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LCL: MergeSort: using insertion sort for small arrays

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git-svn-id: trunk@31168 -
This commit is contained in:
mattias 2011-06-11 15:11:42 +00:00
parent cc455840b2
commit ef8b26114d
1 changed files with 54 additions and 24 deletions
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78
lcl/lclproc.pas
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@ -119,8 +119,8 @@ type
TStringsSortCompare = function(const Item1, Item2: string): Integer; TStringsSortCompare = function(const Item1, Item2: string): Integer;
procedure MergeSort(List: TFPList; const OnCompare: TListSortCompare); procedure MergeSort(List: TFPList; const OnCompare: TListSortCompare); // sort so that for each i is OnCompare(List[i],List[i+1])<=0
procedure MergeSort(List: TStrings; const OnCompare: TStringsSortCompare); procedure MergeSort(List: TStrings; const OnCompare: TStringsSortCompare); // sort so that for each i is OnCompare(List[i],List[i+1])<=0
function GetEnumValueDef(TypeInfo: PTypeInfo; const Name: string; function GetEnumValueDef(TypeInfo: PTypeInfo; const Name: string;
const DefaultValue: Integer): Integer; const DefaultValue: Integer): Integer;
@ -1917,9 +1917,31 @@ begin
end; end;
procedure MergeSort(List: TFPList; const OnCompare: TListSortCompare); procedure MergeSort(List: TFPList; const OnCompare: TListSortCompare);
// sort so that for each i is OnCompare(List[i],List[i+1])<=0
var var
MergeList: PPointer; MergeList: PPointer;
procedure SmallSort(StartPos, EndPos: PtrInt);
// use insertion sort for small lists
var
i: PtrInt;
Best: PtrInt;
j: PtrInt;
Item: Pointer;
begin
for i:=StartPos to EndPos-1 do begin
Best:=i;
for j:=i+1 to EndPos do
if OnCompare(List[Best],List[j])>0 then
Best:=j;
if Best>i then begin
Item:=List[i];
List[i]:=List[Best];
List[Best]:=Item;
end;
end;
end;
procedure Merge(Pos1, Pos2, Pos3: PtrInt); procedure Merge(Pos1, Pos2, Pos3: PtrInt);
// merge two sorted arrays // merge two sorted arrays
// the first array ranges Pos1..Pos2-1, the second ranges Pos2..Pos3 // the first array ranges Pos1..Pos2-1, the second ranges Pos2..Pos3
@ -1954,18 +1976,11 @@ var
procedure Sort(StartPos, EndPos: PtrInt); procedure Sort(StartPos, EndPos: PtrInt);
// sort an interval in List. Use MergeList as work space. // sort an interval in List. Use MergeList as work space.
var var
cmp, mid: integer; mid: integer;
p: Pointer;
begin begin
if StartPos=EndPos then begin if EndPos-StartPos<6 then begin
end else if StartPos+1=EndPos then begin SmallSort(StartPos,EndPos);
cmp:=OnCompare(List[StartPos],List[EndPos]); end else begin
if cmp>0 then begin
p:=List[StartPos];
List[StartPos]:=List[EndPos];
List[EndPos]:=p;
end;
end else if EndPos>StartPos then begin
mid:=(StartPos+EndPos) shr 1; mid:=(StartPos+EndPos) shr 1;
Sort(StartPos,mid); Sort(StartPos,mid);
Sort(mid+1,EndPos); Sort(mid+1,EndPos);
@ -1981,9 +1996,31 @@ begin
end; end;
procedure MergeSort(List: TStrings; const OnCompare: TStringsSortCompare); procedure MergeSort(List: TStrings; const OnCompare: TStringsSortCompare);
// sort so that for each i is OnCompare(List[i],List[i+1])<=0
var var
MergeList: PAnsiString; MergeList: PAnsiString;
procedure SmallSort(StartPos, EndPos: PtrInt);
// use insertion sort for small lists
var
i: PtrInt;
Best: PtrInt;
j: PtrInt;
Item: string;
begin
for i:=StartPos to EndPos-1 do begin
Best:=i;
for j:=i+1 to EndPos do
if OnCompare(List[Best],List[j])>0 then
Best:=j;
if Best>i then begin
Item:=List[i];
List[i]:=List[Best];
List[Best]:=Item;
end;
end;
end;
procedure Merge(Pos1, Pos2, Pos3: PtrInt); procedure Merge(Pos1, Pos2, Pos3: PtrInt);
// merge two sorted arrays // merge two sorted arrays
// the first array ranges Pos1..Pos2-1, the second ranges Pos2..Pos3 // the first array ranges Pos1..Pos2-1, the second ranges Pos2..Pos3
@ -2018,18 +2055,11 @@ var
procedure Sort(StartPos, EndPos: PtrInt); procedure Sort(StartPos, EndPos: PtrInt);
// sort an interval in List. Use MergeList as work space. // sort an interval in List. Use MergeList as work space.
var var
cmp, mid: integer; mid: integer;
s: string;
begin begin
if StartPos=EndPos then begin if EndPos-StartPos<6 then begin
end else if StartPos+1=EndPos then begin SmallSort(StartPos,EndPos);
cmp:=OnCompare(List[StartPos],List[EndPos]); end else begin
if cmp>0 then begin
s:=List[StartPos];
List[StartPos]:=List[EndPos];
List[EndPos]:=s;
end;
end else if EndPos>StartPos then begin
mid:=(StartPos+EndPos) shr 1; mid:=(StartPos+EndPos) shr 1;
Sort(StartPos,mid); Sort(StartPos,mid);
Sort(mid+1,EndPos); Sort(mid+1,EndPos);