/* Part of SWI-Prolog Author: Jan Wielemaker E-mail: J.Wielemaker@vu.nl WWW: http://www.swi-prolog.org Copyright (c) 1997-2023, University of Amsterdam VU University Amsterdam CWI, Amsterdam SWI-Prolog Solutions b.v. 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(tex, [ welcome/0, latex2html/1, % +BaseName latex2html/2, % +BaseName, +Options macro_expand/2, % +In, -Out translate/4, % +In, +ModeIn, -ModeOut, -Out translate/3, % +In, +ModeIn, -Out latex2html_module/0, % Register extension module tex_input_directory/1, % +Input Dir step_counter/2, % +Name, -NewValue ps2gif/3, % +PsFile, -GifFile, +Options translate_command/4, % +In, +ModeIn, -ModeOut, -HTML translate_environment/4, % +In, +ModeIn, -ModeOut, -HTML translate_reference/4, % +Kind, +RefPrefix, +Label, -HTML translate_table/3, % +Format, +BodyTokens, -HTML translate_section/4, % +Level, -/*, +Title, -HTML translate_section/5, % +Level, -/*, +Title, -HTML, +FileBase current_setting/1, % +Type(-Value ...) do_float/2, % +Float(+Number), :Goal tex_load_commands/1, % +BaseName add_to_index/1, % +Term add_to_index/2, % +Term, +Tag clean_tt/2, % +Raw, -Clean op(100, fx, #) ]). :- autoload(library(apply),[maplist/3]). :- autoload(library(backcomp),[convert_time/8]). :- autoload(library(ctypes), [is_lower/1,to_upper/2,is_alpha/1,is_upper/1,to_lower/2]). :- autoload(library(debug),[debug/3]). :- autoload(library(filesex),[copy_file/2,directory_file_path/3]). :- autoload(library(gui_tracer),[gtrace/0]). :- autoload(library(lists), [ reverse/2, member/2, flatten/2, append/3, select/3, nth1/3, last/2 ]). :- autoload(library(main),[main/0,argv_options/3]). :- autoload(library(occurs),[sub_term/2]). :- autoload(library(option),[option/2,select_option/3]). :- autoload(library(readutil),[read_file_to_codes/3]). :- autoload(library(statistics),[statistics/0]). ltx2htm_version('0.98'). % for SWI-Prolog 5.6.18 page_header('\n\n'). :- dynamic html_output_dir/1, % output relative to this dir tex_file_base/1, % Basename of the main file html_file_base/1, % Basename of main output file html_split_level/1, % Split upto this level bodycolor/1, % \bodycolor storage title/1, % \title{} storage author/1, % \auther{} command storage link_image/2, % Id, Image center_tables/0, quiet/0. :- discontiguous cmd/2, cmd/3, cmd/4. html_split_level(2). html_file_base('Title'). :- multifile user:file_search_path/2. :- dynamic user:file_search_path/2. add_my_path :- user:file_search_path(latex2html, _), !. add_my_path :- prolog_load_context(directory, Dir), asserta(user:file_search_path(latex2html, Dir)). :- initialization(add_my_path, now). user:file_search_path(psfig, tex(figs)). user:file_search_path(includegraphics, tex(figs)). user:file_search_path(includegraphics, tex(.)). user:file_search_path(tex, '.'). user:file_search_path(img, '.'). user:file_search_path(img, icons). user:file_search_path(img, latex2html(icons)). :- use_foreign_library(foreign(tex)). % support list_strings/0 :- multifile check:valid_string_goal/1. check:valid_string_goal(tex:delete_all(_,S,_)) :- string(S). check:valid_string_goal(tex:replace_all(_,S1,S2,_)) :- string(S1), string(S2). check:valid_string_goal(tex:string_without(S,_,_,_)) :- string(S). /******************************* * TEX INPUTS * *******************************/ read_tex_inputs :- getenv('TEXINPUTS', Val), !, read_tex_inputs(Val). read_tex_inputs. read_tex_inputs(Val) :- split(Val, 0':, PathElement), retractall(user:file_search_path(tex, _)), reverse(PathElement, RevPath), forall(member(E, RevPath), assert_tex_input(E)). assert_tex_input('') :- !, retractall(user:file_search_path(tex, '.')), asserta(user:file_search_path(tex, '.')). assert_tex_input(Dir) :- retractall(user:file_search_path(tex, Dir)), asserta(user:file_search_path(tex, Dir)). /******************************* * EXTENSION MODULES * *******************************/ :- dynamic tex_extension_module/1. tex_extension_module(tex). :- module_transparent latex2html_module/0. latex2html_module :- context_module(M), ( tex:tex_extension_module(M) -> true ; asserta(tex:tex_extension_module(M)) ), M:dynamic((cmd/2, cmd/3, cmd/4, env/2, (#)/2)), M:discontiguous((cmd/2, cmd/3, cmd/4, env/2, (#)/2)), M:dynamic((list_command/4)). % Load a tex command file tex_load_commands(File) :- ( package_alias(File, Alias), member(Term, [tex(Alias), latex2html(Alias)]), absolute_file_name(Term, CmdFile, [ extensions([cmd]), access(read), file_errors(fail) ]) -> tex_read_commands(CmdFile), ( quiet -> true ; format(user_error, 'Loaded LaTeX commands from "~w"~n', [CmdFile]) ) ; format(user_error, 'Can not find command file "~w"~n', [File]), fail ). tex_input_directory(D) :- asserta(user:file_search_path(tex, D)). % current_setting(?Term) % % Report current settings to the extension module current_setting(keep_figures) :- keep_figures(true). current_setting(html_output_dir(Dir)) :- html_output_dir(Dir). /******************************* * SETTINGS * *******************************/ :- dynamic keep_figures/1, onefile/1, makeindex/1, title/1, auther/1. keep_figures(true). onefile(false). makeindex(false). title('No title'). author('Anonymous'). /******************************* * TOPLEVEL * *******************************/ run_latex2html(TeXFile) :- reset_counters, reset_sections, reset_index, reset_labels, reset_cites, reset_output, tex_tokens(TeXFile, TeXTokens), ( member(env(document, _, _), TeXTokens) -> translate(TeXTokens, preamble, HTML) ; format(user_error, 'No document environment; processing anyway~n', []), translate(TeXTokens, document, HTML) ), once(html_file_base(Base)), expand_macros([tell(Base), #header], Header), make_index(Index), flatten([ Header, HTML, Index ], HtmlDocument), collect_labels(HtmlDocument, Base), write_html(HtmlDocument), close_output. latex2html(Spec) :- latex2html(Spec, []). latex2html(Spec, Options) :- welcome(Options), tex_load_commands(latex), file_name_extension(Spec, tex, TeXFile), file_name_extension(Base, tex, TeXFile), absolute_file_name(tex(TeXFile), [ access(read) ], TheTeXFile), asserta(html_output_dir(Base)), asserta(tex_file_base(Base)), run_latex2html(TheTeXFile), goodbye(Options), retract(tex_file_base(_)), retract(html_output_dir(_)). % make_output_directory % % Create the output directory. :- dynamic done_make_output_directory/0. make_output_directory :- done_make_output_directory, !. make_output_directory :- html_output_dir(Dir), !, ( exists_directory(Dir) -> true ; make_directory(Dir) ), assert(done_make_output_directory). :- dynamic current_html_output_db/1, % Base in_head/1. reset_output :- retractall(current_html_output_db(_)), retractall(in_head(_)). open_output(Base) :- make_output_directory, html_output_dir(Dir), !, atomic_list_concat([Dir, /, Base, '.html'], HtmlFile), tex_tell(HtmlFile), page_header(Header), put_html_token(html(Header)), put_html_token(html('')), asserta(current_html_output_db(Base)). close_output :- ( retract(current_html_output_db(_)) -> put_html_token(html('')), put_html_token(html('')) ; true ), tex_told. current_html_output(Raw) :- current_html_output_db(File), !, File = Raw. welcome :- welcome([]). welcome(Options) :- option(quiet(true), Options), !. welcome(_Options) :- ltx2htm_version(Version), format(user_error, 'Welcome to LaTeX2HTML version ~w~n~n', [Version]). goodbye(Options) :- option(quiet(true), Options), !. goodbye(_Options) :- html_output_dir(Dir), html_file_base(Html), format(user_error, '~*t~72|~n', [0'*]), format(user_error, 'Translation completed; output written to "~w/~w.html".~n', [Dir, Html]), format(user_error, 'Prolog statistics:~n~n', []), statistics. % translate(+TeX, +Mode, -HTML) translate(TeX, Mode, HTML) :- translate(TeX, Mode, _, HTML). translate([], Mode, Mode, []) :- !. translate([\(Section, -, [{Title}])|T], Mode, Mode, HTML) :- trans_section(Section, Title, T, TitleHtml), !, append(TitleHtml, BodyHtml, HTML), translate(T, Mode, Mode, BodyHtml). translate(['`','`'|T0], Mode0, Mode, [html(' “')|T]) :- \+ in_macro(code(_)), !, translate(T0, Mode0, Mode, T). translate(['\'','\''|T0], Mode0, Mode, [html('” ')|T]) :- \+ in_macro(code(_)), !, translate(T0, Mode0, Mode, T). translate([H0|T0], Mode0, Mode, [H|T]) :- !, translate_1(H0, Mode0, Mode1, H), translate(T0, Mode1, Mode, T). translate(X, Mode, Mode, []) :- format(user_error, 'translate(~p) failed in mode "~w"~n', [X, Mode]). translate_1(Term, Mode0, Mode, HTML) :- ( translate_2(Term, Mode0, Mode, HTML) -> true ; format(user_error, 'translate_2(~p, ~w, ...) failed~n', [Term, Mode0]), Mode = Mode0, HTML = [] ). translate_2(\(Cmd, Mod, Args), Mode0, Mode, HTML) :- % \cmd*{Args} Term =.. [Cmd, Mod|Args], translate_command(Term, Mode0, Mode, HTML). translate_2(\(Cmd, Args), Mode0, Mode, HTML) :- % \cmd{Args} Term =.. [Cmd|Args], translate_command(Term, Mode0, Mode, HTML). translate_2(\Cmd, Mode0, Mode, HTML) :- % \cmd translate_command(Cmd, Mode0, Mode, HTML). translate_2(env(Env, Args, Bdy), Mode0, Mode, HTML) :- % \begin{x} ... \end{x} Term =.. [Env, Args, Bdy], translate_environment(Term, Mode0, Mode, HTML). translate_2($$(Expr), Mode, Mode, #quote(#var(HTML))) :-% $$...$$ tex_atom_to_tokens(Expr, Tokens), translate(Tokens, math, _, HTML). translate_2($(Expr), Mode, Mode, #var(HTML)) :- % $...$ tex_atom_to_tokens(Expr, Tokens), translate(Tokens, math, _, HTML). translate_2(verbatim(_Cmd, Text), Mode, Mode, % \begin{verbatim} ... #pre(code, pre(Text))). translate_2(verb(_, Text), pcecode, pcecode, pre(Text)). translate_2(Layout, pcecode, pcecode, []) :- atomic(Layout), !. translate_2('\n', Mode, Mode, [html('
')]) :- Mode = group(Atts), memberchk(obeylines, Atts), !. translate_2(verb(_, Text), Mode, Mode, #code(Text)). % \verbX...X translate_2([Atom], Mode, Mode, nospace(Atom)) :- % {foo} atomic(Atom). translate_2(Group, Mode, Mode, HTML) :- % {...} Group = [_|_], translate_group(Group, HTML). translate_2(~, Mode, Mode, html(' ')). % ~ translate_2('`', Mode, Mode, html('‘')). % ` translate_2('\'', Mode, Mode, html('’')). % ' translate_2(~, Mode, Mode, html(' ')). % ~ translate_2('\\[]', Mode, Mode, html('[]')). % [] translate_2(Atom0, Mode, Mode, Atom) :- % Normal word atomic(Atom0), ( Mode = group(Atts), memberchk(font(sc), Atts) -> upcase_atom(Atom0, Atom) ; Atom = Atom0 ). translate_group(Group, [HTML, Close]) :- % {...} translate(Group, group([]), MEnd, HTML), ( MEnd = group(Attributes), member(font(EndFont), Attributes), html_font(EndFont, _, Close) -> true ; Close = [] ). translate_command(Cmd, Mode0, Mode, HTML) :- translate_cmd(Cmd, Mode0, Mode, HTML0), expand_macros(HTML0, HTML). translate_cmd(Cmd, Mode0, Mode, HTML) :- tex_extension_module(M), M:cmd(Cmd, Mode0, Mode, HTML), !. translate_cmd(Cmd, Mode, Mode, HTML) :- tex_extension_module(M), M:cmd(Cmd, Mode, HTML), !. translate_cmd(Cmd, Mode, Mode, HTML) :- tex_extension_module(M), M:cmd(Cmd, HTML), !. translate_cmd(Cmd, Mode, Mode, []) :- functor(Cmd, Name, _), format(user_error, 'Failed to translate \\~w in mode "~w"~n', [Name, Mode]), format(user_error, 'Term: "~p"~n', [Cmd]), true. translate_environment(Env, Mode, Mode, HTML) :- translate_env(Env, Mode, Mode, HTML0), expand_macros(HTML0, HTML). translate_env(Env, Mode, Mode, HTML) :- tex_extension_module(M), M:env(Env, HTML), !. translate_env(Env, Mode, Mode, []) :- functor(Env, Name, _), format(user_error, 'Failed to translate \\begin{~w} ... \\end{~w}~n', [Name, Name]), % format(user_error, 'Term: "~p"~n', [Env]), true. /******************************* * LANGUAGE * *******************************/ language_map(figure, 'Figure'). language_map(table, 'Table'). /******************************* * # MACROS * *******************************/ :- dynamic in_anchor/0. % avoid nesting anchors % #(+Macro, -Expansion) % Do HTML macro expansion on the fly. #(tell(_File), []) :- onefile(true). #(tell(File), tell(File)). #(head(Head), [html(''), HtmlHead, Style, html('')]) :- expand_macros(Head, HtmlHead), expand_macros(#style, Style). #(style, [ html('') ]) :- absolute_file_name(latex2html('latex2html.css'), StyleFile, [ access(read) ]), read_file_to_codes(StyleFile, Codes, []), atom_codes(Style, Codes). #(beginbody, html(Body)) :- bodycolor(Colour), !, format(string(Body), '', [Colour]). #(beginbody, html('')). #(endbody, html('')). #(thetitle, Title) :- title(Title). #(theauthor, Author) :- author(Author). #(nameof(Type), Name) :- language_map(Type, Name). #(title(Text), [html(''), Text, html('')]). #(var(Text), [html(''), Text, html('')]). #(code(Text), [html(''), Text, html('')]). #(pre(Text), [html('
'),    Text, html('
')]). #(pre(Class, Text), [html(Begin), Text, html('')]) :- format(atom(Begin), '
', [Class]).
#(xmp(Text),            [html(''),    Text, html('')]).
#(strong(Text),         [html(''), Text, html('')]).
#(em(Text),             [html(''),     Text, html('')]).
#(b(Text),              [html(''),      Text, html('')]).
#(i(Text),              [html(''),      Text, html('')]).
#(tt(Text),             [html(''),   Text, html('')]).
#(sc(Text),             [html(''),
                                           Text, html('')]).
#(div(Class, Text),     [html(Begin), Text, html('')]) :-
    format(atom(Begin), '
', [Class]).
#(span(Class, Text),    [html(Begin), Text, html('')]) :-
    format(atom(Begin), '', [Class]).
#(center(Text),         [ html('
'),
                          Text,
                          html('
')
                        ]).
#(navigate(Text),       [html('
'), Text, html('
')]).
#(right(Text),          [html(''),  Text, html('')]).
#(quote(Text),          [html('
'), Text, html('
')]).
#(listing(Text),        [html('
'), Text,
                         html('
')]).
#(abstract(Text),       [ html('
'),
                          html('
Abstract
'),
                          Text,
                          html('
')
                        ]).
#(footnote(Text),       #footnote(Mark, Text)) :-
    step_counter(footnote, Mark).
#(footnote(Mark, Text), [ html(''), Mark,
                          #span('fn-text', Text),
                          html('')
                        ]).
#(embrace(OC,Text),     [nospace(OA), Text, nospace(CA)]) :-
    string_codes(OC, [O,C]),
    char_code(OA, O),
    char_code(CA, C).
#(embrace(Text),        #embrace("()", Text)).
#(h(Level, Title),      [html(OpenH), Title, html(CloseH)]) :-
    h(Level, OpenH, CloseH).
#(h(Level, NumRef, Title), [h(Level, NumRef, Title), Title, html(CloseH)]) :-
    h(Level, _OpenH, CloseH).
#(predref(RN, Arity),   #lref(pred, Label, Text)) :-
    clean_tt(RN, Name),
    format(string(Text), '~w/~w', [Name, Arity]),
    latex2html4pl:predicate_refname(Name, Arity, Label).
#(dcgref(RN, Arity),   #lref(pred, Label, Text)) :-
    clean_tt(RN, Name),
    format(string(Text), '~w//~w', [Name, Arity]),
    latex2html4pl:dcg_refname(Name, Arity, Label).
#(funcref(RN, Arity),   #lref(function, Label, Text)) :-
    clean_tt(RN, Name),
    format(string(Text), '~w/~w', [Name, Arity]),
    latex2html4pl:function_refname(Name, Arity, Label).
#(row(Columns),         [html(''), HtmlCols, html('')]) :-
    add_td(Columns, HtmlCols).
#(label(Lbl, Text, Tag),label(ALabel, Expanded, Tag)) :-
    atom_string(ALabel, Lbl),
    expand_macros(Text, Expanded).
#(label(Lbl, Text),     label(ALabel, Expanded, -)) :-
    atom_string(ALabel, Lbl),
    expand_macros(Text, Expanded).
#(lref(Label, Text), Expanded) :-
    !,
    #(lref('', Label, Text), Expanded).
#(lref(_, _Label, Text),        Text) :-
    in_anchor,
    !.
#(lref(Class, Label, Text),     lref(Class, ALabel, Expanded)) :-
    canonicalise_label(Label, ALabel),
    asserta(in_anchor),
    expand_macros(Text, Expanded),
    retractall(in_anchor).
#(iflref(Label, Text),  iflref(ALabel, Expanded)) :-
    canonicalise_label(Label, ALabel),
    expand_macros(Text, Expanded).
#(url(_URL, Text),      Text) :-
    in_anchor,
    !.
#(url(URL, Text),       [html(Anchor), Expanded, html('')]) :-
    format(string(Anchor), '', URL),
    setup_call_cleanup(
        asserta(in_anchor, Ref),
        expand_macros(Text, Expanded),
        erase(Ref)).
#(cite(Key),            [ html(''),
                          Cites,
                          html('')
                        ]) :-
    cite_references(Key, cite, Cites).
#(opencite(Key),        [ html(''),
                          Cites,
                          html('')
                        ]) :-
    cite_references(Key, cite, Cites).
#(yearcite(Key),        [ html(''),
                          Cites,
                          html('')
                        ]) :-
    cite_references(Key, yearcite, Cites).
#(nocite(_), []).
#(header,               HTML) :-
    node_header(HTML).
#(header(Tag),          HTML) :-
    node_header(Tag, HTML).
#(footer(Tag),          HTML) :-
    node_footer(Tag, HTML).
#(next_and_prev_references,
        [ #iflref(prevfile,         '[Previous]'), ' ',
          #iflref(nextfile,         '[Next]')
        ]).
#(home_reference,
        [ #iflref(home,             '[Home]')
        ]).
#(Macro, []) :-
    format(user_error,
           'Post-processing macro #~p could not be expanded~n',
           [Macro]),
    gtrace, fail.

add_td([], []).
add_td([H|T0], [html(''), H, html('')|T]) :-
    add_td(T0, T).

cite_references(KeyIn, Functor, Refs) :-
    split(KeyIn, 0',, Keys),
    make_cite_references(Keys, Functor, Refs).

make_cite_references([], _, []).
make_cite_references([Key],    F, [#lref(cite, Key, Term)]) :-
    !,
    Term =.. [F, Key].
make_cite_references([Key|T0], F, [#lref(cite, Key, Term), nospace(','), ' '|T]) :-
    Term =.. [F, Key],
    make_cite_references(T0, F, T).

%       canonicalise_label(+Raw, -Canonical)
%
%       Ensures the label is either an atom, or fileof(Atom), so unification
%       will work properly.

canonicalise_label(Atom, Atom) :-
    atom(Atom),
    !.
canonicalise_label(Atomic, Atom) :-
    atomic(Atomic),
    !,
    atom_string(Atom, Atomic).
canonicalise_label(fileof(In), Out) :-
    onefile(true),
    !,
    canonicalise_label(In, Out).
canonicalise_label(fileof(In), fileof(Out)) :-
    canonicalise_label(In, Out).


%!      expand_macros(Raw, Expanded).
%!      macro_expand(Raw, Expanded).
%
%       Expand +Term, Mode+Term and #Macro commands into plain HTML

macro_expand(In, Out) :-
    expand_macros(In, Out).

expand_macros([], []) :- !.
expand_macros([[]|T0], [T]) :-
    !,
    expand_macros(T0, T).
expand_macros([H0|T0], [H|T]) :-
    !,
    expand_macro(H0, H),
    expand_macros(T0, T).
expand_macros(Macro, Expanded) :-
    expand_macro(Macro, Expanded).

expand_macro(+Term, HTML) :-
    !,
    translate(Term, normal, HTML0),
    expand_macros(HTML0, HTML).
expand_macro(Mode+Term, HTML) :-
    !,
    translate(Term, Mode, HTML0),
    expand_macros(HTML0, HTML).
expand_macro(#Macro, HTML) :-
    tex_extension_module(M),
    M:'#'(Macro, HTML0),
    !,
    push_macro(Macro),
    expand_macros(HTML0, HTML),
    pop_macro.
expand_macro(List, Expanded) :-
    List = [_|_],
    !,
    expand_macros(List, Expanded).
expand_macro(NoExpand, NoExpand).

push_macro(Macro) :-
    nb_current(macro_stack, Stack),
    !,
    b_setval(macro_stack, [Macro|Stack]).
push_macro(Macro) :-
    b_setval(macro_stack, [Macro]).

pop_macro :-
    nb_current(macro_stack, [_|Stack]),
    !,
    b_setval(macro_stack, Stack).

in_macro(Env) :-
    nb_current(macro_stack, Stack),
    \+ \+ memberchk(Env, Stack).


                 /*******************************
                 *             CITES            *
                 *******************************/

:- dynamic
    cite/2.                         % Key, Cite (HTML)

reset_cites :-
    retractall(cite(_, _)).

                 /*******************************
                 *             FLOAT            *
                 *******************************/

:- dynamic
    current_float/2.                % Type, Number

:- meta_predicate
    do_float(+, 0).

%       do_float(+Type(+Number), +Goal)
%
%       Run goal, registering the current float object processed.

do_float(Term, Goal) :-
    functor(Term, Type, 1),
    arg(1, Term, Number),
    asserta(tex:current_float(Type, Number), Ref),
    ignore(Goal),
    erase(Ref).


                 /*******************************
                 *            LABEL/REF         *
                 *******************************/

:- dynamic
    label/3,                        % Label, File, Index
    next_file/2,                    % File, NextFile
    section_label/2.                % Label, SecNr

reset_labels :-
    retractall(label(_, _, _)),
    retractall(next_file(_, _)),
    retractall(section_label(_, _)).

collect_labels([], _) :- !.
collect_labels([tell(File)|T], PreviousFile) :-
    !,
    (   PreviousFile \== File
    ->  assert(next_file(PreviousFile, File))
    ;   true
    ),
    collect_labels(T, File).
collect_labels([label(Label, _, Tag)|T], File) :-
    !,
    assert(label(Label, File, Tag)),
    collect_labels(T, File).
collect_labels([_|T], File) :-
    collect_labels(T, File).

label_tag(_Label, Tag) :-
    current_float(_, Tag),
    !.
label_tag(Label, Tag) :-
    section_tag(Tag),
    (   sub_atom(Label, 0, _, _, 'sec:')
    ->  atom_concat('sec:', Tag, SecTag),
        assert(section_label(Label, SecTag))
    ;   true
    ).


                 /*******************************
                 *          ENVIRONMENTS        *
                 *******************************/

%       env(+Env, -HTML)
%
%       Translate an environment.

env(pcecode(_, Tokens), #pre(code, HTML)) :-
    translate(Tokens, pcecode, HTML).
env(summarylist(_, Summary),
    [ html(''),
      +Summary,
      html('
')
    ]).
env(parameters(_, Paramlist),           % Deprecated
    [ html(''),
      Body,
      html('
')
    ]) :-
    table_body(Paramlist, [[], []], Body).
env(arguments(_, Arglist),
    [ html(''),
      Body,
      html('
')
    ]) :-
    table_body(Arglist, [[], []], Body).
env(comment(_, _), []).
env(htmlonly(_, Tokens), HTML) :-
    translate(Tokens, normal, HTML).
env(document(_, Contents), HTML) :-
    !,
    translate(Contents, document, HTML).
env(quote(_, Tokens), #quote(Quote)) :-
    translate_group(Tokens, Quote).
env(abstract(_, Tokens), #abstract(Quote)) :-
    translate(Tokens, normal, Quote).
env(center(_, Tokens), HTML) :-
    phrase(only_table(Table), Tokens),
    setup_call_cleanup(
        asserta(center_tables, Ref),
        translate([Table], normal, HTML),
        erase(Ref)).
env(center(_, Tokens), #center(Center)) :-
    translate(Tokens, normal, Center).
env(titlepage(_, _Page), []) :-
    (   quiet
    ->  true
    ;   format(user_error, 'Ignored the titlepage~n', [])
    ).
env(tabular([{Format}], Tokens), HTML) :-
    translate_table(Format, Tokens, HTML).
env(tabulary([_Width, {Format}], Tokens), HTML) :-
    translate_table(Format, Tokens, HTML).
env(array([{Format}], Tokens), HTML) :-
    translate_table(Format, Tokens, HTML).
env(table(_, Tokens), Table) :-
    step_counter(table, Tab),
    asserta(current_float(table, Tab), Ref),
    translate(Tokens, normal, Table),
    erase(Ref).
env(figure(_, Tokens), Figure) :-
    step_counter(figure, Fig),
    asserta(current_float(figure, Fig), Ref),
    translate(Tokens, normal, Figure),
    erase(Ref).
env(minipage(_, Tokens), Page) :-
    translate(Tokens, normal, Page).
env(thebibliography(Args, Tokens),
    [ SectionHeader,
      Open,
      HtmlItems,
      Close
    ]) :-
    memberchk(\newblock, Tokens),
%       writeln(Tokens),
    (   user_cmd(refname, document, _, Title)
    ->  true
    ;   Title = ['Bibliography']
    ),
    (   documentclass(article)
    ->  SecLevel = 2,
        Number = *
    ;   SecLevel = 1,
        Number = -
    ),
    translate_section(SecLevel, Number, Title, SectionHeader,
                      'Bibliography'),
    List = thebibliography,
    (   list_command(List, Args, Open, Close),
        items(Tokens, Items),
        translate_items(Items, List, HtmlItems)
    ->  true
    ;   format(user_error, 'Failed to translate "~w" list~n', [List])
    ).
env(thebibliography(_Args, _Tokens), []) :- !.
env(Env, [Open, HtmlItems, Close]) :-           % General lists
    functor(Env, List, _),
    tex_environment_function(List, list),
    !,
    arg(1, Env, Args),
    arg(2, Env, Tokens),
    (   tex_extension_module(M),
        M:list_command(List, Args, Open, Close),
        items(Tokens, Items),
        translate_items(Items, List, HtmlItems)
    ->  true
    ;   format(user_error, 'Failed to translate "~w" list~n', [List])
    ).

list_command(description,     _, html('
'), html('
')).
list_command(dlist,           _, html('
'), html('
')).
list_command(itemize,         _, html('
    '), html('
')).
list_command(itemlist,        _, html('
    '), html('
')).
list_command(shortlist,       _, html('
    '), html('
')).
list_command(enumerate,       _, html('
    '), html('
')).
list_command(thebibliography, _, html('
'), html('
')).

%       items(+Tokens, -Items)
%
%       Translate the item-list of a list-environment into a nested list,
%       where each first element is the item command, and the others are
%       the tokens of the item.

items([], []).
items([Cmd|More], [[Cmd|ItemTokens]|Items]) :-
    functor(Cmd, \, _),
    arg(1, Cmd, TexCmd),
    tex_command_function(TexCmd, item),
    !,
    item_commands(More, ItemTokens, Rest),
    items(Rest, Items).
items([Token|More], List) :-
    (   no_item_token(Token)
    ->  true
    ;   format(user_error, 'Skipped "~w"; no item~n', [Token])
    ),
    items(More, List).

%       no_item_token(+Token)
%
%       Succeeds if Tokens is a token that may appear before the first
%       item of a list, and should not be translated.

no_item_token(' ').
no_item_token('\n').
no_item_token(\par).
no_item_token(\(setlength, _)).
no_item_token(\(newcommand, _)).

item_commands(List, [], List) :-
    List = [Cmd|_],
    functor(Cmd, \, _),
    arg(1, Cmd, TexCmd),
    tex_command_function(TexCmd, item),
    !.
item_commands([H|T0], [H|T1], T2) :-
    item_commands(T0, T1, T2).
item_commands([], [], []).

%       translate_items(+ItemTokens, +List, -HTMLTokens)
%
%       Translate the TeX tokens for a list-item.  List is passed as context,
%       to ensure proper translation.

translate_items([], _, []).
translate_items([H0|T0], List, [H1|T1]) :-
    translate(H0, List, _, H1),
    translate_items(T0, List, T1).


                 /*******************************
                 *        ACTIVE COMMANDS       *
                 *******************************/

prolog_function(\(usepackage, [_,{File},_])) :-
    (   package_alias(File, Alias),
        (   atom_concat(sty_, Alias, Extension)
        ;   Extension = Alias
        ),
        member(Term, [tex(Extension), latex2html(Extension)]),
        absolute_file_name(Term, PlFile,
                           [ extensions([pl, qlf]),
                             access(read),
                             file_errors(fail)
                           ])
    ->  ensure_loaded(user:PlFile)
    ;   true
    ).
prolog_function(\(newcommand, [{Name}, [], {Expanded}])) :-
    declare_command(Name, 0, Expanded).
prolog_function(\(newcommand, [{Name}, [Args], {Expanded}])) :-
    declare_command(Name, Args, Expanded).
prolog_function(\(renewcommand, [{Name}, [], {Expanded}])) :-
    declare_command(Name, 0, Expanded).
prolog_function(\(renewcommand, [{Name}, [Args], {Expanded}])) :-
    declare_command(Name, Args, Expanded).

package_alias(pl, pldoc) :- !.
package_alias(Pkg, Pkg).


                 /*******************************
                 *            COMMANDS          *
                 *******************************/

:- dynamic
    documentclass/1.

%!  cmd(+Command, +Mode, -HTML)
%

cmd(onefile, preamble, []) :-
    retractall(onefile(_)),
    assert(onefile(true)).
cmd(htmlpackage({File}), preamble, []) :-
    (   absolute_file_name(tex(File), PlFile,
                           [ extensions([pl, qlf]),
                             access(read),
                             file_errors(fail)
                           ])
    ->  ensure_loaded(user:PlFile)
    ;   format(user_error, 'Cannot find Prolog extension "~w"~n', [File])
    ).
cmd(documentclass(_, {Class}), preamble, []) :-
    assert(documentclass(Class)).
cmd(usepackage(_, {_File}, _), preamble, []) :- !.
cmd(makeindex, preamble, []) :-
    retractall(makeindex(_)),
    asserta(makeindex(true)).
cmd(vskip(_), pcecode, verb('\n')).
cmd(lineno({_Line}), pcecode, verb('\n')).

%       cmd(+Command, -HTML)

cmd(newcommand({Name}, [], {Expanded}), []) :-
    declare_command(Name, 0, Expanded).
cmd(newcommand({Name}, [Args], {Expanded}), []) :-
    declare_command(Name, Args, Expanded).
cmd(renewcommand({Name}, [], {Expanded}), []) :-
    declare_command(Name, 0, Expanded).
cmd(renewcommand({Name}, [Args], {Expanded}), []) :-
    declare_command(Name, Args, Expanded).
cmd(def({'\\booktitle'}, {Title}), HTML) :-
    cmd(title({[Title]}), HTML).
cmd(def(_, _), []).
cmd(sloppy, []).
cmd(noindent, []).
cmd(clearpage, []).
cmd(cleardoublepage, []).
cmd(nopagebreak, []).
cmd(pagebreak, []).
cmd(linebreak, [html('
')]).
cmd(newpage, []).
cmd(hyphenpenalty(_), []).
cmd(newlength(_), []).
cmd(setlength(_,_), []).
cmd(settowidth(_, _), []).
cmd(setcounter({page}, _), []).
cmd(vskip(_), [html('
')]).
cmd(vspace(_), [html('
')]).
cmd(hspace(_), []).
cmd(headheight(_), []).
cmd(footheight(_), []).
cmd(vfill, [html('
')]).
cmd(vfil, [html('
')]).
cmd(hfill, []).
cmd(/, []).
cmd(and, [html('
')]).
cmd(leavevmode, []).
cmd(parskip(_), []).
cmd(parindent(_), []).
cmd(raggedright, []).                   % Always in HTML
cmd(tableofcontents,
    [ #tell('Contents'),
      #header(contents),
      #h(1, #label('document-contents', 'Table of Contents')),
      tableofcontents(document)
    ]).
cmd(printindex, []).

cmd(par, html('
')).                          % \par
cmd(\([]), html('
')).                       % \\
cmd(\([_Skip]), html('
')).                   % \\[skip]
cmd(newline, html('
')).                     % \newline

cmd(part({Title}), #h(1, +Title)).              % \part

cmd(chapter(M, {Title}), HTML) :-               % \chapter, \section, ...
    translate_section(1, M, Title, HTML).
cmd(section(M, {Title}), HTML) :-
    translate_section(2, M, Title, HTML).
cmd(subsection(M, {Title}), HTML) :-
    translate_section(3, M, Title, HTML).
cmd(subsubsection(M, {Title}), HTML) :-
    translate_section(4, M, Title, HTML).
cmd(paragraph({Title}), [#b(+Title), ' ']).
cmd(subparagraph({Title}), [#b(+Title), ' ']).

cmd(label({Label}), #label(Label, [], Tag)) :-  % \label and \xyzref
    label_tag(Label, Tag).
cmd(ref({RefName}), #lref(ref, RefName, ref(RefName))).
cmd(pageref({RefName}), #lref(ref, RefName, ref(RefName))).

cmd(secref({Label}), HTML) :-
    translate_reference(section, sec, Label, HTML).
cmd('Secref'({Label}), HTML) :-
    translate_reference('Section', sec, Label, HTML).
cmd(chapref({Label}), HTML) :-
    translate_reference(chapter, sec, Label, HTML).
cmd('Chapref'({Label}), HTML) :-
    translate_reference('Chapter', sec, Label, HTML).
cmd(figref({Label}), HTML) :-
    translate_reference(figure, fig, Label, HTML).
cmd('Figref'({Label}), HTML) :-
    translate_reference('Figure', fig, Label, HTML).
cmd(tabref({Label}), HTML) :-
    translate_reference(table, tab, Label, HTML).
cmd('Tabref'({Label}), HTML) :-
    translate_reference('Table', tab, Label, HTML).
cmd(appref({Label}), HTML) :-
    translate_reference(appendix, sec, Label, HTML).
cmd('Appref'({Label}), HTML) :-
    translate_reference('Appendix', sec, Label, HTML).
cmd(ifthenelse({Cond},{If},{Else}), [Result]) :-
    (   eval_if_then_else(Cond)
    ->  Result = If
    ;   Result = Else
    ).
cmd(title({Title}), []) :-                      % \title
    retractall(title(_)),
    translate(Title, title, HTML),
    assert(title(HTML)).
cmd(author({Author}), []) :-                    % \author
    retractall(author(_)),
    translate(Author, normal, HTML),
    assert(author(HTML)).
cmd(bodycolor({BG}), []) :-                     % \bodycolor
    retractall(bodycolor(_)),
    assert(bodycolor(BG)).
cmd(linkimage({Name}, {Icon}), []) :-           % \linkimage{Id, Path}
    make_output_directory,
    html_output_dir(Dir),
    absolute_file_name(img(Icon), Path),
    file_base_name(Path, Base),
    atomic_list_concat([Dir, Base], /, To),
    copy_file(Path, To),
    asserta(link_image(Name, Base)).
cmd(htmloutput({Dir}), []) :-
    (   done_make_output_directory
    ->  format(user_error,
               'Cannot change output directory after output has started~n',
               []),
        fail
    ;   clean_tt(Dir, Clean),
        retract(html_output_dir(_)),
        !,
        asserta(html_output_dir(Clean))
    ).
cmd(htmlmainfile({File}), []) :-
    retractall(html_file_base(_)),
    assert(html_file_base(File)).
cmd(htmlfiledepth({Depth}), []) :-
    atom_codes(Depth, Chars),
    number_codes(D, Chars),
    retractall(html_split_level(_)),
    assert(html_split_level(D)).

cmd(maketitle,                                  % \maketitle
    [ #div(title, #thetitle),
      #div(author, #theauthor)
    ]).

cmd(newblock, []).                              % BiBTeX \newblock
cmd(protect, []).                               % BiBTeX produced?
cmd(citename({TeX}), HTML) :-
    translate_group([\sc|TeX], HTML).
cmd(bibitem([TeXCite], {Key}),                  % \bibitem
    [ html('
'), #label(Key, #strong(Cite)),
      html('
') ]) :-
    translate(TeXCite, normal, Cite),
    assert(cite(Key, Cite)).
cmd(bibitem([], {Key}),
    [ html('
'), #label(Key, #strong(Cite)),
      html('
') ]) :-
    flag(cite, N, N+1),
    TeXCite is N + 1,
    expand_macros(#embrace("[]", TeXCite), Cite),
    assert(cite(Key, Cite)).
cmd(cite({Key}),        #cite(Key)).            % \cite
cmd(nocite({Key}),      #nocite(Key)).          % \nocite
cmd(yearcite({Key}),    #yearcite(Key)).        % \yearcite
cmd(opencite({Key}),    #opencite(Key)).        % \opencite
cmd(bibliography({_}), HTML) :-                 % \bibliography
    tex_file_base(File),
    (   absolute_file_name(tex(File), BiBFile,
                           [ extensions([bbl]),
                             access(read),
                             file_errors(fail)
                           ])
    ->  tex_tokens(BiBFile, TeXTokens),
        translate(TeXTokens, file, HTML)
    ;   format(user_error, 'No bibliography file~n', []),
        HTML = []
    ).
cmd(bibliographystyle(_), []).                  % \bibliographystyle
cmd(',', []).                                   % \,
cmd(-, []).                                     % \- (stop hyphenation)

cmd(emph({Tex}),   #em(+Tex)).                  % \emph{text}
cmd(texttt({Tex}), #tt(+Tex)).                  % \texttt{text}
cmd(textbf({Tex}), #b(+Tex)).                   % \textbf{text}
cmd(textit({Tex}), #i(+Tex)).                   % \textit{text}
cmd(mathit({Tex}), #i(+Tex)).                   % \mathit{text}
cmd(textsf({Tex}), #b(+Tex)).                   % \textsf{text}
cmd(textsc({Tex}), #sc(+Tex)).                  % \textsc{text}

cmd(year,       Year) :-                        % \year
    get_time(Time),
    convert_time(Time, Year, _, _, _, _, _, _).
cmd('LaTeX',    'LaTeX').                       % \LaTeX
cmd('TeX',      'TeX').                         % \TeX

cmd(index({Term}), #label(RefName, [])) :-      % \index
    translate_index(Term, RefName).
cmd(idx({Term}), #label(RefName, Term)) :-      % \idx
    translate_index(Term, RefName).

cmd(footnote({TeX}), #(footnote(+TeX))).        % \footnote
cmd(footnotetext([Num], {Tokens}), [html('
'), #embrace(Num), Text]) :-
    translate(Tokens, normal, Text).

cmd(pagenumbering(_), []).                      % pagestyle stuff
cmd(pagestyle(_),     []).
cmd(thispagestyle(_), []).
cmd(fancyplain(_),    []).
cmd(lhead(_,_),       []).
cmd(chead(_,_),       []).
cmd(rhead(_,_),       []).
cmd(lfoot(_,_),       []).
cmd(cfoot(_,_),       []).
cmd(rfoot(_,_),       []).
cmd(rightmark,        []).
cmd(leftmark,         []).
cmd(footrulewidth(_), []).

cmd(centerline({Tex}), #center(+Tex)).
cmd(rightline({Tex}), #right(+Tex)).

cmd(email({Address}), #url(URL, Address)) :-
    format(string(URL), 'mailto:~w', [Address]).
cmd(url({Address}), #url(Address, Address)).
cmd(href({URL}, {Text}), #url(URL, +Text)).
cmd(file({File}), #tt(File)).
cmd(strong(             {A1}), #strong(+A1)).
cmd(tick({Tokens}),
    [ html('
  • '), html(''), Tag, html(''), html('
    ') ]) :-
    translate_group(Tokens, Tag).
cmd(item([]), html('
  • ')).
cmd(item([Tag]),
    [ html('
  • '), html(''), +Tag, html(''), html('
    ') ]).
cmd(mbox({Boxed}), HTML) :-
    translate_group(Boxed, HTML).
cmd(makebox(_, _, {Boxed}), HTML) :-
    translate_group(Boxed, HTML).
cmd(raisebox(_, {Boxed}), HTML) :-
    translate_group(Boxed, HTML).
cmd(parbox(_, _, {Boxed}), HTML) :-
    translate_group(Boxed, HTML).
cmd(string({Text}), nospace(Text)).
cmd(ldots, '...').
cmd(cline(_), []).
cmd('%', nospace('%')).
cmd('#', nospace('#')).
cmd('$', nospace('$')).
cmd('&', nospace('&')).
cmd('{', nospace('{')).
cmd('}', nospace('}')).
cmd('[', nospace('[')).
cmd(']', nospace(']')).
cmd('"'({'\\i'}), html('ï')).      % \"\i
cmd('"'({C}), html(Cmd)) :-             % \"[ouey...]
    atomic_list_concat([&, C, 'uml;'], Cmd).
cmd(''''({C}), html(Cmd)) :-            % \'[ouey...]
    atomic_list_concat([&, C, 'acute;'], Cmd).
cmd(' ', nospace(' ')).                 % :-)
cmd(copyright, html('©')).         % \copyright
cmd(tm, html('®')).                 % \tm
cmd(alpha, html('α')).
cmd(beta, html('β')).
                                        % old stuff (< HTML 3)
cmd(alpha, #var(a)).                    % \alpha
cmd(beta, #var(b)).                     % \beta
cmd(tm, #embrace(tm)).                  % \tm
cmd(sum,  html('Σ')).             % \sum

cmd(include({File}), HTML) :-
    absolute_file_name(tex(File), TeXFile,
                       [ extensions([tex]),
                         access(read),
                         file_errors(error)
                       ]),
    tex_tokens(TeXFile, TeXTokens),
    translate(TeXTokens, file, HTML).
cmd(input({File}), []) :-
    file_name_extension(_, sty, File),
    !.
cmd(input({File}), HTML) :-
    absolute_file_name(tex(File), TeXFile,
                       [ extensions([tex, '']),
                         access(read),
                         file_errors(error)
                       ]),
    tex_tokens(TeXFile, TeXTokens),
    translate(TeXTokens, file, HTML).
cmd('InputIfFileExists'({File},{True},{False}), HTML) :-
    (   absolute_file_name(tex(File), TeXFile,
                           [ extensions([tex, '']),
                             access(read),
                             file_errors(fail)
                           ])
    ->  HTML = [+True|FileHTML],
        tex_tokens(TeXFile, TeXTokens),
        translate(TeXTokens, file, FileHTML)
    ;   HTML = [+False]
    ).
cmd('IfFileExists'({File},{True},{False}), HTML) :-
    (   absolute_file_name(tex(File), _TeXFile,
                           [ extensions([tex, '']),
                             access(read),
                             file_errors(fail)
                           ])
    ->  HTML = [+True]
    ;   HTML = [+False]
    ).
cmd(appendix, []) :-
    appendix.
cmd(caption({Caption}),
    [ html('
    '),
      #b([#nameof(Type), ' ', Number, ':', ' ']),
      +Caption,
      html('
    ')
    ]) :-
    current_float(Type, Number).

cmd(psdirectories({Spec}), []) :-
    split(Spec, 0',, Dirs),
    retractall(user:file_search_path(psfig, _)),
    forall(member(D, Dirs),
           assert(user:file_search_path(psfig, tex(D)))).
cmd(psfig({Spec}), html(Img)) :-
    psfig_options(Spec, Options),
    member(figure(File), Options),
    file_name_extension(Base, Ext, File),
    ps_extension(Ext),
    file_base_name(Base, GifBase),
    file_name_extension(GifBase, gif, GifFile),
    format(string(Img), '', GifFile),
    make_output_directory,
    html_output_dir(Dir),
    atomic_list_concat([Dir, '/', GifFile], OutFile),
    (   keep_figures(true),
        exists_file(OutFile)
    ->  true
    ;   (   is_absolute_file_name(Base)
        ->  FileSpec = Base
        ;   FileSpec = tex(Base)
        ),
        ps2gif(FileSpec, OutFile)
    ).
cmd(includegraphics(_Options, {File}), html(Img)) :-
    findall(Ext, img_extension(Ext), Exts),
    (   is_absolute_file_name(File)
    ->  Spec = File
    ;   Spec = includegraphics(File)
    ),
    absolute_file_name(Spec, AbsImgFile,
                       [ extensions([''|Exts]),
                         access(read),
                         file_errors(fail)
                       ]),
    file_name_extension(_, Ext, AbsImgFile),
    img_extension(Ext),
    !,
    file_base_name(AbsImgFile, ImgFile),
    format(string(Img), '', ImgFile),
    make_output_directory,
    html_output_dir(Dir),
    atomic_list_concat([Dir, '/', ImgFile], OutFile),
    (   keep_figures(true),
        exists_file(OutFile)
    ->  true
    ;   copy_file(AbsImgFile, OutFile)
    ).
cmd(includegraphics(_Options, {File}), html(Img)) :-
    ps_extension(Ext),
    absolute_file_name(includegraphics(File), PsFile,
                       [ extensions([Ext]),
                         access(read),
                         file_errors(fail)
                       ]),
    file_name_extension(Base, Ext, PsFile),
    file_base_name(Base, GifBase),
    file_name_extension(GifBase, gif, GifFile),
    format(string(Img), '', GifFile),
    make_output_directory,
    html_output_dir(Dir),
    atomic_list_concat([Dir, '/', GifFile], OutFile),
    (   keep_figures(true),
        exists_file(OutFile)
    ->  true
    ;   ps2gif(PsFile, OutFile)
    ).
cmd(postscript({_Width}, {File}, Title),
    [ LabelHTML,
      ImgHTML,
      html('
    '),
      Caption
      ]) :-
    file_name_extension(File, gif, GifFile),
    atom_concat('fig:', File, Label),
    step_counter(figure, Fig),
    do_float(figure(Fig),
             (   translate_command(caption(Title), float, _, Caption),
                 translate_command(label({Label}), float, _, LabelHTML)
             )),
    centered_img(GifFile, ImgHTML),
    make_output_directory,
    current_setting(html_output_dir(Dir)),
    atomic_list_concat([Dir, '/', GifFile], OutFile),
    (   current_setting(keep_figures),
        exists_file(OutFile)
    ->  true
    ;   ps2gif(psfig(File), OutFile, [margin(5)])
    ).
cmd(postscriptfig(_Options, {File}, Title),
    [ LabelHTML,
      ImgHTML,
      html('
    '),
      Caption
    ]) :-
    (   absolute_file_name(psfig(File), ImgPath,
                           [ extensions([png,gif]),
                             file_errors(fail),
                             access(read)
                           ])
    ->  file_base_name(ImgPath, ImgFile)
    ;   file_name_extension(File, gif, ImgFile)
    ),
    atom_concat('fig:', File, Label),
    step_counter(figure, Fig),
    do_float(figure(Fig),
             (   translate_command(caption(Title), float, _, Caption),
                 translate_command(label({Label}), float, _, LabelHTML)
             )),
    centered_img(ImgFile, ImgHTML),
    make_output_directory,
    current_setting(html_output_dir(Dir)),
    directory_file_path(Dir, ImgFile, OutFile),
    (   current_setting(keep_figures),
        exists_file(OutFile)
    ->  true
    ;   nonvar(ImgPath)
    ->  copy_file(ImgPath, OutFile)
    ;   ps2gif(psfig(File), OutFile, [margin(5)])
    ).

centered_img(File, html(HTML)) :-
    format(string(HTML),
           '
    ', File).

ps_extension(eps).
ps_extension(ps).

img_extension(gif).
img_extension(png).
img_extension(jpg).
img_extension(jpeg).

%
%       HTML documentation
%

cmd('HTML'({Tag}),      #code(Tag)).
cmd(latexcmd({Cmd}),    #code(BslCmd)) :-
    atom_concat(\, Cmd, BslCmd).
cmd(latexenv({Env}),    #code(Env)).
cmd(mode({Mode}),       #code(Mode)).


%
%       cmd(+Command, +Mode, -HTML
%

cmd(item([Tag]), description,                   % \item in description
    [ html('
    '), #b(+Tag), html('
    ') ]).
cmd(item([Tokens]), itemlist,                   % \item in itemlist
    [ html('
  • '), html(''), Tag, html(''), html('
    ') ]) :-
    translate_group(Tokens, Tag).

cmd(times, math, [' ', html('×'), ' ']).
cmd(wedge, math, ['/\\']).
% Simple arrows
cmd(leftarrow, math, [html('←')]).
cmd(rightarrow, math, [html('→')]).
cmd(leftrightarrow, math, [html('↔')]).
% Long arrows
cmd(longleftarrow, math, [html('⟵')]).
cmd(longrightarrow, math, [html('⟶')]).
cmd(longleftrightarrow, math, [html('⟷')]).
% Double arrows
cmd('Leftarrow', math, [html('⇐')]).
cmd('Rightarrow', math, [html('⇒')]).
cmd('Leftrightarrow', math, [html('⇔')]).
% Long double arrows
cmd('Longleftarrow', math, [html('⟸')]).
cmd('Longrightarrow', math, [html('⟹')]).
cmd('Longleftrightarrow', math, [html('⟺')]).

cmd(pi, math, 'pi').
cmd(mu, math, html('μ')).
cmd(circ, math, html('ο')).
cmd(rhd, math, html('>')).
cmd(leq, math, '&8804#').
cmd(equiv, math, '==').
cmd(geq, math, '&8805#').
cmd(ge, math, '>').
cmd(le, math, '<').
cmd(mid, math, '|').
cmd(pm, math, html('±')).
cmd(langle, math, '<').
cmd(rangle, math, '>').
cmd(sin({Arg}), math, ['sin(', math+Arg, ')']).
cmd(cos({Arg}), math, ['cos(', math+Arg, ')']).
cmd(tan({Arg}), math, ['tan(', math+Arg, ')']).
cmd(sinh({Arg}), math, ['sinh(', math+Arg, ')']).
cmd(cosh({Arg}), math, ['cosh(', math+Arg, ')']).
cmd(tanh({Arg}), math, ['tanh(', math+Arg, ')']).
cmd(arcsin({Arg}), math, ['arcsin(', math+Arg, ')']).
cmd(arccos({Arg}), math, ['arccos(', math+Arg, ')']).
cmd(arctan({Arg}), math, ['arctan(', math+Arg, ')']).
cmd(ln({Arg}), math, ['ln(', math+Arg, ')']).
cmd(lg({Arg}), math, ['log10(', math+Arg, ')']).
cmd(log({Arg}), math, ['log(', math+Arg, ')']).
cmd(sqrt({Arg}), math, ['&8730;(', math+Arg, ')']).
cmd(not({=}), math, html('&ne')).
cmd(neq, math, html('&ne')).
cmd(exists, math, html('&exist')).
cmd(emptyset, math, html('Ø')).
cmd(subset, math, '&8834;').
cmd(frac({A1}, {A2}), math, [math+A1, '/', math+A2]).
cmd(mod({A1}, {A2}), math, [math+A1, ' ', 'mod', ' ', math+A2]).
cmd(rem({A1}, {A2}), math, [math+A1, ' ', 'rem', ' ', math+A2]).
cmd(div, math, div).
cmd(pow({A1}, {A2}), math, [math+A1, '**', math+A2]).
cmd(tt, math, []).                      % just ignore?

cmd(\([]), title, ' ').                 % ignore \\ in title

%
% cmd(+Command, +Mode0, -Mode, -HTML
%

cmd(Cmd, Mode0, Mode, HTML) :-
    user_cmd(Cmd, Mode0, Mode, HTML),
    !.
cmd(obeylines, group(Atts), group([obeylines|Atts]), []).
cmd(Font, group(Old), group([font(Font)|Old1]), HTML) :-
    html_font(Font, Open, _),
    !,
    (   select(font(OldFont), Old, Old1),
        html_font(OldFont, _, Close)
    ->  HTML = [Close,Open]
    ;   Old1 = Old,
        HTML = Open
    ).

html_font(em,           html(''),           html('')).
html_font(bf,           html(''),            html('')).
html_font(it,           html(''),            html('')).
html_font(mathit,       html(''),            html('')).
html_font(cal,          html(''),            html('')).
html_font(tt,           html(''),         html('')).
html_font(sf,           html(''),            html('')).
html_font(sc,           html(''),
                                                html('')).
html_font(rm,           [],                     []).
html_font(sl,           html(''),            html('')).
html_font(scriptsize,   [],                     []).
html_font(footnotesize, html(''), html('')).
html_font(small,        html(''), html('')).
html_font(normalsize,   [],                     []).
html_font(large,        html(''), html('')).
html_font('Large',      html(''), html('')).
html_font('Huge',       html(''), html('')).


                 /*******************************
                 *          \REF, ETC.          *
                 *******************************/

%!  translate_reference(+Name, +Tag, +Label, -HTML)
%
%   Used for the translation of \secref, \figref, etc.

translate_reference(Name, Tag, Label,
          #lref(Tag, RefName, [Name, ' ', ref(RefName)])) :-
    format(atom(RefName), '~w:~w', [Tag, Label]).


%!  eval_if_then_else(+Cond) is semidet.
%
%   Currently only evaluates whether a command is empty, as in
%   \ifthenelse{\equal{}{\command}}{Then}{Else}

eval_if_then_else([\(equal,[{[]},{[\Command]}])]) :-
    clause(user_cmd(Command, Mode, Mode, HTML),
           expand_macro(macro_arg, '', Mode, Mode, HTML)),
    !.
eval_if_then_else(Cond) :-
    format('Cond = ~p~n', [Cond]).

                 /*******************************
                 *            TTY STUFF         *
                 *******************************/

%       clean_tt(+Raw, -Clean)
%
%       Cleans the TeX escapes to write down weird predicate names from
%       the input.

clean_tt([Atom], Atom) :-
    atomic(Atom),
    !.
clean_tt('\\Sdot', '.') :- !.
clean_tt(Raw, Clean) :-
    atom_codes(Raw, S0),
    (   append([0'{], S1, S0),
        append(S2, [0'}], S1)
    ->  true
    ;   S2 = S0
    ),
    (   append([0'\\, 0't, 0't], S3, S2)
    ->  true
    ;   S3 = S2
    ),
    clean_specials(S3, S4),
    replace_all(S4, "\\ldots", "...", S5),
    replace_all(S5, "\\bsl{}", "\\", S6),
    delete_all(S6, "\\string", S7),
    delete_all(S7, " ", S8),
    replace_all(S8, "~", " ", S9),
    atom_codes(Clean, S9).

clean_specials([], []).
clean_specials([0'\\, Special|T0], [Special|T]) :-
    string_code(_, "#$&%{}", Special),
    !,
    clean_specials(T0, T).
clean_specials([H|T0], [H|T]) :-
    clean_specials(T0, T).

delete_all(S0, DS, S) :-
    string_codes(DS, D),
    delete_all_codes(S0, D, S).

delete_all_codes(S0, D, S) :-
    (   append(D, Post, P2)
    ->  (   append(P1, P2, S0)
        ->  append(P1, Post, S1),
            delete_all_codes(S1, D, S)
        ;   S = S0
        )
    ).

replace_all(S0, FS, TS, S) :-
    string_codes(FS, F),
    string_codes(TS, T),
    replace_all_codes(S0, F, T, S).

replace_all_codes(S0, F, T, S) :-
    (   append(F, Post, P2)
    ->  (   append(P1, P2, S0)
        ->  append(P1, T, S1),
            append(S1, Post, S2),
            replace_all_codes(S2, F, T, S)
        ;   S = S0
        )
    ).


                 /*******************************
                 *           CASE (\SC)         *
                 *******************************/

upcase_html([], []).
upcase_html([H0|T0], [H|T]) :-
    atomic(H0),
    !,
    upcase_atom(H0, H),
    upcase_html(T0, T).
upcase_html([H|T0], [H|T]) :-
    upcase_html(T0, T).

capitalise_atom(In, Out) :-
    atom_codes(In, S0),
    capitalise(S0, S1, up),
    atom_codes(Out, S1).

capitalise([], [], _).
capitalise([H0|T0], [H|T], up) :-
    is_lower(H0),
    !,
    to_upper(H0, H),
    capitalise(T0, T, down).
capitalise([H|T0], [H|T], up) :-
    capitalise(T0, T, up).
capitalise([H|T0], [H|T], down) :-
    is_alpha(H),
    !,
    capitalise(T0, T, down).
capitalise([H|T0], [H|T], down) :-
    capitalise(T0, T, up).


                 /*******************************
                 *             SECTION          *
                 *******************************/

:- dynamic
    section_counter_array/1,        % counters(L0, L1, ...)
    section/3,                      % Level, Tag, Title
    appendix_section/1.             % First number of appendix

reset_sections :-
    retractall(section(_,_,_)),
    retractall(section_counter_array(_)),
    retractall(appendix_section(_)).

appendix :-
    section_counter_array(Counters),
    arg(1, Counters, Chapter),
    asserta(appendix_section(Chapter)).

%       trans_section(+SectionCmd, +TexTitle, +RestDocument, -HTML
%
%       Allow look-ahead for \label{}, so the label can be used to
%       generate the section filename.

trans_section(Section, Title, Rest, HTML) :-
    section_level(Section, Level),
    ignore(find_label(Rest, Label)),
    translate_section(Level, -, Title, HTML, Label).

section_level(chapter,       1).
section_level(section,       2).
section_level(subsection,    3).
section_level(subsubsection, 4).

find_label([' '|T], Label) :-
    !,
    find_label(T, Label).
find_label(['\n'|T], Label) :-
    !,
    find_label(T, Label).
find_label([\par|T], Label) :-
    !,
    find_label(T, Label).
find_label([\(label, [{RawLabel}])|_], Label) :-
    (   sub_atom(RawLabel, _, _, A, :)
    ->  sub_atom(RawLabel, _, A, 0, Label)
    ;   Label = RawLabel
    ).

%       translate_section(+Level, +Modify, +TitleTokens, -HTML[, +File])

translate_section(Level, Mod, TexTitle, HTML) :-
    translate_section(Level, Mod, TexTitle, HTML, _).

translate_section(Level, -, TeXTitle,
        [ Footer,
          Tell,
          Header,
          #h(Level, RefName,
             #label(RefName,
                    [ #span('sec-nr', Tag), ' ',
                      #span('sec-title', Title)
                    ]))
        ], NodeFile) :-
    !,
    translate(TeXTitle, normal, Title),
    section_tag(OldTag),
    increment_section_counter(Level, Tag, FirstSubSection),
    (   html_split_level(Split),
        Level =< Split
    ->  Tell = #tell(NodeFile),
        Header = #header(Tag),
        (   var(NodeFile)
        ->  section_file(Tag, Title, NodeFile)
        ;   true
        ),
        (   FirstSubSection
        ->  Footer = #footer(OldTag)
        ;   Footer = []
        )
    ;   Tell = [],
        Footer = [],
        Header = []
    ),
    format(string(RefName), 'sec:~w', [Tag]),
    assert(section(Level, Tag, Title)).
translate_section(Level, *, Title, #h(Level, +Title), _).

h(1, '
    ', '
    ').
h(2, '
    ', '
    ').
h(3, '
    ', '
    ').
h(4, '
    ', '
    ').
h(5, '
    ', '
    ').
h(6, '
    ', '
    ').

section_file(Tag, _, Node) :-
    atom_concat('sec-', Tag, Node).

increment_section_counter(Level, Tag, FirstSubSection) :-
    (   retract(section_counter_array(Old))
    ->  true
    ;   Old = counters(0,0,0,0,0,0)
    ),
    functor(New, counters, 6),
    update_section_counter(1, 6, Level, Old, New, FirstSubSection),
    asserta(section_counter_array(New)),
    section_tag(Tag).

update_section_counter(I, M, L, Old, New, FirstSubSection) :-
    (   I =< M
    ->  (   I == L
        ->  arg(I, Old, N),
            NN is N + 1,
            arg(I, New, NN),
            (   N == 0
            ->  FirstSubSection = true
            ;   FirstSubSection = fail
            )
        ;   I < L
        ->  arg(I, Old, N),
            arg(I, New, N)
        ;   arg(I, New, 0)
        ),
        NI is I + 1,
        update_section_counter(NI, M, L, Old, New, FirstSubSection)
    ;   true
    ).

section_tag(Tag) :-
    section_counter_array(Term),
    !,
    findall(A, (arg(_, Term, A), A > 0), L),
    (   appendix_section(AS),
        arg(1, Term, S),
        S > AS
    ->  App is (S - AS - 1) + 0'A,
        char_code(AN, App),
        L = [_|T],
        atomic_list_concat([AN|T], '.', Tag)
    ;   atomic_list_concat(L, '.', Tag)
    ).
section_tag('').

parent_tag(Section, Parent) :-
    atom_codes(Section, Chars),
    phrase(parent_section(Parent), Chars),
    !.

parent_section(Parent) -->
    string(ParentString),
    ".",
    integer(_),
    {atom_codes(Parent, ParentString)}.

:- dynamic
    section_level/1.

tableofcontents([]) :-
    \+ section(_,_,_),
    !.
tableofcontents(Sections) :-
    tableofcontents('', Sections).

tableofcontents(TagPrefix, #div(toc, Sections)) :-
    findall(S, section_html(TagPrefix, S), Sections).

section_html(TagPrefix,
             [ #div(Class, #lref(sec, Ref,
                                 [ #span('sec-nr', Tag), ' ',
                                   #span('sec-title', Title)
                                 ]))
             ]) :-
    section(Level, Tag, Title),
    html_split_level(Split),
    (   Level =< Split
    ->  Ref = fileof(RefName)
    ;   Ref = RefName
    ),
    atom_concat(TagPrefix, _, Tag),
    format(string(RefName), 'sec:~w', [Tag]),
    atom_concat('toc-h', Level, Class).


                 /*******************************
                 *             INDEX            *
                 *******************************/

:- dynamic
    index/3.                        % SortKey, Word, Tag

reset_index :-
    retractall(index(_,_, _)).

translate_index(Term, RefName) :-
    step_counter(index, N),
    clean_index(Term, Clean),
    format(string(RefName), 'idx:~w:~w', [Clean, N]),
    section_tag(Tag),
    add_to_index(Term, Tag:RefName).

clean_index(Raw, Cleaned) :-
    atom_codes(Raw, RawChars),
    clean_index_2(RawChars, Chars),
    atom_codes(Cleaned, Chars).

clean_index_2([], []).
clean_index_2([H|T0], [H|T]) :-
    valid_index_char(H),
    !,
    clean_index_2(T0, T).
clean_index_2([_|T0], T) :-
    clean_index_2(T0, T).

valid_index_char(C) :-
    between(0'a, 0'z, C).
valid_index_char(C) :-
    between(0'A, 0'Z, C).
valid_index_char(C) :-
    between(0'0, 0'9, C).

add_to_index(Term) :-
    section_tag(Tag),
    add_to_index(Term, Tag).

%!  add_to_index(+Term, +Tag)
%
%   Add Term to the index using the href Tag. If Tag is of the
%   format +Tag, it is the primary index for the term, normally
%   a pointer to the definition of Term.

add_to_index(Term, Tag) :-
    atom_codes(Term, Chars),
    atom_codes(Atom, Chars),        % So, sure we have an atom now
    sort_chars(Chars, Sort),
    atom_codes(SortKey, Sort),
    assert(index(SortKey, Atom, Tag)).

%sort_chars(Chars, Sort) :-
%       append("menu:", X, Chars), !,
%       sort_chars(X, Sort).
sort_chars(Chars, Sort) :-
    member(C, Chars),
    is_alpha(C),
    !,
    get_lower_letters(Chars, Sort).
sort_chars(Chars, Chars).

get_lower_letters([], []).
get_lower_letters([H0|T0], [H|T]) :-
    is_upper(H0),
    !,
    to_lower(H0, H),
    get_lower_letters(T0, T).
get_lower_letters([_|T0], T) :-
    get_lower_letters(T0, T).


make_index([]) :-
    makeindex(false),
    !.
make_index([]) :-
    \+ index(_, _, _),
    !.
make_index(HTML) :-
    HTML0 = [ #tell('DocIndex'),
              #header(index),
              #h(1, #label('document-index', 'Index')),
              html('
    '),
              Index,
              html('
    ')
            ],
    setof(I, T^Tag^index(I, T, Tag), I0),
    index_html(I0, 0, Index),
    expand_macros(HTML0, HTML).

index_html([], _, []).
index_html([SortKey|T0], CL0, [Sep, TermHTML|TH]) :-
    add_separator(SortKey, CL0, CL, Sep),
    setof(Term, Tag^index(SortKey, Term, Tag), Terms),
    index_terms(Terms, TermHTML),
    index_html(T0, CL, TH).

index_terms([], []).
index_terms([Term0|T0], [ html('
    '),
                         HtmlTerm,
                         html('
    '),
                         Where
                       | TH
                       ]) :-
    findall(Tag, index(_, Term0, Tag), Tags),
    term_tokens(Term0, Tokens),
    translate(Tokens, index, _, Term),
    (   member(+PrimeTag, Tags)
    ->  HtmlTerm = #lref(idx, PrimeTag, Term)
    ;   HtmlTerm = Term
    ),
    maplist(index_href, Tags, Where),
    index_terms(T0, TH).

term_tokens('$/0', [verb(!,'$/0')]) :-
    !.
term_tokens('$/1', [verb(!,'$/1')]) :-
    !.
term_tokens(Term, Tokens) :-
    tex_atom_to_tokens(Term, Tokens).


index_href(+(_), []) :- !.
index_href(Tag:Label, [' ', #lref(idx, Label, Tag)]) :- !.
index_href(Tag, [' ', #lref(sec, RefName, Tag)]) :-
    format(string(RefName), 'sec:~w', Tag).

add_separator(Term, CL, CL, []) :-
    atom_chars(Term, [CL|_]),
    !.
add_separator(Term, _, CL, [ html('
    '),
                             Char,
                             html('
    ')
                           ]) :-
    (   atom_chars(Term, [CL|_])
    ->  upcase_atom(CL, Char)
    ;   Char = '?'
    ).


                 /*******************************
                 *        STANDARD LINKS        *
                 *******************************/

node_header([#head(#title(#thetitle)),
             #beginbody
            ]) :-
    onefile(true),
    !.
node_header([#head([#title(#thetitle),
                    link(home),
                    link(contents),
                    link(index),
                    link(summary),
                    link(previous),
                    link(next)]),
             #beginbody,
             #navigate( [ body_link(home),
                          body_link(contents),
                          body_link(index),
                          body_link(summary),
                          body_link(previous),
                          body_link(next)
                      ])
            ]).

node_header(_, []) :-
    onefile(true),
    !.
node_header(SectionTag,
            [#head([#title([#thetitle, nospace(:), ' ',
                            'Section', SectionTag]),
                    link(home),
                    link(contents),
                    link(index),
                    link(summary),
                    link(up(UpRef)),
                    link(previous),
                    link(next)]),
             #beginbody,
             #navigate( [ body_link(home),
                          body_link(contents),
                          body_link(index),
                          body_link(summary),
                          body_link(up(UpRef)),
                          body_link(previous),
                          body_link(next)
                      ])
            ]) :-
    parent_tag(SectionTag, UpTag),
    !,
    format(string(UpRef), 'sec:~w', [UpTag]).
node_header(_, HTML) :-
    node_header(HTML).


node_footer(Tag, tableofcontents(section(Tag))).


subsection_index(Tag,
            [ html('
    '),
              #center([html('
    '), 'Section Index', html('
    ')]),
              html('
    '),
              SubIndex
            ]) :-
    onefile(false),
    Tag \== '',
    atom_concat(Tag, '.', Filter),
    tableofcontents(Filter, SubIndex),
    sub_term(#lref(_,_,_), SubIndex),
    !. % it is not empty
subsection_index(_, []).


                 /*******************************
                 *           COUNTERS           *
                 *******************************/

:- dynamic
    counter/2.                              % Name, Value

reset_counters :-
    retractall(counter(_,_)).

set_counter(Name, Val) :-
    retractall(counter(Name, _)),
    asserta(counter(Name, Val)).


step_counter(Name, NewVal) :-
    (   retract(counter(Name, OldVal))
    ->  NewVal is OldVal + 1
    ;   NewVal is 1
    ),
    asserta(counter(Name, NewVal)).

                 /*******************************
                 *             RULES            *
                 *******************************/

cmd(rule({'\\linewidth'}, {_H}), [html('
    ')]) :- !.
cmd(rule({W}, {H}), []) :-
    format('W = ~w, H = ~w~n', [W, H]).

                 /*******************************
                 *            TABLES            *
                 *******************************/

only_table(Table) -->
    white_spaces,
    [ Table ],
    { tabular_env(Table) },
    white_spaces.

white_spaces --> [' '],  !, white_spaces.
white_spaces --> ['\n'], !, white_spaces.
white_spaces --> [].



tabular_env(env(tabular,_,_)).
tabular_env(env(tabularlp,_,_)).

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Specifying the number of columns makes Netscape make the columns equally
width.  Thats not what we want.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

translate_table(Format, Body, HTML) :-
    atom_codes(Format, Fmt),
    table_frame(Fmt, Body, FrameAttributes, Fmt2, Body2),
    expand_table_commands(Body2, Body3),
    (   table_columns(Fmt2, _Ncols, ColAtts)
    ->  true
    ;   format(user_error, 'ERROR: Failed to parse tabular spec "~s"~n', [Fmt2]),
        ColAtts = []
    ),
    (   table_body(Body3, ColAtts, BodyHTML)
    ->  true
    ;   format(user_error, 'ERROR: Failed to translate table body~n', []),
        trace, fail
    ),
    HTML = [ html(Head),
%                ColHTML,
             BodyHTML,
             html('')
           ],
    atom_concat('frame-', FrameAttributes, FrameClass),
    (   center_tables
    ->  Classes = [latex, FrameClass, center]
    ;   Classes = [latex, FrameClass]
    ),
    atomic_list_concat(Classes, ' ', ClassText),
    format(string(Head), '', [ClassText]).

%       expand_table_commands(+BodyIn, -BodyOut)
%
%       This shouldn't be here, but it translates commands that expand
%       into the table-special commands & or \\.

expand_table_commands([], []).
expand_table_commands([\isa|T0], [&, '::=', &|T]) :-
    !,
    expand_table_commands(T0, T).
expand_table_commands([\ora|T0], [&,   '|', &|T]) :-
    !,
    expand_table_commands(T0, T).
expand_table_commands([H|T0], [H|T]) :-
    expand_table_commands(T0, T).

%!  table_frame(+Format, +Body, -FrameAttributes, -Format2, -Body2)
%
%   Extracts the frame attributes, controlling the border of the
%   table from the format and opening/closing \hline.
%
%   @arg FrameAttributes is one of =void=, =vsides=, =lhs=, =rhs=,
%   =hsides=, =above=, =below= or =box=

table_frame(Fmt, Body, TableAttributes, Fmt2, Body2) :-
    v_table_frame(Fmt, VFr, Fmt2),
    clean_body(Body, Body1),
    h_table_frame(Body1, HFr, Body2),
    table_frame(VFr, HFr, TableAttributes).

v_table_frame([0'||Fmt0], VFr, Fmt) :-
    !,
    (   append(Fmt, [0'|], Fmt0)
    ->  VFr = vsides                % |cols|
    ;   Fmt = Fmt0,                 % |cols
        VFr = lhs
    ).
v_table_frame(Fmt0, VFr, Fmt) :-
    (   append(Fmt, [0'|], Fmt0)
    ->  VFr = rhs                   % cols|
    ;   Fmt = Fmt0,                 % cols
        VFr = void
    ).

h_table_frame([\hline|Body0], VFr, Body) :-
    !,
    (   (   append(Body, [\hline], Body0)
        ;   append(Body, [\hline,\(\, _)], Body0)
        )
    ->  VFr  = hsides               % \hline body \hline [\\]
    ;   Body = Body0,               % \hline body
        VFr  = above
    ).
h_table_frame(Body0, HFr, Body) :-
    (   (   append(Body, [\hline], Body0)
        ;   append(Body, [\hline,\(\, _)], Body0)
        )
    ->  HFr  = below                % body \hline [\\]
    ;   Body = Body0,               % body
        HFr  = void
    ).

table_frame(X, void, X) :- !.
table_frame(void, X, X) :- !.
table_frame(vsides, hsides, box) :- !.
table_frame(X, Y, border) :-
    format(user_error,
           'Cannot combine ~w and ~w for table border~n', [X, Y]).


table_columns(Fmt, Ncols, Cols) :-
    table_columns(Fmt, 0, Ncols, Cols).

table_columns([],      Ncols, Ncols, []).
table_columns([0'l|T], NC0,   NC,    [[]|TH]) :-
    NC1 is NC0 + 1,
    table_columns(T, NC1, NC, TH).
table_columns([0'L|T], NC0,   NC,    [[]|TH]) :-
    NC1 is NC0 + 1,
    table_columns(T, NC1, NC, TH).
table_columns([0'c|T], NC0,   NC,    [[align=center]|TH]) :-
    NC1 is NC0 + 1,
    table_columns(T, NC1, NC, TH).
table_columns([0'C|T], NC0,   NC,    [[align=center]|TH]) :-
    NC1 is NC0 + 1,
    table_columns(T, NC1, NC, TH).
table_columns([0'r|T], NC0,   NC,    [[align=right]|TH]) :-
    NC1 is NC0 + 1,
    table_columns(T, NC1, NC, TH).
table_columns([0'R|T], NC0,   NC,    [[align=right]|TH]) :-
    NC1 is NC0 + 1,
    table_columns(T, NC1, NC, TH).
table_columns([0'p|T0], NC0,   NC,   [Col|TH]) :-
    phrase(parbox_width(_W), T0, T),
    Col = [],
    NC1 is NC0 + 1,
    table_columns(T, NC1, NC, TH).
% align=char is not supported.  There is no sensible way around
table_columns([0'D|T0], NC0,   NC,   [[/*align=char, char=Chr*/]|TH]) :-
    phrase(align_char(_Chr), T0, T),
    NC1 is NC0 + 1,
    table_columns(T, NC1, NC, TH).
table_columns([0'||T], NC0,  NC,     TH) :-
    table_columns(T, NC0, NC, TH).

parbox_width(W) -->
    "{",
    number(N),
    dimension_unit(U),
    "}",
    !,
    { relative_width(U, N, W) }.
parbox_width(-) -->
    "{",
    string_without("{}", _),
    "}",
    !.

align_char(Chr) -->             % D{inputsep}{outputsep}{decimal places}
    "{",
    string_without("{}", W),
    "}{",
    string_without("{}", _),
    "}{",
    number(_),
    "}",
    { atom_codes(Chr, W)
    }.

string_without(L, [C|T]) -->
    [C],
    {\+ string_code(_, L, C)},
    !,
    string_without(L, T).
string_without(_, []) --> [].

number(N) -->
    optional_sign(S),
    digit(C0),
    float_digits(C),
    { append(S, [C0|C], Chars),
      number_codes(N, Chars)
    }.

integer(N) -->
    optional_sign(S),
    digit(C0),
    digits(C),
    { append(S, [C0|C], Chars),
      number_codes(N, Chars)
    }.

optional_sign([0'-]) --> "-", !.
optional_sign([0'+]) --> "+", !.
optional_sign([])  --> "".

digit(C) -->
    [C],
    {between(0'0, 0'9, C)}.

digits([C0|C]) -->
    digit(C0),
    !,
    digits(C).
digits([]) --> [].

float_digits([C0|C]) -->
    digit(C0),
    !,
    float_digits(C).
float_digits([0'.|C]) -->
    ".",
    !,
    float_digits(C).
float_digits([]) --> [].


dimension_unit(in) --> "in".
dimension_unit(pt) --> "pt".
dimension_unit(cm) --> "cm".
dimension_unit(mm) --> "mm".

relative_width(in, N, W) :- W is integer(100 * N / 6).
relative_width(pt, N, W) :- W is integer(100 * (N/72) / 6).
relative_width(cm, N, W) :- W is integer(100 * (N/2.54) / 6).
relative_width(mm, N, W) :- W is integer(100 * (N/25.4) / 6).

%       The valign="top" should be at the table-level, but Netscape
%       doesn't appear to recognise this. It is just LaTeX's default,
%       while HTML's default is middle.


table_body([], _, []).
table_body([\(\, _)|T], _, []) :-
    all_white_space(T).
table_body([' '|T0], ColAtts, T) :-
    table_body(T0, ColAtts, T).
table_body(['\n'|T0], ColAtts, T) :-
    !,
    table_body(T0, ColAtts, T).
table_body([\hline|Body], ColAtts, [[ html(''),
                                      Row,
                                      html('')
                                    ]|Rest]) :-
    !,
    table_row(Body, 1, ColAtts, BodyRest, Row),
    table_body(BodyRest, ColAtts, Rest).
table_body(Body, ColAtts, [[ html(''),
                             Row,
                             html('')
                          ]|Rest]) :-
    table_row(Body, 1, ColAtts, BodyRest, Row),
    table_body(BodyRest, ColAtts, Rest).

table_row([], _, _, [], []) :- !.
table_row([' '|T0], C, ColAtts, T, TH) :-
    !,
    table_row(T0, C, ColAtts, T, TH).
table_row(['\n'|T0], C, ColAtts, T, TH) :-
    !,
    table_row(T0, C, ColAtts, T, TH).
table_row([\(multicolumn, [{N}, {A}, {Tokens}])|R0], C, ColAtts, R,
          [html(MC), Item|THtml]) :-
    column_alignment(A, Alignment),
    !,
    format(string(MC), '')|THtml]) :-
    cell_header(C, ColAtts, CellHeader),
    table_cell(L, T, Tokens, Last),
    translate_group(Tokens, Chtml),
    (   Last == true
    ->  R = T,
        THtml = []
    ;   C2 is C + 1,
        table_row(T, C2, ColAtts, R, THtml)
    ).

cell_header(C, ColAtts, Header) :-
    nth1(C, ColAtts, Spec),
    maplist(sgml_attribute, Spec, Attributes),
    atomic_list_concat(['', Header).

sgml_attribute(Name=Value, Att) :-
    atomic_list_concat([Name, =, Value], Att).

to_integer(Atom, Integer) :-
    atom_codes(Atom, Chars),
    number_codes(Integer, Chars).

column_alignment(X, Alignment) :-
    atom_codes(X, Chars),
    phrase(column_alignment(Alignment), Chars).

column_alignment(A) -->
    vlines,
    calignment(A),
    !,
    vlines.

vlines -->
    "|",
    !,
    vlines.
vlines -->
    [].

calignment(left) --> "l".
calignment(center) --> "c".
calignment(right) --> "r".
calignment(left) --> [X],
    {format(user_error, 'Unknown multicolumn alignment: "~w"~n', [X])}.

table_cell([], [], [], true).
table_cell([&|L], L, [], false) :- !.
table_cell([\(\, _)|L], L, [], true) :- !.
table_cell([H|T0], R, [H|T], Last) :-
    table_cell(T0, R, T, Last).

all_white_space([]).
all_white_space([' '|T]) :-
    all_white_space(T).
all_white_space(['\n'|T]) :-
    all_white_space(T).

clean_body([], []).
clean_body([' '|T0], T) :-
    !,
    clean_body(T0, T).
clean_body(['\n'|T0], T) :-
    !,
    clean_body(T0, T).
clean_body(Body, Body1) :-
    (   append(Body1, T, Body),
        all_white_space(T)
    ->  true
    ).

                 /*******************************
                 *            FIGURES           *
                 *******************************/

%       psfig_options(+PsFigOptions, -OptionList)
%
%       Translate an option-list of psfig into a list of Name(Value)
%       terms for easy further processing.

psfig_options(Text, Options) :-
    atom_codes(Text, Chars),
    phrase(psfigoptions(Options), Chars).

psfigoptions([H|T]) -->
    psfigoption(H),
    psfigoptions(T).
psfigoptions([]) --> [].

psfigoption(Term) -->
    string(NS),
    "=",
    string_without(",", VS),
    (   ","
    ;   ""
    ),
    !,
    { atom_codes(Name, NS),
      atom_codes(Val, VS),
      Term =.. [Name, Val]
    }.


%!  fix_predicate_reference(+Ref0, -Ref)
%
%   Deal with references such as name/[1,2], send/2-12, etc and find
%   the first matching predicate from the referenced set.

fix_predicate_reference(Ref0, Ref) :-
    atom_codes(Ref0, Chars),
    phrase(predref(Name, Arities), Chars),
    member(Arity, Arities),
    format(atom(Ref), '~w/~w', [Name, Arity]),
    label(Ref, _, _),
    !.

predref(Name, Arities) -->
    string(Str0),
    "/[",
    arityspec(Arities),
    "]",
    !,
    {atom_codes(Name, Str0)}.

arityspec(As) -->
    integer(Low),
    "-",
    integer(High),
    {findall(A, between(Low, High, A), As)}.
arityspec(As) -->
    integer(Low),
    "..",
    {findall(A, between(Low, 10, A), As)}.
arityspec(A) -->
    enumerated_arities(A).

enumerated_arities([H|T]) -->
    integer(H),
    (   ","
    ->  enumerated_arities(T)
    ;   {T = []}
    ).

string([]) --> [].
string([H|T]) --> [H], string(T).

                 /*******************************
                 *           NEWCOMMAND         *
                 *******************************/

:- dynamic
    user_cmd/4.

declare_command(Name, ArgCAtom, Expanded) :-
    atom_concat(\, CmdName, Name),
    (   tex_command_property(CmdName, _, _) % test for existence
    ->  true
    ;   atom_codes(ArgCAtom, ArgCChars),
        number_codes(Args, ArgCChars),
        make_cmd_spec(Name, Args, CmdSpec), % \Name{+}...
        tex_declare(CmdSpec),
        functor(Head, CmdName, Args),
        cmd_parms(0, Args, Head, ParmList),
        Parms =.. [macro_arg|ParmList],
        assert((user_cmd(Head, Mode0, Mode, HTML) :-
                       expand_macro(Parms, Expanded, Mode0, Mode, HTML)))
    ).

make_cmd_spec(Name, ArgC, Spec) :-
    make_cmd_arg_spec(ArgC, ArgSpec),
    atomic_list_concat([Name|ArgSpec], Spec).

make_cmd_arg_spec(0, []).
make_cmd_arg_spec(N, ['{-}'|T]) :-
    NN is N - 1,
    make_cmd_arg_spec(NN, T).

cmd_parms(N, N, _, []) :- !.
cmd_parms(N, A, Head, [A0|AT]) :-
    I is N + 1,
    arg(I, Head, {A0}),
    cmd_parms(I, A, Head, AT).

expand_macro(Args, Macro, Mode0, Mode, HTML) :-
    atom_codes(Macro, Chars),
    replace_args(Chars, Args, Expanded),
    tex_atom_to_tokens(Expanded, Tokens),
    translate(Tokens, Mode0, Mode, HTML).

replace_args([], _, []).
replace_args([0'#,N|T], Args, Result) :-
    !,
    ArgN is N - 0'0,
    arg(ArgN, Args, Val),
    atom_codes(Val, Chars),
    append(Chars, RT, Result),
    replace_args(T, Args, RT).
replace_args([C|T0], Args, [C|T]) :-
    replace_args(T0, Args, T).


                 /*******************************
                 *            UTIL              *
                 *******************************/

%!  split(+Atom, +SepCode, -ListOfAtoms)

split(Atom, Sep, List) :-
    string_codes(SepS, [Sep]),
    split_string(Atom, SepS, "", Parts),
    maplist(atom_string, List, Parts).


                 /*******************************
                 *             PS2GIF           *
                 *******************************/

default_option(gs,      gs).
default_option(res,     72).
default_option(device,  ppmraw).
default_option(tmp,     Tmp) :-
    tmp_file(ps2gif, Tmp).

ps2gif(In, Out) :-
    ps2gif(In, Out, []).

ps2gif(In, Out, _Options) :-
    absolute_file_name(In, InFile,
                       [ access(read),
                         extensions([gif]),
                         file_errors(fail)
                       ]),
    !,
    atomic_list_concat(['cp ', InFile, ' ', Out], Cmd),
    shell(Cmd).
ps2gif(In, Out, Options) :-
    get_option(Options, tmp(Tmp)),
    get_option(Options, res(Res0)),
    (   absolute_file_name(In, InFile,
                           [ access(read),
                             extensions([ps, eps]),
                             file_errors(fail)
                           ])
    ->  true
    ;   format(user_error, 'Could not find figure "~w"~n', In),
        fail
    ),
    format(user_error, 'Converting ~w to .GIF~n', [InFile]),
    get_ps_parameters(InFile, EPS, bb(X1,Y1,X2,Y2)),
    (   get_option(Options, width(W))
    ->  ScaleX is W/((X2-X1)/72)
    ;   ScaleX is 1
    ),
    (   get_option(Options, height(H))
    ->  ScaleY is H/((Y2-Y1)/72)
    ;   ScaleY is 1
    ),
    ResX is Res0 * ScaleX,
    ResY is Res0 * ScaleY,
    (   ResX =:= ResY
    ->  Res = ResX
    ;   format(string(Res), '~wx~w', [ResX, ResY])
    ),
    BBX is -X1,
    BBY is -Y1,
    BBW0 = X2 - X1,
    BBH0 = Y2 - Y1,
    BBW is round(BBW0 * ResX / 72),
    BBH is round(BBH0 * ResY / 72),
    gs_command([size(BBW,BBH),tmp(Tmp),res(Res)|Options], Cmd),
    setup_call_cleanup(open(pipe(Cmd), write, Pipe),
                       (   format(Pipe, '~w ~w translate ', [BBX, BBY]),
                           format(Pipe, '(~w) run ', InFile),
                           (   EPS = eps
                           ->  format(Pipe, 'showpage ', [])
                           ;   true
                           ),
                           format(Pipe, 'quit~n', [])
                       ),
                       close(Pipe)),
    ppm2gif(Tmp, Out, Options),
    delete_file(Tmp).

ppm2gif(Tmp, Out, Options) :-
    (   get_option(Options, margin(B))
    ->  format(atom(Cmd),
               'pnmcrop < ~w | pnmmargin ~w | pnmmargin -black 1 | ppmquant 192 | ppmtogif > ~w',
                [Tmp, B, Out])
    ;   format(atom(Cmd), 'pnmcrop < ~w | ppmquant 192 | ppmtogif > ~w',
               [Tmp, Out])
    ),
    shell(Cmd).

gs_command(Options, Cmd) :-
    get_option(Options, gs(GS)),
    get_option(Options, res(Res)),
    get_option(Options, device(Dev)),
    get_option(Options, tmp(Tmp)),
    (   get_option(Options, size(W, H))
    ->  format(string(SCmd), '-g~wx~w', [W, H])
    ;   SCmd = ''
    ),
    format(atom(Cmd),
           '~w -q -dNOPAUSE -sDEVICE=~w ~w -r~w -sOutputFile=~w',
           [GS, Dev, SCmd, Res, Tmp]).


get_option(List, Term) :-
    memberchk(Term, List),
    !.
get_option(_, Term) :-
    functor(Term, Name, _),
    default_option(Name, Def),
    !,
    arg(1, Term, Def).


                 /*******************************
                 *            OUTPUT            *
                 *******************************/


:- dynamic
    pending_par/0.

%!  is_begin(-Tag, +HTML)
%
%   True when Tag is the (lowercase) open tag of HTML.

is_begin(Tag, HTML) :-
    atom(HTML),
    !,
    sub_atom(HTML, 0, _, _, <),
    (   sub_atom(HTML, 1, L, _, X),
        N is L+1,
        (   sub_atom(HTML, N, _, _, ' ')
        ;   sub_atom(HTML, N, _, _, '>')
        )
    ->  downcase_atom(X, Tag)
    ).
is_begin(X, HTML) :-
    var(HTML),
    format(atom(HTML), '<~w>', [X]).

is_end(Tag, HTML) :-
    atom(HTML),
    !,
    sub_atom(HTML, 0, _, _, '')
    ->  downcase_atom(X, Tag)
    ).
is_end(X, HTML) :-
    var(HTML),
    format(atom(HTML), '', [X]).



implicit_par(html(Begin)) :-
    implicit_par_tag(Tag),
    is_begin(Tag, Begin),
    !.

implicit_par_tag(h1).
implicit_par_tag(h2).
implicit_par_tag(h3).
implicit_par_tag(h4).
implicit_par_tag(pre).
implicit_par_tag(xmp).
implicit_par_tag(dl).
implicit_par_tag(dt).
implicit_par_tag(dd).
implicit_par_tag(table).
implicit_par_tag(blockquote).
implicit_par_tag(div).
%implicit_par_tag(center).

:- dynamic
    is_open/1.

%!  create_pending_open(+Token) is det.
%!  close_pending_open(+Token) is det.
%!  close_by(+Open, -CloseBy) is nondet.

create_pending_open(Cmd) :-
    (   close_by(Open, _)
    ;   create_env(Open)
    ),
    is_begin(Open, Cmd),
    !,
    debug(html, 'Push open of ~w', [Open]),
    asserta(is_open(Open)).
create_pending_open(_).

close_pending_open(Cmd) :-
    pop_implicit_close(Cmd),
    pop_close(Cmd).

pop_implicit_close(Cmd) :-
    (   once(is_open(Open)),
        close_by(Open, CloseOn),
        call(CloseOn, Cmd)
    ->  retract(is_open(Open)),
        debug(html, 'Pop open ~w on ~w', [Open, Cmd]),
        is_end(Open, Close),
        cmd_layout(Close, Pre, Post),
        !,
        put_html_token(html(Close, Pre, Post))
    ;   true
    ).

pop_close(Cmd) :-
    (   once(is_open(Open)),
        is_end(Open, Cmd)
    ->  retract(is_open(Open)),
        debug(html, 'Pop open ~w on ~w', [Open, Cmd])
    ;   true
    ).


create_env(dl).

close_by(dd, is_begin(dt)).
close_by(dd, is_end(dl)).
close_by(dt, is_begin(dd)).
close_by(dt, is_begin(dt)).
close_by(dt, is_end(dl)).

%!  write_html(+Tokens) is det.

write_html([]) :- !.                    % Unpack lists
write_html([html(DD)|T]) :-     % Delete empty DD followed by DT
    is_begin(dd, DD),
    empty_dd(T, Rest),
    !,
    write_html(Rest).
write_html([H|T]) :-
    !,
    write_html(H),
    write_html(T).
write_html('\n') :-
    pending_par,
    !.
write_html(' ') :-
    pending_par,
    !.
write_html(html('
    ')) :-
    !,
    (   once(is_open(Open)),
        Open = 'dl'
    ->  true
    ;   pending_par
    ->  true
    ;   assert(pending_par)
    ).
write_html(Token) :-
    retract(pending_par),
    !,
    (   implicit_par(Token)
    ->  true
    ;   cmd_layout(p, begin, Pre, Post)
    ->  put_html_token(html('
    ', Pre, Post))
    ),
    write_html(Token).
write_html(html(Cmd)) :-                        % HTML commands
    close_pending_open(Cmd),
    cmd_layout(Cmd, Pre, Post),
    !,
    put_html_token(html(Cmd, Pre, Post)),
    create_pending_open(Cmd).
write_html(ref(Label)) :-                      % References and labels
    !,
    (   label(Label, _, Ref)
    ->  write_html(Ref)
    ;   write_html('??'),
        format(user_error, 'No label for ref "~w"~n', [Label])
    ).
write_html(label(Label, Text, _)) :-
    !,
    (   in_anchor
    ->  write_html(Text)
    ;   format(string(Anchor), '', [Label]),
        asserta(in_anchor),
        write_html([html(Anchor), Text, html('')]),
        retractall(in_anchor)
    ).
write_html(h(Level, NumRefS, TitleTerm)) :-
    !,
    h(Level, OpenH0, _CloseH),
    (   atom_string(NumRef, NumRefS),
        section_label(Human, NumRef)
    ->  format(string(OpenH), '', [Level, Human])
    ;   OpenH = OpenH0,
        (   sub_term(span('sec-title', Title), TitleTerm)
        ->  (   quiet,
                Title == ['Bibliography']
            ->  true
            ;   format(user_error,
                       'No label for section ~w ~w~n', [NumRefS, Title])
            )
        ;   format(user_error,
                   'No label for section ~w~n', [NumRefS])
        )
    ),
    write_html([html(OpenH)]).
write_html(body_link(Link)) :-
    !,
    (   translate_ref(Link, Ref, Type)
    ->  format(string(Anchor), '', [Ref]),
        capitalise_atom(Type, Text),
        (   link_image(Type, Image)
        ->  format(string(Img), '~w', [Image, Text]),
            Label = html(Img)
        ;   Label = Text
        ),
        write_html([html(Anchor), Label, html('')]),
        nl_html
    ;   true
    ).
write_html(link(Link)) :-
    !,
    (   translate_ref(Link, Ref, Type)
    ->  format(string(Html), '', [Type, Ref]),
        write_html(html(Html)),
        nl_html
    ;   true
    ).
write_html(iflref(fileof(Label), Text)) :-
    !,
    (   label(Label, _, _)
    ->  write_html(lref(fileof(Label), Text))
    ;   true
    ).
write_html(iflref(Label, Text)) :-
    !,
    (   label(Label, _, _)
    ->  write_html(lref(Label, Text))
    ;   true
    ).
write_html(lref(Label, Text)) :-
    !,
    write_html(lref('', Label, Text)).
write_html(lref(sec, Label, Text)) :-
    label(Label, File, Nr),
    section(Level, _Title, Nr),
    html_split_level(Split),
    Level =< Split,
    !,
    format(string(Anchor),
           '', [sec, File]),
    write_html([html(Anchor), Text, html('')]).
write_html(lref(Class, fileof(Label), Text)) :-
    !,
    (   label(Label, File, _)
    ->  format(string(Anchor),
               '', [Class, File]),
        write_html([html(Anchor), Text, html('')])
    ;   write_html(lref(Label, Text))
    ).
write_html(lref(Class, Label, Text)) :-
    label(Label, File, _),
    !,
    (   section_label(Label, TheLabel)
    ->  true
    ;   TheLabel = Label
    ),
    (   in_anchor
    ->  macro_expand(Text, Expanded),
        write_html(Expanded)
    ;   asserta(in_anchor),
        (   onefile(false)
        ->  format(string(Anchor),
                   '',
                   [Class, File, TheLabel])
        ;   format(string(Anchor),
                   '', [Class, TheLabel])
        ),
        write_html([html(Anchor), Text, html('')]),
        retractall(in_anchor)
    ).
write_html(lref(pred, Label, Text)) :-
    fix_predicate_reference(Label, FixedLabel),
    !,
    write_html(lref(pred, FixedLabel, Text)).
write_html(lref(pred, Label, Text)) :-
    !,
    (   quiet
    ->  true
    ;   format(user_error, 'No description for predicate "~w"~n', [Label])
    ),
    macro_expand(#span('pred-ext', Text), Expanded),
    write_html(Expanded).
write_html(lref(Class, Label, Text)) :-
    !,
    (   quiet
    ->  true
    ;   format(user_error, 'No label for ~w reference "~w"~n', [Class, Label])
    ),
    macro_expand(#b(Text), Expanded),
    write_html(Expanded).
write_html(cite(Key)) :-
    !,
    (   cite(Key, Cite)
    ->  write_html(Cite)
    ;   write_html([nospace('['), Key, nospace(']')]),
        format(user_error, 'No bibliography entry for "~w"~n', Key)
    ).
write_html(yearcite(Key)) :-
    !,
    (   cite(Key, CiteList)
    ->  (   last(CiteList, Year),
            name(Year, Chars),
            name(YearInt, Chars),
            integer(YearInt)
        ->  write_html(Year)
        ;   format(user_error,
                   'No year for bibliography entry "~w"~n', Key),
            write_html(cite(Key))
        )
    ;   write_html(cite(Key))
    ).
write_html(tableofcontents(document)) :-
    !,
    tableofcontents(Table),
    macro_expand(Table, HTML),
    write_html(HTML).
write_html(tableofcontents(section(Tag))) :-
    !,
    subsection_index(Tag, Table),
    macro_expand(Table, HTML),
    write_html(HTML).
write_html(tell(Base)) :-
    !,
    close_output,
    open_output(Base).
write_html(H) :-
    put_html_token(H),
    !.
write_html(_).

nl_html :-
    write_html(verb('\n')).

empty_dd([], []) :- !.
empty_dd(L, L) :-
    L = [html(DT)|_],
    is_begin(dt, DT),
    !.
empty_dd(['\n'|T0], T) :-
    empty_dd(T0, T).


%       translate_ref(+Label, -Anchor, -TextLabel)

translate_ref(next, Anchor, next) :-
    current_html_output(Current),
    next_file(Current, Next),
    atom_concat(Next, '.html', Anchor).
translate_ref(previous, Anchor, previous) :-
    current_html_output(Current),
    next_file(Prev, Current),
    atom_concat(Prev, '.html', Anchor).
translate_ref(up(Label), Anchor, up) :-
    label(Label, File, _),
    atom_concat(File, '.html', Anchor).
translate_ref(home, Anchor, home) :-
    html_file_base(Home),
    \+ current_html_output(Home),
    onefile(false),
    atom_concat(Home, '.html', Anchor).
translate_ref(contents, Anchor, contents) :-
    label('document-contents', File, _),
    atom_concat(File, '.html', Anchor).
translate_ref(index, Anchor, index) :-
    label('document-index', File, _),
    atom_concat(File, '.html', Anchor).
translate_ref(summary, Anchor, summary) :-
    label('sec:summary', File, _),
    atom_concat(File, '.html', Anchor).

cmd_layout(HTML, Pre, Post) :-
    is_end(Tag, HTML),
    !,
    cmd_layout(Tag, end, Pre, Post).
cmd_layout(HTML, Pre, Post) :-
    is_begin(Tag, HTML),
    !,
    cmd_layout(Tag, begin, Pre, Post).
cmd_layout(_, 0, 0).

cmd_layout(p,          begin, 2, 0).
cmd_layout(dl,         begin, 2, 1).
cmd_layout(dl,         end,   1, 2).
cmd_layout(dd,         begin, 0, 1).
cmd_layout(h1,         begin, 2, 0).
cmd_layout(h2,         begin, 2, 0).
cmd_layout(h3,         begin, 2, 0).
cmd_layout(h4,         begin, 2, 0).
cmd_layout(h5,         begin, 2, 0).
cmd_layout(h6,         begin, 2, 0).
cmd_layout(h1,         end,   0, 2).
cmd_layout(h2,         end,   0, 2).
cmd_layout(h3,         end,   0, 2).
cmd_layout(h4,         end,   0, 2).
cmd_layout(h5,         end,   0, 2).
cmd_layout(h6,         end,   0, 2).
cmd_layout(hr,         begin, 1, 1).
cmd_layout(br,         begin, 0, 1).
cmd_layout(div,        begin, 1, 0).
cmd_layout(div,        end,   0, 1).
cmd_layout(li,         begin, 1, 0).
cmd_layout(dt,         begin, 1, 0).
cmd_layout(dt,         end,   0, 1).
cmd_layout(dd,         begin, 1, 0).
cmd_layout(dd,         end,   0, 1).
cmd_layout(ul,         begin, 1, 1).
cmd_layout(ul,         end,   1, 1).
cmd_layout(ol,         begin, 1, 1).
cmd_layout(ol,         end,   1, 1).
cmd_layout(tr,         begin, 1, 0).
cmd_layout(tr,         end,   0, 1).
cmd_layout(tbody,      begin, 1, 1).
cmd_layout(thead,      begin, 1, 1).
cmd_layout(table,      begin, 1, 1).
cmd_layout(table,      end,   1, 1).
cmd_layout(listing,    begin, 2, 0).
cmd_layout(listing,    end,   0, 2).
cmd_layout(pre,        begin, 2, 0).
cmd_layout(pre,        end,   0, 2).
cmd_layout(xmp,        begin, 2, 0).
cmd_layout(xmp,        end,   0, 2).
cmd_layout(head,       begin, 1, 1).
cmd_layout(head,       end,   1, 1).
cmd_layout(center,     begin, 1, 1).
cmd_layout(center,     end,   1, 1).
cmd_layout(body,       begin, 2, 1).
cmd_layout(body,       end,   1, 1).
cmd_layout(html,       begin, 0, 1).
cmd_layout(html,       end,   1, 1).
cmd_layout(blockquote, begin, 1, 0).
cmd_layout(blockquote, end,   0, 1).
cmd_layout(style,      begin, 1, 1).
cmd_layout(style,      end, 1, 1).
cmd_layout(sloppy,     end,   1, 1).

:- initialization
   read_tex_inputs.


		 /*******************************
		 *            MAIN		*
		 *******************************/

:- initialization(main, main).

main(Argv) :-
    argv_options(Argv, Files, Options),
    set_debugging(Options),
    set_quiet(Options),
    set_text_inputs(Options),
    (   select_option(pl(true), Options, ROptions)
    ->  set_prolog_flag(toplevel_goal, prolog),
        (   input_file(Files, File)
        ->  format('Run using ?- ~q.~n', [latex2html(File, ROptions)])
        ;   true
        )
    ;   input_file(Files, File)
    ->  latex2html(File, Options)
    ;   usage,
        halt(1)
    ).

input_file([File], Base) :-
    file_name_extension(Base, tex, File),
    !.
input_file([File], File).

set_quiet(Options) :-
    option(quiet(true), Options),
    !,
    assert(quiet).
set_quiet(_).

set_text_inputs(Options) :-
    option(texinputs(Val), Options),
    !,
    read_tex_inputs(Val).
set_text_inputs(_).

set_debugging(Options) :-
    (   option(gtrace(true), Options)
    ->  gtrace
    ;   option(trace(true), Options)
    ->  trace
    ;   true
    ).


usage :-
    format('Usage: latex2html [--pl] [--quiet] [--tex_inputs=...] file~n').

    ', [N, Alignment]),
    translate_group(Tokens, Item),
    to_integer(N, N2),
    C2 is C + N2,
    table_cell(R0, R1, _, Last),          % discard tokens upto &
    (   Last == true
    ->  R = R1,
        THtml = []
    ;   table_row(R1, C2, ColAtts, R, THtml)
    ).
table_row(L, C, ColAtts, R,  [html(CellHeader), Chtml, html('