------------------------------------------------------------------
--| File:	Calculator.Ada
--| Comments:	Main routine
--| Author:	Eugene Giuliano
------------------------------------------------------------------
with TEXT_IO;
 
with CAL_TEXT_IO;
with CAL_FUNCTIONS;
 
procedure CALCULATOR is
 
  FIRST_NUMBER  : CAL_FUNCTIONS.VALUE_TYPE := 0;
  SECOND_NUMBER : CAL_FUNCTIONS.VALUE_TYPE := 0;
  RESULT        : CAL_FUNCTIONS.VALUE_TYPE := 0;
  OPERATION     : CHARACTER                := '+';
  REPEAT        : BOOLEAN                  := TRUE;
 
begin    -- Calculator
 
  while REPEAT loop
 
    CAL_FUNCTIONS.GET_NUMBER("first", FIRST_NUMBER);
    CAL_FUNCTIONS.GET_OPERATOR(OPERATION);
    CAL_FUNCTIONS.GET_NUMBER("second", SECOND_NUMBER);
 
    CAL_FUNCTIONS.PERFORM_OPERATION(FIRST_NUMBER, SECOND_NUMBER,
     OPERATION, RESULT);
    TEXT_IO.PUT(ITEM => "Result = ");
    CAL_TEXT_IO.DATA_IO.PUT(ITEM => RESULT);
    TEXT_IO.NEW_LINE;
 
    CAL_FUNCTIONS.PROMPT_AGAIN(REPEAT);
 
  end loop;
 
end CALCULATOR;
------------------------------------------------------------------
--| File:	Cal_Functions_.Ada
--| Comments:	Specification file - DEC convention,
--|		use .ads for gnat compiler
--| Author:	Eugene Giuliano
------------------------------------------------------------------
package CAL_FUNCTIONS is
 
  type VALUE_TYPE is range -32768 .. 32767;
 
  procedure GET_OPERATOR(OPERATOR : out CHARACTER);
 
  procedure PROMPT_AGAIN(RESPONSE : out BOOLEAN);
 
  procedure GET_NUMBER(WORD : in STRING; DIGIT : out VALUE_TYPE);
 
  procedure PERFORM_OPERATION(FIRST_DIGIT  : in VALUE_TYPE;
                              SECOND_DIGIT : in VALUE_TYPE;
                              OPERATION    : in CHARACTER;
                              RESULT       : out VALUE_TYPE);
 
end CAL_FUNCTIONS;
------------------------------------------------------------------
--| File:	Cal_Functions.Ada
--| Comments:	Package body
--| Author:	Eugene Giuliano
------------------------------------------------------------------
package body CAL_FUNCTIONS is
 
  procedure GET_OPERATOR(OPERATOR : out CHARACTER) is separate;
 
  procedure PROMPT_AGAIN(RESPONSE : out BOOLEAN) is separate;
 
  procedure GET_NUMBER(WORD  : in STRING;
                       DIGIT : out VALUE_TYPE) is separate;
 
  procedure PERFORM_OPERATION(FIRST_DIGIT  : in VALUE_TYPE;
                              SECOND_DIGIT : in VALUE_TYPE;
                              OPERATION    : in CHARACTER;
                              RESULT       : out VALUE_TYPE) is separate;
 
end CAL_FUNCTIONS;
------------------------------------------------------------------
--| File:	Cal_Text_IO_.Ada
--| Comments:	Package spec (DEC convention) use .abs for gnat
--| Author:	Eugene Giuliano
------------------------------------------------------------------
with TEXT_IO;
with CAL_FUNCTIONS;
 
package CAL_TEXT_IO is
 
  package DATA_IO is new TEXT_IO.INTEGER_IO(CAL_FUNCTIONS.VALUE_TYPE);
 
end CAL_TEXT_IO;
------------------------------------------------------------------
--| File:	Get_Operator_.Ada
--| Comments:	Generic speicifier (DEC Convention)
--| Author:	Eugene Giuliano
------------------------------------------------------------------
generic
  type INPUT_VALUE is range <>;
 
procedure GET_NUMBER(WORD : in STRING; DIGIT : out INPUT_VALUE);
------------------------------------------------------------------
--| File:	Get_Number.Ada
--| Comments:	-
--| Author:	Eugene Giuliano
------------------------------------------------------------------
with TEXT_IO;
with CAL_TEXT_IO;
 
separate(CAL_FUNCTIONS)
 
procedure GET_NUMBER(WORD : in STRING; DIGIT : out VALUE_TYPE) is
 
  TEMP : VALUE_TYPE;
 
begin    -- Get_First_Digit
 
  loop
    begin
      TEXT_IO.PUT(ITEM => "Enter the ");
      TEXT_IO.PUT(ITEM => WORD);
      TEXT_IO.PUT(ITEM => " number: ");
      CAL_TEXT_IO.DATA_IO.GET(ITEM => TEMP);
      DIGIT := TEMP;
 
      exit;
 
    exception
      when CONSTRAINT_ERROR =>
        TEXT_IO.PUT("Value entered is out of range. Please try again.");
        TEXT_IO.NEW_LINE;
      when TEXT_IO.DATA_ERROR =>
        TEXT_IO.PUT("Value entered is not an integer. Please try again.");
        TEXT_IO.NEW_LINE;
        TEXT_IO.SKIP_LINE;
    end;
  end loop;
 
end GET_NUMBER;
------------------------------------------------------------------
--| File:	Get_Operator.Ada
--| Comments:	-
--| Author:	Eugene Giuliano
------------------------------------------------------------------
with TEXT_IO;
 
separate(CAL_FUNCTIONS)
 
procedure GET_OPERATOR(OPERATOR : out CHARACTER) is
 
  TEMP        : CHARACTER;
  RESPONSE_OK : BOOLEAN := FALSE;
 
begin    -- Get_Operator
 
  while not RESPONSE_OK loop
 
    TEXT_IO.PUT(ITEM => "Enter the operator [+,-,*,/]: ");
    TEXT_IO.GET(ITEM => TEMP);
 
    case TEMP is
      when '+' | '-' | '*' | '/' =>
        OPERATOR := TEMP;
        RESPONSE_OK := TRUE;
 
      when others =>
        TEXT_IO.PUT("Unrecognized operator. Please try again.");
        TEXT_IO.NEW_LINE;
    end case;
  end loop;
 
end GET_OPERATOR;
------------------------------------------------------------------
--| File:	Perform_Operation.Ada
--| Comments:	-
--| Author:	Eugene Giuliano
------------------------------------------------------------------
with TEXT_IO;
 
separate(CAL_FUNCTIONS)
 
procedure PERFORM_OPERATION(FIRST_DIGIT  : in CAL_FUNCTIONS.VALUE_TYPE;
                            SECOND_DIGIT : in CAL_FUNCTIONS.VALUE_TYPE;
                            OPERATION    : in CHARACTER;
                            RESULT       : out CAL_FUNCTIONS.VALUE_TYPE) is
 
begin    -- Perform_Operation
 
  case OPERATION is
    when '+' =>
      RESULT := FIRST_DIGIT + SECOND_DIGIT;
 
    when '-' =>
      RESULT := FIRST_DIGIT - SECOND_DIGIT;
 
    when '*' =>
      RESULT := FIRST_DIGIT * SECOND_DIGIT;
 
    when '/' =>
      RESULT := FIRST_DIGIT / SECOND_DIGIT;
 
    when others =>
      RESULT := 0;
      TEXT_IO.PUT("Unrecognized operator. Please try again.");
      TEXT_IO.NEW_LINE;
 
  end case;
  
 
exception
  when CONSTRAINT_ERROR =>
    RESULT := 0;
    TEXT_IO.PUT("Value generated is out of range. Result set to zero.");
    TEXT_IO.NEW_LINE;
  when TEXT_IO.DATA_ERROR =>
    TEXT_IO.PUT("Value entered is not an integer. Please try again.");
    TEXT_IO.NEW_LINE;
    TEXT_IO.SKIP_LINE;
 
end PERFORM_OPERATION;
------------------------------------------------------------------
--| File:	Prompt_Again.Ada
--| Comments:	-
--| Author:	Eugene Giuliano
------------------------------------------------------------------
with TEXT_IO;
 
separate(CAL_FUNCTIONS)
 
procedure PROMPT_AGAIN(RESPONSE : out BOOLEAN) is
 
  TEMP        : CHARACTER;
  RESPONSE_OK : BOOLEAN := FALSE;
 
begin    -- Prompt_Again
 
  while not RESPONSE_OK loop
 
    TEXT_IO.PUT(ITEM => "Perform Another Calculation [Y/N]? ");
    TEXT_IO.GET(ITEM => TEMP);
 
    case TEMP is
      when 'y' | 'Y' =>
        RESPONSE := TRUE;
        RESPONSE_OK := TRUE;
 
      when 'n' | 'N' =>
        RESPONSE := FALSE;
        RESPONSE_OK := TRUE;
 
      when others =>
        TEXT_IO.PUT("Enter only a 'Y' or 'N'. Please try again.");
        TEXT_IO.NEW_LINE;
    end case;
  end loop;
 
end PROMPT_AGAIN;