String Encoding Standards

unit StringEncoding;

interface

type
  TEncodingRule = record
    Original: String;
    Replace: String;
  end;

  TEncodingRules = array of TEncodingRule;

function Encode(const S: String): String;
function Decode(const S: String): String;

implementation

var
  _EncodingRules: TEncodingRules;

function Encode(const S: String): String;
var
  X, Y: Integer;
  R: TEncodingRule;
  T: String;
begin
  Result:= S;
  for X := Length(Result) downto 1 do begin
    for Y := 0 to Length(_EncodingRules) - 1 do begin
      R:= _EncodingRules[Y];
      T:= Copy(Result, X, Length(R.Original));
      if T = R.Original then begin
        Delete(Result, X, Length(R.Original));
        Insert(R.Replace, Result, X);
      end;
    end;
  end;
end;

function Decode(const S: String): String;
var
  X, Y: Integer;
  R: TEncodingRule;
  T: String;
begin
  Result:= S;
  for X := Length(Result) downto 1 do begin
    for Y := Length(_EncodingRules) - 1 downto 0 do begin
      R:= _EncodingRules[Y];
      T:= Copy(Result, X, Length(R.Replace));
      if T = R.Replace then begin
        Delete(Result, X, Length(R.Replace));
        Insert(R.Original, Result, X);
      end;
    end;
  end;
end;

procedure InitEncodingRules;
  procedure A(const Orig, Repl: String);
  begin
    SetLength(_EncodingRules, Length(_EncodingRules) + 1);
    _EncodingRules[Length(_EncodingRules)-1].Original:= Orig;
    _EncodingRules[Length(_EncodingRules)-1].Replace:= Repl;
  end;
begin
  A('_', '_UND_');
  A('%', '_PER_');
  A('&', '_AMP_');
  A(' ', '_SPC_');
  A('=', '_EQU_');
  A('/', '_FSL_');
  A('\', '_BSL_');
  A('(', '_OPR_');
  A(')', '_CPR_');
end;

procedure UninitEncodingRules;
begin
  SetLength(_EncodingRules, 0);
end;

initialization
  InitEncodingRules;
finalization
  UninitEncodingRules;
end.