unit AG.PascalTokenizer;

interface

uses
  {$IFDEF FPC}fgl,SysUtils,Classes{$ELSE}System.Generics.Collections,System.SysUtils,System.Classes{$ENDIF};

{$IFDEF FPC}
  {$mode Delphi}
{$ENDIF}

type
  {$IFDEF FPC}TFpcList=specialize TFPGList<String>;{$ENDIF}

  TAGTokenizerPos = record
    x, y: integer;
  end;

  TAGToken = record
    Text: string;
    &begin, &end: TAGTokenizerPos;
    ended: boolean;
    {$IFNDEF FPC}constructor Create(Text: string; &begin, &end: TAGTokenizerPos;ended:boolean);{$ENDIF}
  end;

  TAGPasTokenizer = class
  strict protected
    s: TStrings;
    y: integer;
    x: integer;
    function DoReadable():boolean;
    function IsReadable():boolean;
    function NextReadable():boolean;
    procedure SkipSpaces();
    function GetPos():TAGTokenizerPos;
    procedure SetPos(pos:TAGTokenizerPos);
  public
    ended: boolean;
    function GetNext(): TAGToken;
    // procedure read_next();
    constructor Create(input:TStrings);
    property Pos:TAGTokenizerPos read GetPos write SetPos;
  end;

  {PasTokenizerStack = class
  private
    stack: TStack<integer>;
    // _pop
    procedure _get_with_comments();
    procedure _get_without_comments();
  public
    procedure push(s: string);
    procedure pop();
    procedure read_last();
    procedure is_ended();
  end;}

function IsComment(s: string): boolean;
function IsName(s: string): boolean;
function IsString(s: string): boolean;

implementation

{$IFNDEF FPC}
constructor TAGToken.Create(Text: string; &begin, &end: TAGTokenizerPos;
  ended: boolean);
begin
  Self.Text := Text;
  Self.&begin := &begin;
  Self.&end := &end;
  Self.ended := ended;
end;
{$ENDIF}

const
  SYMS1 = '()[]/|\@#=><:;,.$+-*^';
  SPACES = #12#10#13#9#11' ';
  NO_NAME_SYMS = SYMS1 + SPACES + '{}';
  CHARS_ID0 = '&abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_';
  CHARS_ID = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_';
  fix = {$IFDEF NEXTGEN}-1{$ELSE}0{$ENDIF};

var
  SYMS2:{$IFDEF FPC}TFpcList{$ELSE}TList<string>{$ENDIF}; // array[0..8]of string=();

function IsComment(s:string):boolean;
begin
  Result:=(s.startswith('{') or s.startswith('(*') or s.startswith('//'));
end;

function IsName(s:string):boolean;
var
  i: integer;
begin
  if length(s) <= 0 then
    Exit(False);
  if s = '&' then
    Exit(False);
  if not CHARS_ID0.Contains(s[1 + fix]) then
    Exit(False);
  for i := 1 to length(s) do
  begin
    if not CHARS_ID.Contains(s[i]) then
      Exit(False);
  end;
  Result:=True;
end;

function IsString(s: string):boolean;
begin
  Result:=s.StartsWith(#39);
end;

function TAGPasTokenizer.DoReadable(): boolean;
begin
  if not IsReadable() then
  begin
    if (y + 1 = s.Count) then
      ended := True
    else
    begin
      inc(y);
      x := 1+Fix;
      while s[y]='' do
      begin
	if y + 1 = s.Count then
	begin
	  ended := True;
	  break;
	end;
	inc(y);
      end;
    end;
    Exit(True);
  end
  else
    Exit(False);
end;

function TAGPasTokenizer.IsReadable(): boolean;
begin
  Exit(length(s[y])+1+Fix > x);
end;

function TAGPasTokenizer.NextReadable(): boolean;
begin
  inc(x);
  Result := DoReadable();
end;

procedure TAGPasTokenizer.SkipSpaces();
begin
  DoReadable();
  if not ended then
  begin
    while SPACES.Contains(s[y][x]) do
      NextReadable();
  end;
end;

function TAGPasTokenizer.GetPos(): TAGTokenizerPos;
begin
  Result.x := x;
  Result.y := y;
end;

procedure TAGPasTokenizer.SetPos(pos:TAGTokenizerPos);
begin
  y:=Pos.x;
  x:=Pos.y;
  ended:=False;
  DoReadable();
end;

function TAGPasTokenizer.GetNext(): TAGToken;
var
  l,i,last_i0:integer;
  ml,ss,line:string;
  now_sym,next_sym:char;
  f{$IFDEF FPC},ff{$ENDIF}:boolean;
  begin_pos:TAGTokenizerPos;
begin
  ml := '';
  ss := '';
  f := True;
  begin_pos := GetPos();
  while f and not ended do
  begin
    line := s[y];
    now_sym := line[x];
    l := length(line);
    if x<>l+Fix then
      next_sym := line[x + 1]
    else
      next_sym := #0;
    if ml='' then
    begin
      if now_sym = '/' then
      begin
	if next_sym = '/' then
	begin
	  for i:=x to l+Fix do
	    ss:=ss+line[i];
	  x := l+Fix;
	  break;
	end;
      end
      else if now_sym = '{' then
      begin
	ml := '}';
	ss := now_sym;
	last_i0 := y;
      end
      else if now_sym = '(' then
      begin
	if next_sym = '*' then
	begin
	  ml := ')';
	  inc(x);
	  last_i0 := y;
	  ss := now_sym + next_sym;
	end
	else
	begin
	  ss := '(';
	  inc(x);
	  break;
	end;
      end
      else
      begin
	if SYMS1.Contains(now_sym) then
	begin
	  ss := now_sym;
	  inc(x);
          {$IFDEF FPC}
          ff:=false;
          for i:=0 to SYMS2.Count-1 do
            if SYMS2[i]=now_sym+next_sym then
            begin
              ff:=true;
              break;
            end;
          if ff then
          {$ELSE}
	  if SYMS2.Contains(now_sym+next_sym) then
          {$ENDIF}
	  begin
	    inc(x);
	    ss := ss + next_sym;
	  end;
	  break;
	end
	else if now_sym = #39 then
	begin
	  ss := #39;
	  inc(x);
	  if next_sym <> '' then
	  begin
	    ss := ss + next_sym;
	    while line[x] <> #39 do
	    begin
	      inc(x);
	      if not IsReadable() then
	      begin
		dec(x);
		break;
	      end;
	      ss := ss + line[x];
	    end;
	    inc(x);
	  end;
	  break;
	end
	else
	begin
	  while not NO_NAME_SYMS.Contains(line[x]) do
	  begin
	    ss := ss + line[x];
	    inc(x);
	    if not IsReadable() then
	      break;
	  end;
	  break;
	end;
      end;
    end
    else
    begin
      while last_i0 <> y do
      begin
	ss := ss + #10;
	inc(last_i0);
      end;
      ss:=ss+now_sym;
      if now_sym = ml then
	if ml = '}' then
	begin
	  inc(x);
	  break;
	end
	else if (x <> 0) and (line[x - 1] = '*') then
	begin
	  inc(x);
	  break;
	end;
    end;
    NextReadable();
  end;
  {$IFDEF FPC}
  Result.Text:=ss;
  Result.&begin:=begin_pos;
  Result.&end:=GetPos;
  Result.ended:=ended;
  {$ELSE}
  Result := TAGToken.Create(ss, begin_pos, GetPos, ended);
  {$ENDIF}
  SkipSpaces;
end;

constructor TAGPasTokenizer.Create(input:TStrings);
begin
  s:=input;
  y:=0;
  x:=1+fix;
  ended:=False;
  SkipSpaces;
end;

initialization
SYMS2 := {$IFDEF FPC}TFpcList{$ELSE}TList<string>{$ENDIF}.Create();
SYMS2.Add('>=');
SYMS2.Add('<=');
SYMS2.Add('<>');
SYMS2.Add(':=');
SYMS2.Add('..');
SYMS2.Add('-=');
SYMS2.Add('+=');
SYMS2.Add('/=');
SYMS2.Add('*=');
SYMS2.Add('**');
SYMS2.Add('><');
SYMS2.Add('(.');
SYMS2.Add('.)');
SYMS2.Add('<<');
SYMS2.Add('>>');
end.