Snippets
Created by
Stefan Glienke
last modified
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{$I Spring.inc}
interface
uses
Spring,
SysUtils,
TypInfo;
type
TConversion<TSource,TTarget> = function(const value: TSource): TTarget;
TConverter = record
private
class function SingleToStr(const value: Single): string; static; inline;
class function DoubleToStr(const value: Double): string; static; inline;
class function CurrToStr(const value: Currency): string; static; inline;
public
function Convert<TSource,TTarget>(const value: TSource): TTarget; inline;
end;
TConverter<T> = record
private
class function EnumToStr(const value: Integer): string; static; inline;
end;
TConverter<TSource,TTarget> = record
strict private
class function GetDefault: TConversion<TSource,TTarget>; static; inline;
public
class property Default: TConversion<TSource,TTarget> read GetDefault;
end;
implementation
{ TConverter }
function TConverter.Convert<TSource, TTarget>(
const value: TSource): TTarget;
begin
// if FindConverter then
// ...
// else
Result := TConversion<TSource,TTarget>(TConverter<TSource, TTarget>.Default)(value);
end;
class function TConverter.CurrToStr(const value: Currency): string;
var
Buffer: array[0..63] of Char;
begin
SetString(Result, Buffer, FloatToText(Buffer, Value, fvCurrency,
ffGeneral, 0, 0, FormatSettings));
end;
class function TConverter.DoubleToStr(const value: Double): string;
begin
Result := FloatToStr(value, FormatSettings);
end;
class function TConverter.SingleToStr(const value: Single): string;
begin
Result := FloatToStr(value, FormatSettings);
end;
{ TConverter<T> }
class function TConverter<T>.EnumToStr(const value: Integer): string;
begin
Result := GetEnumName(TypeInfo(T), value);
end;
{ TConverter<TSource, TTarget> }
class function TConverter<TSource, TTarget>.GetDefault: TConversion<TSource, TTarget>;
begin
case {$IFDEF DELPHIXE7_UP}System.GetTypeKind(TSource){$ELSE}GetTypeKind(TypeInfo(TSource)){$ENDIF} of
tkInteger:
case {$IFDEF DELPHIXE7_UP}System.GetTypeKind(TTarget){$ELSE}GetTypeKind(TypeInfo(TTarget)){$ENDIF} of
tkUString: TConversion<Integer,string>(Result) := @IntToStr;
end;
tkEnumeration:
case {$IFDEF DELPHIXE7_UP}System.GetTypeKind(TTarget){$ELSE}GetTypeKind(TypeInfo(TTarget)){$ENDIF} of
tkUString: TConversion<Integer,string>(Result) := TConverter<TSource>.EnumToStr;
end;
tkFloat:
case {$IFDEF DELPHIXE7_UP}System.GetTypeKind(TTarget){$ELSE}GetTypeKind(TypeInfo(TTarget)){$ENDIF} of
tkUString:
case SizeOf(TSource) of
10: TConversion<Single,string>(Result) := @FloatToStr;
SizeOf(Single): TConversion<Single,string>(Result) := TConverter.SingleToStr;
SizeOf(Double):
if TypeInfo(TSource) = TypeInfo(Double) then
TConversion<Double,string>(Result) := TConverter.DoubleToStr
else if TypeInfo(TSource) = TypeInfo(Currency) then
TConversion<Currency,string>(Result) := TConverter.CurrToStr
else
case GetTypeData(PTypeInfo(TypeInfo(TSource))).FloatType of
ftDouble: TConversion<Double,string>(Result) := TConverter.DoubleToStr;
ftCurr: TConversion<Currency,string>(Result) := TConverter.CurrToStr;
end;
end;
end;
tkUString:
case {$IFDEF DELPHIXE7_UP}System.GetTypeKind(TTarget){$ELSE}GetTypeKind(TypeInfo(TTarget)){$ENDIF} of
tkInteger: TConversion<string,Integer>(Result) := StrToInt;
end;
end;
end;
end.
program Converter;
{$APPTYPE CONSOLE}
{$R *.res}
uses
SysUtils,
Converters in 'Converters.pas';
type
MyDouble = type Double;
MyCurrency = type Currency;
{$SCOPEDENUMS ON}
{$MINENUMSIZE 1}
TByteEnum = (Element);
{$MINENUMSIZE 2}
TWordEnum = (Element);
{$MINENUMSIZE 4}
TLongEnum = (Element);
procedure Main;
var
s: string;
i: Integer;
c: TConverter;
f: Single;
begin
try
s := TConverter<Integer,string>.Default(42);
Writeln(s);
s := c.Convert<Integer,string>(42);
Writeln(s);
i := TConverter<string,Integer>.Default('42');
Writeln(i);
s := TConverter<Double,string>.Default(3.14);
s := TConverter<MyDouble,string>.Default(3.14);
s := TConverter<Currency,string>.Default(3.14);
s := TConverter<MyCurrency,string>.Default(3.14);
s := TConverter<Single, string>.Default(3.14);
f := 3.14;
s := FloatToStr(f);
s := TConverter<TByteEnum,string>.Default(TByteEnum.Element);
s := TConverter<TWordEnum,string>.Default(TWordEnum.Element);
s := TConverter<TLongEnum,string>.Default(TLongEnum.Element);
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
Readln;
end;
begin
Main;
end.
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