letdown/letdown.ebnf at main · htogta/letdown · GitHub

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(*
this grammar leaves out #tags and ;; comments ;; which are stripped out from
anywhere in the file, except within the bodies of code blocks and inline code.
*)

content = { block , "\n" } , EOF ;

block = heading
      | list
      | linkdef
      | image
      | quote
      | hr
      | code
      | paragraph ;

heading = ( h1 | h2 | h3 ) , "\n" ;
h1 = "= " , TEXT ;
h2 = "== " , TEXT ;
h3 = "=== " , TEXT ;

hr = "---" , "\n";

linkdef = "[" , TEXT , "]: " , PATH , "\n"

image = "=> " , PATH , [ TEXT ] , "\n\n" ;

list = listitem , { listitem } ;
listitem = "- " , paragraph ;

quote = quoteline , { quoteline } ;
quoteline = "> " , paragraph ;

code = "```" , "\n" , TEXT , "\n" , "```\n\n" ;

paragraph = { span } , "\n" ;

span = link
     | pre
     | emphasis
     | TEXT ;

link = "[" , TEXT , "]" ;
pre = "`" , TEXT , "`" ;
emphasis = "*" , TEXT , "*" ;