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-- A sample custom reader for a very simple markup language.
-- This parses a document into paragraphs separated by blank lines.
-- This is _{italic} and this is *{boldface}
-- This is an escaped special character: \_, \*, \{, \}
-- == text makes a level-2 heading
-- That's it!
-- For better performance we put these functions in local variables:
local P, S, R, Cf, Cc, Ct, V, Cs, Cg, Cb, B =
lpeg.P, lpeg.S, lpeg.R, lpeg.Cf, lpeg.Cc, lpeg.Ct, lpeg.V,
lpeg.Cs, lpeg.Cg, lpeg.Cb, lpeg.B
local whitespacechar = S(" \t\r\n")
local specialchar = S("_*{}\\")
local escapedchar = P"\\" * specialchar
/ function (x) return string.sub(x,2) end
local wordchar = (P(1) - (whitespacechar + specialchar)) + escapedchar
local spacechar = S(" \t")
local newline = P"\r"^-1 * P"\n"
local blanklines = newline * spacechar^0 * newline^1
local endline = newline - blanklines
-- Grammar
G = P{ "Pandoc",
Pandoc = blanklines^-1 * Ct(V"Block"^0) / pandoc.Pandoc;
Block = V"Header" + V"Para";
Para = Ct(V"Inline"^1) * blanklines^-1 / pandoc.Para;
Header = Ct(Cg(P("=")^1 / function(x) return #x end, "length")
* spacechar^1
* Cg(Ct(V"Inline"^0), "contents")
* blanklines^-1) /
function(res) return pandoc.Header(res.length, res.contents) end;
Inline = V"Emph" + V"Str" + V"Space" + V"SoftBreak" + V"Special" ;
Str = wordchar^1 / pandoc.Str;
Space = spacechar^1 / pandoc.Space;
SoftBreak = endline / pandoc.SoftBreak;
Emph = Ct(P"_{" * Cg(Ct((V"Inline" - P"}")^1), "contents") * P"}") /
function(res) return pandoc.Emph(res.contents) end;
Special = specialchar / pandoc.Str;
}
function Reader(input)
return lpeg.match(G, input)
end
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