mirror of
https://github.com/jgm/pandoc.git
synced 2026-09-05 15:15:41 +00:00
88 lines
2.8 KiB
Lua
88 lines
2.8 KiB
Lua
-- A sample custom reader for a very simple markup language.
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-- This parses a document into paragraphs separated by blank lines.
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-- This is /italic/ and this is *boldface* and this is `code`
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-- and `code``with backtick` (doubled `` = ` inside backticks).
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-- This is an escaped special character: \_, \*, \\
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-- == text makes a level-2 heading
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-- That's it!
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-- For better performance we put these functions in local variables:
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local P, S, R, Cf, Cc, Ct, V, Cs, Cg, Cb, B, C, Cmt =
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lpeg.P, lpeg.S, lpeg.R, lpeg.Cf, lpeg.Cc, lpeg.Ct, lpeg.V,
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lpeg.Cs, lpeg.Cg, lpeg.Cb, lpeg.B, lpeg.C, lpeg.Cmt
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--- if item is a table, concatenate it to acc;
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-- otherwise insert it at the end.
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local function add_item(acc, item)
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if acc == nil then
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acc = {}
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end
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if type(item) == "table" then
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for i = 1,#item do
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add_item(acc, item[i])
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end
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else
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acc[#acc + 1] = item
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end
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return acc
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end
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local function Many1(parser)
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return Cf(Cc(nil) * parser^1 , add_item)
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end
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local function Many(parser)
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return (Many1(parser) + Cc{})
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end
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local whitespacechar = S(" \t\r\n")
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local specialchar = S("/*\\`")
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local wordchar = (1 - (whitespacechar + specialchar))
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local spacechar = S(" \t")
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local newline = P"\r"^-1 * P"\n"
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local blanklines = newline * (spacechar^0 * newline)^1
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local endline = newline - blanklines
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local function BetweenDelims(c, parser, constructor)
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local starter = P(c) * #(- whitespacechar)
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local ender = B(1 - whitespacechar) * P(c)
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return starter * Many(parser - ender) * C(ender^-1) /
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function(contents, ender)
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if ender == "" then -- fallback
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return { pandoc.Str(c) , contents }
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else
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return constructor(contents)
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end
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end
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end
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-- Grammar
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G = P{ "Pandoc",
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Pandoc = Many(V"Block") / pandoc.Pandoc;
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Block = blanklines^0 * (V"Header" + V"Para") ;
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Para = Many1(V"Inline") * blanklines^-1 / pandoc.Para;
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Header = (P("=")^1 / string.len)
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* spacechar^1
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* Many(V"Inline" - (spacechar^0 * P("=")^0 * blanklines))
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* spacechar^0
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* P("=")^0
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* blanklines^-1 /
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function(lev, contents) return pandoc.Header(lev, contents) end;
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Inline = V"Emph" + V"Strong" + V"Str" + V"Space" + V"SoftBreak" +
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V"Code" + V"Escaped" + V"Special";
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Str = wordchar^1 / pandoc.Str;
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Escaped = "\\" * C(specialchar) / function(s) return pandoc.Str(s) end;
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Space = spacechar^1 / pandoc.Space;
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SoftBreak = endline / pandoc.SoftBreak;
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Emph = BetweenDelims("/", V"Inline", pandoc.Emph);
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Strong = BetweenDelims("*", V"Inline", pandoc.Strong);
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Code = P"`" * Ct(( (P"``" / "`") + (C(1) - S"`"))^1) * P"`"
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/ table.concat / pandoc.Code;
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Special = S"`\\" / pandoc.Str;
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}
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function Reader(input, opts)
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return lpeg.match(G, input)
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end
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