Modul:JSONutil

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local JSONutil = { suite = "JSONutil",

                  serial = "2019-07-18",
                  item   = 63869449 }

--[=[ preprocess JSON data ]=] local Failsafe = JSONutil


JSONutil.more = 50 -- length of trailing context


local Fallback = function ()

   -- Retrieve current default language code
   --     Returns  string
   return mw.language.getContentLanguage():getCode()
                                          :lower()

end -- Fallback()


JSONutil.fair = function ( apply )

   -- Reduce enhanced JSON data to strict JSON
   -- Parameter:
   --     apply  -- string, with enhanced JSON
   -- Returns:
   --     1    -- string|nil|false, with error keyword
   --     2    -- string, with JSON or context
   local m   = 0
   local n   = 0
   local s   = mw.text.trim( apply )
   local sep = string.char( 10 )
   local i, j, last, r, scan, sep0, sep1, stab, start, stub, suffix
   local framework = function ( a )
                             -- syntax analysis outside strings
                             local k = 1
                             local c
                             while k do
                                 k = a:find( "[{%[%]}]", k )
                                 if k then
                                     c = a:byte( k, k )
                                     if c == 0x7B then    -- {
                                         m = m + 1
                                     elseif c == 0x7D then    -- }
                                         m = m - 1
                                     elseif c == 0x5B then    -- [
                                         n = n + 1
                                     else    -- ]
                                         n = n - 1
                                     end
                                     k = k + 1
                                 end
                             end   -- while k
                     end    -- framework()
   local free = function ( a, at, f )
                    -- Throws: error if /* is not matched by */
                    local s = a
                    local i = s:find( "//", at, true )
                    local k = s:find( "/*", at, true )
                    if i or k then
                        local m = s:find( sep0, at )
                        if i   and   ( not m  or  i < m ) then
                            k = s:find( "\n",  i + 2,  true )
                            if k then
                                if i == 1 then
                                    s = s:sub( k + 1 )
                                else
                                    s = s:sub( 1,  i - 1 )   ..
                                        s:sub( k + 1 )
                                end
                            elseif i > 1 then
                                s = s:sub( 1,  i - 1 )
                            else
                                s = ""
                            end
                        elseif k   and   ( not m  or  k < m ) then
                            i = s:find( "*/",  k + 2,  true )
                            if i then
                                if k == 1 then
                                    s = s:sub( i + 2 )
                                else
                                    s = s:sub( 1,  k - 1 )   ..
                                        s:sub( i + 2 )
                                end
                            else
                                error( s:sub( k + 2 ), 0 )
                            end
                            i = k
                        else
                            i = false
                        end
                        if i then
                            s = mw.text.trim( s )
                            if s:find( "/", 1, true ) then
                                s = f( s, i, f )
                            end
                        end
                    end
                    return s
                end    -- free()
   if s:sub( 1, 1 ) == '{' then
       stab = string.char( 9 )
       s    = s:gsub( string.char( 13, 10 ),  sep )
               :gsub( string.char( 13 ),  sep )
       stub = s:gsub( sep, "" ):gsub( stab, "" )
       scan = string.char( 0x5B, 0x01, 0x2D, 0x1F, 0x5D )    -- [ \-\ ]
       j    = stub:find( scan )
       if j then
           r = "ControlChar"
           s = mw.text.trim( s:sub( j + 1 ) )
           s = mw.ustring.sub( s, 1, JSONutil.more )
       else
           i    = true
           j    = 1
           last = ( stub:sub( -1 ) == "}" )
           sep0 = string.char( 0x5B, 0x22, 0x27, 0x5D )    -- [ " ' ]
           sep1 = string.char( 0x5B, 0x5C, 0x22, 0x5D )    -- [ \ " ]
       end
   else
       r = "Bracket0"
       s = mw.ustring.sub( s, 1, JSONutil.more )
   end
   while i do
       i, s = pcall( free, s, j, free )
       if i then
           i = s:find( sep0, j )
       else
           r = "CommentEnd"
           s = mw.text.trim( s )
           s = mw.ustring.sub( s, 1, JSONutil.more )
       end
       if i then
           if j == 1 then
               framework( s:sub( 1, i - 1 ) )
           end
           if s:sub( i, i ) == '"' then
               stub = s:sub( j,  i - 1 )
               if stub:find( '[^"]*,%s*[%]}]' ) then
                   r = "CommaEnd"
                   s = mw.text.trim( stub )
                   s = mw.ustring.sub( s, 1, JSONutil.more )
                   i = false
                   j = false
               else
                   if j > 1 then
                       framework( stub )
                   end
                   i = i + 1
                   j = i
               end
               while j do
                   j = s:find( sep1, j )
                   if j then
                       if s:sub( j, j ) == '"' then
                           start  = s:sub( 1,  i - 1 )
                           suffix = s:sub( j )
                           if j > i then
                               stub = s:sub( i,  j - 1 )
                                       :gsub( sep,  "\\n" )
                                       :gsub( stab, "\\t" )
                               j = i + stub:len()
                               s = string.format( "%s%s%s",
                                                  start, stub, suffix )
                           else
                               s = start .. suffix
                           end
                           j = j + 1
                           break   -- while j
                       else
                           j = j + 2
                       end
                   else
                       r = "QouteEnd"
                       s = mw.text.trim( s:sub( i ) )
                       s = mw.ustring.sub( s, 1, JSONutil.more )
                       i = false
                   end
               end   -- while j
           else
               r = "Qoute"
               s = mw.text.trim( s:sub( i ) )
               s = mw.ustring.sub( s, 1, JSONutil.more )
               i = false
           end
       elseif not r then
           stub = s:sub( j )
           if stub:find( '[^"]*,%s*[%]}]' ) then
               r = "CommaEnd"
               s = mw.text.trim( stub )
               s = mw.ustring.sub( s, 1, JSONutil.more )
           else
               framework( stub )
           end
       end
   end   -- while i
   if not r   and   ( m ~= 0  or  n ~= 0 ) then
       if m ~= 0 then
           s = "}"
           if m > 0 then
               r = "BracketCloseLack"
               j = m
           elseif m < 0 then
               r = "BracketClosePlus"
               j = -m
           end
       else
           s = "]"
           if n > 0 then
               r = "BracketCloseLack"
               j = n
           else
               r = "BracketClosePlus"
               j = -n
           end
       end
       if j > 1 then
           s =  string.format( "%d %s", j, s )
       end
   elseif not ( r or last ) then
       stub = suffix or apply or ""
       j    = stub:find( "/", 1, true )
       if j then
           i, stub = pcall( free, stub, j, free )
       else
           i = true
       end
       stub = mw.text.trim( stub )
       if i then
           if stub:sub( - 1 ) ~= "}" then
               r = "Trailing"
               s = stub:match( "%}%s*(%S[^%}]*)$" )
               if s then
                   s = mw.ustring.sub( s, 1, JSONutil.more )
               else
                   s = mw.ustring.sub( stub,  - JSONutil.more )
               end
           end
       else
           r = "CommentEnd"
           s = mw.ustring.sub( stub, 1, JSONutil.more )
       end
   end
   if r and s then
       s = mw.text.encode( s:gsub( sep,  " " ) ):gsub( "|", "|" )
   end
   return r, s

end -- JSONutil.fair()


JSONutil.fault = function ( alert, add, adapt )

   -- Retrieve formatted message
   -- Parameter:
   --     alert  -- string, with error keyword, or other text
   --     add    -- string|nil|false, with context
   --     adapt  -- function|string|table|nil|false, for I18N
   -- Returns string, with HTML span
   local e = mw.html.create( "span" )
                    :addClass( "error" )
   local s = alert
   if type( s ) == "string" then
       s = mw.text.trim( s )
       if s == "" then
           s = "EMPTY JSONutil.fault key"
       end
       if not s:find( " ", 1, true ) then
           local storage = string.format( "I18n/Module:%s.tab",
                                          JSONutil.suite )
           local lucky, t = pcall( mw.ext.data.get, storage, "_" )
           if type( t ) == "table" then
               t = t.data
               if type( t ) == "table" then
                   local e
                   s = "err_" .. s
                   for i = 1, #t do
                       e = t[ i ]
                       if type( e ) == "table" then
                           if e[ 1 ] == s then
                               e = e[ 2 ]
                               if type( e ) == "table" then
                                   local q = type( adapt )
                                   if q == "function" then
                                       s = adapt( e, s )
                                       t = false
                                   elseif q == "string" then
                                       t = mw.text.split( adapt, "%s+" )
                                   elseif q == "table" then
                                       t = adapt
                                   else
                                       t = { }
                                   end
                                   if t then
                                       table.insert( t, Fallback() )
                                       table.insert( t, "en" )
                                       for k = 1, #t do
                                           q = e[ t[ k ] ]
                                           if type( q ) == "string" then
                                               s = q
                                               break   -- for k
                                           end
                                       end   -- for k
                                   end
                               else
                                   s = "JSONutil.fault I18N bad #" ..
                                       tostring( i )
                               end
                               break   -- for i
                           end
                       else
                           break   -- for i
                       end
                   end   -- for i
               else
                   s = "INVALID JSONutil.fault I18N corrupted"
               end
           else
               s = "INVALID JSONutil.fault commons:Data: " .. type( t )
           end
       end
   else
       s = "INVALID JSONutil.fault key: " .. tostring( s )
   end
   if type( add ) == "string" then
       s = string.format( "%s – %s", s, add )
   end
   e:wikitext( s )
   return tostring( e )

end -- JSONutil.fault()


JSONutil.fetch = function ( apply, always, adapt )

   -- Retrieve JSON data, or error message
   -- Parameter:
   --     apply   -- string, with presumable JSON text
   --     always  -- true, if apply is expected to need preprocessing
   --     adapt   -- function|string|table|nil|false, for I18N
   -- Returns table, with data, or string, with error as HTML span
   local lucky, r
   if not always then
       lucky, r = pcall( mw.text.jsonDecode, apply )
   end
   if not lucky then
       lucky, r = JSONutil.fair( apply )
       if lucky then
           r = JSONutil.fault( lucky, r, adapt )
       else
           lucky, r = pcall( mw.text.jsonDecode, r )
           if not lucky then
               r = JSONutil.fault( r, false, adapt )
           end
       end
   end
   return r

end -- JSONutil.fetch()


Failsafe.failsafe = function ( atleast )

   -- Retrieve versioning and check for compliance
   -- Precondition:
   --     atleast  -- string, with required version or "wikidata" or "~"
   --                 or false
   -- Postcondition:
   --     Returns  string  -- with queried version, also if problem
   --              false   -- if appropriate
   local last  = ( atleast == "~" )
   local since = atleast
   local r
   if last  or  since == "wikidata" then
       local item = Failsafe.item
       since = false
       if type( item ) == "number"  and  item > 0 then
           local entity = mw.wikibase.getEntity( string.format( "Q%d",
                                                                item ) )
           if type( entity ) == "table" then
               local vsn = entity:formatPropertyValues( "P348" )
               if type( vsn ) == "table"  and
                  type( vsn.value ) == "string"  and
                  vsn.value ~= "" then
                   if last  and  vsn.value == Failsafe.serial then
                       r = false
                   else
                       r = vsn.value
                   end
               end
           end
       end
   end
   if type( r ) == "nil" then
       if not since  or  since <= Failsafe.serial then
           r = Failsafe.serial
       else
           r = false
       end
   end
   return r

end -- Failsafe.failsafe()


-- Export local p = { }

p.failsafe = function ( frame )

   -- Versioning interface
   local s = type( frame )
   local since
   if s == "table" then
       since = frame.args[ 1 ]
   elseif s == "string" then
       since = frame
   end
   if since then
       since = mw.text.trim( since )
       if since == "" then
           since = false
       end
   end
   return Failsafe.failsafe( since )  or  ""

end -- p.failsafe()

p.JSONutil = function ()

   -- Module interface
   return JSONutil

end

return p