Save/Load Lua Image

[Steve Dekorte <steve@...>]

Here's some psuedo code for reading and writing a Lua image.
I think this addresses the circular reference problem.
It also deals with not having access to function source from within Lua
by assuming that all functions in the image are from seperate externally
existing files.

The one tricky bit is how to get a function definition that's in a file
to get executed and stuck into the write slot value.

(object# = object reference #)

Does it look like this would work to you guys?


----
///////////////////////////////////
// Save Lua image psuedo code
// Writes out all unique tables and functions by
// remembering what's already been written and what has not
///////////////////////////////////
saveLuaImage()
    add globals to unwrittenList
    while ( unwrittenList count > 0 )
        loop through unwrittenList
             writeObject(object)
          endloop
     endwhile
     delete function files that aren't in the writtenList
     print("wrote ".. writtenList count.." objects to image)
end

 writeObject(object)
    if (object is a table ) writeTable(object)
    if (object is a function ) writeFunction(object)
 end

writeTable(aTable)
    remove table# from unwrittenList
    put table# in writtenList
    write "table "..table#.."\n"
    loop through slots
        write slot name
        if (value is string or number ) write raw value
        if (value is an object and is not in writtenList )
            put value object in unwrittenList
        endif
     endloop
end

writeFunction(aFunction)
    remove object# from unwrittenList
    put object# in writtenList
    write "function "..object#..fileNameforFunction(function).."\n"
end

///////////////////////////////////
// Load Lua image psuedo C code
// Reads in all unique tables and functions
// then links all the slots to the right functions and tables
//////////////////////////////////
loadLuaImage()
     open image file
     assume image starts with "globals" table
     create globals table
     call readSlotsForTable(globalsTable)
     put globalsTable in readObjectsArray

     while ( still more in file )
        read object type
        if ( type is table ) readTable() else readFunction() endif
     endwhile

     while ( unlinkedTableList count > 0 )
         loop through unlinkedTableList
             linkSlotsForTable(aTable)
           endloop
     endwhile

     dump globals table slots into globals
end

readFunction()
    read oldObject#, fileName
    if ( oldNewObjectArray[oldObject#] == nil )
       read file with fileName, execute it and get newObject# for function in it
       oldNewObjectArray[oldObject#] = newObject#
    endif
end

readTable()
     read oldObject#
     newObject# = ref of newly created table
     oldNewObjectArray[oldObject#] = newObject#
     if ( tableIsNotDoneLinking(newObject #) )
       add newObject# to unlinkedTableList
     endif
     readSlotsForTable(aTable)
end

readSlotsForTable(aTable)
     loop through slots
          read slot name & value ( or string encoding object#)
          set slot name and value in table
     endloop	
end

linkSlotsForTable(aTable)
     loop through slots
     if ( value is object# and object# in oldNewObjectArray)
               value = oldNewObjectArray[object#]
     endif
     endloop
     if (no unlinked slots left)
         remove aTable from unlinkedTableList
     endif
end