[Lazarus] Lazarus support for Sorting is completely inadequate.

[Mattias Gaertner]

On Sat, 1 Dec 2012 16:43:34 +0200
Avishai <avishai.gore at gmail.com> wrote:

> Lazarus support for Sorting is completely inadequate.  You can not
> sort a list of strings without knowing the language of the list.  This
> should be a simple process. I would like to try to improve this, but I
> will need some help from the Lazarus community.
> 
> It appears that each Control that has a List has its own separate Sort
> routine and each is different.  I would think that there would be a
> single Sort routine and could be called by each control.

I'm not sure if I can follow you here. Maybe this helps:

A string list can be sorted with a single line of code or you can
write your own compare function. The default sort algorithm is
quicksort and there are other available too.
So support for "Sorting" is good.

Maybe you are missing some "String compare functions"?

There are many basic compare functions in the RTL, FCL and LazUtils.
For instance CompareStr, CompareText, AnsiCompareText, UTF8CompareStr,
UTF8CompareText.
All these functions have their pros and cons.

Keep in mind that some human languages have multiple official compare
functions and it gets even more difficult when mixing languages
(unicode).


> This could be a starting point that could be expanded to include other
> Languages and Sort Methods, but it is only a suggestion.
> 
> {===== Sorting =====}
> 
> const
>   SortAscending: Boolean = True;
> 
> function SortHebrew(List: TStringList; Index1, Index2: Integer):
> Integer;  {Hebrew}
> begin
>   Result:= UTF8CompareStr(List[Index1],List[Index2]);
>   if not SortAscending then
>     Result:= -Result;
> end;
> 
> function SortPortuguese(List: TStringList; Index1, Index2: Integer):
> Integer;  {Portuguese}
> begin
>   Result:= WideCompareText(UTF8Decode(List[Index1]),UTF8Decode(List[Index2]));
>   if not SortAscending then
>     Result:= -Result;
> end;
> 
> {===== Numeric Sort =====}
> 
> function DoNumSort(List: TStringList; Index1, Index2: Integer): Integer;
> var
>   N1, N2: Double;
> begin
>   N1:= StrToFloatDef(List[Index1],0);
>   N2:= StrToFloatDef(List[Index2],0);
>   if N1 < N2 then
>     result := -1
>   else if N1 > N2 then
>     result := 1
>   else
>   result := 0;
>   if not SortAscending then
>     Result:= -Result;
> end;
> 
> procedure SortNumeric(Items: TStrings);
> var
>   Alist: TStringList;
> begin
>   Alist:= TStringList.Create;
>     with Items do begin
>       Alist.CommaText:= CommaText;
>       Alist.CustomSort(@DoNumSort);
>       CommaText:= Alist.commaText;
>     end;
>   FreeAndNil(Alist);
> end;
> 
> { This is the User Sort main routine }
> { Example Call: SortStringList(Memo1.Lines, HebrewSort); }
> { Example Call: SortStringList(ListBox1.Items, HebrewSort); }
> { Example Call: SortStringList(ComboBox1.Items, HebrewSort); }
> 
> function SortStringList(AStringList: TStrings; SortStyle: Integer): Integer;
> var
>   SortList: TStringList;
> begin
>   SortList:= TStringList.Create;
>     SortList.CaseSensitive:= True;
>     SortList.Assign(AStringList);
> 	{ Sort according to Language }
>     case SortStyle of
>       EnglishSort: SortList.Sort;
>       HebrewSort: SortList.CustomSort(@SortHebrew);
>       PortugueseSort: SortList.CustomSort(@SortPortuguese);
>       NumericSort: SortList.CustomSort(@DoNumSort);
> 	  { need input from Lazarus community for other Sort Methods }
>     end;
>     AStringList.Assign(SortList);
>   FreeAndNil(SortList);
> end;

Maybe you are searching for a unit with lots of string compare
functions?

Mattias