/** PEGjs lexer/parser */
{
$this->tu = TexUtil::getInstance();

# get reference of the options for usage in functions.


# get reference of the options for usage in functions.
$this->options = ParserUtil::createOptions($options);

}
// first rule is the start production.
start
  = _ t:tex_expr
    {
        assert($t instanceof TexArray);
        return $t;
    }

// the PEG grammar doesn't automatically ignore whitespace when tokenizing.
// so we add `_` productions in appropriate places to eat whitespace.
// Lexer rules (which are capitalized) are expected to always eat
// *trailing* whitespace.  Leading whitespace is taken care of in the `start`
// rule above.
_
  = [ \t\n\r]*

/////////////////////////////////////////////////////////////
// PARSER
//----------------------------------------------------------

tex_expr
  = e:expr EOF
    { return $e; }
  / e1:ne_expr name:FUN_INFIX e2:ne_expr EOF
    { return new TexArray( new Infix($name, $e1, $e2)); }

expr
  = ne_expr
  / ""
    { return new TexArray(); }

ne_expr
  = h:lit_aq t:expr
    { return $t->unshift($h); }
  / h:litsq_aq t:expr
    { return $t->unshift($h); }
  / d:DECLh e:expr
    { return new TexArray(new Declh($d->getFname(), $e)); }
litsq_aq
  = litsq_fq
  / litsq_dq
  / litsq_uq
  / litsq_zq
litsq_fq
  = l1:litsq_dq SUP l2:lit
    { return new FQ($l1->getBase(), $l1->getDown(), $l2); }
  / l1:litsq_uq SUB l2:lit
    { return new FQ($l1->getBase(), $l2, $l1->getUp()); }
litsq_uq
  = base:litsq_zq SUP upi:lit
    { return new UQ($base, $upi); }
litsq_dq
  = base:litsq_zq SUB downi:lit
    { return new DQ($base, $downi); }
litsq_zq
  = SQ_CLOSE
    { return new Literal( "]"); }
expr_nosqc
  = l:lit_aq e:expr_nosqc
    { return $e ->unshift( $l ); }
  / "" /* */
    { return new TexArray(); }
lit_aq
  = lit_fq
  / lit_dq
  / lit_uq
  / lit_dqn
  / lit_uqn
  / lit

lit_fq
  = l1:lit_dq SUP l2:lit
    { return new FQ($l1->getBase(), $l1->getDown(), $l2); }
  / l1:lit_uq SUB l2:lit
    { return new FQ ($l1->getBase(), $l2, $l1->getUp()); }
  / l1:lit_dqn SUP l2:lit
    { return new FQ(new TexArray(), $l1->getDown(), $l2); }

lit_uq
  = base:lit SUP upi:lit
    { return new UQ($base, $upi); }
lit_dq
  = base:lit SUB downi:lit
    { return new DQ($base, $downi); }
lit_uqn
  = SUP l:lit
    { return new UQ(new TexArray(),$l); }
lit_dqn
  = SUB l:lit
    { return new DQ(new TexArray(),$l); }


left
  = LEFTI d:DELIMITER
    { return $d; }
  / LEFTI SQ_CLOSE
    { return  "]"; }
right
  = RIGHTI d:DELIMITER
    { return $d; }
  / RIGHTI SQ_CLOSE
    { return  "]"; }
lit
  = r:LITERAL                   { return new Literal($r); }
  / f:generic_func &{ return $this->tu->latex_function_names($f); } _
   c:( "(" / "[" / "\\{" / "" { return " ";}) _
   { return new TexArray( new Literal( $f ) , new Literal( $c ) ) ; }
  // quasi-literal; this is from Texutil.find(...) but the result is not
  // guaranteed to be Tex.LITERAL(...)
  / f:generic_func &{ return $this->tu->nullary_macro_aliase($f); } _ // from Texutil.find(...)
   {
     $parser = new Parser();
     $ast = $parser->parse($this->tu->nullary_macro_aliase($f), $this->options);
     assert($ast instanceof TexArray && $ast->getLength() === 1);
     return $ast->first();
   }
  / f:generic_func &{ return $this->tu->deprecated_nullary_macro_aliase($f); } _ // from Texutil.find(...)
   {
     $parser = new Parser();
     $ast = $parser->parse($this->tu->deprecated_nullary_macro_aliase($f), $this->options);
     assert($ast instanceof TexArray && $ast->getLength() === 1);
     if ($this->options['oldtexvc']){
       return $ast->first();
     } else {
          throw new SyntaxError("Deprecation: Alias no longer supported.", [], $this->text(), $this->offset(),
            $this->line(), $this->column());
     }
   }
   / f:generic_func &{ return $this->tu->mediawiki_function_names($f); } _
         {
             if(is_array($f)) {
                 // This is an unexpected case, but covers the ambiguity of slice in javascript.
                 $fProcessed = implode(array_slice($f, 1));
             } else {
                 $fProcessed = substr($f,1);
             }
             return new Fun1nb( '\\operatorname', new Literal( $fProcessed ) );
         }
  / r:DELIMITER                 { return new Literal($r); }
  / b:BIG r:DELIMITER           { return new Big($b, $r); }
  / b:BIG SQ_CLOSE              { return new Big($b,  "]"); }
  / l:left e:expr r:right       {return new Lr($l, $r, $e); }
  / name:FUN_AR1opt e:expr_nosqc SQ_CLOSE l:lit /* must be before FUN_AR1 */
    { return new Fun2sq($name, $e->setCurly(), $l); }
  / name:FUN_AR1 l:lit          { return new Fun1($name, $l); }
  / name:FUN_AR1nb l:lit        { return new Fun1nb($name, $l); }
  / name:FUN_MHCHEM l:chem_lit  { return new Mhchem($name, $l); }
  / name:FUN_AR2 l1:lit l2:lit  { return new Fun2($name, $l1, $l2); }
  / name:FUN_AR4_MHCHEM_TEXIFIED l1:lit l2:lit l3:lit l4:lit  { return new Fun4($name, $l1, $l2, $l3, $l4); }
  / name:FUN_AR2nb l1:lit l2:lit { return new Fun2nb($name, $l1, $l2); }
  / BOX
  / CURLY_OPEN e:expr CURLY_CLOSE
    { return $e->setCurly(); }
  / CURLY_OPEN e1:ne_expr name:FUN_INFIX e2:ne_expr CURLY_CLOSE
    { return new Infix($name, $e1, $e2); }
  / BEGIN_MATRIX   m:(array/matrix) END_MATRIX
    { return $m->setTop( 'matrix' ); }
  / BEGIN_PMATRIX  m:(array/matrix) END_PMATRIX
    { return $m->setTop( 'pmatrix' ); }
  / BEGIN_BMATRIX  m:(array/matrix) END_BMATRIX
    { return $m->setTop( 'bmatrix' ); }
  / BEGIN_BBMATRIX m:(array/matrix) END_BBMATRIX
    { return $m->setTop( 'Bmatrix' ); }
  / BEGIN_VMATRIX  m:(array/matrix) END_VMATRIX
    { return $m->setTop( 'vmatrix' ); }
  / BEGIN_VVMATRIX m:(array/matrix) END_VVMATRIX
    { return $m->setTop( 'Vmatrix' ); }
  / BEGIN_ARRAY    opt_pos m:array END_ARRAY
    { return $m->setTop( 'array' ); }
  / BEGIN_ALIGN    opt_pos m:matrix END_ALIGN
    { return $m->setTop( 'aligned' ); }
  / BEGIN_ALIGNED  opt_pos m:matrix END_ALIGNED // parse what we emit
    { return $m->setTop( 'aligned' ); }
  / BEGIN_ALIGNAT  m:alignat END_ALIGNAT
    { return $m->setTop( 'alignedat' ); }
  / BEGIN_ALIGNEDAT m:alignat END_ALIGNEDAT // parse what we emit
    { return $m->setTop( 'alignedat' ); }
  / BEGIN_SMALLMATRIX m:(array/matrix) END_SMALLMATRIX
    { return $m->setTop( 'smallmatrix' ); }
  / BEGIN_CASES    m:matrix END_CASES
    { return $m->setTop( 'cases' ); }
  / "\\begin{" alpha+ "}" /* better error messages for unknown environments */
    { throw new SyntaxError("Illegal TeX function", [], $this->text(), $this->offset(),
                            $this->line(), $this->column()); }
  / f:generic_func &{ return !$this->tu->getAllFunctionsAt($f); }
    { throw new SyntaxError("Illegal TeX function", [], $f, $this->offset(), $this->line(), $this->column()); }


// "array" requires mandatory column specification
array
  = cs:column_spec m:matrix
    { return $m->setColumnSpecs( $cs ); }

// "alignat" requires mandatory # of columns
alignat
  = as:alignat_spec m:matrix
    { return $m->setColumnSpecs( $as ); }

// "matrix" does not require column specification
matrix
  = l:line_start tail:( r:NEXT_ROW m:matrix { return [$m,$r]; } )?
    { if ($tail === null) { return new Matrix( 'matrix', new TexArray( $l ) ); }
     return new Matrix( 'matrix', $tail[0]->unshift($l), $tail[1] ); }
line_start
  = f:HLINE l:line_start
    {
        if ($l->first() === null ) {
            $l->push(new TexArray());
        }
        $l->first()->unshift(new Literal($f . " ")); return $l;}
  / line
line
  = e:expr tail:( NEXT_CELL l:line { return $l; } )?
    {
    if ($tail === null) { return new TexArray( $e )  ; }
    return $tail->unshift($e);
    }

column_spec
  = CURLY_OPEN cs:(one_col+ { return $this->text(); }) CURLY_CLOSE
    { return TexArray::newCurly(new Literal($cs)); }

one_col
  = [lrc] _
  / "p" CURLY_OPEN boxchars+ CURLY_CLOSE
  / "*" CURLY_OPEN [0-9]+ _ CURLY_CLOSE
     ( one_col
     / CURLY_OPEN one_col+ CURLY_CLOSE
     )
  / "||" _
  / "|" _
  / "@" _ CURLY_OPEN boxchars+ CURLY_CLOSE

alignat_spec
  = CURLY_OPEN num:([0-9]+ { return $this->text(); }) _ CURLY_CLOSE
    { return TexArray::newCurly(new Literal($num)); }

opt_pos
  = "[" _ [tcb] _ "]" _
  / "" /* empty */

/////////////////////////////////////////////////////////////
// MHCHEM grammar rules
//----------------------------------------------------------


chem_lit
  = CURLY_OPEN e:chem_sentence CURLY_CLOSE               { return $e->setCurly(); }

chem_sentence =
    _ p:chem_phrase " " s:chem_sentence                  { return new TexArray($p,new TexArray(new Literal(" "),$s)); } /
    _ p:chem_phrase _                                    { return new TexArray($p,new TexArray()); }

chem_phrase =
    m:"(^)"                                              { return new Literal($m); } /
    m:chem_word n:CHEM_SINGLE_MACRO                      { return new ChemWord($m, new Literal($n)); }/
    m:chem_word                                          { return $m; } /
    m:CHEM_SINGLE_MACRO                                  { return new Literal($m); } /
    m:"^"                                                { return new Literal($m); }

chem_word =
    m:chem_char n:chem_word_nt                           { return new ChemWord($m, $n); } /
    m:CHEM_SINGLE_MACRO n:chem_char_nl o:chem_word_nt    { return new ChemWord(new ChemWord(new Literal($m), $n), $o); }

chem_word_nt = m:chem_word                               { return $m; } /
    ""                                                   { return new Literal(""); }

chem_char =
    m:chem_char_nl                                       { return $m;} /
    c:CHEM_LETTER                                        { return new Literal($c); }

chem_char_nl =
    m:chem_script                                        { return $m;} /
    CURLY_OPEN c:chem_text CURLY_CLOSE                   { return TexArray::newCurly($c); } /
    BEGIN_MATH c:expr END_MATH                           { return new Dollar($c); }/
    name:CHEM_BONDI l:chem_bond                           { return new Fun1($name, $l); } /
    m:chem_macro                                         { return $m; } /
    c:CHEM_NONLETTER                                     { return new Literal($c); }

chem_bond
 = CURLY_OPEN e:CHEM_BOND_TYPE CURLY_CLOSE               { return TexArray::newCurly(new Literal($e)); }

chem_script =
    a:CHEM_SUPERSUB b:CHEM_SCRIPT_FOLLOW                 { return new ChemWord(new Literal($a), new Literal($b)); } /
    a:CHEM_SUPERSUB b:chem_lit                           { return new ChemWord(new Literal($a), $b); } /
    a:CHEM_SUPERSUB BEGIN_MATH b:expr END_MATH           { return new ChemWord(new Literal($a), new Dollar($b)); }

// TODO \color is a not documented feature of mhchem for MathJax, at the moment named colors are accepted
chem_macro =
    name:CHEM_MACRO_2PU l1:chem_lit "_" l2:chem_lit      { return new ChemFun2u($name, $l1, $l2); }/ //return new Fun1nb($name, $l);
    name:CHEM_MACRO_2PC l1:CHEM_COLOR l2:chem_lit        { return new Fun2($name, $l1, $l2); } /
    name:CHEM_MACRO_2P l1:chem_lit l2:chem_lit           { return new Fun2($name, $l1, $l2); } /
    name:CHEM_MACRO_1P l:chem_lit                        { return new Fun1($name, $l); }

chem_text = cs:boxchars+                                 { return new Literal(join('',$cs)); }
CHEM_COLOR = "{" _ name:alpha+ _ "}" _                   { return new Literal(join('',$name)); }

/////////////////////////////////////////////////////////////
// LEXER
//----------------------------------------------------------
//space =           [ \t\n\r]
alpha =           [a-zA-Z]
literal_id =      [a-zA-Z]
literal_mn =      [0-9]
literal_uf_lt =   [,:;?!\']
delimiter_uf_lt = [().]
literal_uf_op =   [-+*=]
delimiter_uf_op = [\/|]
boxchars // match only valid UTF-16 sequences
 = [-0-9a-zA-Z+*,=():\/;?.!'` \[\]\[\u0080-\ud7ff\]\[\ue000-\uffff\]]

BOX
 = b:generic_func &{ return $this->tu->box_functions($b); } _ "{" cs:boxchars+ "}" _
   { return new Box($b, join('', $cs)); }

LITERAL
 = c:( literal_id / literal_mn / literal_uf_lt / "-" / literal_uf_op ) _
   { return $c; }
 / f:generic_func &{ return $this->tu->nullary_macro($f); } _ // from Texutil.find(...)
   { return $f . " "; }
 / f:generic_func &{ return $this->options['usemathrm'] && $this->tu->nullary_macro_in_mbox($f); } _ // from Texutil.find(...)
   { return "\\mathrm {" . $f . "} "; }
 / mathrm:generic_func &{ return $this->options['usemathrm'] && $mathrm === "\\mathrm"; } _
   "{" f:generic_func &{ return $this->options['usemathrm'] && $this->tu->nullary_macro_in_mbox($f); } _ "}" _
   /* make sure we can parse what we emit */
   {  return  $this->options['usemathrm'] ? "\\mathrm {" . $f . "} " : false;}
 / f:generic_func &{ return $this->tu->nullary_macro_in_mbox($f); } _ // from Texutil.find(...)
   { return "\\mbox{" . $f . "} "; }
 / mbox:generic_func &{ return $mbox === "\\mbox"; } _
   "{" f:generic_func &{ return $this->tu->nullary_macro_in_mbox($f); } _ "}" _
 /* make sure we can parse what we emit */
  { return "\\mbox{" . $f . "} "; }
 / f:(COLOR / DEFINECOLOR)
   { return $f; }
 / "\\" c:[, ;!_#%$&] _
   { return "\\" . $c; }
 / c:[><~] _
   { return $c; }
 / c:[%$] _
   { if($this->options['oldtexvc']) {
    return "\\" . $c; /* escape dangerous chars */
    } else {
     throw new SyntaxError("Deprecation: % and $ need to be escaped.", [], $this->text(), $this->offset(),
        $this->line(), $this->column());
    }}

DELIMITER
 = c:( delimiter_uf_lt / delimiter_uf_op / "[" ) _
   { return $c; }
 / "\\" c:[{}|] _
   { return "\\" . $c; }
 / f:generic_func &{ return $this->tu->other_delimiters1($f); } _ // from Texutil.find()
   { return $f . " "; }
 / f:generic_func &{ return $this->tu->other_delimiters2($f); } _ // from Texutil.find()
   {
     $parser = new Parser();
     $p = $parser->parse($this->tu->other_delimiters2($f), $this->options);
     # assert.ok(p instanceof TexArray && p.length === 1);
     assert($p instanceof TexArray && count($p->getArgs()) === 1);

     # assert.ok(p.first() instanceof Literal);
      assert($p->first() instanceof Literal);

     return $p->first()->getArg();
   }

FUN_AR1nb
 = f:generic_func &{ return $this->tu->fun_ar1nb($f); } _ { return $f; }

FUN_AR1opt
 = f:generic_func &{ return $this->tu->fun_ar1opt($f); } _ "[" _ { return $f; }

NEXT_CELL
 = "&" _

LATEX_LENGTH
  = s:LATEX_SIGN? n:LATEX_NUMBER u:LATEX_UNIT { return new LengthSpec($s, $n, $u); }

LATEX_SIGN
  = [+-]

LATEX_NUMBER
  = literal_mn+ "."? literal_mn*
  / "." literal_mn+

// from http://latexref.xyz/Units-of-length.html
LATEX_UNIT
  = "pt"
  / "pc"
  / "in"
  / "bp"
  / "cm"
  / "mm"
  / "dd"
  / "cc"
  / "sp"
  / "em"
  / "ex"
  / "mu"

  / "nd"
  / "nc"

NEXT_ROW
 = ("\\\\" s:("[" l:LATEX_LENGTH "]" { return $l; })?  _  {return $s; })

BEGIN
 = "\\begin" _
END
 = "\\end" _

BEGIN_MATRIX
 = BEGIN "{matrix}" _
END_MATRIX
 = END "{matrix}" _
BEGIN_PMATRIX
 = BEGIN "{pmatrix}" _
END_PMATRIX
 = END "{pmatrix}" _
BEGIN_BMATRIX
 = BEGIN "{bmatrix}" _
END_BMATRIX
 = END "{bmatrix}" _
BEGIN_BBMATRIX
 = BEGIN "{Bmatrix}" _
END_BBMATRIX
 = END "{Bmatrix}" _
BEGIN_VMATRIX
 = BEGIN "{vmatrix}" _
END_VMATRIX
 = END "{vmatrix}" _
BEGIN_VVMATRIX
 = BEGIN "{Vmatrix}" _
END_VVMATRIX
 = END "{Vmatrix}" _
BEGIN_ARRAY
 = BEGIN "{array}" _
END_ARRAY
 = END "{array}" _
BEGIN_ALIGN
 = BEGIN "{align}" _
END_ALIGN
 = END "{align}" _
BEGIN_ALIGNED
 = BEGIN "{aligned}" _
END_ALIGNED
 = END "{aligned}" _
BEGIN_ALIGNAT
 = BEGIN "{alignat}" _
END_ALIGNAT
 = END "{alignat}" _
BEGIN_ALIGNEDAT
 = BEGIN "{alignedat}" _
END_ALIGNEDAT
 = END "{alignedat}" _
BEGIN_SMALLMATRIX
 = BEGIN "{smallmatrix}" _
END_SMALLMATRIX
 = END "{smallmatrix}" _
BEGIN_CASES
 = BEGIN "{cases}" _
END_CASES
 = END "{cases}" _

SQ_CLOSE
 =  "]" _
CURLY_OPEN
 = "{" _
CURLY_CLOSE
 = "}" _
SUP
 = "^" _
SUB
 = "_" _

// This is from Texutil.find in texvc
generic_func
 = "\\" alpha+ { return $this->text(); }

BIG
 = f:generic_func &{ return $this->tu->big_literals($f); } _
   { return $f; }

FUN_AR1
 = f:generic_func &{ return $this->tu->fun_ar1($f); } _
   { return $f; }
 / f:generic_func &{ return $this->options['oldmhchem'] && $this->tu->fun_mhchem($f);} _
   { return $f; }
 / f:generic_func &{ return $this->tu->other_fun_ar1($f); } _
   { if ($this->options['oldtexvc']) {
        return $this->tu->other_fun_ar1($f);
     } else {
        throw new SyntaxError("Deprecation: \\Bbb and \\bold are not allowed in math mode.", [],
            $this->text(), $this->offset(), $this->line(),$this->column());
     }
   }

FUN_MHCHEM
 = f:generic_func &{ return $this->tu->fun_mhchem($f); } _
   { return $f; }

FUN_AR2
 = f:generic_func &{ return $this->tu->fun_ar2($f); } _
   { return $f; }

FUN_AR4_MHCHEM_TEXIFIED
 = f:generic_func &{ return $this->tu->fun_ar4($f) && $this->tu->mhchemtexified_required($f); } _
   { return $f; }

FUN_INFIX
 = f:generic_func &{ return $this->tu->fun_infix($f); } _
   { return $f; }

DECLh
 = f:generic_func &{ return $this->tu->declh_function($f); } _
   { return new Declh($f, new TexArray()); }

FUN_AR2nb
 = f:generic_func &{ return $this->tu->fun_ar2nb($f); } _
   { return $f; }

LEFTI
 = f:generic_func &{ return $this->tu->left_function($f); } _

RIGHTI
 = f:generic_func &{ return $this->tu->right_function($f); } _

HLINE
 = f:generic_func &{ return $this->tu->hline_function($f); } _
   { return $f; }

COLOR
 = f:generic_func &{ return $this->tu->color_function($f); } _ cs:COLOR_SPEC
   { return $f . " " . $cs; }

DEFINECOLOR
 = f:generic_func &{ return $this->tu->definecolor_function($f); } _
   "{" _ name:alpha+ _ "}" _ "{" _
     a:( "named"i _ "}" _ cs:COLOR_SPEC_NAMED { return "{named}" . $cs; }
       / "gray"i  _ "}" _ cs:COLOR_SPEC_GRAY  { return "{gray}" . $cs; }
       / "rgb"    _ "}" _ cs:COLOR_SPEC_rgb   { return "{rgb}" . $cs; }
       // Note that we actually convert RGB format to rgb format here.
       / "RGB"    _ "}" _ cs:COLOR_SPEC_RGBI   { return "{rgb}" . $cs; }
       / "cmyk"i  _ "}" _ cs:COLOR_SPEC_CMYK  { return "{cmyk}" . $cs; } )
   { return $f . " {" . join('',$name) . "}" . $a; }

COLOR_SPEC
 = COLOR_SPEC_NAMED
 / "[" _ "named"i _ "]" _ cs:COLOR_SPEC_NAMED
   { return "[named]" . $cs; }
 / "[" _ "gray"i _ "]" _ cs:COLOR_SPEC_GRAY
   { return "[gray]" . $cs; }
 / "[" _ "rgb"  _ "]" _ cs:COLOR_SPEC_rgb
   { return "[rgb]" . $cs; }
 / "[" _ "RGB"  _ "]" _ cs:COLOR_SPEC_RGBI
   // Note that we actually convert RGB format to rgb format here.
   { return "[rgb]" . $cs; }
 / "[" _ "cmyk"i _ "]" _ cs:COLOR_SPEC_CMYK
   { return "[cmyk]" . $cs; }

COLOR_SPEC_NAMED
 = "{" _ name:alpha+ _ "}" _
   { return "{" . join('', $name) . "}"; }
COLOR_SPEC_GRAY
 = "{" _ k:CNUM + "}"
    { $s = is_array($k) ? $k[0] : $k;
      return "{" . $s . "}";}
COLOR_SPEC_rgb
 = "{" _ r:CNUM "," _ g:CNUM "," _ b:CNUM "}" _
   { return "{" . $r . "," . $g . "," . $b . "}"; }
COLOR_SPEC_RGBI
 = "{" _ r:CNUM255 "," _ g:CNUM255 "," _ b:CNUM255 "}" _
   // Note that we normalize the values to [0,1] here.
   { return "{" . $r . "," . $g . "," . $b . "}"; }
COLOR_SPEC_CMYK
 = "{" _ c:CNUM "," _ m:CNUM "," _ y:CNUM "," _ k:CNUM "}" _
   { return "{" . $c . "," . $m . "," . $y . "," . $k . "}"; }

// An integer in [0, 255] => normalize it to [0,1]
CNUM255
 = n:$( "0" / ([1-9] ([0-9] [0-9]?)? ) ) &{ return intval($n, 10) <= 255; } _
   { return $n / 255; }

// A floating-point number in [0, 1]
CNUM
 = n:$( "0"? "." [0-9]+ ) _
   { return $n; }
 / n:$( [01] "."? ) _
   { return $n; }


// MHCHEM LEXER RULES
CHEM_SINGLE_MACRO
 = f:generic_func &{ return $this->tu->mhchem_single_macro($f); } { return $f; }
 / "\\" c:[, ;!_#%$&] { return "\\" . $c; }

CHEM_BONDI = f:generic_func &{ return $this->tu->mhchem_bond($f); } _ { return $f; }

CHEM_MACRO_1P = f:generic_func &{ return $this->tu->mhchem_macro_1p($f); } _   { return $f; }

CHEM_MACRO_2P = f:generic_func &{ return $this->tu->mhchem_macro_2p($f); } _   { return $f; }

CHEM_MACRO_2PU = f:generic_func &{ return $this->tu->mhchem_macro_2pu($f); } _ { return $f; }

CHEM_MACRO_2PC = f:generic_func &{ return $this->tu->mhchem_macro_2pc($f); } _ { return $f; }

CHEM_SCRIPT_FOLLOW = literal_mn / literal_id / [+-.*']

CHEM_SUPERSUB = "_" / "^"

CHEM_BOND_TYPE = "=" / "#" / "~--" / "~-"  / "~=" / "~" / "-~-" / "...." / "..." / "<-" / "->" / "-" / "1" / "2" / "3"


// As '$' cannot be used (dangerous char in math mode) to switch from chem mode to math mode
// \begin{math} and \end{math} are introduced to do so
BEGIN_MATH = BEGIN "{math}" _

END_MATH = END "{math}" _

CHEM_LETTER = [a-zA-Z]

CHEM_NONLETTER =
    c: "\\{" { return $c; } /
    c: "\\}" { return $c; } /
    c: "\\\\" { return $c; } /
    c:[+-=#().,;/*<>|@&\'\[\]] { return $c; } /
    c:literal_mn { return $c; } /
    CURLY_OPEN CURLY_CLOSE { return "{}"; }

// Missing lexer tokens!
FUN_INFIXh = impossible
FUN_AR1hl = impossible
FUN_AR1hf = impossible
FUN_AR2h = impossible
impossible = & { return false; }

// End of file
EOF = & { return $this->peg_currPos === $this->input_length; }