if not modules then modules = { } end modules ['buff-ini'] = {
    version   = 1.001,
    comment   = "companion to core-buf.tex",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

-- ctx lua reference model / hooks and such
-- to be optimized

-- redefine buffers.get

buffers             = { }
buffers.data        = { }
buffers.hooks       = { }
buffers.flags       = { }
buffers.commands    = { }
buffers.visualizers = { }

-- if needed we can make 'm local

local utf = unicode.utf8

local concat, texsprint, texprint, texwrite = table.concat, tex.sprint, tex.print, tex.write
local utfbyte, utffind, utfgsub = utf.byte, utf.find, utf.gsub
local type, next = type, next
local byte, sub, find, char, gsub, rep, lower = string.byte, string.sub, string.find, string.char, string.gsub, string.rep, string.lower
local utfcharacters, utfvalues = string.utfcharacters, string.utfvalues
local ctxcatcodes = tex.ctxcatcodes

local data, commands, flags, hooks, visualizers = buffers.data, buffers.commands, buffers.flags, buffers.hooks, buffers.visualizers

function buffers.raw(name)
    return data[name] or { }
end

function buffers.erase(name)
    data[name] = nil
end

function buffers.set(name, str)
    data[name] = { str } -- CHECK THIS
end

function buffers.append(name, str)
    data[name] = (data[name] or "") .. str
end

buffers.flags.store_as_table = true

-- to be sorted out: crlf + \ ; slow now

local n = 0

function buffers.grab(name,begintag,endtag,bufferdata)
    local dn = data[name] or ""
    if dn == "" then
        buffers.level = 0
    end
    buffers.level = buffers.level + bufferdata:count("\\"..begintag) - bufferdata:count("\\"..endtag)
    local more = buffers.level > 0
    if more then
        dn = dn .. bufferdata .. endtag
        buffers.level = buffers.level - 1
    else
        if dn == "" then
            dn = bufferdata:sub(1,#bufferdata-1)
        else
            dn = dn .. "\n" .. bufferdata:sub(1,#bufferdata-1)
        end
        dn = dn:gsub("[\010\013]$","")
        if flags.store_as_table then
            dn = dn:splitlines()
        end
    end
    data[name] = dn
    cs.testcase(more)
end

function buffers.exists(name)
    return data[name] ~= nil
end

function buffers.doifelsebuffer(name)
    cs.testcase(data[name] ~= nil)
end

flags.optimize_verbatim        = true
flags.count_empty_lines        = false

commands.no_break              = "\\doverbatimnobreak"
commands.do_break              = "\\doverbatimgoodbreak"
commands.begin_of_line_command = "\\doverbatimbeginofline"
commands.end_of_line_command   = "\\doverbatimendofline"
commands.empty_line_command    = "\\doverbatimemptyline"

function buffers.verbatimbreak(n,m)
    if flags.optimize_verbatim then
        if n == 2 or n == m then
            texsprint(commands.no_break)
        else
            texsprint(commands.do_break)
        end
    end
end

function buffers.strip(lines)
    local first, last = 1, #lines
    for i=first,last do
        if #lines[i] == 0 then
            first = first + 1
        else
            break
        end
    end
    for i=last,first,-1 do
        if #lines[i] == 0 then
            last = last - 1
        else
            break
        end
    end
    return first, last, last - first + 1
end

function buffers.type(name)
    local lines = data[name]
    local action = buffers.typeline
    if lines then
        if type(lines) == "string" then
            lines = lines:splitlines()
        end
        local line, n = 0, 0
        local first, last, m = buffers.strip(lines)
        for i=first,last do
            n, line = action(lines[i], n, m, line)
        end
    end
end

function buffers.loaddata(filename) -- this one might go away
    -- this will be cleaned up when we have split supp-fil completely
    -- instead of half-half
    local ok, str, n = resolvers.loaders.tex(filename)
    if not str then
        ok, str, n = resolvers.loaders.tex(file.addsuffix(filename,'tex'))
    end
    return str or ""
end

function buffers.typefile(name) -- still somewhat messy, since name can be be suffixless
    local str = buffers.loaddata(name)
    if str and str~= "" then
        local lines = str:splitlines()
        local line, n, action = 0, 0, buffers.typeline
        local first, last, m = buffers.strip(lines)
        for i=first,last do
            n, line = action(lines[i], n, m, line)
        end
    end
end

function buffers.typeline(str,n,m,line)
    n = n + 1
    buffers.verbatimbreak(n,m)
    if str:find("%S") then
        line = line + 1
        hooks.begin_of_line(line)
        hooks.flush_line(hooks.line(str))
        hooks.end_of_line()
    else
        if flags.count_empty_lines then
            line = line + 1
        end
        hooks.empty_line(line)
    end
    return n, line
end

function buffers.save(name,list,encapsulate)
    if not name or name == "" then
        name = tex.jobname
    end
    if list then
        -- ok
    else
        list = name
        name = tex.jobname .. "-" .. name .. ".tmp"
    end
    local content = buffers.collect(list)
    if content == "" then
        content = "empty buffer"
    end
    if encapsulate then
        io.savedata(name, "\\starttext\n"..content.."\n\\stoptext\n")
    else
        io.savedata(name, content)
    end
end

local printer = (lpeg.linebyline/texprint)^0

function buffers.get(name)
    local b = buffers.data[name]
    if b then
        if type(b) == "table" then
            for i=1,#b do
                texprint(b[i])
            end
        else
            printer:match(b)
        end
    end
end

local function content(name,separator) -- no print
    local b = data[name]
    if b then
        if type(b) == "table" then
            return concat(b,separator or "\n")
        else
            return b
        end
    else
        return ""
    end
end

buffers.content = content

function buffers.collect(names,separator) -- no print
    -- maybe we should always store a buffer as table so
    -- that we can pass if directly
    local t = { }
    if type(names) == "table" then
        for i=1,#names do
            local c = content(names[i],separator)
            if c ~= "" then
                t[#t+1] = c
            end
        end
    else
        for name in names:gmatch("[^,%s]+") do
            local c = content(name,separator)
            if c ~= "" then
                t[#t+1] = c
            end
        end
    end
    return concat(t,separator or "\r") -- "\n" is safer due to comments and such
end

function buffers.feedback(names,separator)
    -- don't change the texprint into texsprint as it fails on mp buffers
    -- because (p<nl>enddef) becomes penddef then
    texprint(ctxcatcodes,string.splitlines(buffers.collect(names,separator)))
end

local function tobyte(c)
    return " [" .. utfbyte(c) .. "] "
end

function buffers.inspect(name)
    local b = data[name]
    if b then
        if type(b) == "table" then
            for _,v in ipairs(b) do
                if v == "" then
                    texsprint(ctxcatcodes,"[crlf]\\par ") -- space ?
                else
                    texsprint(ctxcatcodes,(gsub(b,"(.)",tobyte)),"\\par")
                end
            end
        else
            texsprint(ctxcatcodes,(gsub(b,"(.)",tobyte)))
        end
    end
end

-- maybe just line(n,str) empty(n,str)

visualizers.default      = visualizers.default or { }
visualizers.tex          = visualizers.tex     or { }
visualizers.mp           = visualizers.mp      or { }

visualizers.escapetoken  = nil
visualizers.tablength    = 7

visualizers.enabletab    = true -- false
visualizers.enableescape = false
visualizers.obeyspace    = true

local default = visualizers.default

function visualizers.reset()
--~     visualizers.enabletab     = false
--~     visualizers.enableescape  = false
--~     buffers.currentvisualizer = 'default'
end

buffers.currentvisualizer = 'default' -- could become a local

function buffers.setvisualizer(str)
    buffers.currentvisualizer = lower(str)
    local v = visualizers[buffers.currentvisualizer]
    if not v then
        buffers.currentvisualizer = 'default'
    elseif v.reset then
        v.reset()
    end
end

function buffers.doifelsevisualizer(str)
    cs.testcase((str ~= "") and (visualizers[lower(str)] ~= nil))
end

-- calling routines, don't change

function hooks.flush_line(str,nesting)
    str = gsub(str," *[\n\r]+ *"," ") ; -- semi colon needed
    (visualizers[buffers.currentvisualizer].flush_line or default.flush_line)(str,nesting)
end

function hooks.begin_of_line(n)
    (visualizers[buffers.currentvisualizer].begin_of_line or default.begin_of_line)(n)
end

function hooks.end_of_line()
    (visualizers[buffers.currentvisualizer].end_of_line or default.end_of_line)()
end

function hooks.empty_line()
    (visualizers[buffers.currentvisualizer].empty_line or default.empty_line)()
end

function hooks.line(str)
    if visualizers.enabletab then
        str = string.tabtospace(str,visualizers.tablength)
    else
        str = gsub(str,"\t"," ")
    end
    return (visualizers[buffers.currentvisualizer].line or default.line)(str)
end

-- defaults

function default.begin_of_line(n)
    texsprint(ctxcatcodes, commands.begin_of_line_command,"{",n,"}")
end

function default.end_of_line()
    texsprint(ctxcatcodes,commands.end_of_line_command)
end

function default.empty_line()
    texsprint(ctxcatcodes,commands.empty_line_command)
end

function default.line(str)
    return str
end

function default.flush_line(str)
    str = str:gsub(" *[\n\r]+ *"," ")
    if visualizers.obeyspace then
        for c in utfcharacters(str) do
            if c == " " then
                texsprint(ctxcatcodes,"\\obs ")
            else
                texwrite(c)
            end
        end
    else
        texwrite(str)
    end
end

-- not needed any more

local function escaped_token(c)
    if utffind(c,"^(%a%d)$") then
        return c
    elseif c == " " then
        return "\\obs "
    else
        return "\\char" .. utfbyte(c) .. " "
    end
end

buffers.escaped_token = escaped_token

function buffers.escaped(str)
    -- use the utfcharacters loop
    return (utfgsub(str,"(.)", escaped_token))
end

-- special one

commands.nested = "\\switchslantedtype "

-- todo : utf + faster, direct print and such. no \\char, vrb catcodes, see end

function visualizers.flush_nested(str, enable) -- no utf, kind of obsolete mess
    str = str:gsub(" *[\n\r]+ *"," ")
    local result, c, nested, i = "", "", 0, 1
    while i < #str do -- slow
        c = sub(str,i,i+1)
        if c == "<<" then
            nested = nested + 1
            if enable then
                result = result .. "{" .. commands.nested
            else
                result = result .. "{"
            end
            i = i + 2
        elseif c == ">>" then
            if nested > 0 then
                nested = nested - 1
                result = result .. "}"
            end
            i = i + 2
        else
            c = sub(str,i,i)
            if c == " " then
                result = result .. "\\obs "
            elseif c:find("%a") then
                result = result .. c
            else
                result = result .. "\\char" .. byte(c) .. " "
            end
            i = i + 1
        end
    end
    result = result .. "\\char" .. byte(sub(str,i,i)) .. " " .. string.rep("}",nested)
    texsprint(ctxcatcodes,result)
end

-- handy helpers
--
-- \sop[color] switch_of_pretty
-- \bop[color] begin_of_pretty
-- \eop        end_of_pretty
-- \obs        obeyedspace
-- \char <n>   special characters

buffers.currentcolors = { }

function buffers.change_state(n, state)
    if n then
        if state ~= n then
            if state > 0 then
                texsprint(ctxcatcodes,"\\sop[",buffers.currentcolors[n],"]")
            else
                texsprint(ctxcatcodes,"\\bop[",buffers.currentcolors[n],"]")
            end
            return n
        end
    elseif state > 0 then
        texsprint(ctxcatcodes,"\\eop")
        return 0
    end
    return state
end

function buffers.finish_state(state)
    if state > 0 then
        texsprint(ctxcatcodes,"\\eop")
        return 0
    else
        return state
    end
end

buffers.open_nested  = rep("\\char"..byte('<').." ",2)
buffers.close_nested = rep("\\char"..byte('>').." ",2)

function buffers.replace_nested(result)
    result = gsub(result,buffers.open_nested, "{")
    result = gsub(result,buffers.close_nested,"}")
    return result
end

function buffers.flush_result(result,nested)
    if nested then
        texsprint(ctxcatcodes,buffers.replace_nested(concat(result,"")))
    else
        texsprint(ctxcatcodes,concat(result,""))
    end
end

-- THIS WILL BECOME A FRAMEWORK: the problem with prety printing is that
-- we deal with snippets and therefore we need tolerant parsing

--~ local type = type

--~ visualizers = visualizers or { }

--~ local function fallback(s) return s end

--~ function visualizers.visualize(visualizer,kind,pattern)
--~     if type(visualizer) == "table" and type(kind) == "string" then
--~         kind = visualizer[kind] or visualizer.default or fallback
--~     else
--~         kind = fallback
--~     end
--~     return (lpeg.C(pattern))/kind
--~ end

--~ local flusher = texio.write
--~ local format = string.format

--~ local visualizer = {
--~     word    = function(s) return flusher(format("\\bold{%s}",s)) end,
--~     number  = function(s) return flusher(format("\\slanted{%s}",s)) end,
--~     default = function(s) return flusher(s) end,
--~ }

--~ local word   = lpeg.R("AZ","az")^1
--~ local number = lpeg.R("09")^1
--~ local any    = lpeg.P(1)

--~ local pattern = lpeg.P { "start",
--~     start = (
--~         visualizers.visualize(visualizer,"word",word) +
--~         visualizers.visualize(visualizer,"number",number) +
--~         visualizers.visualize(visualizer,"default",any)
--~     )^1
--~ }

--~ str = [[test 123 test $oeps$]]

--~ pattern:match(str)