#!/usr/bin/env texlua
--------------------------------------------------------------------------------
--         FILE:  rst_context.lua
--        USAGE:  ./rst_context.lua 
--  DESCRIPTION:  
--      OPTIONS:  ---
-- REQUIREMENTS:  ---
--       AUTHOR:  Philipp Gesang (Phg), <megas.kapaneus@gmail.com>
--      VERSION:  1.0
--      CREATED:  31/08/10 19:35:15 CEST
--------------------------------------------------------------------------------
--
--- TODO
-- - Find an appropriate way to handle generic tables irrespective of the grid
--   settings. The problem is:
--   http://archive.contextgarden.net/message/20100912.112605.8a1aaf13.en.html
--   Seems we'll have to choose either the grid or split tables as default. Not
--   good.


require "lpeg"
help = require "rst_helpers"

local dbg_write = help.dbg_writef

local C, Cb, Cc, Cg, Cmt, Cp, Cs, Ct, P, R, S, V, match = lpeg.C, lpeg.Cb, lpeg.Cc, lpeg.Cg, lpeg.Cmt, lpeg.Cp, lpeg.Cs, lpeg.Ct, lpeg.P, lpeg.R, lpeg.S, lpeg.V, lpeg.match

-- This one should ignore escaped spaces.
do
    local stripper = P{
        [1] = "stripper",
        stripper = V"space"^0 * C((V"space"^0 * (V"escaped" + V"nospace")^1)^0),
        space    = S(" \t\v\n"),
        nospace  = 1 - V"space",
        escaped  = P"\\" * V"space"
    }
    function string.strip(str)
        return stripper:match(str) or ""
    end 
end

local err = function(str)
    if str then
        io.write("\n*[rstctx] Error: " .. str .. "\n\n")
    end
end

local rst_context = {}

rst_context.collected_adornments = {}
rst_context.last_section_level   = 0
rst_context.anonymous_targets    = 0
rst_context.anonymous_links      = {}

rst_context.collected_references = {}
rst_context.context_references   = {}
rst_context.structure_references = {}
rst_context.anonymous_set        = {}

rst_context.substitutions        = {}
rst_context.lastitemnumber       = 0  -- enumerations in RST allow arbitrary skips

rst_context.current_footnote_number   = 0
rst_context.current_symbolnote_number = 0

function rst_context.footnote_reference (label)
    local tf = state.footnotes
    if label:match("^%d+$") then -- all digits
        local c = tonumber(label)
        --print("creating footnote nr " .. c)
        return [[\\footnote{\\getbuffer[__footnote_number_]].. c .."]}"
    elseif label == "#" then --autonumber
        local rc = rst_context.current_footnote_number
        rc = rc + 1
        --print("creating footnote nr " .. rc)
        rst_context.current_footnote_number = rc
        return [[\\footnote{\\getbuffer[__footnote_number_]].. rc .."]}"
    elseif label:match("^#.+$") then
        local thelabel = label:match("^#(.+)$")
        --print("creating labeled footnote " .. thelabel)
        return [[\\footnote{\\getbuffer[__footnote_label_]].. thelabel .."]}"
    elseif label == "*" then
        local rc = rst_context.current_symbolnote_number
        rc = rc + 1
        --print("creating symbolnote nr " .. rc)
        rst_context.current_symbolnote_number = rc
        return [[\\symbolnote{\\getbuffer[__footnote_symbol_]].. rc .."]}"
    else -- “citation reference” for now treating them like footnotes
        local rc = rst_context.current_footnote_number
        rc = rc + 1
        --rst_context.current_footnote_number = rst_context.current_footnote_number + 1
        --print("creating footnote nr " .. rc)
        rst_context.current_footnote_number = rc
        return [[\\footnote{\\getbuffer[__footnote_number_]].. rc .."]}"
        --return [[\\cite{]] .. label .. "}"
    end
end

function rst_context.addsetups(item)
    state.addme[item] = state.addme[item] or true
    return 0
end

do
    local w = S" \v\t\n" / "_"
    local wp = Cs((w + 1)^1)
    function rst_context.whitespace_to_underscore(str)
        return  str and wp:match(str) or ""
    end
end

-- So we can use crefs[n][2] to refer to the place where the reference was
-- created.
local function get_context_reference (str)
    local crefs = rst_context.context_references
    local srefs = rst_context.structure_references
    srefs[str] = true
    refstring = "__target_" .. rst_context.whitespace_to_underscore(str)
    crefs[#crefs + 1] = { refstring, str }
    return refstring
end

function rst_context.emphasis (str)
    return [[{\\em ]] .. str .. [[}]]
end

function rst_context.strong_emphasis (str)
    return [[{\\sc ]] .. str .. [[}]]
end

function rst_context.literal (str)
    str = str:gsub([[\]], [[\\]]) -- evade escaping of backslashes
    return [[\\type{]] .. str .. [[}]]
    --return [[\\starttyping ]] .. str .. [[\\stoptyping]]
end


function rst_context.interpreted_text (...)
    local tab = { ... }
    local role, str
    role = tab[1]:match("^:(.*):$") or tab[3]:match("^:(.*):$")
    str  = tab[2]

    if not role then -- implicit role
        role = "emphasis"
    end

    return rst_context[role](str)
end

function rst_context.link_standalone (str)
    return "\n"
        .. [[\\goto{\\hyphenatedurl{]] .. str .. [[}}[url(]] .. str .. [=[)]]=]
end

function rst_context.reference (str)
    rst_context.addsetups("references")
    str = str:match("^`?([^`]+)`?_$") -- LPEG could render this gibberish legible but not time
    return [[\\RSTchoosegoto{__target_]] .. rst_context.whitespace_to_underscore(str) .. "}{"
            .. str .. "}"
end

function rst_context.anon_reference (str)
    rst_context.addsetups("references")
    str = str:match("^`?([^`]+)`?__$")
    rst_context.anonymous_links[#rst_context.anonymous_links+1] = str
    link = "__target_anon_" .. #rst_context.anonymous_links
    return string.format([[\\RSTchoosegoto{%s}{%s}]], link, str)
end

local whitespace = S" \n\t\v"
local nowhitespace = 1 - whitespace
local removewhitespace = Cs((nowhitespace^1 + Cs(whitespace / ""))^0)

function rst_context.target (tab)
    rst_context.addsetups("references")
    --local tab = { ... }
    local  refs = rst_context.collected_references
    local arefs = rst_context.anonymous_set
    local target = tab[#tab] -- Ct + C could be clearer but who cares
    tab[#tab] = nil

    local function create_anonymous ()
        rst_context.anonymous_targets = rst_context.anonymous_targets + 1
        return { "anon_" .. rst_context.anonymous_targets, rst_context.anonymous_targets }
    end

    local insert = ""

    if target == "" then -- links here
        for _, id in next, tab do
            insert = insert .. "\n\\reference[__target_" .. id .. "]{}"
        end
    else
        for i=1,#tab do
            local id = tab[i]
            if id == "" then -- anonymous
                local anon = create_anonymous()
                id, arefs[anon[1]] = anon[1], anon[2]
            else
                id = tab[i]:gsub("\\:",":"):match("`?([^`]+)`?") -- deescaping
            end
            if id then
                refs[id] = refs[id] or target
            end
        end
    end

    return insert
end

function rst_context.inline_internal_target (str)
    return "\\\\reference[__target_" .. rst_context.whitespace_to_underscore(str) .."]{}"
end

function rst_context.substitution_reference (str, underscores)
    local sub = ""
    rst_context.addsetups("substitutions")
    if underscores == "_" then -- normal reference
        sub = sub .. [[\\reference[__target_]] .. rst_context.whitespace_to_underscore(string.strip(str)) .. "]{}"
    elseif underscores == "__" then -- normal reference
        rst_context.anonymous_targets = rst_context.anonymous_targets + 1
        sub = sub .. [[\\reference[__target_anon_]] .. rst_context.anonymous_targets .. "]{}"
    end
    return sub .. [[{\\RSTsubstitution]] .. str:gsub("%s", "") .. "}"
end

function rst_context.escape (str)
    str = str:gsub("\\(.)", "%1")
    str = str:gsub("&", "\\letterampersand")
    return str
end

function rst_context.joinindented (tab)
    return table.concat (tab, "")
end

local corresponding = {
    ['"'] = '"',
    ["'"] = "'",
    ["{"] = "}",
    ["("] = ")",
    ["["] = "]",
    ["<"] = ">",
}

local inline_parser = P{
    [1] = "block",

    block = Cs(V"inline_as_first"^-1 * (V"enclosed" + V"inline_element" + 1)^1),

    inline_element = V"precede_inline"
                    * Cs(V"inline_do_elements")
                    * V"succede_inline"
                    + V"footnote_reference"
                    ,

    -- Ugly but needed in case the first element of a paragraph is inline
    -- formatted.
    inline_as_first = V"inline_do_elements" * V"succede_inline",

    inline_do_elements = V"strong_emphasis"
                     + V"substitution_reference"
                     + V"anon_reference"
                     + V"reference"
                     + V"emphasis"
                     + V"inline_literal"
                     + V"interpreted_text"
                     + V"inline_internal_target"
                     + V"link_standalone"
                     ,

    precede_inline = V"spacing"
                   + V"eol"
                   + -P(1)
                   + S[['"([{<-/:]]
                   + P"‘" + P"“" + P"’" + P"«" + P"¡" + P"¿"
                   + V"inline_delimiter"
                   + P"„", -- not in standard Murkin reST

    succede_inline = V"spacing"
                   + V"eol"
                   + S[['")]}>-/:.,;!?\]]
                   + P"’" + P"”" + P"»"
                   + V"inline_delimiter"
                   + -P(1)
                   + P"“", -- non-standard again but who cares

    enclosed = V"precede_inline"^-1
             * Cg(V"quote_single" + V"quote_double" + V"leftpar", "lastgroup")
             * V"inline_delimiter"
             * Cmt(C(V"quote_single" + V"quote_double" + V"rightpar") * Cb("lastgroup"), function(s, i, char, oldchar)
                    return corresponding[oldchar] == char
                end)
             * V"succede_inline"^-1
             * -V"underscore"
             ,

    space = P" ",
    whitespace = (P" " + Cs(P"\t") / "        " + Cs(S"\v") / " "),
    spacing = V"whitespace"^1,

    eol = P"\n",
    --inline_delimiters = P"‐" + P"‑" + P"‒" + P"–" + V"emdash" + V"space",        -- inline markup
    inline_delimiter = P"‐" + P"‑" + P"‒" + P"–" + V"emdash" + V"space"
                     + V"bareia"
                     + V"asterisk"
                     + V"bar"
                     + V"lsquare" + V"rsquare"
                     ,        -- inline markup
    asterisk = P"*",
    quote_single = P"'",
    quote_double = P'"',
    double_asterisk = V"asterisk" * V"asterisk",
    bareia = P"`",
    backslash = P"\\",
    bar = P"|",
    double_bareia = V"bareia" * V"bareia",
    escaped_bareia = (Cs(V"backslash") / "" * V"bareia") + 1,
    colon = P":",
    semicolon = P";",
    underscore = P"_",
    double_underscore = V"underscore" * V"underscore",
    dot = P".",
    interpunct = P"·",
    comma = P",",
    dash = P"-",
    emdash = P"—",
    ellipsis   = P"…" + P"...",
    exclamationmark = P"!",
    questionmark = P"?",
    interrobang = P"‽",
    double_dash = V"dash" * V"dash",
    triple_dash = V"double_dash" * V"dash",
    hyphen = P"‐",
    dashes = V"dash" + P"‒" + P"–" + V"emdash" + P"―",

    lparenthesis = P"(",
    rparenthesis = P")",
    lsquare = P"[",
    rsquare = P"]",
    lbrace = P"{",
    rbrace = P"}",
    less    = P"<",
    greater = P">",
    leftpar  = V"lparenthesis" + V"lsquare" + V"lbrace" + V"less",
    rightpar = V"rparenthesis" + V"rsquare" + V"rbrace" + V"greater",

    --groupchars = S"()[]{}",
    groupchars = V"leftpar" + V"rightpar",
    apostrophe = P"’" + P"'",

    guillemets = P"«" + P"»",
    quotationmarks= P"‘" + P"’" + P"“" + P"”",
    solidus= P"⁄",
    slash = P"/",

    gartenzaun = P"#",
    digit  = R"09",
    letter = R"az" + R"AZ",

    punctuation = V"apostrophe"
                + V"colon" 
                + V"comma" 
                + V"dashes"
                + V"dot" 
                + V"ellipsis"
                + V"exclamationmark"
                + V"guillemets"
                + V"hyphen"
                + V"interpunct"
                + V"interrobang"
                + V"questionmark" 
                + V"quotationmarks"
                + V"semicolon" 
                + V"slash"
                + V"solidus"
                + V"underscore"
                ,

    emphasis        = (V"asterisk" - V"double_asterisk") 
                    * Cs((1 - V"spacing" - V"eol" - V"asterisk")
                       * ((1 - (1 * V"asterisk"))^0 
                        * (1 - V"spacing" - V"eol" - V"asterisk"))^-1) 
                    * V"asterisk" 
                    / rst_context.emphasis,

    strong_emphasis = V"double_asterisk" 
                    * Cs((1 - V"spacing" - V"eol" - V"asterisk")
                       * ((1 - (1 * V"double_asterisk"))^0 
                        * (1 - V"spacing" - V"eol" - V"asterisk"))^-1) 
                    * V"double_asterisk"  
                    / rst_context.strong_emphasis,

    inline_literal  = V"double_bareia"
                    * C ((V"escaped_bareia" - V"spacing" - V"eol" - V"bareia")
                       * ((V"escaped_bareia" - (1 * V"double_bareia"))^0
                        * (V"escaped_bareia" - V"spacing" - V"eol" - V"bareia"))^-1)
                    * V"double_bareia"
                    / rst_context.literal,

    interpreted_text = C(V"role_marker"^-1)
                     * (V"bareia" - V"double_bareia")
                     * C ((1 - V"spacing" - V"eol" - V"bareia")
                        * ((1 - (1 * V"bareia"))^0
                         * (1 - V"spacing" - V"eol" - V"bareia"))^-1)
                     * V"bareia"
                     * C(V"role_marker"^-1)
                     / rst_context.interpreted_text,

    role_marker = V"colon" * (V"letter" + V"dash" + V"underscore" + V"dot")^1 * V"colon",

    link_standalone = C(V"uri")
                    / rst_context.link_standalone,

    anon_reference = Cs(V"anon_phrase_reference" + V"anon_normal_reference")
              / rst_context.anon_reference,

    anon_normal_reference = C((1 - V"underscore" - V"spacing" - V"eol" - V"punctuation" - V"groupchars")^1) * V"double_underscore",

    anon_phrase_reference = (V"bareia" - V"double_bareia")
                          * C((1 - V"bareia")^1)
                          * V"bareia" * V"double_underscore"
                          ,

    reference = Cs(V"normal_reference" + V"phrase_reference")
              / rst_context.reference,

    normal_reference = (1 - V"underscore" - V"spacing" - V"eol" - V"punctuation" - V"groupchars")^1 * V"underscore",

    phrase_reference = (V"bareia" - V"double_bareia")
                     * C((1 - V"bareia")^1)
                     * V"bareia" * V"underscore"
                     ,

    footnote_reference = V"lsquare" 
                       * Cs(V"footnote_label" + V"citation_reference_label") 
                       * V"rsquare" 
                       * V"underscore"
                       / rst_context.footnote_reference
                       ,

    footnote_label = V"digit"^1
                   + V"gartenzaun" * V"letter"^1
                   + V"gartenzaun"
                   + V"asterisk"
                   ,

    citation_reference_label = V"letter" * (1 - V"rsquare")^1,

    inline_internal_target = V"underscore"
                           * V"bareia"
                           * Cs((1 - V"bareia")^1)
                           * V"bareia"
                           / rst_context.inline_internal_target
                           ,

    substitution_reference = V"bar"
                           * C((1 - V"bar")^1)
                           * V"bar"
                           * C((V"double_underscore" + V"underscore")^-1)
                           / rst_context.substitution_reference
                           ,

--------------------------------------------------------------------------------
-- Urls
--------------------------------------------------------------------------------
    uri = V"url_protocol" * V"url_domain" * (V"slash" * V"url_path")^0,

    url_protocol = (P"http" + P"ftp" + P"shttp" + P"sftp") * P"://",
    url_domain_char = 1 - V"dot" - V"spacing" - V"eol" - V"punctuation",
    url_domain = V"url_domain_char"^1 * (V"dot" * V"url_domain_char"^1)^0,
    url_path_char = R("az", "AZ", "09") + S"-_.!~*'()",
    url_path = V"slash" * (V"url_path_char"^1 * V"slash"^-1)^1,
}

function rst_context.paragraph (data)
    local str
    if not data then
        return ""
    elseif type(data) == "table" then
        str = #data > 1 and  helpers.string.wrapat(inline_parser:match(table.concat(data, " ")), 65) 
                        or   inline_parser:match(data[1])
    else
        str = data
    end
    --print(str)
    return string.format([[

\\startparagraph
%s
\\stopparagraph
]], str)
end

local sectionlevels = {
    [1] = "chapter",
    [2] = "section",
    [3] = "subsection",
    [4] = "subsubsection",
    [5] = "subsubsubsection",
}

local function get_line_pattern (chr)
    return P(chr)^1 * (-P(1))
end

function rst_context.section (...)  -- TODO general cleanup; move validity
    local tab = { ... }             -- checking to parser.
    local section, str = true, ""
    local adornchar 
    local ulen = unicode.utf8.len
    if #tab == 3 then -- TODO use unicode length with ConTeXt
        adornchar = tab[1]:sub(1,1)
        section = ulen(tab[1]) >= ulen(tab[2])
        --section = get_line_pattern(adornchar):match(tab[1]) ~= nil and section
        str = string.strip(tab[2])
    else -- no overline
        adornchar = tab[2]:sub(1,1)
        section = ulen(tab[1]) <= ulen(tab[2])
        --section = get_line_pattern(adornchar):match(tab[2]) ~= nil and section
        str = tab[1]
    end

    if section then -- determine level
        local level = rst_context.last_section_level
        local rca = rst_context.collected_adornments
        if rca[adornchar] then
            level = rca[adornchar]
        else
            level = level + 1
            rca[adornchar] = level
            rst_context.last_section_level = level
        end

        ref = get_context_reference (str)

        str = string.format("\n\\\\%s[%s]{%s}\n", sectionlevels[level], ref, str)
    else
        return [[{\\bf fix your sectioning!}\\endgraf}]]
    end

    return section and str or ""
end

-- Prime time for the fancybreak module.
function rst_context.transition (str)
    rst_context.addsetups("breaks")
    --return "\\fancybreak\n"
    return "\\fancybreak{$* * *$}\n"
end

function rst_context.bullet_marker(str)
    return "marker"
end

-- This one should ignore escaped spaces.
do
    local stripper = P{
        [1] = "stripper",
        stripper = V"space"^0 * C((V"space"^0 * V"nospace"^1)^0),
        space    = S(" \t\v\n"),
        escaped  = P"\\" * V"space",
        nospace  = V"escaped" + (1 - V"space"),
    }
    function string.strip(str)
        return stripper:match(str) or ""
    end 
end

local enumeration_types = {
    ["*"] = "*", -- unordered bulleted
    ["+"] = "*",
    ["-"] = "*",
    ["•"] = "*",
    ["‣"] = "*",
    ["⁃"] = "*",

    ["#"] = "n", -- numbered lists and conversion
    ["A"] = "A",
    ["a"] = "a",
    ["I"] = "R",
    ["i"] = "r",
}

-- \setupitemize[left=(, right=), margin=4em, stopper=]

local stripme   = S"()."
local dontstrip = 1 - stripme
local itemstripper = stripme^0 * C(dontstrip^1) * stripme^0

local function parse_itemstring(str)
    local offset = nil
    local setup = ",fit][itemalign=flushright,"
    -- string.match is slightly faster than string.find
    if str:match("^%(") then
        setup = setup .. [[left=(,]]
    end
    if str:match("%)$") then
        setup = setup .. [[right=)]]
    end
    if str:match("%.$") then
        setup = setup .. [[stopper={.\\space}]]
    end
    local num = str:match("^%d")
    if num then
        -- http://thread.gmane.org/gmane.comp.tex.context/61728/focus=61729
        setup = setup .. ",start=" .. num
        str = "n"
    end

    str = itemstripper:match(str)
    str = enumeration_types[str] or str
    return {setup = setup, str = str}
end

function rst_context.startitemize(str)
    local setup = ""
    local result = ""
    str = string.strip(str)

    local listtype = enumeration_types[str] or parse_itemstring(str)

    if type(listtype) == "table" then
        setup = listtype.setup
        listtype = listtype.str
    end

    result = [[
\\startitemize[]] .. listtype .. setup .. [[]
]] 
    return result
end

local last_item = {} -- stack
local current_itemdepth = 0
function rst_context.stopitemize(str)
    last_item[current_itemdepth] = nil
    current_itemdepth = current_itemdepth - 1
    return str .. [[
\\stopitemize
]]
end

function rst_context.bullet_item (tab)
    local li = last_item
    -- The capture of the first item has the \startitemize as 
    -- *second* element in the array.
    local content  = #tab == 2 and tab[2] or tab[3]
    local startstr = #tab == 3 and tab[2] or nil
    local itemtype = tab[1]
    local result = startstr or ""
    if startstr then
        current_itemdepth = current_itemdepth + 1
        li[current_itemdepth] = itemtype
    elseif li[current_itemdepth] then
        if helpers.list.successor(itemtype, li[current_itemdepth]) then
            -- just leave it alone
        elseif helpers.list.greater(itemtype, li[current_itemdepth]) then
            local itemnum = tonumber(string.strip(itemtype)) or helpers.list.get_decimal(itemtype)
            result = result .. string.format([[
\\setnumber[itemgroup:itemize]{%s}
]], itemnum)
        end
        li[current_itemdepth] = itemtype
    end

    return result .. [[

\\item ]] .. inline_parser:match(content) .. [[

]]
end

--------------------------------------------------------------------------------
-- Definition lists 
--------------------------------------------------------------------------------
-- TODO define proper setups (probably bnf-like and some narrower for def-paragraphs)

function rst_context.deflist (list)
    rst_context.addsetups("deflist")

    local deflist = [[
\\startRSTdefinitionlist
]] 
    for nd, item in ipairs(list) do
        local term = item[1]
        local nc = 2
        local tmp = [[

  \\RSTdeflistterm{]] .. string.strip(term) .. "}"
        if #item > 2 then
            while nc < #item do
                tmp = tmp .. [[

  \\RSTdeflistclassifier{]] .. string.strip(item[nc]) .. "}"
                nc = nc + 1
            end
        end
        tmp = tmp .. [[

  \\RSTdeflistdefinition{%
]]
        for np, par in ipairs(item[#item]) do -- definitions, multi-paragraph
            tmp = tmp .. [[
    \\RSTdeflistparagraph{%
]] .. inline_parser:match(par) .. "}\n"
        end
        tmp = tmp .. "  }"
        deflist = deflist .. tmp
    end
    return deflist .. [[

\\stopRSTdefinitionlist
]]
end

--------------------------------------------------------------------------------
-- Field lists
--------------------------------------------------------------------------------

-- TODO Do something useful with field lists. For now I'm not sure what as the
-- bibliography directives from the reST specification seem to make sense only
-- when using docinfo and, after all, we have .bib files that are portable.

function rst_context.field_list (str)
    rst_context.addsetups("fieldlist")
    return [[

\\startRSTfieldlist]] .. str .. [[\\eTABLEbody\\stopRSTfieldlist
]]
end

function rst_context.field_name (str)
    return [[\\fieldname{]] .. str .. [[}]]
end

function rst_context.field_body (str)
    return [[\\fieldbody{]] .. inline_parser:match(str) .. [[}]]
end

function rst_context.field (tab)
    local name, body = tab[1], tab[2]
    return string.format([[

    \\RSTfieldname{%s}
    \\RSTfieldbody{%s}
]], name, inline_parser:match(body))
end

function rst_context.line_comment (str)
    return "% " .. str
end

function rst_context.block_comment (str)
    return string.format([[

\iffalse
%s\fi
]], str)
end

function rst_context.option_list (str)
    return [[
\\setupTABLE[c][first] [background=color, backgroundcolor=grey, style=\tt]
\\setupTABLE[c][each]  [frame=off]
\\setupTABLE[r][each]  [frame=off]
\\bTABLE[split=yes,option=stretch]
\\bTABLEhead
\\bTR
  \\bTH  Option \\eTH
  \\bTH  Description \\eTH
\\eTR
\\eTABLEhead
\\bTABLEbody
]] .. inline_parser:match(str) .. [[

\\eTABLEbody
\\eTABLE
]]
end

function rst_context.option_item (tab)
    return string.format([[\\bTR\\bTC %s \\eTC\\bTC %s \\eTC\\eTR
]], tab[1], tab[2])
end

function rst_context.test(str)
    return ":"
end

function rst_context.literal_block (str, included)
    local indent = P" "^1
    --local stripme = indent:match(str) or 0
    local stripme = #str
    for line in str:gmatch("[^\n]+") do
        -- setting to the lowest indend of all lines
        local idt = indent:match(line)
        if line and idt then
            stripme = idt < stripme and idt or stripme
        end
    end

    local strip = P{
        [1] = "strip",
        strip = Cs(V"line"^1),
        eol = P"\n",
        restofline = (1 - V"eol")^0,
        stop = Cs(V"eol" * P" "^0) * -P(1) / "", -- remove trailing blank lines
        line = Cs(V"restofline" * (V"stop" + V"eol")) / function (line)
            return #line > stripme and line:sub(stripme) or line
        end,
    }

    str = strip:match(str)
    str = [[

\starttyping[lines=hyphenated]
]] .. str .. [[

\stoptyping
]]
    if included then -- escaping can ruin your day
        str = str:gsub("\\", "\\\\")
    end
    return str
end

function rst_context.included_literal_block (str)
    return rst_context.literal_block(str, true)
end

function rst_context.line_block (str)
    rst_context.addsetups("lines")
    return [[

\\startlines
]] .. inline_parser:match(str) .. [[\\stoplines
]]
end

function rst_context.line_block_line(str)
    str = str:gsub("\n", " ")
    return str .. "\n"
end

function rst_context.line_block_empty()
    return "\n"
end

function rst_context.block_quote (tab)
    rst_context.addsetups("blockquote")
    local str = [[
\\startlinecorrection
\\blank[small]
\\startblockquote
]] .. inline_parser:match(tab[1]) .. [[

\\stopblockquote
]]

    return tab[2] and str .. [[
\\blank[small]
\\startattribution
]] .. inline_parser:match(tab[2]) .. [[
\\stopattribution
\\blank[small]
\\stoplinecorrection
]]  or str .. [[
\\blank[small]
\\stoplinecorrection
]] 
end

--function rst_context.table (str)
    --return [[
--\\startlinecorrection
--]] .. str .. [[

--\\stoplinecorrection
--]]
--end

function rst_context.grid_table (tab)
    local body = ""
    local nr = 1
    local head
    if tab.has_head then
        head = [[
\\setupTABLE[c][each]  [frame=off]
\\setupTABLE[r][each]  [frame=off]
%\\startlinecorrection
\\bTABLE[split=repeat,option=stretch]
\\bTABLEhead
]]
        while nr <= tab.head_end do
            local r = tab.rows[nr]
        --for i,r in ipairs(tab.rows) do
            local isempty = true
            for n, cell in ipairs(r) do
                if cell.variant == "normal" then
                    isempty = false
                    break
                end
            end

            if not isempty then
                local row = [[\\bTR]]
                for n,c in ipairs(r) do
                    if not (c.parent or
                            c.variant == "separator") then
                        local celltext = inline_parser:match(c.stripped)
                        if c.span.x or c.span.y then
                            local span_exp = "["
                            if c.span.x then
                                span_exp = span_exp .. "nc=" .. c.span.x .. ","
                            end
                            if c.span.y then
                                span_exp = span_exp .. "nr=" .. c.span.y
                            end
                            celltext  = span_exp .. "] " .. celltext

                        end

                        row = row .. "\n  " .. [[\\bTH ]] .. celltext .. [[\\eTH]]
                    end
                end
                head = head .. row .. "\n" .. [[\\eTR]] .. "\n"
            end
            nr = nr + 1
        end
        head = head .. [[
\\eTABLEhead
\\bTABLEbody
]] 
    else
        head = [[
\\setupTABLE[c][each]  [frame=off]
\\setupTABLE[r][each]  [frame=off]
%\\startlinecorrection
\\bTABLE[split=repeat,option=stretch]
\\bTABLEbody
]] 
    end
    while nr <= #tab.rows do
        local r = tab.rows[nr]
    --for i,r in ipairs(tab.rows) do
        local isempty = true
        for n, cell in ipairs(r) do
            if cell.variant == "normal" then
                isempty = false
                break
            end
        end

        if not isempty then
            local row = [[\\bTR]]
            for n,c in ipairs(r) do
                if not (c.parent or
                        c.variant == "separator") then
                    local celltext = inline_parser:match(c.stripped)
                    if c.span.x or c.span.y then
                        local span_exp = "["
                        if c.span.x then
                            span_exp = span_exp .. "nc=" .. c.span.x .. ","
                        end
                        if c.span.y then
                            span_exp = span_exp .. "nr=" .. c.span.y
                        end
                        celltext  = span_exp .. "] " .. celltext

                    end

                    row = row .. "\n  " .. [[\\bTC ]] .. celltext .. [[\\eTC]]
                end
            end
            body = body .. row .. "\n" .. [[\\eTR]] .. "\n"
        end
        nr = nr + 1
    end
    local tail = [[
\\eTABLEbody
\\eTABLE
%\\stoplinecorrection
]]
    return head .. body .. tail
end


function rst_context.simple_table(tab)
    local head
    local nr = 1
    if tab.head_end then
        head = [[
\\setupTABLE[c][each]  [frame=off]
\\setupTABLE[r][each]  [frame=off]
%\\startlinecorrection
\\bTABLE[split=yes,option=stretch]
\\bTABLEhead
]]
        while nr <= tab.head_end do
            local row = tab[nr]
            if not row.ignore then
                dbg_write(">hr>" .. #row)
                head = head .. [[\\bTR]]
                for nc,cell in ipairs(row) do
                    dbg_write("%7s | ", cell.content)
                    local celltext = inline_parser:match(cell.content)
                    if cell.span then
                        head = head .. string.format([=[\\bTH[nc=%s]%s\\eTH]=], cell.span.x, celltext)
                    else
                        head = head .. [[\\bTH ]] .. celltext .. [[\\eTH]]
                    end
                end
                dbg_write("\n")
                head = head .. "\\\\eTR\n"
            end
            nr = nr + 1
        end

        head = head .. [[
\\eTABLEhead
\\bTABLEbody
]] 
    else
        head = [[
\\setupTABLE[c][each]  [frame=off]
\\setupTABLE[r][each]  [frame=off]
%\\startlinecorrection
\\bTABLE[split=yes,option=stretch]
\\bTABLEbody
]] 
    end
    local tail = [[
\\eTABLEbody
\\eTABLE
%\\stoplinecorrection
]]
    local body = ""
    while nr <= #tab do
        local row = tab[nr]
        if not row.ignore then
            dbg_write(">tr>" .. #row)
            body = body .. [[\\bTR]]
            for nc,cell in ipairs(row) do
                dbg_write("%7s | ", cell.content)
                local celltext = inline_parser:match(cell.content)
                if cell.span then
                    body = body .. string.format([=[\\bTC[nc=%s]%s\\eTC]=], cell.span.x, celltext)
                else
                    body = body .. [[\\bTC ]] .. celltext .. [[\\eTC]]
                end
            end
            dbg_write("\n")
            body = body .. "\\\\eTR\n"
        end
        nr = nr + 1
    end
    return head .. body .. tail
end

function rst_context.footnote (label, content)
    local tf = state.footnotes
    rst_context.addsetups("footnotes")
    if label:match("^%d+$") then -- all digits
        tf.numbered[tonumber(label)] = rst_context.escape(inline_parser:match(content))
    elseif label == "#" then --autonumber
        repeat -- until next unrequested number
            tf.autonumber = tf.autonumber + 1
        until tf.numbered[tf.autonumber] == nil
        tf.numbered[tf.autonumber] = rst_context.escape(inline_parser:match(content))
    elseif label:match("^#.+$") then
        local thelabel = label:match("^#(.+)$")
        tf.autolabel[thelabel] = rst_context.escape(inline_parser:match(content))
    elseif label == "*" then
        rst_context.addsetups("footnote_symbol")
        tf.symbol[#tf.symbol+1] = rst_context.escape(inline_parser:match(content))
    else -- “citation reference” treated like ordinary footnote
        repeat -- until next unrequested number
            tf.autonumber = tf.autonumber + 1
        until tf.numbered[tf.autonumber] == nil
        tf.numbered[tf.autonumber] = rst_context.escape(inline_parser:match(content))
    end
    return ""
end

function rst_context.substitution_definition (subtext, directive, data)
    data = table.concat(data, "\n")
    local rs = rst_context.substitutions
    rs[subtext] = { directive = directive, data = data }
    return ""
end

-- not to be confused with the directive definition table rst_context.directives
function rst_context.directive(directive, ...)
    local rd = rst_context.directives
    rst_context.addsetups("directive")
    local data = {...}
    local result = ""
    if rd[directive] then
        result = rd[directive](data)
    end
    return result
end

optional_setups = {}
function optional_setups.footnote_symbol ()
    local setup = [[
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Footnotes with symbol conversion                              %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\definenote[symbolnote][footnote]
\setupnote [symbolnote][way=bypage,numberconversion=set 2]
]]
    return setup
end

function optional_setups.footnotes ()
    local tf = state.footnotes
    local fn = [[

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Footnotes                                                     %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
]]
    local buffer = [[

%% %s
\startbuffer[%s]
%s\stopbuffer
]]
    
    for nf, note in next, tf.numbered do
        fn = fn .. string.format(buffer, "Autonumbered footnote", "__footnote_number_"..nf, note)
    end
    for nf, note in next, tf.autolabel do
        fn = fn .. string.format(buffer, "Labeled footnote", "__footnote_label_"..nf, note)
    end
    for nf, note in next, tf.symbol do
        fn = fn .. string.format(buffer, "Symbol footnote", "__footnote_symbol_"..nf, note)
    end
    return fn
end

function optional_setups.references ()
    local refs  = rst_context.collected_references
    local crefs = rst_context.context_references
    local arefs = rst_context.anonymous_set

    local function resolve_indirect (r)
        if r and r:match(".*_$") then -- pointing elsewhere
            local look_me_up = r:match("^`?([^`]*)`?_$")
            local result = resolve_indirect (refs[look_me_up])
            if result then
                return result
            else
                if rst_context.structure_references[look_me_up] then
                    -- Internal link, no useURL etc.
                    return false
                end
            end
        end
        return r
    end

    local refsection = [[

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% References                                                    %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

]]
    local references = {}
    local ref_keys   = {}
    for ref, target in next, refs do
        ref_keys[#ref_keys+1] = [[__target_]] .. rst_context.whitespace_to_underscore(ref)
        target = resolve_indirect(target)
        if target ~= false then
            ref_text = ref
            if arefs[ref_text] then
                ref_text = rst_context.anonymous_links[tonumber(arefs[ref_text])]
            end
            references[#references+1] = string.format([[
\useURL[__target_%s] [%s] []   [%s] ]], rst_context.whitespace_to_underscore(ref), target, ref_text)
        end
    end
    refsection = refsection .. table.concat(references, "\n")
    -- this is needed in order to select the right reference command later
    refsection = refsection .. "\n\n" .. [[\def \RSTexternalreferences{]] .. table.concat(ref_keys, ",") .. [[}

% #1 target name, #2 link text
\def\RSTchoosegoto#1#2{%
  \rawdoifinsetelse{#1}{\RSTexternalreferences}%
    {\from[#1]}%
    {\goto{#2}[#1]}%
}
]]

    return refsection
end

--------------------------------------------------------------------------------
-- Directives for use with |substitutions|
--------------------------------------------------------------------------------

rst_context.directives = {}
rst_context.directives.anonymous = 0
rst_context.directives.images        = {}
rst_context.directives.images.done   = {}
rst_context.directives.images.values = {}

rst_context.directives.images.keys = {
    ["width"]   = "width",
    ["size"]    = "width",
    ["caption"] = "caption",
    ["scale"]   = "scale",
}

rst_context.directives.images.values.scale = function (orig)
    -- http://wiki.contextgarden.net/Reference/en/useexternalfigure
    -- scale=1000 is original size; to get 72%, use scale=720.
    return tonumber(orig) * 1000
end

rst_context.directives.images.values.width = {
    ["fit"]    = "\\hsize",
    ["hsize"]  = "\\hsize",
    ["broad"]  = "\\hsize",
    ["normal"] = "local",
    ["normal"] = "local",
}

-- we won't allow passing arbitrary setups to context
rst_context.directives.images.permitted_setups = {
    "width", "scale"
}

local function img_setup (properties)
    local result = ""
    for _, prop in next, rst_context.directives.images.permitted_setups do
        if properties[prop] then
            result = result .. prop .. "=" .. properties[prop] .. ","
        end
    end
    if result ~= "" then
        result = "[" .. result .. "]"
    end
    return result
end

rst_context.directives.image = function(name, data)
    local properties = {}
    local anon = false
    local rd = rst_context.directives
    if not data then -- this makes the “name” argument optional
        data = name
        rd.anonymous = rd.anonymous + 1
        anon = true -- indicates a nameless picture
        name = "anonymous" .. rd.anonymous
    end
    properties.caption = name
    --properties.width = "\\local"

    local processed = "" -- stub; TODO do something useful with optional dimension specifications
    if type(data) == "table" then -- should always be true
        local p = helpers.patterns
        for _, str in ipairs(data) do
            local key, val
            key, val = p.colon_keyval:match(str)
            local rdi = rst_context.directives.images
            if key and val then
                key = rdi.keys[key] -- sanitize key expression
                if     type(rdi.values[key]) == "table" then
                    val = rdi.values[key][val]
                elseif type(rdi.values[key]) == "function" then
                    val = rdi.values[key](val)
                end
                properties[key] = val
            else
                processed = processed .. (str and str ~= "" and string.strip(str))
            end
        end
    end
    properties.setup = img_setup(properties) or ""
    data = processed
    processed = nil
    local img = ""
    local images_done = rd.images.done
    if not anon then
        if not images_done[name] then
            img = img .. string.format([[

\useexternalfigure[%s][%s][]
]], name, data)
        images_done[name] = true
        end
        img = img .. string.format([[
\def\RSTsubstitution%s{%%
  \placefigure[here]{%s}{\externalfigure[%s]%s}
}
]], name, inline_parser:match(properties.caption), name, properties.setup)
    else -- image won't be referenced but used instantly
        img = img .. string.format([[

\placefigure[here]{%s}{\externalfigure[%s]%s}
]], inline_parser:match(properties.caption), data, properties.setup)
    end
    return img
end

rst_context.directives.caution = function(raw)
    rst_context.addsetups("dbend")
    rst_context.addsetups("caution")
    local text 
    local first = true
    for _, line in ipairs(raw) do
        if not helpers.patterns.spacesonly:match(line) then
            if first then
                text =  line
                first = false
            else
                text = text .. " " .. line
            end
        end
    end
    text = rst_context.escape(helpers.string.wrapat(inline_parser:match(text))) 
    return string.format([[
\startRSTcaution
%s
\stopRSTcaution
]], text)
end

rst_context.directives.danger = function(raw)
    rst_context.addsetups("dbend")
    rst_context.addsetups("danger")
    local text 
    local first = true
    for _, line in ipairs(raw) do
        if not helpers.patterns.spacesonly:match(line) then
            if first then
                text =  line
                first = false
            else
                text = text .. " " .. line
            end
        end
    end
    text = rst_context.escape(helpers.string.wrapat(inline_parser:match(text))) 
    return string.format([[
\startRSTdanger
%s
\stopRSTdanger
]], text)
end

-- http://docutils.sourceforge.net/docs/ref/rst/directives.html
rst_context.directives.DANGER = function(addendum)
    local result = ""
    for _,str in ipairs(addendum) do
        result = result .. (string.strip(str))
    end
    return string.format([[

%% The Rabbit of Caerbannog
\startlinecorrection
\blank[force,big]
\framed[frame=on,
        corner=round,
        rulethickness=5pt,
        align=middle,
        width=\hsize,
        frameoffset=.5em,
        backgroundoffset=1em,
        background=color,
        backgroundcolor=red,
        foreground=color,
        foregroundcolor=black]{%%
  \language[en-gb]\tfb\bf
  Follow only if ye be men of valour, for the entrance to this cave is guarded
  by a creature so foul, so cruel that no man yet has fought with it and lived.
  Bones of full fifty men lie strewn about its lair. So, brave knights, if you
  do doubt your courage or your strength, come no further, for death awaits you
  all with nasty, big, pointy teeth.%%
  \blank[force,big]
  %s%%
}
\blank[force,big]
\stoplinecorrection
]], result)
end

rst_context.directives.ctx = function(name, data)
    local ctx = string.format([[

\startbuffer[%s]
%s
\stopbuffer
\def\RSTsubstitution%s{%%
  \getbuffer[%s]
}
]], name, data, name, name)
    return ctx
end

rst_context.directives.lua = function(name, data)
    local luacode = string.format([[

\startbuffer[%s]
\startluacode
%s
\stopluacode
\stopbuffer
\def\RSTsubstitution%s{%%
  \getbuffer[%s]%%
}
]], name, data, name, name)
    return luacode
end

rst_context.directives.replace = function(name, data)
    return string.format([[

\def\RSTsubstitution%s{%s}
]], name, data)
end

function optional_setups.substitutions ()
    local directives = rst_context.directives
    local substitutions = [[

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Substitutions                                                 %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
]]
    local rs = rst_context.substitutions
    for name, content in next, rs do
        local directive, data = content.directive, content.data
        name, data = name:gsub("%s", ""), string.strip(data)
        if directives[directive] then
            substitutions = substitutions .. directives[directive](name, data)
        else
            err(directive .. " does not exist.")
        end
    end
    return substitutions
end

function optional_setups.directive ()
    --local directives = rst_context.directives
    --local dirstr = [[

--%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
--% Directives                                                    %
--%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
--]]
    --return dirstr
    return ""
end

function optional_setups.blockquote ()
    return [[

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Blockquotes                                                   %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\setupdelimitedtext  [blockquote][style={\tfx}] % awful placeholder
\definedelimitedtext[attribution][blockquote]
\setupdelimitedtext [attribution][style={\tfx\it}]
]]
end

function optional_setups.deflist ()
    return [[

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Definitionlist                                                %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\def\startRSTdefinitionlist{
  \bgroup
  \def      \RSTdeflistterm##1{{\bf ##1}}
  \def\RSTdeflistclassifier##1{\hbox to 1em{\it ##1}}
  \def\RSTdeflistdefinition##1{%
    \startnarrower[left]
    ##1%
    \stopnarrower}
  \def\RSTdeflistparagraph ##1{%
    \startparagraph{%
      \noindentation ##1
    \stopparagraph}
  }
}

\let\stopRSTdefinitionlist\egroup
]]
end

function optional_setups.lines ()
    return [[

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Lines environment (line blocks)                               %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\setuplines[%
  space=on,%
  before={\startlinecorrection\blank[small]},%
  after={\blank[small]\stoplinecorrection},%
]
]]
end

function optional_setups.breaks ()
    return [[

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Fancy transitions                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\usemodule[fancybreak]
\setupfancybreak[symbol=star]
]]
end

function optional_setups.fieldlist ()
    return [[

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Fieldlists                                                    %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\def\startRSTfieldlist{%
  \bgroup%
  \unexpanded\def\RSTfieldname##1{\bTR\bTC ##1\eTC}
  \unexpanded\def\RSTfieldbody##1{\bTC ##1\eTC\eTR}
%
  \setupTABLE[c][first] [background=color, backgroundcolor=grey, style=\bf]
  \setupTABLE[c][2]     [align=right]
  \setupTABLE[c][each]  [frame=off]
  \setupTABLE[r][each]  [frame=off]
  \bTABLE[split=yes,option=stretch]
  \bTABLEhead
  \bTR
   \bTH  Field       \eTH
   \bTH  Body        \eTH
  \eTR
  \eTABLEhead
  \bTABLEbody
}

\def\stopRSTfieldlist{%
  %\eTABLEbody % doesn't work, temporarily moved to rst_context.field_list()
  \eTABLE
  \egroup%
}
]]
end

function optional_setups.dbend ()
    -- There's just no reason for not providing this.
    optional_setups.dbend_done = true
    return [[
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Dangerous bend                                                %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\loadmapfile [manfnt.map]
\definefontsynonym [bends] [manfnt]

\def\GetSym#1{\getglyph{bends}{\char#1}}

\startsymbolset [Dangerous Bends]
    \definesymbol [dbend]       [\GetSym{127}]
    \definesymbol [lhdbend]     [\GetSym{126}]
    \definesymbol [lhdbend]     [\GetSym{0}]
\stopsymbolset

\setupsymbolset [Dangerous Bends]

]]
end

function optional_setups.caution ()
    local result = ""
    --if not optional_setups.dbend_done then
        --result = result .. optional_setups.dbend()
    --end
    return result .. [[
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Caution directive                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\usemodule[lettrine]

\setbox0=\hbox{\symbol[dbend]}
\newskip\RSTbendskip
\RSTbendskip=\wd0
\advance\RSTbendskip by 1em % These two lines should add
\advance\RSTbendskip by 1pt % 13.4pt in mkiv and 13.14983pt in mkii
                            % to make the indent equal to the indent
                            % of the “danger” directive.
                            % (2*(width)dbend + (kern)1pt + 1em

\def\startRSTcaution{%
\startparagraph
\dontleavehmode\lettrine[Lines=2,Raise=.6,Findent=\RSTbendskip,Nindent=0pt]{\symbol[dbend]}{}%
}

\let\stopRSTcaution\stopparagraph

]]

end

function optional_setups.danger ()
    local result = ""
    --if not optional_setups.dbend_done then
        --result = result .. optional_setups.dbend()
    --end
    return result .. [[
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Danger directive                                              %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\usemodule[lettrine]

\def\startRSTdanger{%
\startparagraph
\lettrine[Lines=2,Raise=.6,Findent=1em,Nindent=0pt]{\symbol[dbend]\kern 1pt\symbol[dbend]}{}%
}

\let\stopRSTdanger\stopparagraph

]]

end

return rst_context