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Markup spec/ANTLR/draft

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This is a rough draft that has reached a certain level of completeness. I'm calling this version "10" because that's what the file happens to be called at the moment. Probably best to contact me before hacking on it.

Aside: I realise this grammar doesn't even support a feature on this page: <source>. I didn't know about that one.

This ANTLR3 code, and all ANTLR code published myself on mediawiki.org, are licensed under the GPL, as well as the GFDL. Full preamble is in a comment just below. 


grammar mediawiki10;
options { /*tokenVocab=mediawikil;*/ output=AST; memoize=true;}
tokens {
   ARTICLE;
   START;
   INTERNAL_LINK;
   ENTITY;
   RD;
   H1;
   H2;
   H3;
   H4;
   H5;
   H6;
   HR;
   P;
   IMG;
   NBSP;
   PROTOCOL;
   TEXT; // all subnodes should be concatenated
   BALD_URL;
   EXTERNAL_LINK;
   IMG;
   ITALICS;
   BOLD;
   B_ON;
   B_OFF;
   BOLD_ITALICS;
   I_ON;
   I_OFF;
   BR;
   UL;
   OL;
   DL;
   LI;
   DD;
   DT;
   ISBN;
   RFC;
   PMID;
   PRE;
   NBSP160; // a real nbsp, like &#160;
   PAGENAME;
   ANGLE_TAG;
   
   LT; // generally set by the nowiki rule...
   ESCAPED_PUNC;
   CATEGORY;
   TABLE;
   TR;
   TD;
   TH;
   CAPTION;

   IMG_OPTION;
   IMG_OPTION_THUMBNAIL;
   IMG_OPTION_SIZE;
   IMG_OPTION_MANUALTHUMB;
   IMG_OPTION_THUMB;
   IMG_OPTION_FRAME;
   IMG_OPTION_FRAMELESS;
   IMG_OPTION_UPRIGHT;
   IMG_OPTION_BORDER;
   IMG_OPTION_SIZE;
   IMG_OPTION_LEFT;
   IMG_OPTION_CENTER;
   IMG_OPTION_RIGHT;
   IMG_OPTION_NONE;
   IMG_OPTION_BASELINE;
   IMG_OPTION_SUB;
   IMG_OPTION_SUPER;
   IMG_OPTION_TOP;
   IMG_OPTION_TEXT_TOP;
   IMG_OPTION_MIDDLE;
   IMG_OPTION_BOTTOM;
   IMG_OPTION_TEXT_BOTTOM;
   
   MAGIC_WORD;
  
}

@lexer::members {
  boolean in_nowiki = false;
  boolean in_noparse = false;
  boolean in_pre = false;
  boolean in_html = false;
  boolean in_listprefix = false;
}



/* Bugs:
<Nowiki> at start of article

ISBN 123456789xxx shouldn't match but does.
<!-- comments at start of line doesn't seem to work -->


Why do I have to write ((ws)=>ws)? everywhere instead of ws?
grrr.

Supports:
* Internal links
* External links (limited range of characters allowed)
* Images (all options)
* Headings (limits on ='s in the text)
* Nowiki, pre
* French punctuation ( foo ? -> foo&nbsp;?)
* HTML entities (&nbsp; is recognised, &foo; is converted to literals)
* Dangerous HTML, < -> &lt; etc
* Bold, italics (supports the basic rules, not the single-character stuff)
* Paragraphs
* Space-indented blocks
* Lists (intentionally doesn't support nested ; lists, does support ;foo:blah)
* ISBN, RFC, PMID (fully, I think)
* HTML comments
* HTML entities: &nbsp; ...
* Inline HTML (<b>, <div> etc)
* Categories
* Tables
* __TOC__, NOTOC, NOEDITSECTION, NOGALLERY, FORCETOC (all minimally - simply recognises and tags them)

Does not support:
* -{ ... }- auto translation stuff


Other limitations:
* Very reduced ranges of characters for many things, like it doesn't
know that Ă© is a letter rather than punctuation, for instance
* Case sensitivity in some places (<NOWIKI> is not recognised)

*/




@members {
  String _mw_image_namespace = "image";
  String _mw_category_namespace = "category";
  boolean in_header=false;
  boolean prohibit_literal_colon=false;
  boolean text_bold=false;
  boolean text_italics=false;
  boolean literal_whitespace=false;
  // These flags are ints because they nest: value 3 means inside 3 levels of stuff that prohibits that character
  int prohibit_literal_pipe=0;
  int prohibit_literal_link_end=0;
  int prohibit_literal_double_pipe=0;
  int prohibit_literal_double_exclamation=0;
  int prohibit_opening_literal_pipe=0; // in table cells, can't start a line with a literal pipe
  int prohibit_literal_exclamation=0; // in table header cells, can't start a line with an exclamation
  
//  int prohibit_literal_right_bracket=0;
  // this doesn't nest: external links can't contain external links
  boolean prohibit_literal_right_bracket=false;
  int caption_levels = 0;
  int text_levels =0;
 
  boolean textis(String mw) {
    return input.LT(1).getText().equalsIgnoreCase(mw);
  }

  boolean is_magic_word() {
    return 
        input.LT(1).getText().equalsIgnoreCase("NOTOC") || 
        input.LT(1).getText().equalsIgnoreCase("TOC") || 
        input.LT(1).getText().equalsIgnoreCase("FORCETOC") || 
        input.LT(1).getText().equalsIgnoreCase("NOGALLERY") || 
        input.LT(1).getText().equalsIgnoreCase("NOEDITSECTION")
    ;
  }
 
 
}

/*
At the very highest level, a page is either a redirect or an article.
*/
start    : {System.out.println("<html>"); }
    (redirect | article) 

{System.out.println("</html>"); }
-> ^(START redirect? article?)

;

//////////////////////////////////////////////////////////////////////

/*
A redirect of the form:
 #REDIRECT [[foo]]
Any trailing text is essentially irrelevant. (I guess it should not be parsed)
*/ 
 
redirect:
    REDIRECT ws? internal_link (((ws)=>ws)? ((article)=>article)?)
-> ^(RD internal_link article?);


//////////////////////////////////////////////////////////////////////

/*
Treat an article as a series of connected lines with occasional paragraph separators between them.
*/
article: (NL*) (line NL paragraph_separator)*
-> ^(ARTICLE (line paragraph_separator)* );

paragraph_separator: pn*;
pn:
        NL 
        /*close_bold_italics */
        { System.out.println("<br />"); } -> /*close_bold_italics */BR ;

close_bold_italics
@after {text_bold=false; text_italics = false;}
: /*
        {text_bold==true && text_italics==true}? =>  -> B_OFF I_OFF
       |{text_bold==false && text_italics==true}? => -> I_OFF
       |{text_bold==true && text_italics==false}? => -> B_OFF
*/       
       ;

/*
Paragraph level organisation. These are decisions made by the first character on the line, one of:
  - header, eg == foo ==
  - list, eg **:foo
  - horizontal line, eg ----
  - space block, eg <space>foo
  - paragraph, anything else
*/

line: 
    (table) => table^
    | (headerline) => headerline^
    | (listmarker) => listline^
    | (hrline)     => hrline^
    | (spaceline)  => spaceline^
    | paragraph^ ;


/*nonpipeline: 
    (table) => table^
    | (headerline) => headerline^
    | (listmarker) => listline^
    | (hrline)     => hrline^
    | (spaceline)  => spaceline^
    | (nonpipe) => paragraph^
    ;
*/
nonpipe
@init { prohibit_literal_pipe++; }:
formatted_text_elem;
finally { prohibit_literal_pipe--;}

not_pipe_or_exclamation
@init { prohibit_literal_exclamation++; }:
nonpipe;
finally { prohibit_literal_exclamation--;}



/*

{|style               
!foo !! style| foo    <- table_header_cells
|-style               <- row_separator
!foo                  <- table_header_cells again
|style|foo || boo     <- table_data_cells with simple_cells
|blah multi
line row              <- multiline_cell
}|                    
*/

table:
   LEFT_BRACE PIPE ws? table_format? NL
   ws?
   (table_line ws?)*
   /*ws? */PIPE RIGHT_BRACE
-> ^(TABLE ^(ATTR table_format?) table_line*);

table_line:
//   ws? /* left-factored out to allow parsing without real backtracking.
   (
   (PIPE PLUS) => table_caption
   | (PIPE HYPHEN) => table_row_separator
   | (EXCLAMATION) => table_header_cells
   | (PIPE ~RIGHT_BRACE) => table_data_cells
   );
   
table_caption: 
    PIPE PLUS ws? formatted_text? NL
-> ^(CAPTION formatted_text);

table_row_separator:
    PIPE HYPHEN ws? table_format? NL
-> ^(TR ^(ATTR table_format?));



table_header_cells:
// ! a series of !! header || cells !! terminated by an optional multi-
// line header cell.
    (
         EXCLAMATION! ws?
        ((table_simple_header_cell table_col_heading_separator ) => table_simple_header_cell table_col_heading_separator! ws?)*
         ws?
        (table_multiline_header_cell | NL!)
    );

   
table_col_heading_separator:
   (EXCLAMATION EXCLAMATION) |
   (PIPE PIPE);

table_simple_header_cell
@init { prohibit_literal_double_exclamation++; prohibit_literal_double_pipe++; }:
   ((table_cell_format single_pipe) =>  table_cell_format single_pipe ws?)? 
   contents=inline_text
-> ^(TH ^(ATTR table_cell_format?) $contents?)
;
finally { prohibit_literal_double_exclamation--; prohibit_literal_double_pipe--; }
    
table_multiline_header_cell:
   ((table_cell_format single_pipe) =>  table_cell_format single_pipe ws?)? 
   table_multiline_header_cell_contents
-> ^(TH ^(ATTR table_cell_format?) table_multiline_header_cell_contents?);

// | a series of || style|data || cells || terminated by an optional multi-
// line header cell.
table_data_cells:
        {input.LA(2) != RIGHT_BRACE && input.LA(2) != HYPHEN}? =>  // HYPHEN restriction probably redundant now
         PIPE! ws?
        ((table_simple_data_cell table_simple_data_cell_separator ) => table_simple_data_cell table_simple_data_cell_separator ws?)*
        (table_multiline_data_cell | NL!)
	;

// simple cell is a single liner and uses || separator    
table_simple_data_cell
@init { prohibit_literal_double_pipe++; }:
   ((table_cell_format single_pipe) =>  table_cell_format single_pipe ws?)? 
   contents=inline_text
-> ^(TD ^(ATTR table_cell_format?) $contents?)
;
finally { prohibit_literal_double_pipe--; }

table_simple_data_cell_separator:
   PIPE PIPE 
->   ;

    
table_multiline_data_cell:
   ((table_cell_format single_pipe) =>  table_cell_format single_pipe ws?)? 
   table_multiline_data_cell_contents
-> ^(TD ^(ATTR table_cell_format?) table_multiline_data_cell_contents?);


table_multiline_data_cell_contents
@init { prohibit_opening_literal_pipe++; }:
// basically *anything* is allowed in a table cell...
    NL* ((ws? nonpipe) => line NL+)*
-> line*;
finally { prohibit_opening_literal_pipe--; }

table_multiline_header_cell_contents:
// basically *anything* is allowed in a table header cell...
    NL* ((ws? not_pipe_or_exclamation) => line NL+)*
-> line*;


   
table_cell_format
@init { prohibit_literal_pipe++; }:
//   formatted_text;
// At some stage this needs to be replaced by something more precise. In particular we don't really want to attempt to actually parse wikitext in CSS...
    inline_text;
finally { prohibit_literal_pipe--; }
   
   
table_format: 
    formatted_text;

   

////////////////////////// Lists ////////////////////////////////

/*
Lists are nestable collections of these forms:
*Unordered list
#Ordered list
:Indented list (aka definition item)
;Defined item
;Defined item:defininition item

They nest like this:
**## Two layers of unordered and two layers of ordered list.

Mediawiki supports ";" lists anywhere in the nesting, but it's ugly and useless. I restrict it to the innermost nesting.
*/

listline:
        ul_item
       |ol_item
       |dt_item
       |definition_item
       ;

listprefix: (listmarker)+;
listmarker:    HASH | ASTERISK | COLON | SEMICOLON;

ul_item:
        ASTERISK (
        (listmarker) => { System.out.println("\n<ul><li>"); } listline { System.out.println("\n</li></ul>\n"); }    -> ^(UL listline)
       |                { System.out.println("\n<ul><li>"); } ws? inline_text { System.out.println("\n</li></ul>\n"); } -> ^(UL  inline_text)
       |                { System.out.println("\n<ul>"); }             { System.out.println("\n</ul>\n"); } -> ^(UL) );

ol_item:
        HASH (
        (listmarker) => { System.out.println("\n<ol><li>"); } listline        { System.out.println("\n</li></ol>\n"); } -> ^(OL listline)
       |                { System.out.println("\n<ol><li>"); } ws? inline_text { System.out.println("\n</li></ol>\n"); } -> ^(OL inline_text)
       |                { System.out.println("\n<ol>"); }                     { System.out.println("\n</ol>\n"); }      -> ^(OL) );

dt_item:
        COLON (
        (listmarker) => listline    -> ^(DD listline)
       |                ((ws)=>ws)? inline_text -> ^(DD inline_text)
       |                            -> ^(DD) );

definition_item:
    SEMICOLON  
    ((ws) => ws)? 
    (
        term=definition_term 
        ( 
            (     COLON) => COLON ((ws)=>ws)? def=inline_text  -> ^(DT $term ^(DD $def))  // ;term:def     (:def is not a real DT as it doesn't nest)
            | (NL COLON) => NL dt_item                         -> ^(DT $term dt_item)     // ;term\n:def   (:def can nest)
            |                                                  -> ^(DT $term)             // ;term
        )
        | -> ^(DT) // a plain ;
    );


/* As in:  ;definition term:Definition - it obviously can't contain a colon. */
definition_term
@init {prohibit_literal_colon = true;}:
    inline_text;
finally {prohibit_literal_colon=false;}


/////////////////////////// Space blocks ///////////////////
spaceline
@init {literal_whitespace = true;}
:
    SPACE ((printing_ws)=>printing_ws)? inline_text? 
-> ^(PRE printing_ws? inline_text?);
finally {literal_whitespace = false;}


////////////////////////// Headers /////////////////////////////////

headerline:/* {in_header = true;}*/
(     (header6) => header6^
    | (header5) => header5^
    | (header4) => header4^
    | (header3) => header3^
    | (header2) => header2^
    | (header1) => header1^)
/* {in_header = false;}  */
    ;
   
header6:
{ System.out.println ("<h6>"); } 
                              EQUALS EQUALS EQUALS EQUALS EQUALS EQUALS a+=EQUALS* header_simple_text b+=EQUALS*  EQUALS EQUALS EQUALS EQUALS EQUALS EQUALS
{ System.out.println ("\n</h6>"); } 
-> ^(H6 $a* header_simple_text $b*);

header5:
{ System.out.println ("<h5>"); } 
                                     EQUALS EQUALS EQUALS EQUALS EQUALS a+=EQUALS* header_simple_text b+=EQUALS* EQUALS EQUALS EQUALS EQUALS EQUALS
{ System.out.println ("\n</h5>"); } 
-> ^(H5 $a* header_simple_text $b*);

header4:
{ System.out.println ("<h4>"); } 
                                            EQUALS EQUALS EQUALS EQUALS a+=EQUALS* header_simple_text b+=EQUALS* EQUALS EQUALS EQUALS EQUALS
{ System.out.println ("\n</h4>"); } 
-> ^(H4 $a* header_simple_text $b*);

header3:
{ System.out.println ("<h3>"); } 
                                                   EQUALS EQUALS EQUALS a+=EQUALS* header_simple_text b+=EQUALS* EQUALS EQUALS EQUALS
{ System.out.println("\n</h3>"); }
-> ^(H3 $a* header_simple_text $b*);
 
header2:
{ System.out.println ("<h2>"); } 
                                                          EQUALS EQUALS a+=EQUALS* header_simple_text b+=EQUALS* EQUALS EQUALS
{ System.out.println("\n</h2>"); }
-> ^(H2 $a* header_simple_text $b*);
 
header1: // buggy I think
{ System.out.println ("<h1>"); } 
                                                                 EQUALS a+=EQUALS* header_simple_text b+=EQUALS*  EQUALS
{ System.out.println("\n</h1>"); }

-> ^(H1 $a* header_simple_text $b*);

/********************************** Horizontal rule ***********************/

hrline: HYPHEN HYPHEN HYPHEN HYPHEN HYPHEN*
-> ^(HR);

/********************************** Paragraph *****************************/
/* Paragraph is rich marked up text that is not covered under one of the other block categories */
// uncertain whether inline_text should be mandatory. problems with lines that consist only of <!-- comment -->...
paragraph: ((ws)=>ws)?  inline_text? 
-> ^(P inline_text);

/********************************** Inline text **************************/
inline_text
/*
The highest level of text formatting, appearing in paragraphs and image captions. All character formatting and inline elements are possible, including:
  - inline images: [[image:foo.jpg]]
  - external links: [http://foo.com]
  - internal links: [[foo]]
  - magic links: ISBN 12345667890x
  - 'pre' blocks (wait, are these just a special case of html tags?)
  - "simple inline elements" - see the next section for those.
*/
@init { text_levels++; }
:
(
    // [[http://foo.com]] has to be treated as: [, [http;//foo.com], ]
    ((LEFT_BRACKET LEFT_BRACKET LEFT_BRACKET) => literal_left_bracket // try and save it some time on [[[foo]]]?
    |(literal_left_bracket bracketed_url) => literal_left_bracket
    |(image)              => image
    |(category)           => category
    |(external_link)      => external_link
    |(internal_link)      => internal_link
    |(magic_link)         => magic_link
    |(magic_word)         => magic_word
    |pre_block
    |(formatted_text_elem) =>formatted_text_elem
    )
    ((nbsp_before_punctuation) => nbsp_before_punctuation)?
    ((ws) =>printing_ws)?
)+;
finally { text_levels --;}



/* 
Internal links link to somewhere else in the wiki. The most complicated form is:
[[namespace:path/to/page name|Caption with ''formatting'']]trails

Image and category links look very similar, but are treated separately due to special flags etc.

*/
internal_link:    
    link_start COLON? pagename
    { System.out.print("<a href='" + $pagename.text + "'>");}
    // [[foo]] and [[foo|]] are both acceptable.
    // this internal question mark seems to be getting ignored?
    (PIPE internal_link_caption?)? 
    {
      try {
         String s = $internal_link_caption.text;
      } catch (NullPointerException e) {
        System.out.print($pagename.text);
      }
    }
    // if letters immediately follow the internal link, they are tacked onto the end of the caption. eg [[horse]]s == [[horse|horses]]
    link_end ((letters)=>internal_link_trail)?
    {
     try {
        System.out.print($internal_link_trail.text);
     } catch (NullPointerException e) {
     }
     System.out.print("</a>"); 
    }
// Issue: Can't currently distinguish [[foo|]] from [[foo]].
-> ^(INTERNAL_LINK ^(PAGENAME pagename) ^(TEXT internal_link_caption? internal_link_trail?));


/* Caption for an internal link is just "simple_text", minus ]]'s.
// Strangely enough, a literal pipe is allowed: [[foo|bar|wa]]
// It would be good if this behaviour were proscribed to allow for future options
*/
internal_link_caption
@init {prohibit_literal_link_end++;}:
        formatted_text;
finally {prohibit_literal_link_end--;}
 
internal_link_trail: letters; // need to check this, maybe digits ok too? what's the full range?

///////////////////////////////////// Categories /////////////////////////////////////////////////

category: (link_start category_namespace) =>
link_start category_namespace COLON ws? categoryname ( PIPE categorysortkey )? link_end
-> ^(CATEGORY ^(TEXT category_namespace COLON ^(PAGENAME categoryname)) categorysortkey?);

category_namespace        : {textis(_mw_category_namespace)}? mwletters;

categoryname: pagename;

categorysortkey: unformatted_characters;

//////////////////////////////////// Images ///////////////////////////////////////////
/*
Images: option-heavy beasts like [[image:foo.jpg|thumb|100px|Here's a caption...]]
Complications: There's no real way to distinguish a caption from an option. Captions can contain virtually anything, including other images...

Todo: 
  - clarify whether /image/paths are ok?
  - clarify whether image names really are just page names...?
  
*/
image: (link_start image_namespace) =>
link_start image_namespace COLON ws? imagename (  PIPE optionorcaption )* link_end
-> ^(IMG ^(TEXT image_namespace COLON ^(PAGENAME imagename)) optionorcaption*);

image_namespace        : {textis(_mw_image_namespace)}? mwletters;

 imagename
 @init {prohibit_literal_right_bracket=true; prohibit_literal_pipe++;}:
        image_filename_elem
              ((image_filename_elem) => image_filename_elem
               |(SPACE) => SPACE
              )*
        ws? DOT ws? imageextension 
//-> ^(PAGENAME pagename DOT imageextension)
;
finally { prohibit_literal_right_bracket=false; prohibit_literal_pipe--;}

image_filename_elem: (letters | digits | accidental_magic_link | UNKNOWN); //| punctuation/* | DIGITS | DOT | UNDERSCORE | HYPHEN | OPEN_PAREN | CLOSE_PAREN*/);


/* Future passes/actions etc can readily retrieve the extension text, so just validate for now? */
 imageextension:
     {textis("jpeg")
     | textis("jpg")
     | textis("png")
     | textis("svg")
     | textis("gif")
     | textis("bmp")}? letters;


optionorcaption
     :    (mw_img_thumbnail (PIPE | link_end)) => mw_img_thumbnail /* move it up here as it's so common */
     |    (SPACE | punctuation) => image_caption
     |    (imageoption (PIPE | link_end)) => imageoption
     |     image_caption;
   
image_caption
@init {caption_levels++; prohibit_literal_link_end++; prohibit_literal_pipe++;}
: inline_text?
-> ^(TEXT inline_text);
finally {caption_levels--; prohibit_literal_link_end--; prohibit_literal_pipe--;}


mw_img_manualthumb    : {textis("thumbnail") | textis("thumb")}? mwletters EQUALS imagename -> ^(IMG_OPTION_THUMBNAIL imagename);
imageoption:  
    mw_img_manualthumb          -> ^(IMG_OPTION_MANUALTHUMB mw_img_manualthumb)
    | mw_img_thumbnail          -> ^(IMG_OPTION_THUMB mw_img_thumbnail)
    | mw_img_frame              -> ^(IMG_OPTION_FRAME mw_img_frame)
    | mw_img_frameless          -> ^(IMG_OPTION_FRAMELESS mw_img_frameless)
    //| mw_img_page weirdly doesn't work, but why?
    | mw_img_upright            -> ^(IMG_OPTION_UPRIGHT mw_img_upright)
    | mw_img_border             -> ^(IMG_OPTION_BORDER mw_img_border)
    | positive_int mw_img_width -> ^(IMG_OPTION_SIZE positive_int)
    | mw_img_left               -> ^(IMG_OPTION_LEFT mw_img_left)
    | mw_img_center             -> ^(IMG_OPTION_CENTER mw_img_center)
    | mw_img_right              -> ^(IMG_OPTION_RIGHT mw_img_right)
    | mw_img_none               -> ^(IMG_OPTION_NONE mw_img_none)
    | mw_img_baseline           -> ^(IMG_OPTION_BASELINE mw_img_baseline)
    | mw_img_sub                -> ^(IMG_OPTION_SUB mw_img_sub)
    | mw_img_super              -> ^(IMG_OPTION_SUPER mw_img_super)
    | mw_img_top                -> ^(IMG_OPTION_TOP mw_img_top)
    | mw_img_text_top           -> ^(IMG_OPTION_TEXT_TOP mw_img_text_top)
    | mw_img_middle             -> ^(IMG_OPTION_MIDDLE mw_img_middle)
    | mw_img_bottom             -> ^(IMG_OPTION_BOTTOM mw_img_bottom)
    | mw_img_text_bottom        -> ^(IMG_OPTION_TEXT_BOTTOM mw_img_text_bottom);

/* default settings: */
/* Hmm, user-definable grammar seems to be a bad idea. Assume that the img_manualthumb is always something followed by the name. */
  mw_img_thumbnail      : {textis("thumbnail") | textis("thumb")}? mwletters -> ^(IMG_OPTION_THUMBNAIL);
 mw_img_frame          : {textis("framed") | textis("enframed") | textis("frame")}? mwletters; //'framed' | 'enframed' | 'frame';
 mw_img_frameless      : {textis("frameless")}? mwletters;
 mw_img_page           : {textis("page")}? mwletters (SPACE | EQUALS) mwletters; //'page=$1' | 'page $1' ; /*??? (where is this used?);*/
 mw_img_upright        : {textis("upright")}? mwletters EQUALS? positive_int?; //'upright' (  '='? POSITIVE_INT)?;
 mw_img_border         : {textis("border")}? mwletters;
 mw_img_width          : {textis("px")}? mwletters;

 mw_img_baseline       : {textis("baseline")}? mwletters;
 mw_img_sub            : {textis("sub")}? mwletters;
 mw_img_super          : {textis("super") | textis("sup")}? mwletters;
 mw_img_top            : {textis("top")}? mwletters;
 mw_img_text_top       : {textis("text-top")}? mwletters;
 mw_img_middle         : {textis("middle")}? mwletters;
 mw_img_bottom         : {textis("bottom")}? mwletters;
 mw_img_text_bottom    : {textis("text-bottom")}? mwletters;

mw_img_left            : {textis("left")}? mwletters;
mw_img_center          : {textis("center") | textis("centre")}? mwletters;
mw_img_right           : {textis("right")}? mwletters;
mw_img_none            : {textis("none")}? mwletters;




/*
External links link to other sites in one of three forms:
  - http://foo.com - bald
  - [http://foo.com] - explicit
  - [http://fooc.com Explicit with caption]
*/
external_link:  
        url -> ^(EXTERNAL_LINK ^(TEXT url) ^(TEXT url)) //attempt to use url as caption
        | bracketed_url -> ^(EXTERNAL_LINK bracketed_url);

bracketed_url:    LEFT_BRACKET url (ws external_link_caption)? RIGHT_BRACKET -> ^(TEXT url) ^(TEXT external_link_caption?);

/* badly underspec'ed so far */
url:
    protocol COLON SLASH SLASH domain_elem+ DOT domain_elem+  //    http://foo.com (minimum)
    ((DOT domain_elem+)=>DOT domain_elem+)*                   //    .lom.wom ...
    (SLASH ((urlpath_elem) => urlpath_elem)*)?                                    //    /foo?blah@33!boo.html
    ;
    
domain_elem: 
    letters | digits | HYPHEN;

urlpath_elem: 
    letters | digits | HYPHEN | UNDERSCORE | PERCENT | SLASH | DOT | QUESTION | HASH | PLUS | AMP | TILDE | EQUALS | AT | EXCLAMATION | COLON;

protocol: {textis("ftp") | textis("http")}? letters;

external_link_caption
@init {prohibit_literal_right_bracket=true;}
:
    formatted_text;
finally {prohibit_literal_right_bracket=false;}


/*
  Magic links don't require any special punctuation:
    - ISBN 1234567890x
    - RFC 1234
    - PMID 1234
*/    

magic_link: isbn_link | pmid_link | rfc_link;
accidental_magic_link: isbn_accidental | pmid_accidental | rfc_accidental;

isbn_link: ISBN_LINK          -> ^(ISBN ISBN_LINK);
isbn_accidental: ISBN_LINK    -> ^(TEXT ISBN_LINK); // the TEXT node is possibly superfluous?

rfc_link: RFC_LINK            -> ^(RFC RFC_LINK);
rfc_accidental: RFC_LINK      -> ^(TEXT RFC_LINK);

pmid_link: PMID_LINK          -> ^(PMID PMID_LINK);
pmid_accidental: PMID_LINK    -> ^(TEXT PMID_LINK);
/////////////////////////////////////////////////////////////////////////

magic_word: UNDERSCORE UNDERSCORE  magic_word_text UNDERSCORE UNDERSCORE
-> ^(MAGIC_WORD magic_word_text);

magic_word_text: {is_magic_word()}? letters;
//magic_word_text: {textis("TOC")}? letters;
        
////////////////////////////////////////////////////////////////////////

pre_block: 
    PRE_OPEN pre_block_body PRE_CLOSE 
-> ^(PRE pre_block_body);

pre_block_body: 
    (unformatted_characters|pre_ws|NL)*;



/*************** Formatted text *************************/
/*
simple text is basically character formatting. It's used notably:
  - in link captions:  [[The Blah|The ''Blah'']]
  - in external link captions: [http://foo.com '''foo''']
*/
formatted_text
@init { text_levels++; } :
(
    (formatted_text_elem) => formatted_text_elem
    ((nbsp_before_punctuation) => nbsp_before_punctuation)*
    ((printing_ws) => printing_ws)?
)+;
finally { text_levels --; }

formatted_text_elem:
    (
      (accidental_magic_link) => accidental_magic_link
    | ((punctuation_before_nbsp)=> punctuation_before_nbsp)
    | (APOSTROPHES) => bold_and_italics
    |  angle_tag
    | ((html_entity) => html_entity)
    | unformatted_characters
    );

/*
The lowest level: mere text with no formatting. & and < characters are allowed, but are generally converted.
*/    
unformatted_characters:
    (html_dangerous
    |punctuation { System.out.print($text); }//* if punctuation+, risk of swallowing too many characters: [[[foo.jpg]]] needs to swallow just one */
    |meaningless_characters { System.out.print($text); }
    |digits { System.out.print($text); } 
    );


/*textline: simple_text -> ^(P simple_text);*/

///////////////////////////////////////////////////////////////////////////
bold_and_italics:
     {textis("''") && text_italics}? => APOSTROPHES  {text_italics=false; System.out.print("</i>"); } ->            ^(I_OFF)
    |{textis("''") && !text_italics}? => APOSTROPHES {text_italics=true; System.out.print("<i>"); }   ->            ^(I_ON)
    |{textis("'''") && text_bold}? => APOSTROPHES    {text_bold=false; System.out.print("</b>"); }    ->            ^(B_OFF)
    |{textis("'''") && !text_bold}? => APOSTROPHES   {text_bold=true; System.out.print("<b>"); }      ->            ^(B_ON)
    |{textis("''''") && text_bold}? => APOSTROPHES   {text_bold=false; System.out.print("'</b>"); }   -> APOSTROPHE ^(B_OFF)
    |{textis("''''") && !text_bold}? => APOSTROPHES  {text_bold=true; System.out.print("'<b>"); }     -> APOSTROPHE ^(B_ON)
    |{textis("'''''") && text_bold && text_italics}? =>  APOSTROPHES {text_bold=false; text_italics=false; System.out.print("'</b> </i>");} -> ^(B_OFF) ^(I_OFF)
    |{textis("'''''") && text_bold && !text_italics}? => APOSTROPHES {text_bold=false; text_italics=true; System.out.print("'</b> <i>");}   -> ^(B_OFF) ^(I_ON)
    |{textis("'''''") && !text_bold && text_italics}? => APOSTROPHES {text_bold=true; text_italics=false; System.out.print("'<b> </i>"); }  -> ^(B_ON)  ^(I_OFF)
    |{textis("'''''") && !text_bold && !text_italics}? =>APOSTROPHES {text_bold=true; text_italics=true; System.out.print("'<b> <i>");}     -> ^(B_ON)  ^(I_ON)
    // Hopefully we never get more than 6 or less than 2. The lexer should take care of that.
    ;
////////////////////////Nbsp punctuation/////////////////////////////////
nbsp_before_punctuation:
    
    SPACE (R_GUILLEMET          { System.out.print("&nbsp; »"); } ->  NBSP160 R_GUILLEMET
          | QUESTION            { System.out.print("&nbsp; ?"); } -> NBSP160 QUESTION
          | COLON               { System.out.print("&nbsp; :"); } -> NBSP160 COLON
          | SEMICOLON           { System.out.print("&nbsp; ;"); } -> NBSP160 SEMICOLON
          | literal_exclamation { System.out.print("&nbsp; !"); } -> NBSP160 EXCLAMATION
          | PERCENT             { System.out.print("&nbsp; \%"); }-> NBSP160 PERCENT
          ) ;        


punctuation_before_nbsp:
    L_GUILLEMET SPACE 
{ System.out.print("« &nbsp;"); }
    -> L_GUILLEMET NBSP160;

//«»

html_entity:
    AMP (
        html_entity_name SEMICOLON  { System.out.print("&" + $html_entity_name.text + ";"); }        -> ^(ENTITY html_entity_name)
// this line removed as it was causing a crash
//        |  HASH digits SEMICOLON      { System.out.print("&#" + $digits.text + ";"); }         -> ^(ENTITY digits)
//        | '#x' hex_digits SEMICOLON
        )
        ;
 
// ### To be expanded with help from sanitizer.php
html_entity_name: 
        {textis("nbsp")}? => letters;
        
/*html_open_tag:
        LT html_tag_name        */


//////// //////////////////////////////////////////////////////////////////
pagename
@init {prohibit_literal_right_bracket=true; prohibit_literal_pipe++;}:
        pagename_elem
              ((pagename_elem) => pagename_elem
               | COLON
               | SLASH // will need something a bit more sophisticated
//               | punctuation
               |(SPACE) => SPACE
              )*;
finally { prohibit_literal_right_bracket=false; prohibit_literal_pipe--;}

pagename_elem: (letters | digits | accidental_magic_link | UNKNOWN | punctuation/* | DIGITS | DOT | UNDERSCORE | HYPHEN | OPEN_PAREN | CLOSE_PAREN*/);




/////////////////////////////////// Very basic types ///////////////////////////////////////

/* Currently doesn't support equals during a header title...*/
header_simple_text
@init {in_header=true;}:
        inline_text; /* Pretty much everything seems to be tolerated in headings. (!) */
finally {in_header=false;}
        
// any need for accidental_magic_link?        
mwletters:    letters (letters | HYPHEN | UNDERSCORE | (digits)=>positive_int)*;

/////////////////////////////////// Semi-literals, literal sets etc ///////////////////////////

single_pipe:
   {input.LA(2) != PIPE}? => PIPE;


punctuation :   
    DOT |COMMA|OPEN_PAREN | CLOSE_PAREN | HYPHEN 
    | HASH | ASTERISK | SEMICOLON | literal_colon
    | UNDERSCORE | SLASH | APOSTROPHE 
    | literal_left_bracket 
    | literal_right_bracket 
    | literal_pipe | literal_equals 
    | literal_exclamation
    | L_GUILLEMET | R_GUILLEMET | QUESTION | PERCENT | PLUS | AT | TILDE
    | LEFT_BRACE | RIGHT_BRACE // unconfirmed
    | ESCAPED_PUNC;

html_dangerous:   
        LT { System.out.print("&lt;"); } -> ^(ENTITY LT)
      | GT { System.out.print("&gt;"); } -> ^(ENTITY GT)
      | AMP { System.out.print("&amp;"); } -> ^(ENTITY AMP);

angle_tag: ANGLE_TAG { System.out.print($text);}/* -> ANGLE_TAG */;

meaningless_characters: 
    (LETTERS | UNKNOWN)+;

letters: (LETTERS);
positive_int: digits; /* needs to be refined to remove 0s at start */
literal_link_end:          {prohibit_literal_link_end <= 0}? => link_end;


literal_right_bracket:
/*@init {
         System.out.println("Entering LRB");
}:     */
//         { !prohibit_literal_right_bracket && (prohibit_literal_link_end <= 0 || input.LA(2)!= RIGHT_BRACKET) }?
//        { !prohibit_literal_right_bracket && (prohibit_literal_link_end <= 0 || input.LA(2)!= RIGHT_BRACKET)  }? => '&';
// weird: if the semantic predicate returns true, everything is ok. if it returns false, an exception is raised.
         //{ false }? => RIGHT_BRACKET;
{ !prohibit_literal_right_bracket && (prohibit_literal_link_end <= 0 || input.LA(2)!= RIGHT_BRACKET) }? => 
    RIGHT_BRACKET;

literal_pipe:              
{ !(   prohibit_literal_pipe > 0 ||   (prohibit_literal_double_pipe > 0 && input.LA(2) == PIPE))  }? => PIPE;
  //  || (prohibit_opening_literal_pipe > 0 && getCharPositionInLine()==0) // not correct, need to deal with opening spaces too

/* Three ways of getting a literal right bracket:
1) You're neither in an external nor internal link: foo]
2) You're in an internal link, and not followed by another right bracket:  [[Boop|here] see?]]
3) You're in a nowiki block: [http://square.bracket.com The <nowiki>]</nowiki> foundation.]
*/
//      => RIGHT_BRACKET;
/*finally {
         System.out.println("Exiting LRB");
}*/


/* Dodgy - doesn't really know whether it's a literal left bracket or not */
literal_left_bracket:      LEFT_BRACKET; 

/* ;foo:blah is special. ;foo[blah|bl:ah] is not special. TODO: make sure this doesn't break namespaces in defs */
literal_colon:             {!prohibit_literal_colon || text_levels > 1}? => COLON;

// Only supports a single =. So no ==foo==blah==. Currently =<nowiki>=</nowiki>blah== etc doesn't work either.
literal_equals:            
    {!in_header || input.LA(2) != EQUALS}? => EQUALS
;

literal_exclamation:              
{!(prohibit_literal_exclamation > 0 || prohibit_literal_double_exclamation > 0 && input.LA(2) == EXCLAMATION)}? => EXCLAMATION;


link_start: LEFT_BRACKET LEFT_BRACKET;
link_end: RIGHT_BRACKET RIGHT_BRACKET;

// TODO: apparently image captions always treat spaces literally...
printing_ws:
    {literal_whitespace && text_levels <= 1}? => (pre_ws) => pre_ws
    | ws -> SPACE;

digits:    digit+;
digit: DIGIT;


// Handling of spaces is a bit unclear atm.
ws: ((ws_elem)=>ws_elem)+ { System.out.print(" "); };

pre_ws: ((ws_elem)=>ws_elem)+;
ws_elem:
      SPACE        -> SPACE
    | NOWIKI       ->
    | NOWIKI_OFF   ->
    ;
//    | HTML_COMMENT -> ; // in current mediawiki, comments are stripped out

// apparently identical to previous entry?
/*ws: (SPACE
    | NOWIKI!
    | NOWIKI_OFF!)+ ;*/






///////////////////////////////////////////////////////////////////////////////


REDIRECT:     {getCharPositionInLine()==0 && getLine()==1}? => '#REDIRECT';


//-----------------------------------------------------
/* ISBN magic links. Care will be needed to make sure they're treated as literals wherever they aren't supported. */
// Broken example: [http://ISBN 1234567890] - current parser does correctly. But does it matter?
ISBN_LINK: {!in_noparse}? =>
  // Parser.php l081, ~DIGIT is actually regexp \b
  ((ISBN_LINK_ACTUAL ~DIGIT) => ISBN_LINK_ACTUAL
//  | LETTER { $type=LETTERS; }
  );

fragment
ISBN_LINK_ACTUAL:
    'ISBN'
    ' '+
    ('97' ('8' | '9') (' ' | '-')?)?
    ('0'..'9')
    ((' ' | '-')? '0'..'9')
    ((' ' | '-')? '0'..'9')
    ((' ' | '-')? '0'..'9')
    ((' ' | '-')? '0'..'9')
    ((' ' | '-')? '0'..'9')
    ((' ' | '-')? '0'..'9')
    ((' ' | '-')? '0'..'9')
    ((' ' | '-')? '0'..'9')
    ((' ' | '-')? ('0'..'9' | 'X' | 'x'));
   
    
RFC_LINK: {!in_noparse}?=>
  ((RFC_LINK_ACTUAL) => RFC_LINK_ACTUAL
//  | LETTER { $type=LETTER; }
  );
 
fragment
RFC_LINK_ACTUAL:
    'RFC'
    ' '+
    ('0'..'9')+;
    
    

PMID_LINK : {!in_noparse}? =>
  ((PMID_LINK_ACTUAL) => PMID_LINK_ACTUAL
//  | LETTER { $type=LETTERS; }
  );
 
fragment
PMID_LINK_ACTUAL:
    'PMID'
    ' '+
    ('0'..'9')+;

///////////// <nowiki> / </nowiki>

NOWIKI:
    ({!in_noparse}? => (NOWIKI_ACTUAL) => NOWIKI_ACTUAL { in_nowiki=true; in_noparse=true;}
    |(HTML_COMMENT) => HTML_COMMENT { $type=HTML_COMMENT; $channel=HIDDEN;}
    | '<' { $type=LT; }
    );

fragment
NOWIKI_ACTUAL: '<nowiki>' ;

NOWIKI_OFF: {in_nowiki}? =>
    ((NOWIKI_OFF_ACTUAL) => NOWIKI_OFF_ACTUAL { in_nowiki=false; in_noparse=false;}
    | '<' { $type=LT; }
    );

fragment
NOWIKI_OFF_ACTUAL: '</nowiki>' ;

fragment
HTML_COMMENT: '<!--' .* '-->';


/////////// <pre> / </pre>

PRE_OPEN: {!in_noparse}? =>
    ((PRE_OPEN_ACTUAL) => PRE_OPEN_ACTUAL { in_pre=true; in_noparse=true;}
    | '<' { $type=LT; }
    );

fragment
PRE_OPEN_ACTUAL: '<pre>' ;

PRE_CLOSE: {in_pre}? =>
    ((PRE_CLOSE_ACTUAL) => PRE_CLOSE_ACTUAL { in_pre=false; in_noparse=false; }
    | '<' { $type=LT; }
    );

fragment
PRE_CLOSE_ACTUAL: '</pre>' ;

ANGLE_TAG: { !in_noparse}? =>
    ((ANGLE_TAG_OPEN_ACTUAL) => ANGLE_TAG_OPEN_ACTUAL
    |(ANGLE_TAG_CLOSE_ACTUAL) => ANGLE_TAG_CLOSE_ACTUAL
    | '<' { $type=LT; }
    );

fragment
ANGLE_TAG_OPEN_ACTUAL:   HTML_OPEN | REF_OPEN; // or REF or whatever...

fragment
ANGLE_TAG_CLOSE_ACTUAL:   HTML_CLOSE | REF_CLOSE; // or REF or whatever...
fragment

WS : SPACE+; // should include line feeds later 

/* This section from Terrence Parr's HTML grammar */
fragment
ATTR
	:	WORD ('=' (WORD ('%')? | ('-')? INT | STRING | HEXNUM))?
	;
//don't need uppercase for case-insen.
//the '.' is for words like "image.gif"
fragment
WORD:	(	LETTER  | '.' | SLASH )
	(	LETTER  | DIGIT | '.' )+
	;

fragment
STRING	: '"'  (~'"')* '"'
        | '\'' (~'\'')* '\''
	;

fragment
WSCHARS : ' ' | '\t' | '\n' | '\r';

	
fragment
HEXNUM : HASH HEXINT;

fragment
INT: (DIGIT)+;

fragment
HEXINT
	:	(HEXDIGIT)+
	;

fragment
HEXDIGIT: '0'..'9' | 'a'..'f';

/******************************************************/


/* should be in the tokens section - why didn't that work? */
R_GUILLEMET: '»';
L_GUILLEMET: '«';
QUESTION:    '?';
EXCLAMATION: '!';
PERCENT:     '%';



/* The three 'dangerous' HTML characters */
//LT:                   '<';
GT:                   '>';
AMP:                  '&';


/* It's a literal apostrophe if either the next character is *not* an apostrophe, or the next 5 characters *are* apostrophes. Yummy. */
APOSTROPHE      :  {
      input.LA(1)=='\'' && (
          in_noparse || (
              input.LA(2)!='\'' ||
              input.LA(3)=='\'' &&
              input.LA(4)=='\'' &&
              input.LA(5)=='\'' &&
              input.LA(6)=='\''
          )
      )
}? => APOS;

/* It's a swarm of meaningful apostrophes if it is not the case that this and the next five characters are apostrophes, and there are at least two, and we're not in a nowiki.*/
APOSTROPHES     : {
        !in_noparse &&
        input.LA(1)=='\'' && !(
             input.LA(2)=='\'' &&
             input.LA(3)=='\'' &&
             input.LA(4)=='\'' &&
             input.LA(5)=='\'' &&
             input.LA(6)=='\''
        )
}? => APOS APOS+ ;

fragment
APOS            : '\'';

HASH            : {!in_noparse}? => '#';// {if (in_noparse) $type=ESCAPED_PUNC;};
ASTERISK        : {!in_noparse}? => '*';// {if (in_noparse) $type=ESCAPED_PUNC;};
COLON           : {!in_noparse}? => ':';// {if (in_noparse) $type=ESCAPED_PUNC;};
SEMICOLON       : {!in_noparse}? => ';';// {if (in_noparse) $type=ESCAPED_PUNC;};
PIPE            : {!in_noparse}? => '|';// {if (in_noparse) $type=ESCAPED_PUNC;};
//LEFT_BRACKET    : {!in_noparse}? => '[' {if (in_noparse) $type=ESCAPED_PUNC;};

LEFT_BRACKET    : {!in_noparse}? => '[';
RIGHT_BRACKET   : {!in_noparse}? => ']';
EQUALS          : {!in_noparse}? => '=';// {if (in_noparse) $type=ESCAPED_PUNC;};
SLASH           : {!in_noparse}? => '/';// {if (in_noparse) $type=ESCAPED_PUNC;}; // this is almost harmless...
LEFT_BRACE      : {!in_noparse}? => '{';
RIGHT_BRACE     : {!in_noparse}? => '}';

// escaped special characters are just punctuation...
ESCAPED_PUNC     : {in_noparse}? => ('#' | '*' | ':' | ';' | '|' | '[' | ']' | '=' | '/' | '{' | '}' | STUPID);

fragment
STUPID: '!$()#*%&!*%$(!#&$'; 

DIGIT: '0'..'9';

LETTERS    :    LETTER+;

fragment
LETTER    :    ('A'..'Z'|'a'..'z');

SPACE:    ' ';
NL    :    '\r'? '\n' {setText("\\n\n");};

/* totally harmless punctuation? */
DOT             :    '.'; // Only purpose of dot is [[image:foo.jpg]]...
UNDERSCORE      :    '_';
HYPHEN          :    '-';
COMMA           :    ',';
OPEN_PAREN      :    '(';
CLOSE_PAREN     :    ')';
PLUS            :    '+';
TILDE           :    '~';
AT              :    '@';      

UNKNOWN    :    .;

/* inline HTML tags */

/*fragment
HTML_OBR : '<br' (WS ATTR)? WS? ('>' | '/>') ;*/

fragment 
HTML_OPEN: '<' ALLOWED_HTML (WS ATTR)? WS? ('>' | '/>');

fragment 
HTML_CLOSE: '</' ALLOWED_HTML '>';

fragment 
REF_OPEN: '<ref' (WS ATTR)? WS? ('>' | '/>');

fragment 
REF_CLOSE: '</ref>';



fragment
ALLOWED_HTML: 
    'h1' | 'h2' | 'h3' | 'h4' | 'h5' | 'h6' | 'cite' | 'center' | 'blockquote' | 'caption' |  'br' /*| 'pre' -- treated specially */
    | 'b' | 'del' | 'i' | 'ins' | 'u' | 'font' | 'big' | 'small' | 'sub' | 'sup' | 'code' | 'em' | 's' | 'strike' | 'strong' | 'tt' | 'var'
    | 'ol' | 'ul' | 'dl'
    | 'p' | 'span' | 'table' | 'div'
    | 'rt' | 'rb ' | 'rp' | 'ruby'
    | 'hr' | 'li' | 'dt' | 'dd'
    | 'tr' | 'td' | 'th';
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