> Is there any functions in delphi for string replacing?
> I want to have a string with certain tokens that get replaced, i.e. "%user
> logged in at %now.". I initially thought I could just use Format() and
> %s's but that means I need to always have the same amount of params in the
> string, which I don't.
> I wrote a little replace function but it keeps getting stuck in some
> recursion problems which I'm gonna look at, but I was wondering if there
> was actually any built-in functions with delphi that do this?
Nothing builtin that will do token substitution...
I have a simple one (that I'm sure could be improved considerably)...
function ExtFormat(Terminator :Char; const FormatString :String; const Params :array
of String):String;
// Note throws away strings of length less than 3 since that's the smallest a parameter
// can be imbedded in a string.
var
PARAM :String;
STATE,P,iPARAM :Integer;
begin
Result := '';
if Terminator in ['0'..'9'] then raise Exception.Create('Terminator cannot be a
digit');
P := 1;
STATE:=1;
while P<=Length(FormatString) do begin
case STATE of
1: begin
if FormatString[P]=Terminator then STATE:=2
else Result := Result+FormatString[P];
end;
2: begin
if FormatString[P]=Terminator then begin
STATE:=1;
Result := Result+Terminator;
end
else if FormatString[P] in ['0'..'9'] then begin
STATE := 3;
PARAM := FormatString[P];
end
else raise Exception.Create('Invalid character ('+FormatString[P]+') in
FormatString parameter');
end;
3: begin
if FormatString[P] in ['0'..'9'] then PARAM := PARAM+FormatString[P]
else if FormatString[P]=Terminator then begin
STATE := 1;
iParam := StrToInt(PARAM);
if iParam>High(Params) then
raise Exception.Create('Too few parameters ('+IntToStr(Length(Params))+')
provided')
else Result := Result + Params[iParam];
end
else raise Exception.Create('Invalid character ('+FormatString[P]+') in
FormatString parameter');
end;
end;
inc(P);
end;
if STATE<>1 then raise Exception.Create('Unexpected termination of FormatString');
end;
This is just a quick Pushdown FSM implementation to quickly implement substitution of
numbered
parameters in the form
'%0% is the first String passed in whilst %1% is the strnig that followed %0%. %% puts
a percent sign in'
This is assuming that parameter terminator is '%'.
There is no reason why parameters cannot be named and enumerated from a string
parameter passed in
and substitutions performed on strings instead of numbers - it would be less
effificent to do a string search in
a list (even sorted to allow bin search) to find if the parameter exists though.
Does anyone know if FLEX is available for delphi... and does it produce a delphi
Lexical analyser class rather
than spagetti. It would be handy to have as a class that handles TStreams. NB the
name of the Parser generator
slips my mind at the moment but I'm assuming that it too has been ported if FLEX has...
--
Aaron Scott-Boddendijk
Jump Productions
(07) 838-3371 Voice
(07) 838-3372 Fax
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