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Thread: Typed List

  1. #1
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    Cool Typed List

    Linked Lists are currently somewhat like treeview-structure that can store string-values and LL-Elements don't inherit structure of previous elements,
    I imagine lists different, so here some pseudo-code how to use:

    Type myUDT
     A as Long
     B as Dword
     C as String
    End Type
    
    [Dim]   NewList myList() as myUDT
    [Local] NewList myList() as myUDT
    
    ' create an empty new list, has zero elements now
    ' could also do just: NewList someOtherList() as Long
    
    All list-elements of this Typed-List should now have a 'myUDT'-structure, so every list-element has now A,B and C or whatever the type says.
    I think it would enhance the use of objects with similar properties that can be stored in a list, where you currently use Arrays for that always have to be re-dimensioned if one elements gets added or redimensioned and re-ordered if an element gets removed.

    There has to be an internal pointer to the currently active element of the list and a few commands like:

    AddElement myList() 
    ' will add one element to list myList() and this one is now the currently active one
    
    with myList()
       .A = 1
       .B = 2
       .C = "hello"
    end with
    
    AddElement myList()
    ' add another element to list myList() and this one is now the currently active one
    
    myList().A = 2
    myList().B = 1
    myList().C = "world"
    
    ' GetElementCount myList() should return 2 now...
    
    Now run through that list like this:
    ResetList myList()     
    
    ' set the pointer to 0 (before first element)
    ' so there's no currently active element
    
    While IsNextElement myList()
      ' set pointer in myList() to next element
      ' do something with that (now current) element
      ' like 
       Print myList().C
    Wend
    ' now pointer is at last element of myList()...
    
    if IsPreviousElement myList() then
     ' should set the Pointer to previous element or return False/0 if not exists
      my_A_Value = myList().A
      myList().C = "good bye world"
      ' refers all to current element of myList()
    else
       ' there's no previous element...
    endif
    
    additional needs:
    DeleteElement myList() ' kill the current element, (if one)
                               ' active element is now the previous one or zero
                                  
    ClearList myList()         ' nothing to explain...
    
    myCount = GetElementCount myList() ' return total of elements in myList()
    
    and perhaps some indexing to select a certain element:
    myCurrentElementIndex = GetElementIndex myList() 
    ' returns Index of current element 
    ' or 0 if pointer is before list (after resetting) or if list is empty 
    ' so 0 means there's no current element
    
    if SelectElement myList(), 25 then
    ' make element 25 the current one of myList()
    else
     ' element 25 does not exist in myList()
    endif
    
    ' so this
    if SelectElement myList(), GetElementCount myList()
      ' will select the last element of myList()
      do
       ' something with current element
      loop until not isPreviousElement myList()
      'goes backward through list
    endif
    
    "TypedList" would be a very small module, could also be built-in to core-engine, I think I would use it together with FILE-module if FILE would provide some built-in File-Type (Filename, FileAtrribute etc.) so can easy read-in directories and I will use together with TBGL anyway to store a lot of different objects like sprites, triangles, vertices, meshes etc. and use it to loop through those object-lists mainly.
    Could also provide some sorting methods f.e.:
    SortList myList().C, %SortDescending
    SortList myList().A, %SortAscending
    
    Last edited by ReneMiner; 20-11-2012 at 19:26.
    I think there are missing some Forum-sections as beta-testing and support

  2. #2
    thinBasic author ErosOlmi's Avatar
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    Thanks a lot
    Will take for sure into consideration as soon as I will have stabilized thinBasic 1.9.x beta stage
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  3. #3
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    OK, Eros I hope you'll look in here before you start writing it. Idea's growing since I had to find a solution to organize my current mesh-stuff without any dynamic UDT-subsets.

    Instead of those parenthesis "()" I use these "{}" for better pointing out that it's not a dynamic array but a typed list.

    now an example, (uses Music-CDs since they all have different amounts of songs on it):
    Type t_MusicTitle
      Artist         As String
      Title           As String
    End Type
    
    Type t_MusicCD
      CDTitle     as String
      Published  as Long
    ' --------------------------------------------------------------------------
      SongList    as LONG ' *this will contain a pointer, maybe has to be DWord 
    ' --------------------------------------------------------------------------
    End Type
    
    NewList myCDs{} as t_MusicCD 
    ' same list as described in first post, just the {}-brackets
    ' and "NewList" indicate it's a (single, simple) Typed-List 
    
    ' this is it - see different constructor:
    ' for these lists it needs an additional internal pointer which 
    ' of mySongs{}-Lists is the currently active list
    
    NewListArray mySongs{} as t_MusicTitle 
                                      
    
    ' this will add one dimension to mySongs{}:
    AddListArray mySongs{}, X
    
    ' we had zero before, now is one empty mySongs{}-List
    ' the X gets treated ByRef !
    
    X holds now a pointer to the start of this list!!!
    X is not an Index and value does not matter except:
    If X < 1 Then Stop  ' creation failure
    
    ' now let's create a music-library and replace X with myCDs{}.SongList
    
    AddElement myCDs{}
    myCDs{}.SongList = X         ' just to have it right
    
    myCDs{}.CDTitle = "please wear ear-protection!"
    myCDs{}.Published = "2012"
    
    ' here create a new element of  mySongs{}-List:
    
    AddElement( mySongs{} , myCDs{}.SongList ) 
    
    '  myCDs{}.SongList will hold new pointer if it was necessary
    ' to reallocate memory and now the current mySongs{}-List has one element
    ' mySongs{}-current list is the by myCDs{}.SongList indicated one
    ' current element of current mySongs{}-List is the just added one...
    
    With mySongs{}
      .Artist = "Lady Gaga"
      .Title  = "I can't sing"
    End With
    
    AddElement mySongs{}, myCDs{}.SongList
    mySongs{}.Artist = "Eminem"
    mySongs{}.Title  = "I cannot sing either"
    
    ' not new:
    CountOfMyCDs    =  GetElementCount( myCDs{} )
    if SelectElement( ' ...etc... see first post
    
    ' new, array-Typed-List only: 
    
    CountOfCurrentCDsSongs = GetElementCount( mySongs{} , myCDs{}.SongList  )
    
    if SelectElement( mySongs{}, myCDs{}.SongList, 25 ) then ' ...
    
    if SelectListArray( mySongs{}, myCds{}.SongList ) then 
    ' makes the list indicated by myCDs{}.SongList the active one 
    ' can loop through mySongs{} of current CD now etc.
    
    ' now create another CD just for fun:
    
    AddElement myCDs{} 
    AddListArray mySongs{}, myCDs{}.SongList 
    
    AddElement mySongs{}, myCDs{}.SongList
    
    With mySongs{}  
      .Title = "Oh what a wonderful tB-world"
      .Artist = "Eros Olmi"
    End With
    
    AddElement mySongs{}, myCDs{}.Songs
    
    mySongs{}.Title = "TBGL rules!"
    mySongs{}.Artist = "Petr Schreiber"
    
    ' other exceptions/changes in methods of first post:
    
    ClearList( mySongs{}, myCDs{}.SongList )
    
    ' in this case there will be no empty list left like in simple TypedList
    ' and ClearList() should set list-ref - myCDs{}.SongList  - to 0 now
    
    AddElement anyTypedList{}  
    ' will work just for simple/single typed lists, for TypedList-Arrays needs 
    ' always a variable to store the new pointer
    DeleteElement anyTypedList{}
    ' maybe will work for both, but seems better to FORCE USERS to 
    ' generally give a Pointer-Ref when using array-Typed List
    
    this is fully functional replacement - and even more - for dynamic UDT-Subsets

    * as Long/Dword - or even better as "TypedListArray" that will automatic create Sub-List and receive the Sub-List-Pointer when a new myCDs-Element gets created. Could be tricky to connect these. Maybe TypedListArray mySongs{} has to be created first -then:
    Type t_MusicCD
    ...
      Songlist as Long
    End Type
     
    'now:
    NewList myCDs{}
    ConnectListArray mySongs{}, SubsetOf(myCDs{}.Songlist)
    
    AddElement myCDs{}
    
    Sub-List-Arrays dimension gets created with it and subset Songlist could receive the Pointer automatically.
    Last edited by ReneMiner; 22-11-2012 at 06:06.
    I think there are missing some Forum-sections as beta-testing and support

  4. #4
    thinBasic author ErosOlmi's Avatar
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    thinBasic has a linked list module called LL but it has some bugs and I wanted to release e better one.

    In the meanwhile, have you checked thinBasic dictionary functionalities:

    A dictionary can store any variable size memory sequence of bytes thanks to the fact it can stores any dynamic string.
    Maybe it can help
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  5. #5
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    ok, dictionary is misleading name for that. I thought it would be some a... dictionary as described in a... dictionary (?) Better call it enhanced, sophisticated well organized very cooool memory-stuff. Should have told me ealier. I wasted days now to create some functions to poke pointers to allocated heap - which I don't like at all cause I fear, even it I free it, there will be some leftover bits somewhere in memory especially when crash while testing. Just the fixed number of keys is so...less dynamic.

    the above described might be a little cumbersome, maybe I should just write this to explain what I was up to:
    Dim NewTypedList myBooks()() as t_Book
    
    Redim TypedList myBooks()(5)
    
    AddElement myBooks()(%french) :myBooks()(%french) = "dictionnaire"
    AddElement myBooks()(%english):myBooks()(%english) = "dictionary"
    AddElement myBooks()(%czech) :myBooks()(%czech) = "slovnik"
    AddElement myBooks()(%italian):myBooks()(%italian) = "dizionario"
    AddElement myBooks()(%german):myBooks()(%german) = "Wörterbuch"
    
    now have 5 different lists of books but can adress them by index
    Last edited by ReneMiner; 23-11-2012 at 00:21.
    I think there are missing some Forum-sections as beta-testing and support

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