Task: Roman numerals_Decode




Go: package main

import (
    "errors"
    "fmt"
)

var m = map[rune]int{
    'I': 1,
    'V': 5,
    'X': 10,
    'L': 50,
    'C': 100,
    'D': 500,
    'M': 1000,
}

func parseRoman(s string) (r int, err error) {
    if s == "" {
        return 0, errors.New("Empty string")
    }
    is := []rune(s) 
    var c0 rune     
    var cv0 int     

    
    for i := len(is) - 1; i >= 0; i-- {
        
        c := is[i]
        k := c == '\u0305' 
        if k {
            if i == 0 {
                return 0, errors.New(
                    "Overbar combining character invalid at position 0")
            }
            i--
            c = is[i]
        }
        cv := m[c]
        if cv == 0 {
            if c == 0x0305 {
                return 0, fmt.Errorf(
                    "Overbar combining character invalid at position %d", i)
            } else {
                return 0, fmt.Errorf(
                    "Character unrecognized as Roman digit: %c", c)
            }
        }
        if k {
            c = -c 
            cv *= 1000
        }

        
        switch {
        default: 
            fallthrough
        case c0 == 0: 
            c0 = c
            cv0 = cv
        case c == c0: 
        case cv*5 == cv0 || cv*10 == cv0: 
            
            
            c0 = 0
            r -= cv  
            continue 
        }
        r += cv 
    }
    return r, nil
}

func main() {
    
    for _, r := range []string{"MCMXC", "MMVIII", "MDCLXVI"} {
        v, err := parseRoman(r)
        if err != nil {
            fmt.Println(err)
        } else {
            fmt.Println(r, "==", v)
        }
    }
}








Ada: Pragma Ada_2012;
Pragma Assertion_Policy( Check );

With
Unchecked_Conversion,
Ada.Text_IO;

Procedure Test_Roman_Numerals is

    
    
    
    Type Roman_Digits is ('I', 'V', 'X', 'L', 'C', 'D', 'M' )
    with Size => Integer'Size;

    
    
    For Roman_Digits use
      (
    'I' => 1,
    'V' => 5,
    'X' => 10,
    'L' => 50,
    'C' => 100,
    'D' => 500,
    'M' => 1000
      );

    
    
    Function Convert is new Unchecked_Conversion
      (	Source => Roman_Digits,	Target => Integer );

    
    Type Roman_Numeral is array (Positive range <>) of Roman_Digits;

    
    
    Type Numeral_List is array (Positive range <>) of
      not null access Roman_Numeral;

    
    
    
    
    
    

    subtype Test_Cases is Positive range 1..14;

    Test_Data : constant Numeral_List(Test_Cases):=
      (
       New Roman_Numeral'("III"),	
       New Roman_Numeral'("XXX"),	
       New Roman_Numeral'("CCC"),	
       New Roman_Numeral'("MMM"),	

       New Roman_Numeral'("VII"),	
       New Roman_Numeral'("LXVI"),	
       New Roman_Numeral'("CL"),	
       New Roman_Numeral'("MCC"),	

       New Roman_Numeral'("IV"),	
       New Roman_Numeral'("IX"),	
       New Roman_Numeral'("XC"),	

       New Roman_Numeral'("ICM"),	
       New Roman_Numeral'("CIM"),	
       
       New Roman_Numeral'("MDCLXVI")	
      );

    Validation_Data : constant array(Test_Cases) of Natural:=
      (	3, 30, 300, 3000,
	7, 66, 150, 1200,
	4, 9, 90,
	901, 899,
	1666
      );


    
    
    

    
    Function Sum( Number : Roman_Numeral ) return Natural is
    begin
	Return Result : Natural:= 0 do
	    For Item of Number loop
		    Result:= Result + Convert( Item );
	    end loop;
	End Return;
    end Sum;

    
    Function Eval( Number : Roman_Numeral ) return Natural is
	Current : Roman_Digits:= 'I';
    begin
	Return Result : Natural:= 0 do
	    For Item of Number loop
		if Current < Item then
		    Result:= Convert(Item) - Result;
		    Current:= Item;
		else
		    Result:= Result + Convert(Item);
		end if;
	    end loop;
	End Return;
    end Eval;

    
    Procedure Put( S: Roman_Numeral ) is
    begin
	For Ch of S loop
	    declare
		
		
		C : Character renames Roman_Digits'Image(Ch)(2);
	    begin
		Ada.Text_IO.Put( C );
	    end;
	end loop;
    end;

    
    Function PF ( Value : Boolean ) Return String is
    begin
	Return Result : String(1..4):= ( if Value then"pass"else"fail" );
    End PF;

Begin
    Ada.Text_IO.Put_Line("Starting Test:");

    for Index in Test_Data'Range loop
	declare
	    Item  : Roman_Numeral renames Test_Data(Index).all;
	    Value : constant Natural := Eval(Item);
	begin
	    Put( Item );

	    Ada.Text_IO.Put( ASCII.HT & "= ");
	    Ada.Text_IO.Put( Value'Img );
	    Ada.Text_IO.Put_Line( ASCII.HT & '[' &
			  PF( Value = Validation_Data(Index) )& ']');
	end;
    end loop;

    
    Ada.Text_IO.Put_Line("Testing complete.");
End Test_Roman_Numerals;