// That is, the Source consists ONLY of
// aFindString, and we''''re going to replace
// every one of them!
ActualResultLen :=
SourceLen +
(SourceLen * ReplaceLen div FindLen) +
ReplaceLen;
// Set the length of Result; this
// will assign the memory, etc.
SetLength(Result,ActualResultLen);
CurrentPos := 1;
ResultLen := 0;
LastPos := 1;
//Again, I’m eliminating an IF statement in a loop by repeating code–this ap
//proach results in very slightly larger code, but if ever you can trade some
//memory in exchange for speed, go for it!
if ReplaceLen > 0 then begin
repeat
// Get the position of the first (or next)
// aFindString in aSourceString.
// Note that there''''s no If CaseSensitive,
// I just call FastPOSProc, which is pointing
// to the correct pre-determined routine.
CurrentPos :=
FastPosProc(aSourceString, aFindString,
SourceLen, FindLen, CurrentPos);
// If 0, then we''''re finished.
if CurrentPos = 0 then break;
// Number of bytes to copy from the
// source string is CurrentPos - lastPos,
// i.e. " cat " in "the cat the".
BytesToCopy := CurrentPos-LastPos;
// Copy chars from aSourceString
// to the end of Result.
MyMove(aSourceString[LastPos],
Result[ResultLen+1], BytesToCopy);
// Copy chars from aReplaceString to
// the end of Result.
MyMove(aReplaceString[1],
Result[ResultLen+1+BytesToCopy], ReplaceLen);
// Remember, using COPY would copy all of
// the data over and over again.
// Never fall into this trap (like a certain
// software company did).
// Set the running length to
ResultLen := ResultLen +
BytesToCopy + ReplaceLen;
// Set the position in aSourceString to where
// we want to continue searching from.
CurrentPos := CurrentPos + FindLen;
LastPos := CurrentPos;
until false;
end else begin
// You might have noticed If ReplaceLen > 0.
// Well, if ReplaceLen = 0, then we''''re deleting the
// substrings, rather than replacing them, so we
// don''''t need the extra MyMove from aReplaceString.
repeat
CurrentPos := FastPos(aSourceString,
aFindString, SourceLen, FindLen, CurrentPos);
if CurrentPos = 0 then break;
BytesToCopy := CurrentPos-LastPos;
MyMove(aSourceString[LastPos],
Result[ResultLen+1], BytesToCopy);
ResultLen := ResultLen +
BytesToCopy + ReplaceLen;
CurrentPos := CurrentPos + FindLen;
LastPos := CurrentPos;
until false;
end;
//Now that we’ve finished doing all of the replaces, I just need to adjust th
//e length of the final result:
Dec(LastPOS);
//Now I set the length to the Length plus the bit of string left. That is, " m
//at" when replacing "the" in "sat on the mat".
SetLength(Result, ResultLen + (SourceLen-LastPos));
// If there''''s a bit of string dangling, then
// add it to the end of our string.
if LastPOS+1 <= SourceLen then
MyMove(aSourceString[LastPos+1],
Result[ResultLen+1],SourceLen-LastPos);
end;
end.
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