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// Generic types for FreeSparta.com and FreePascal!
// by Maciej Izak (hnb), 2014
program THashMapExtendedEqualityComparer;
{$MODE DELPHI}
{$APPTYPE CONSOLE}
uses
SysUtils, Generics.Collections, Generics.Defaults;
type
{ TTaxPayer }
TTaxPayer = record
TaxID: Integer;
Name: string;
constructor Create(ATaxID: Integer; const AName: string);
function ToString: string;
end;
constructor TTaxPayer.Create(ATaxID: Integer; const AName: string);
begin
TaxID := ATaxID;
Name := AName;
end;
function TTaxPayer.ToString: string;
begin
Result := Format('TaxID = %-10d Name = %-17s', [TaxID, Name]);
end;
function EqualityComparison(constref ALeft, ARight: TTaxPayer): Boolean;
begin
Result := ALeft.TaxID = ARight.TaxID;
end;
procedure ExtendedHasher(constref AValue: TTaxPayer; AHashList: PUInt32);
begin
// don't work with TCuckooD6 map because default TCuckooD6 needs TDelphiSixfoldHashFactory
// and TDefaultHashFactory = TDelphiQuadrupleHashFactory
// (TDelphiQuadrupleHashFactory is compatible with TDelphiDoubleHashFactory and TDelphiHashFactory)
TDefaultHashFactory.GetHashList(@AValue.TaxID, SizeOf(Integer), AHashList);
end;
var
map: THashMap<TTaxPayer, string>; // THashMap = TCuckooD4
LTaxPayer: TTaxPayer;
LSansa: TTaxPayer;
LPair: TPair<TTaxPayer, string>;
begin
WriteLn('program of tax office - ExtendedEqualityComparer for THashMap');
WriteLn;
// to identify the taxpayer need only nip
map := THashMap<TTaxPayer, string>.Create(
TExtendedEqualityComparer<TTaxPayer>.Construct(EqualityComparison, ExtendedHasher));
map.Add(TTaxPayer.Create(1234567890, 'Joffrey Baratheon'), 'guilty');
map.Add(TTaxPayer.Create(90, 'Little Finger'), 'swindler');
map.Add(TTaxPayer.Create(667, 'John Snow'), 'delinquent tax');
// useless in this place but we can convert Keys to TArray<TKey> :)
WriteLn(Format('All taxpayers (count = %d)', [Length(map.Keys.ToArray)]));
for LTaxPayer in map.Keys do
WriteLn(' > ', LTaxPayer.ToString);
LSansa := TTaxPayer.Create(667, 'Sansa Stark');
// exist because custom EqualityComparison and ExtendedHasher
WriteLn;
WriteLn(LSansa.Name, ' exist in map = ', map.ContainsKey(LSansa));
WriteLn;
//
WriteLn('All taxpayers');
for LPair in map do
WriteLn(' > ', LPair.Key.ToString, ' is ', LPair.Value);
// Add or set sansa? :)
WriteLn;
WriteLn(Format('AddOrSet(%s, ''innocent'')', [LSansa.ToString]));
map.AddOrSetValue(LSansa, 'innocent');
WriteLn;
//
WriteLn('All taxpayers');
for LPair in map do
WriteLn(' > ', LPair.Key.ToString, ' is ', LPair.Value);
// Add or set sansa? :)
WriteLn;
LSansa.TaxID := 668;
WriteLn(Format('AddOrSet(%s, ''innocent'')', [LSansa.ToString]));
map.AddOrSetValue(LSansa, 'innocent');
WriteLn;
//
WriteLn('All taxpayers');
for LPair in map do
WriteLn(' > ', LPair.Key.ToString, ' is ', LPair.Value);
ReadLn;
map.Free;
end.
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