{
    $Id$
    This file is part of the Free Pascal run time library.
    Copyright (c) 1993,97 by Michael Van Canneyt,
    member of the Free Pascal development team.

    This file implements AnsiStrings for FPC

    See the file COPYING.FPC, included in this distribution,
    for details about the copyright.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

 **********************************************************************}

{ This will release some functions for special shortstring support }
{ define EXTRAANSISHORT}

{
  This file contains the implementation of the AnsiString type,
  and all things that are needed for it.
  AnsiString is defined as a 'silent' pchar :
  a pchar that points to :

  @-12 : Longint for maximum size;
  @-8  : Longint for size;
  @-4  : Longint for reference count;
  @    : String + Terminating #0;
  Pchar(Ansistring) is a valid typecast.
  So AS[i] is converted to the address @AS+i-1.

  Constants should be assigned a reference count of -1
  Meaning that they can't be disposed of.
}

Type
  PAnsiRec = ^TAnsiRec;
  TAnsiRec = Packed Record
    Maxlen,
    len,
    ref   : Longint;
    First : Char;
  end;

Const
  AnsiRecLen = SizeOf(TAnsiRec);
  FirstOff   = SizeOf(TAnsiRec)-1;


{****************************************************************************
                    Internal functions, not in interface.
****************************************************************************}

{$ifdef AnsiStrDebug}
Procedure DumpAnsiRec(S : Pointer);
begin
  If S=Nil then
    Writeln ('String is nil')
  Else
    Begin
      With PAnsiRec(S-Firstoff)^ do
       begin
         Write   ('(Maxlen: ',maxlen);
         Write   (' Len:',len);
         Writeln (' Ref: ',ref,')');
       end;
    end;
end;
{$endif}


Function NewAnsiString(Len : Longint) : Pointer;
{
  Allocate a new AnsiString on the heap.
  initialize it to zero length and reference count 1.
}
Var
  P : Pointer;
begin
  { Also add +1 for a terminating zero }
  GetMem(P,Len+AnsiRecLen);
  If P<>Nil then
   begin
     PAnsiRec(P)^.Maxlen:=Len;    { Maximal length }
     PAnsiRec(P)^.Len:=0;         { Initial length }
     PAnsiRec(P)^.Ref:=1;         { Set reference count }
     PAnsiRec(P)^.First:=#0;      { Terminating #0 }
     P:=P+FirstOff;               { Points to string now }
   end;
  NewAnsiString:=P;
end;


Procedure DisposeAnsiString(Var S : Pointer);
{
  Deallocates a AnsiString From the heap.
}
begin
  If S=Nil then
    exit;
  Dec (Longint(S),FirstOff);
  FreeMem (S,PAnsiRec(S)^.Maxlen+AnsiRecLen);
  S:=Nil;
end;


Procedure AnsiStr_Decr_Ref (Var S : Pointer);[Public,Alias:'FPC_ANSISTR_DECR_REF'];
{
  Decreases the ReferenceCount of a non constant ansistring;
  If the reference count is zero, deallocate the string;
}
Type
  plongint = ^longint;
Var
  l : plongint;
Begin
  { Zero string }
  If S=Nil then exit;
  { check for constant strings ...}
  l:=@PANSIREC(S-FirstOff)^.Ref;
  If l^<0 then exit;
  Dec(l^);
  If l^=0 then
    { Ref count dropped to zero }
    DisposeAnsiString (S);        { Remove...}
  { this pointer is not valid anymore, so set it to zero }
  S:=nil;
end;


Procedure AnsiStr_Incr_Ref (Var S : Pointer);[Public,Alias:'FPC_ANSISTR_INCR_REF'];
Begin
  If S=Nil then
    exit;
  { Let's be paranoid : Constant string ??}
  If PAnsiRec(S-FirstOff)^.Ref<0 then exit;
  Inc(PAnsiRec(S-FirstOff)^.Ref);
end;


Procedure AnsiStr_Assign (Var S1 : Pointer;S2 : Pointer);[Public,Alias:'FPC_ANSISTR_ASSIGN'];
{
  Assigns S2 to S1 (S1:=S2), taking in account reference counts.
}
begin
  If S2<>nil then
    If PAnsiRec(S2-FirstOff)^.Ref>0 then
      Inc(PAnsiRec(S2-FirstOff)^.ref);
  { Decrease the reference count on the old S1 }
  ansistr_decr_ref (S1);
  { And finally, have S1 pointing to S2 (or its copy) }
  S1:=S2;
end;


Procedure AnsiStr_Concat (S1,S2 : Pointer;var S3 : Pointer);[Public, alias: 'FPC_ANSISTR_CONCAT'];
{
  Concatenates 2 AnsiStrings : S1+S2.
  Result Goes to S3;
}
Var
  Size,Location : Longint;
begin
{ create new result }
  if S3<>nil then
    AnsiStr_Decr_Ref(S3);
{ only assign if s1 or s2 is empty }
  if (S1=Nil) then
    AnsiStr_Assign(S3,S2)
  else
    if (S2=Nil) then
      AnsiStr_Assign(S3,S1)
  else
    begin
       Size:=PAnsiRec(S2-FirstOff)^.Len;
       Location:=Length(AnsiString(S1));
       SetLength (AnsiString(S3),Size+Location);
       Move (S1^,S3^,Location);
       Move (S2^,(S3+location)^,Size+1);
    end;
end;


{$ifdef EXTRAANSISHORT}
Procedure AnsiStr_ShortStr_Concat (Var S1: AnsiString; Var S2 : ShortString);
{
  Concatenates a Ansi with a short string; : S2 + S2
}
Var
  Size,Location : Longint;
begin
  Size:=Length(S2);
  Location:=Length(S1);
  If Size=0 then
    exit;
  { Setlength takes case of uniqueness
    and alllocated memory. We need to use length,
    to take into account possibility of S1=Nil }
  SetLength (S1,Size+Length(S1));
  Move (S2[1],Pointer(Pointer(S1)+Location)^,Size);
  PByte( Pointer(S1)+length(S1) )^:=0; { Terminating Zero }
end;
{$endif EXTRAANSISHORT}


Procedure AnsiStr_To_ShortStr (Var S1 : ShortString;S2 : Pointer);[Public, alias: 'FPC_ANSISTR_TO_SHORTSTR'];
{
  Converts a AnsiString to a ShortString;
}
Var
  Size : Longint;
begin
  if S2=nil then
   S1:=''
  else
   begin
     Size:=PAnsiRec(S2-FirstOff)^.Len;
     If Size>high(S1) then
      Size:=high(S1);
     Move (S2^,S1[1],Size);
     byte(S1[0]):=Size;
   end;
end;


Procedure ShortStr_To_AnsiStr (Var S1 : Pointer; Const S2 : ShortString);[Public, alias: 'FPC_SHORTSTR_TO_ANSISTR'];
{
  Converts a ShortString to a AnsiString;
}
Var
  Size : Longint;
begin
  Size:=Length(S2);
  Setlength (AnsiString(S1),Size);
  if Size>0 then
   begin
     Move (S2[1],Pointer(S1)^,Size);
     { Terminating Zero }
     PByte(Pointer(S1)+Size)^:=0;
   end;
end;


Procedure Char_To_AnsiStr(var S1 : Pointer; c : Char);[Public, alias: 'FPC_CHAR_TO_ANSISTR'];
{
  Converts a ShortString to a AnsiString;
}
begin
  Setlength (AnsiString(S1),1);
  PByte(Pointer(S1))^:=byte(c);
  { Terminating Zero }
  PByte(Pointer(S1)+1)^:=0;
end;


Procedure PChar_To_AnsiStr(var a : ansistring;p : pchar);[Public,Alias : 'FPC_PCHAR_TO_ANSISTR'];
Var
  L : Longint;
begin
  if pointer(a)<>nil then
    begin
       AnsiStr_Decr_Ref(Pointer(a));
       pointer(a):=nil;
    end;
  if (not assigned(p)) or (p[0]=#0) Then
    Pointer(a):=nil
  else
    begin
      //!! Horribly inneficient, but I see no other way...
      L:=1;
      While P[l]<>#0 do
        inc (l);
      Pointer(a):=NewAnsistring(L);
      SetLength(A,L);
      Move (P[0],Pointer(A)^,L)
    end;
end;


Procedure CharArray_To_AnsiStr(var a : ansistring;p : pchar;l:longint);[Public,Alias : 'FPC_CHARARRAY_TO_ANSISTR'];
var
  i  : longint;
  hp : pchar;
begin
  if p[0]=#0 Then
    Pointer(a):=nil
  else
    begin
      Pointer(a):=NewAnsistring(L);
      hp:=p;
      i:=0;
      while (i<l) and (hp^<>#0) do
       begin
         inc(hp);
         inc(i);
       end;
      SetLength(A,i);
      Move (P[0],Pointer(A)^,i)
    end;
end;


Function AnsiStr_Compare(S1,S2 : Pointer): Longint;[Public,Alias : 'FPC_ANSISTR_COMPARE'];
{
  Compares 2 AnsiStrings;
  The result is
   <0 if S1<S2
   0 if S1=S2
   >0 if S1>S2
}
Var
  i,MaxI,Temp : Longint;
begin
  i:=0;
  Maxi:=Length(AnsiString(S1));
  temp:=Length(AnsiString(S2));
  If MaxI>Temp then
   MaxI:=Temp;
  Temp:=0;
  While (i<MaxI) and (Temp=0) do
   begin
     Temp:= PByte(S1+I)^ - PByte(S2+i)^;
     inc(i);
   end;
  if temp=0 then
   temp:=Length(AnsiString(S1))-Length(AnsiString(S2));
  AnsiStr_Compare:=Temp;
end;


Procedure AnsiStr_CheckZero(p : pointer);[Public,Alias : 'FPC_ANSISTR_CHECKZERO'];
begin
  if p=nil then
    HandleErrorFrame(201,get_frame);
end;


Procedure AnsiStr_CheckRange(len,index : longint);[Public,Alias : 'FPC_ANSISTR_RANGECHECK'];
begin
  if (index>len) or (Index<1) then
    HandleErrorFrame(201,get_frame);
end;


{$ifdef EXTRAANSISHORT}
Function AnsiStr_ShortStr_Compare (Var S1 : Pointer; Var S2 : ShortString): Longint;
{
  Compares a AnsiString with a ShortString;
  The result is
   <0 if S1<S2
   0 if S1=S2
   >0 if S1>S2
}
Var
  i,MaxI,Temp : Longint;
begin
  Temp:=0;
  i:=0;
  MaxI:=Length(AnsiString(S1));
  if MaxI>byte(S2[0]) then
    MaxI:=Byte(S2[0]);
  While (i<MaxI) and (Temp=0) do
   begin
     Temp:= PByte(S1+I)^ - Byte(S2[i+1]);
     inc(i);
   end;
  AnsiStr_ShortStr_Compare:=Temp;
end;
{$endif EXTRAANSISHORT}


{*****************************************************************************
                     Public functions, In interface.
*****************************************************************************}

Function Length (Const S : AnsiString) : Longint;
{
  Returns the length of an AnsiString.
  Takes in acount that zero strings are NIL;
}
begin
  If Pointer(S)=Nil then
    Length:=0
  else
    Length:=PAnsiRec(Pointer(S)-FirstOff)^.Len;
end;


Procedure SetLength (Var S : AnsiString; l : Longint);
{
  Sets The length of string S to L.
  Makes sure S is unique, and contains enough room.
}
Var
  Temp : Pointer;
begin
   if (l>0) then
    begin
      if Pointer(S)=nil then
       begin
         { Need a complete new string...}
         Pointer(s):=NewAnsiString(l);
       end
      else
       If (PAnsiRec(Pointer(S)-FirstOff)^.Maxlen < L) or
          (PAnsiRec(Pointer(S)-FirstOff)^.Ref <> 1) then
        begin
          { Reallocation is needed... }
          Temp:=Pointer(NewAnsiString(L));
          if Length(S)>0 then
            Move(Pointer(S)^,Temp^,L);
          ansistr_decr_ref(Pointer(S));
          Pointer(S):=Temp;
       end;
      { Force nil termination in case it gets shorter }
      PByte(Pointer(S)+l)^:=0;
      PAnsiRec(Pointer(S)-FirstOff)^.Len:=l;
    end
  else
    begin
      { Length=0 }
      if Pointer(S)<>nil then
       ansistr_decr_ref (Pointer(S));
      Pointer(S):=Nil;
    end;
end;


Procedure UniqueAnsiString(Var S : AnsiString); [Public,Alias : 'FPC_ANSISTR_UNIQUE'];
{
  Make sure reference count of S is 1,
  using copy-on-write semantics.
}
Var
  SNew : Pointer;
begin
  If Pointer(S)=Nil then
    exit;
  if PAnsiRec(Pointer(S)-Firstoff)^.Ref<>1 then
   begin
     SNew:=NewAnsiString (PAnsiRec(Pointer(S)-FirstOff)^.len);
     Move (Pointer(S)^,SNew^,PAnsiRec(Pointer(S)-FirstOff)^.len+1);
     PAnsiRec(SNew-FirstOff)^.len:=PAnsiRec(Pointer(S)-FirstOff)^.len;
     ansistr_decr_ref (Pointer(S));  { Thread safe }
     Pointer(S):=SNew;
   end;
end;


Function Copy (Const S : AnsiString; Index,Size : Longint) : AnsiString;
var
  ResultAddress : Pointer;
begin
  ResultAddress:=Nil;
  dec(index);
  { Check Size. Accounts for Zero-length S, the double check is needed because
    Size can be maxint and will get <0 when adding index }
  if (Size>Length(S)) or
     (Index+Size>Length(S)) then
   Size:=Length(S)-Index;
  If Size>0 then
   begin
     If Index<0 Then
      Index:=0;
     ResultAddress:=Pointer(NewAnsiString (Size));
     if ResultAddress<>Nil then
      begin
        Move (Pointer(Pointer(S)+index)^,ResultAddress^,Size);
        PAnsiRec(ResultAddress-FirstOff)^.Len:=Size;
        PByte(ResultAddress+Size)^:=0;
      end;
   end;
  Pointer(Copy):=ResultAddress;
end;


Function Pos (Const Substr : AnsiString; Const Source : AnsiString) : Longint;
var
  substrlen,
  maxi,
  i,j : longint;
  e   : boolean;
  S   : AnsiString;
  se  : Pointer;
begin
  i := 0;
  j := 0;
  substrlen:=Length(SubStr);
  maxi:=length(source)-substrlen;
  e:=(substrlen>0);
  while (e) and (i <= maxi) do
   begin
     inc (i);
     if Source[i]=SubStr[1] then
      begin
        S:=copy(Source,i,substrlen);
        Se:=pointer(SubStr);
        if AnsiStr_Compare(se,Pointer(S))=0 then
         begin
           j := i;
           break;
         end;
      end;
   end;
  pos := j;
end;


Function ValAnsiFloat(Const S : AnsiString; Var Code : ValSInt): ValReal; [public, alias:'FPC_VAL_REAL_ANSISTR'];
Var
  SS : String;
begin
  AnsiStr_To_ShortStr(SS,Pointer(S));
  ValAnsiFloat := ValFloat(SS,Code);
end;


Function ValAnsiUnsigendInt (Const S : AnsiString; Code : ValSInt): ValUInt; [public, alias:'FPC_VAL_UINT_ANSISTR'];
Var
  SS : ShortString;
begin
  AnsiStr_To_ShortStr(SS,Pointer(S));
  ValAnsiUnsigendInt := ValUnsignedInt(SS,Code);
end;


Function ValAnsiSignedInt (DestSize: longint; Const S : AnsiString; Var Code : ValSInt): ValSInt; [public, alias:'FPC_VAL_SINT_ANSISTR'];
Var
  SS : ShortString;
begin
  AnsiStr_To_ShortStr (SS,Pointer(S));
  ValAnsiSignedInt := ValSignedInt(DestSize,SS,Code);
end;


{$IfDef SUPPORT_FIXED}
Function ValAnsiFixed(Const S : AnsiString; Var Code : ValSint): ValReal; [public, alias:'FPC_VAL_FIXED_ANSISTR'];
Var
  SS : String;
begin
  AnsiStr_To_ShortStr (SS,Pointer(S));
  ValAnsiFixed := Fixed(ValFloat(SS,Code));
end;
{$EndIf SUPPORT_FIXED}


procedure AnsiStr_Float(d : ValReal;len,fr,rt : longint;var s : ansistring);[public,alias:'FPC_ANSISTR_FLOAT'];
var
  ss : shortstring;
begin
  str_real(len,fr,d,treal_type(rt),ss);
  s:=ss;
end;


Procedure AnsiStr_Cardinal(C : Cardinal;Len : Longint; Var S : AnsiString);[Public,Alias : 'FPC_ANSISTR_CARDINAL'];
Var
  SS : ShortString;
begin
  int_str_cardinal(C,Len,SS);
  S:=SS;
end;



Procedure AnsiStr_Longint(L : Longint; Len : Longint; Var S : AnsiString);[Public,Alias : 'FPC_ANSISTR_LONGINT'];
Var
  SS : ShortString;
begin
  int_Str_Longint (L,Len,SS);
  S:=SS;
end;


Procedure Delete (Var S : AnsiString; Index,Size: Longint);
Var
  LS : Longint;
begin
  If Length(S)=0 then
   exit;
  if index<=0 then
   begin
     inc(Size,index-1);
     index:=1;
   end;
  LS:=PAnsiRec(Pointer(S)-FirstOff)^.Len;
  if (Index<=LS) and (Size>0) then
   begin
     UniqueAnsiString (S);
     if Size+Index>LS then
      Size:=LS-Index+1;
     if Index+Size<=LS then
      begin
        Dec(Index);
        Move(PByte(Pointer(S))[Index+Size],PByte(Pointer(S))[Index],LS-Index+1);
      end;
     Setlength(s,LS-Size);
   end;
end;


Procedure Insert (Const Source : AnsiString; Var S : AnsiString; Index : Longint);
var
  Temp : AnsiString;
  LS : Longint;
begin
  If Length(Source)=0 then
   exit;
  if index <= 0 then
   index := 1;
  Ls:=Length(S);
  if index > LS then
   index := LS+1;
  Dec(Index);
  Pointer(Temp) := NewAnsiString(Length(Source)+LS);
  SetLength(Temp,Length(Source)+LS);
  If Index>0 then
    move (Pointer(S)^,Pointer(Temp)^,Index);
  Move (Pointer(Source)^,PByte(Temp)[Index],Length(Source));
  If (LS-Index)>0 then
    Move(PByte(Pointer(S))[Index],PByte(temp)[Length(Source)+index],LS-Index);
  S:=Temp;
end;


Function StringOfChar(c : char;l : longint) : AnsiString;
begin
  SetLength(StringOfChar,l);
  FillChar(Pointer(StringOfChar)^,Length(StringOfChar),c);
end;

{
  $Log$
  Revision 1.35  1999-11-06 14:35:38  peter
    * truncated log

  Revision 1.34  1999/11/02 23:57:54  peter
    * fixed copy where size+index could be < 0

  Revision 1.33  1999/10/27 14:27:49  florian
    * StringOfChar fixed, how can be a bug in two lines of code ?????

  Revision 1.32  1999/10/27 14:17:20  florian
    + StringOfChar

  Revision 1.31  1999/10/04 20:48:18  peter
    * pos function speed up by a factor 40 :)

  Revision 1.30  1999/07/05 20:04:21  peter
    * removed temp defines

  Revision 1.29  1999/06/14 00:47:33  peter
    * merged

  Revision 1.28.2.1  1999/06/14 00:39:07  peter
    * setlength finally fixed when l < length(s)

  Revision 1.28  1999/06/09 23:00:16  peter
    * small ansistring fixes
    * val_ansistr_sint destsize changed to longint
    * don't write low/hi ascii with -al

  Revision 1.27  1999/06/05 20:48:56  michael
  Copy checks index now for negative values.

  Revision 1.26  1999/05/31 20:37:39  peter
    * fixed decr_ansistr which didn't set s to nil

  Revision 1.25  1999/05/17 22:41:24  florian
    * small fixes for the new ansistring temp. management

  Revision 1.24  1999/05/17 21:52:35  florian
    * most of the Object Pascal stuff moved to the system unit

  Revision 1.23  1999/05/06 09:05:11  peter
    * generic write_float str_float

  Revision 1.22  1999/04/22 10:51:17  peter
    * fixed pchar 2 ansi

  Revision 1.21  1999/04/13 09:02:06  michael
  + 1 byte too much allocated in new_ansiStringastrings.inc

  Revision 1.20  1999/04/09 07:33:15  michael
  * More fixes and optimizing for ansistr_concat

  Revision 1.19  1999/04/08 15:57:53  peter
    + subrange checking for readln()

  Revision 1.18  1999/04/08 10:19:55  peter
    * fixed concat when s1 or s2 was nil

  Revision 1.17  1999/04/06 11:23:58  peter
    * fixed insert on last char
    * saver chararray 2 ansi

  Revision 1.16  1999/04/06 10:06:51  michael
  * Fixed chararray to ansistring conversion

}