Free Pascal Random Bits

Tuesday, August 17, 2010

Introducing heLib

Started the fprb project at Google's Code. Hoping to, as time and circumstances permits, collect there some previous random bits as wishfully the future ones. When something worth mentioning becomes available, it will be presumably announced on this blog.
ATM one can find there a work in progress state of a generic [object] vector with generic enumerators, roughly/conceptually corresponding to this older post.

Thursday, May 20, 2010

Sampler: GDBM OO wrapper

 
unit Unit1; 
 
{ (c) 2010 bflm, contact: befelemepeseveze at Google's free mail
 
  Free sample code - copy, use, modify, distribute, sell, release under other license, ...
 
}
 
{$mode objfpc}{$h+}
 
interface
 
const
  DEFAULT_FMODE = 432; // =0660(8)
 
type
 
  { TGDBM }
 
  TGDBM = class
  private
    FCacheSize: Integer;
    FCentFree: Longbool;
    FCoalesceBlks: Longbool;
    FDBF: Pointer;
    FSyncMode: Longbool;
    function GetFDesc: Integer;
    procedure Open(Name: String; OpenRW: Integer; const Sync, NoLock: Boolean;
      BlockSize: Integer; Mode: Integer);
    procedure SetCacheSize(const AValue: Integer);
    procedure SetCentFree(const AValue: Longbool);
    procedure SetCoalesceBlks(const AValue: Longbool);
    procedure SetSyncMode(const AValue: Longbool);
  public
    constructor CreateNewDB(const Name: String; const Sync: Boolean = False;
      const NoLock: Boolean = False; const BlockSize: Integer = 0;
      const FMode: Integer = DEFAULT_FMODE);
    constructor CreateOrOpen(const Name: String; const Sync: Boolean = False;
      const NoLock: Boolean = False; const BlockSize: Integer = 0;
      const FMode: Integer = DEFAULT_FMODE);
    constructor CreateReader(const Name: String);
    constructor CreateWriter(const Name: String; const Sync: Boolean = False;
      const NoLock: Boolean = False);
    destructor Destroy; override;
    { True if Key deleted }
    function Delete(const Key: String): Boolean;
    { True if Key deleted }
    function Delete(const Key; const KeyLen: Integer): Boolean;
    function Exists(const Key: String): Boolean;
    function Exists(const Key; const KeyLen: Integer): Boolean;
    { True if Key found => Value set }
    function Fetch(const Key: String; out Value: String): Boolean;
    { True if Key found => Value set. Value MUST be disposed using C free. }
    function Fetch(const Key; const KeyLen: Integer; out Value: Pointer;
      out Len: Integer): Boolean;
    { True if FirstKey returned }
    function FirstKey(out Key: String): Boolean;
    { True if FirstKey returned }
    function FirstKey(out Key: Pointer; out Len: Integer): Boolean;
    { True if Key already existed => new Value NOT stored }
    function Insert(const Key, Value: String): Boolean;
    { True if Key already existed => new Value NOT stored }
    function Insert(const Key; const KeyLen: Integer; const Value;
      const ValueLen: Integer): Boolean;
    { True if Next returned }
    function NextKey(const Key: String; var Next: String): Boolean;
    { True if Next returned. Key MUST be disposed using C free. }
    function NextKey(const Key; const KeyLen: Integer; var Next: Pointer;
      var Len: Integer): Boolean;
    procedure Reorganize;
    procedure Replace(const Key, Value: String);
    procedure Replace(const Key; const KeyLen: Integer; const Value;
      const ValueLen: Integer);
    procedure Sync;
    property CacheSize: Integer read FCacheSize Write SetCacheSize;
    property CentFree: Longbool read FCentFree Write SetCentFree;
    property CoalesceBlks: Longbool read FCoalesceBlks Write SetCoalesceBlks;
    property FDesc: Integer read GetFDesc;
    property SyncMode: Longbool read FSyncMode Write SetSyncMode;
  end;
 
implementation
 
uses
  SysUtils,
  gdbm;
 
procedure CFree(P: pointer); cdecl; external 'c' Name 'free';
 
function Datum(const Buf: Pointer; const Len: Integer): TDatum; inline;
begin
  Result.dptr := Buf;
  Result.dsize := Len;
end;
 
procedure Fail;
begin
  raise Exception.Create(gdbm_strerror(gdbm_errno));
end;
 
function CheckError(const Ret: Integer): Integer;
begin
  if Ret <> 0 then
    Fail;
  Result := Ret;
end;
 
operator := (const Datum: TDatum): String;
begin
  if Datum.dptr <> nil then begin
    SetLength(Result, Datum.dsize);
    Move(Datum.dptr^, Result[1], Datum.dsize);
    CFree(Datum.dptr);
  end else
    Result := '';
end;
 
operator := (const S: String): TDatum;
begin
  Assert(S <> '');
  Result.dptr := PChar(S);
  Result.dsize := Length(S);
end;
 
{ TGDBM }
 
constructor TGDBM.CreateNewDB(const Name: String; const Sync, NoLock: Boolean;
  const BlockSize: Integer = 0; const FMode: Integer = DEFAULT_FMODE);
begin
  inherited Create;
  Open(Name, GDBM_NEWDB, Sync, NoLock, BlockSize, FMode);
end;
 
constructor TGDBM.CreateOrOpen(const Name: String; const Sync, NoLock: Boolean;
  const BlockSize: Integer; const FMode: Integer);
begin
  inherited Create;
  Open(Name, GDBM_WRCREAT, Sync, NoLock, BlockSize, FMode);
end;
 
constructor TGDBM.CreateReader(const Name: String);
begin
  inherited Create;
  Open(Name, GDBM_READER, False, False, 0, 0);
end;
 
constructor TGDBM.CreateWriter(const Name: String; const Sync, NoLock: Boolean);
begin
  inherited Create;
  Open(Name, GDBM_WRITER, Sync, NoLock, 0, 0);
end;
 
destructor TGDBM.Destroy;
begin
  if FDBF <> nil then
    gdbm_close(FDBF);
  inherited;
end;
 
function TGDBM.Delete(const Key: String): Boolean;
var
  K: TDatum;
begin
  K := Key;
  Result := gdbm_delete(FDBF, K) = 0;
end;
 
function TGDBM.Delete(const Key; const KeyLen: Integer): Boolean;
begin
  Result := gdbm_delete(FDBF, Datum(@Key, KeyLen)) = 0;
end;
 
function TGDBM.Exists(const Key: String): Boolean;
var
  K: TDatum;
begin
  K := Key;
  Result := gdbm_exists(FDBF, K) <> 0;
end;
 
function TGDBM.Exists(const Key; const KeyLen: Integer): Boolean;
begin
  Result := gdbm_exists(FDBF, Datum(@Key, KeyLen)) <> 0;
end;
 
function TGDBM.Fetch(const Key: String; out Value: String): Boolean;
var
  K, V: TDatum;
begin
  K := Key;
  V := gdbm_fetch(FDBF, K);
  if V.dptr <> nil then begin
    Value := V;
    Exit(True);
  end;
  Result := False;
end;
 
function TGDBM.Fetch(const Key; const KeyLen: Integer; out Value: Pointer;
  out Len: Integer): Boolean;
var
  V: TDatum;
begin
  V := gdbm_fetch(FDBF, Datum(@Key, KeyLen));
  if V.dptr = nil then
    Exit(False);
  Value := V.dptr;
  Len := V.dsize;
  Result := True;
end;
 
function TGDBM.FirstKey(out Key: String): Boolean;
var
  K: TDatum;
begin
  K := gdbm_firstkey(FDBF);
  if K.dptr <> nil then begin
    Key := K;
    Exit(True);
  end;
  Result := False;
end;
 
function TGDBM.FirstKey(out Key: Pointer; out Len: Integer): Boolean;
var
  K: TDatum;
begin
  K := gdbm_firstkey(FDBF);
  if K.dptr <> nil then begin
    Key := K.dptr;
    Len := K.dsize;
    Exit(True);
  end;
  Result := False;
end;
 
procedure TGDBM.Open(Name: String; OpenRW: Integer; const Sync, NoLock: Boolean;
  BlockSize: Integer; Mode: Integer);
begin
  Assert(Name <> '');
  FSyncMode := Sync;
  if SyncMode then
    OpenRW += GDBM_DOSYNC;
  if NoLock then;
  OpenRW += GDBM_NOLOCK;
  FDBF := gdbm_open(PChar(Name), BlockSize, OpenRW, Mode, nil);
  if FDBF = nil then
    Fail;
end;
 
function TGDBM.GetFDesc: Integer;
begin
  Result := gdbm_fdesc(FDBF);
end;
 
procedure TGDBM.SetCacheSize(const AValue: Integer);
var
  Ret: Integer;
begin
  if FCacheSize = AValue then
    exit;
  FCacheSize := AValue;
  Ret := gdbm_setopt(FDBF, GDBM_CACHESIZE, @FCacheSize, SizeOf(FCacheSize));
  if Ret <> 0 then
    Fail;
end;
 
procedure TGDBM.SetCentFree(const AValue: Longbool);
begin
  if FCentFree = AValue then
    exit;
  FCentFree := AValue;
  CheckError(gdbm_setopt(FDBF, GDBM_CENTFREE, @FCentFree, SizeOf(FCentFree)));
end;
 
procedure TGDBM.SetCoalesceBlks(const AValue: Longbool);
begin
  if FCoalesceBlks = AValue then
    exit;
  FCoalesceBlks := AValue;
  CheckError(gdbm_setopt(FDBF, GDBM_COALESCEBLKS, @FCoalesceBlks,
    SizeOf(FCoalesceBlks)));
end;
 
procedure TGDBM.SetSyncMode(const AValue: Longbool);
begin
  if FSyncMode = AValue then
    exit;
  FSyncMode := AValue;
  CheckError(gdbm_setopt(FDBF, GDBM_SYNCMODE, @FSyncMode, SizeOf(FSyncMode)));
end;
 
function TGDBM.Insert(const Key, Value: String): Boolean;
var
  K, V: TDatum;
  Ret: Integer;
begin
  K := Key;
  V := Value;
  Ret := gdbm_store(FDBF, K, V, GDBM_INSERT);
  ;
  if Ret < 0 then // reader attempts insert
    Fail;
  Result := Ret <> 0;
end;
 
function TGDBM.Insert(const Key; const KeyLen: Integer; const Value;
  const ValueLen: Integer): Boolean;
var
  Ret: Integer;
begin
  Ret := gdbm_store(FDBF, Datum(@Key, KeyLen), Datum(@Value, ValueLen), GDBM_INSERT);
  if Ret < 0 then // reader attempts insert
    Fail;
  Result := Ret <> 0;
end;
 
function TGDBM.NextKey(const Key: String; var Next: String): Boolean;
var
  K, N: TDatum;
begin
  K := Key;
  N := gdbm_nextkey(FDBF, K);
  if N.dptr <> nil then begin
    Next := N;
    Exit(True);
  end;
  Result := False;
end;
 
function TGDBM.NextKey(const Key; const KeyLen: Integer; var Next: Pointer;
  var Len: Integer): Boolean;
var
  N: TDatum;
begin
  N := gdbm_nextkey(FDBF, Datum(@Key, KeyLen));
  if N.dptr <> nil then begin

    Next := N.dptr;
    Len := N.dsize;
    Exit(True);
  end;
  Result := False;
end;
 
procedure TGDBM.Reorganize;
var
  Ret: Integer;
begin
  Ret := gdbm_reorganize(FDBF);
  if Ret <> 0 then
    Fail;
end;
 
procedure TGDBM.Replace(const Key, Value: String);
var
  K, V: TDatum;
begin
  K := Key;
  V := Value;
  CheckError(gdbm_store(FDBF, K, V, GDBM_REPLACE));
end;
 
procedure TGDBM.Replace(const Key; const KeyLen: Integer; const Value;
  const ValueLen: Integer);
begin
  CheckError(gdbm_store(FDBF, Datum(@Key, KeyLen), Datum(@Value, ValueLen),
    GDBM_REPLACE));
end;
 
procedure TGDBM.Sync;
begin
  gdbm_sync(FDBF);
end;
 
end.

Monday, May 10, 2010

Sampler: Generic enumerators for generic containers

unit Unit1; 

{ (c) 2010 bflm, contact: befelemepeseveze at Google's free mail

  Free sample code - copy, use, modify, distribute, sell, release under other license, ...

}

{$mode objfpc}{$H+}

interface

type

  { TEnumerator }

  generic TEnumerator<TValue, TIterator> = object
  public type
    TGetCurrent = function(const Iterator: TIterator): TValue of object;
    TMoveNext = function(var Iterator: TIterator): Boolean of object;
  private var
    FGetCurrent: TGetCurrent;
    FMoveNext: TMoveNext;
    FIterator: TIterator;
    function GetCurrent: TValue;
  public
    procedure Init(const InitialIterator: TIterator; const Mover: TMoveNext; const Getter: TGetCurrent);
    function MoveNext: Boolean;
    property Current: TValue read GetCurrent;
  end;

  { TVector }

  generic TVector<T> = object
  public type
    TData = array of T;
    TCompare = function(const A, B: T): Integer;
    TVectorEnumerator = specialize TEnumerator<T, Integer>;
  private var
    FData: TData;
    FLen: Integer;
  private
    function GetCap: Integer;
    function GetData: TData;
    function GetItems(const Index: Integer): T; inline;
    function GetLen: Integer; inline;
    function MoveNext(var Index: Integer): Boolean;
    procedure Sort(Left, Right: Integer; const Compare: TCompare);
    procedure SetCap(const AValue: Integer);
    procedure SetData(const AValue: TData);
    procedure SetItems(const Index: Integer; const AValue: T); inline;
    procedure SetLen(const AValue: Integer);
  public
    function GetEnumerator: TVectorEnumerator;
    function Add(const Value: T): Integer;
    procedure Clear;
    procedure Pack;
    procedure Sort(const Compare: TCompare);
    property Cap: Integer read GetCap write SetCap;
    property Data: TData read GetData write SetData;
    property Items[const Index: Integer]: T read GetItems write SetItems; default;
    property Len: Integer read GetLen write SetLen;
  end;

implementation

{ TEnumerator }

function TEnumerator.GetCurrent: TValue;
begin
  Result := FGetCurrent(FIterator);
end;

function TEnumerator.MoveNext: Boolean;
begin
  Result := FMoveNext(FIterator);
end;

procedure TEnumerator.Init(const InitialIterator: TIterator; const Mover: TMoveNext; const Getter: TGetCurrent);
begin
  Assert(Assigned(Mover));
  Assert(Assigned(Getter));
  FIterator := InitialIterator;
  FMoveNext := Mover;
  FGetCurrent := Getter;
end;

{ TVector }

function TVector.Add(const Value: T): Integer;
var NeedCap: Integer;
begin
  NeedCap := Len + 1;
  if NeedCap > Cap then
    Cap := 2 * NeedCap;
  Result := FLen;
  Inc(FLen);
  Items[Result] := Value;
end;

procedure TVector.Clear;
begin
  Cap := 0;
end;

function TVector.GetItems(const Index: Integer): T;
begin
  Result := FData[Index];
end;

function TVector.GetCap: Integer;
begin
  Result := Length(FData);
end;

function TVector.GetData: TData;
begin
  Result := Copy(FData, 0, Len);
end;

function TVector.GetEnumerator: TVectorEnumerator;
begin
  Result.Init(-1, @MoveNext, @GetItems);
end;

function TVector.GetLen: Integer;
begin
  if FData = nil then
    FLen := 0; // boot
  Result := FLen;
end;

function TVector.MoveNext(var Index: Integer): Boolean;
begin
  Result := Index + 1 < Len;
  if Result then
    Inc(Index);
end;

procedure TVector.SetCap(const AValue: Integer);
begin
  if AValue = Cap then
    Exit;
  if Len > AValue then
    FLen := AValue;
  SetLength(FData, AValue);
end;

procedure TVector.SetData(const AValue: TData);
begin
  FData := AValue;
  FLen := Cap;
end;

procedure TVector.SetItems(const Index: Integer; const AValue: T);
begin
  FData[Index] := AValue;
end;

procedure TVector.SetLen(const AValue: Integer);
begin
  if AValue = Len then
    Exit;
  if AValue > Cap then
    Cap := AValue
  else if AValue <= Cap div 2 then
    Cap := Cap div 2;
  FLen := AValue;
end;

procedure TVector.Sort(Left, Right: Integer; const Compare: TCompare);
var
  L, R: Integer;
  Pivot, Swap: T;
begin
 repeat
   L := Left;
   R := Right;
   Pivot := Items[(Left + Right) div 2];
   repeat
     while Compare(Pivot, Items[L]) > 0 do
       L += 1;
     while Compare(Pivot, Items[R]) < 0 do
       R -= 1;
     if L <= R then begin
       Swap := Items[L];
       Items[L] := Items[R];
       Items[R] := Swap;
       L += 1;
       R -= 1;
     end;
   until L > R;
   if Left < R then
     Sort(Left, R, Compare);
   Left := L;
 until L >= Right;
end;

procedure TVector.Pack;
begin
  Cap := Len;
end;

procedure TVector.Sort(const Compare: TCompare);
begin
  if Len > 1 then
    Sort(0, FLen - 1, Compare);
end;

end.

program project1;

{$mode objfpc}{$H+}

uses Unit1;

type
  TIntVector = specialize TVector<Integer>;

function IntCmp(const A, B: Integer): Integer;
begin
  Result := A - B;
end;

procedure Dump(const Vector: TIntVector);
var V: Integer;
begin
  Write(Vector.Len, ' item(s): ');
  for V in Vector do
    Write(V, ' ');
  Writeln;
end;

procedure Test(const N, X: Integer);
var
  Vector: TIntVector;
  I: Integer;
begin
  for I := 1 to N do
    Vector.Add(I xor X);
  Dump(Vector);
  Vector.Sort(@IntCmp);
  Dump(Vector);
  WriteLn;
end;

begin // main
  {$if declared(HaltOnNotReleased)}
  HaltOnNotReleased := True;
  {$endif}
  Test(0, 0);
  Test(1, 0);
  Test(11, 0);
  Test(13, $55);
  Test(17, $AA);
  Test(19, $FF);
end.

$ fpc -B -gh project1 && ./project1 
Free Pascal Compiler version 2.5.1 [2010/05/05] for x86_64
Copyright (c) 1993-2009 by Florian Klaempfl
Target OS: Linux for x86-64
Compiling project1.pas
Compiling unit1.pas
Linking project1
/usr/bin/ld: warning: link.res contains output sections; did you forget -T?
259 lines compiled, 0.1 sec 
0 item(s): 
0 item(s): 

1 item(s): 1 
1 item(s): 1 

11 item(s): 1 2 3 4 5 6 7 8 9 10 11 
11 item(s): 1 2 3 4 5 6 7 8 9 10 11 

13 item(s): 84 87 86 81 80 83 82 93 92 95 94 89 88 
13 item(s): 80 81 82 83 84 86 87 88 89 92 93 94 95 

17 item(s): 171 168 169 174 175 172 173 162 163 160 161 166 167 164 165 186 187 
17 item(s): 160 161 162 163 164 165 166 167 168 169 171 172 173 174 175 186 187 

19 item(s): 254 253 252 251 250 249 248 247 246 245 244 243 242 241 240 239 238 237 236 
19 item(s): 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 

Heap dump by heaptrc unit
11 memory blocks allocated : 840/840
11 memory blocks freed     : 840/840
0 unfreed memory blocks : 0
True heap size : 98304
True free heap : 98304
$

Wednesday, May 5, 2010

Unicode Category Membership Checking

Submitted a feature proposal on Mantis. Reviews are welcome.

Wednesday, February 10, 2010

String Buffer Performance

Benchmarks for the yesterday's post.

 
program project1;
 
{$mode objfpc}{$H+}
 
uses
  Classes, DateUtils, SysUtils, StrBuf;
 
type
  TBench = procedure(const PartSize, MaxSize: Integer);
 
procedure BuildString(const PartSize, MaxSize: Integer);
var
  Buf: String;
  BufSize: Integer;
begin
  Buf := '';
  BufSize := 0;
  while BufSize < MaxSize do begin
    Buf += StringOfChar(' ', PartSize);
    BufSize += PartSize;
  end;
end;
 
procedure BuildStringList(const PartSize, MaxSize: Integer);
var
  Buf: TStringList;
  BufSize: Integer;
begin
  Buf := TStringList.Create;
  BufSize := 0;
  while BufSize < MaxSize do begin
    Buf.Add(StringOfChar(' ', PartSize));
    BufSize += PartSize;
  end;
  Buf.Free;
end;
 
procedure BuildStrBuf(const PartSize, MaxSize: Integer);
var
  Buf: TStrBuf;
  BufSize: Integer;
begin
  BufSize := 0;
  while BufSize < MaxSize do begin
    Buf.W(StringOfChar(' ', PartSize));
    BufSize += PartSize;
  end;
end;
 
procedure Build(const PartSize, MaxSize: Integer; Bench: TBench; const Name: String);
const RUN = 5;
var
  T0: TDateTime;
  Msec: Int64;
  I: Integer;
begin
  T0 := Now;
  for I := 1 to RUN do
    Bench(PartSize, MaxSize);
  MSec := MilliSecondsBetween(Now, T0);
  Writeln(Format('partsize: %.5d T: %.7dms %s ', [PartSize, MSec, Name]));
end;
 
const
  UBOUND_PART = 100;
  UBOUND_BUF = 1000000;
var
  PartSize: Integer;
begin
  PartSize := 1;
  repeat
    Build(PartSize, UBOUND_BUF, @BuildString, 'String');
    Build(PartSize, UBOUND_BUF, @BuildStringList, 'StringList');
    Build(PartSize, UBOUND_BUF, @BuildStrBuf, 'StrBuf');
    PartSize := ((3 * PartSize) + 1) div 2;
  until PartSize > UBOUND_PART;
end.

$ fpc -B ./project1 && ./project1 | sort
Free Pascal Compiler version 2.5.1 [2010/02/07] for x86_64
Copyright (c) 1993-2009 by Florian Klaempfl
Target OS: Linux for x86-64
Compiling ./project1.pas
Compiling strbuf.pas
Linking project1
/usr/bin/ld: warning: link.res contains output sections; did you forget -T?
189 lines compiled, 0.2 sec 
partsize: 00001 T: 0000446ms StrBuf 
partsize: 00001 T: 0000602ms String 
partsize: 00001 T: 0001150ms StringList 
partsize: 00002 T: 0000233ms StrBuf 
partsize: 00002 T: 0000261ms String 
partsize: 00002 T: 0000534ms StringList 
partsize: 00003 T: 0000159ms StrBuf 
partsize: 00003 T: 0000190ms String 
partsize: 00003 T: 0000379ms StringList 
partsize: 00005 T: 0000101ms StrBuf 
partsize: 00005 T: 0000127ms String 
partsize: 00005 T: 0000211ms StringList 
partsize: 00008 T: 0000076ms StrBuf 
partsize: 00008 T: 0000086ms String 
partsize: 00008 T: 0000167ms StringList 
partsize: 00012 T: 0000050ms StrBuf 
partsize: 00012 T: 0000060ms String 
partsize: 00012 T: 0000100ms StringList 
partsize: 00018 T: 0000038ms StrBuf 
partsize: 00018 T: 0000043ms String 
partsize: 00018 T: 0000069ms StringList 
partsize: 00027 T: 0000030ms StrBuf 
partsize: 00027 T: 0000033ms String 
partsize: 00027 T: 0000045ms StringList 
partsize: 00041 T: 0000023ms String 
partsize: 00041 T: 0000024ms StrBuf 
partsize: 00041 T: 0000034ms StringList 
partsize: 00062 T: 0000015ms StrBuf 
partsize: 00062 T: 0000020ms String 
partsize: 00062 T: 0000020ms StringList 
partsize: 00093 T: 0000014ms String 
partsize: 00093 T: 0000015ms StringList 
partsize: 00093 T: 0000017ms StrBuf 
$

StrBuf's performance looks good or better compared to TStringList and/or String concatenating while you're appending short pieces of text, say up to few dozens of characters and that's what it was intended and written for.

Tuesday, February 9, 2010

Simple String Buffer

 
unit StrBuf;
 
{$mode objfpc}{$H+}
 
{ Simple string buffer
 
  No setup/teardown required, memory mngmt, initialization, and finalization
  is done by FPC itself.
 
  Copyright (C) 2010 bflm, contact: befelemepeseveze at Google's free mail
 
  This library is free software; you can redistribute it and/or modify it
  under the terms of the GNU Library General Public License as published by
  the Free Software Foundation; either version 2 of the License, or (at your
  option) any later version with the following modification:
 
  As a special exception, the copyright holders of this library give you
  permission to link this library with independent modules to produce an
  executable, regardless of the license terms of these independent modules,and
  to copy and distribute the resulting executable under terms of your choice,
  provided that you also meet, for each linked independent module, the terms
  and conditions of the license of that module. An independent module is a
  module which is not derived from or based on this library. If you modify
  this library, you may extend this exception to your version of the library,
  but you are not obligated to do so. If you do not wish to do so, delete this
  exception statement from your version.
 
  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. See the GNU Library General Public License
  for more details.
 
  You should have received a copy of the GNU Library General Public License
  along with this library; if not, write to the Free Software Foundation,
  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
}
 
interface
 
uses
  SysUtils;
 
type
 
  { TStrBuf }
 
  TStrBuf = object
  private
    FLen: Integer;
    FS: String;
    function GetS: String;
  public
    procedure W(const S: String);
    procedure W(const Fmt: String; Args: array of const);
    property S: String read GetS;
  end;
 
operator +(var Buf: TStrBuf; const S: String): TStrBuf;
operator :=(const S: String): TStrBuf;
operator :=(var Buf: TStrBuf): String;
 
implementation
 
{ TStrBuf }
 
function TStrBuf.GetS: String;
begin
  if FS = '' then
    FLen := 0;
  Result := LeftStr(FS, FLen);
end;
 
procedure TStrBuf.W(const S: String);
var Len, Len1: Integer;
begin
  Len := Length(S);
  if Len = 0 then
    Exit;
  if FS = '' then
    FLen := 0;
  Len1 := FLen + Len;
  if Len1 > Length(FS) then
    SetLength(FS, 2 * Len1);
  Move(S[1], FS[FLen + 1], Len);
  FLen += Len;
end;
 
procedure TStrBuf.W(const Fmt: String; Args: array of const);
begin
  W(Format(Fmt, Args));
end;
 
operator +(var Buf: TStrBuf; const S: String): TStrBuf;
begin
  Result.FS := Buf.FS;
  Result.FLen := Buf.FLen;
  Result.W(S);
end;
 
operator :=(const S: String): TStrBuf;
begin
  Result.FLen := Length(S);
  Result.FS := S;
end;
 
operator :=(var Buf: TStrBuf): String;
begin
  Result := Buf.S;
end;
 
end.

 
program project1;
 
{$mode objfpc}{$H+}
 
// Simple string buffer example
 
uses
  heaptrc, StrBuf;
 
function F(N: Integer): String;
var
  Buf: TStrBuf;
  I: Integer;
begin
  for I := 1 to N do
    Buf.W('line %d%s', [I, sLineBreak]);
  Result := Buf.S;
end;
 
var
  Buf, Buf2: TStrBuf;
 
begin
  Buf.W('abc');
  Buf.W('%d', [123]);
  Buf += 'xyz';
  Writeln(Buf.S);
  Writeln(String(Buf));
  Buf := '456';
  Writeln(Buf.S);
  Buf2 := Buf + ' bar';
  Buf += ' foo';
  Writeln(Buf.S);
  Writeln(Buf2.S);
  Write(F(10));
end.

$ fpc -B project1.pas && ./project1 
Free Pascal Compiler version 2.5.1 [2010/02/07] for x86_64
Copyright (c) 1993-2009 by Florian Klaempfl
Target OS: Linux for x86-64
Compiling project1.pas
Compiling strbuf.pas
Linking project1
/usr/bin/ld: warning: link.res contains output sections; did you forget -T?
148 lines compiled, 0.2 sec 
abc123xyz
abc123xyz
456
456 foo
456 bar
line 1
line 2
line 3
line 4
line 5
line 6
line 7
line 8
line 9
line 10
Heap dump by heaptrc unit
71 memory blocks allocated : 2926/3200
71 memory blocks freed     : 2926/3200
0 unfreed memory blocks : 0
True heap size : 360448
True free heap : 360448
$

Thursday, November 5, 2009

Multicore Compiler Make

Tested today Jonas Maebe's multicore FPC build tip from the Recompiling new changes thread at the Free Pascal Community.

$ time ( cd ~/svn/fpc/trunk && make clean && make all OPT="-gl" && make install INSTALL_PREFIX=~ )
...
real 3m15.641s
user 2m16.350s
sys  0m28.710s
$ 

# vs

$ time ( cd ~/svn/fpc/trunk && make -j 2 clean && make -j 2 all OPT="-gl" && make -j 2 install INSTALL_PREFIX=~ )
...
real 2m44.049s
user 2m18.530s
sys  0m27.990s
$

Both runs were "hot cache" on a dual core PC.

Free Pascal Random Bits

Tuesday, August 17, 2010

Introducing heLib

Thursday, May 20, 2010

Sampler: GDBM OO wrapper

Monday, May 10, 2010

Sampler: Generic enumerators for generic containers

Wednesday, May 5, 2010

Unicode Category Membership Checking

Wednesday, February 10, 2010

String Buffer Performance

Tuesday, February 9, 2010

Simple String Buffer

Thursday, November 5, 2009

Multicore Compiler Make

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