classify] ]) :- compound(Term), compound_name_arity(Term, Name, 1). attr_colours(Term, html_attribute(Name)-[VColour]) :- compound(Term), compound_name_arity(Term, Name, 1), !, Term =.. [Name,Value], attr_value_colour(Value, VColour). attr_colours(Name, html_attribute(Name)) :- atom(Name), !. attr_colours(Term, classify) :- compound(Term), compound_name_arity(Term, '.', 2), !. attr_colours(_, error). attr_list_colours(Var, classify) :- var(Var), !. attr_list_colours([], []). attr_list_colours([H0|T0], [H|T]) :- attr_colours(H0, H), attr_list_colours(T0, T). attr_value_colour(Var, classify) :- var(Var). attr_value_colour(location_by_id(ID), sgml_attr_function-[Colour]) :- !, location_id(ID, Colour). attr_value_colour(#(ID), sgml_attr_function-[Colour]) :- !, location_id(ID, Colour). attr_value_colour(A+B, sgml_attr_function-[CA,CB]) :- !, attr_value_colour(A, CA), attr_value_colour(B, CB). attr_value_colour(encode(_), sgml_attr_function-[classify]) :- !. attr_value_colour(Atom, classify) :- atomic(Atom), !. attr_value_colour([_|_], classify) :- !. attr_value_colour(_Fmt-_Args, classify) :- !. attr_value_colour(Term, classify) :- compound(Term), compound_name_arity(Term, '.', 2), !. attr_value_colour(_, error). location_id(ID, classify) :- var(ID), !. :- if(current_predicate(http_location_for_id/1)). location_id(ID, Class) :- ( catch(http_location_by_id(ID, Location), _, fail) -> Class = http_location_for_id(Location) ; Class = http_no_location_for_id(ID) ). :- endif. location_id(_, classify). format_colours(Format, format_string) :- atom(Format), !. format_colours(Format, format_string) :- string(Format), !. format_colours(_Format, type_error(text)). format_arg_colours(Args, _Format, classify) :- is_list(Args), !. format_arg_colours(_, _, type_error(list)). :- op(990, xfx, :=). % allow compiling without XPCE :- op(200, fy, @). prolog_colour:style(html(_), [colour(magenta4), bold(true)]). prolog_colour:style(entity(_), [colour(magenta4)]). prolog_colour:style(html_attribute(_), [colour(magenta4)]). prolog_colour:style(html_xmlns(_), [colour(magenta4)]). prolog_colour:style(format_string(_), [colour(magenta4)]). prolog_colour:style(sgml_attr_function, [colour(blue)]). prolog_colour:style(http_location_for_id(_), [bold(true)]). prolog_colour:style(http_no_location_for_id(_), [colour(red), bold(true)]). prolog_colour:message(html(Element)) --> [ '~w: SGML element'-[Element] ]. prolog_colour:message(entity(Entity)) --> [ '~w: SGML entity'-[Entity] ]. prolog_colour:message(html_attribute(Attr)) --> [ '~w: SGML attribute'-[Attr] ]. prolog_colour:message(sgml_attr_function) --> [ 'SGML Attribute function'-[] ]. prolog_colour:message(http_location_for_id(Location)) --> [ 'ID resolves to ~w'-[Location] ]. prolog_colour:message(http_no_location_for_id(ID)) --> [ '~w: no such ID'-[ID] ]. % prolog:called_by(+Goal, -Called) % % Hook into library(pce_prolog_xref). Called is a list of callable % or callable+N to indicate (DCG) arglist extension. prolog:called_by(Goal, Called) :- html_meta_head(Goal, _Module, Head), html_meta_called(Head, Goal, Called). called_by(Term) --> called_by(Term, _). called_by(Var, _) --> { var(Var) }, !, []. called_by(\G, M) --> !, ( { is_list(G) } -> called_by(G, M) ; {atom(M)} -> [(M:G)+2] ; [G+2] ). called_by([], _) --> !, []. called_by([H|T], M) --> !, called_by(H, M), called_by(T, M). called_by(M:Term, _) --> !, ( {atom(M)} -> called_by(Term, M) ; [] ). called_by(Term, M) --> { compound(Term), !, Term =.. [_|Args] }, called_by(Args, M). called_by(_, _) --> []. :- multifile prolog:hook/1. prolog:hook(body(_,_,_)). prolog:hook(body(_,_,_,_)). prolog:hook(head(_,_,_)). prolog:hook(head(_,_,_,_)). /******************************* * MESSAGES * *******************************/ :- multifile prolog:message/3. prolog:message(html(expand_failed(What))) --> [ 'Failed to translate to HTML: ~p'-[What] ]. prolog:message(html(wrong_encoding(Stream, Enc))) --> [ 'XHTML demands UTF-8 encoding; encoding of ~p is ~w'-[Stream, Enc] ]. prolog:message(html(multiple_receivers(Id))) --> [ 'html_post//2: multiple receivers for: ~p'-[Id] ]. prolog:message(html(no_receiver(Id))) --> [ 'html_post//2: no receivers for: ~p'-[Id] ].