MBCDN

Dies ist eine alte Version des Dokuments!

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TinyPG

<% @TinyPG Language="c#" OutputPath="C:\chroot\Parser\" %>

NUMBER 	-> @"[0-9]+";
PLUSMINUS 	-> @"(\+|-)";
MULTDIV 	-> @"\*|/";
BROPEN 	->  @"\(";
BRCLOSE 	->  @"\)";
EOF         -> @"^$";

[Skip] WHITESPACE  -> @"\s+";

Start 		-> (AddExpr)? EOF;
AddExpr 	-> MultExpr (PLUSMINUS MultExpr)*;
MultExpr 	-> Atom (MULTDIV Atom)*;
Atom 		-> NUMBER | BROPEN AddExpr BRCLOSE;

// Simple expression calculator with print + strings + variables
<% @TinyPG Language="C#" Namespace="MyScript" OutputPath="C:\Users\manuel.zarat\source\repos\ConsoleApp1\ConsoleApp1\"  %>


// -------- Tokens --------
EOF                  -> @"^\s*$";
[Color(255, 0, 0)]   NUMBER     -> @"[0-9]+";
[Color(163, 21, 21)] STRING     -> @"""[^""]*""";
[Color(128, 0, 128)] PRINT      -> @"print";
[Color(0, 128, 0)]   IDENT      -> @"[a-zA-Z_][a-zA-Z0-9_]*";
[Color(0, 0, 255)]   ASSIGN     -> @"=";
[Color(0, 0, 255)]   PLUSMINUS  -> @"(\+|-)";
[Color(0, 0, 255)]   MULTDIV    -> @"\*|/";
[Color(0, 0, 255)]   BROPEN     -> @"\(";
[Color(0, 0, 255)]   BRCLOSE    -> @"\)";

[Skip]               WHITESPACE -> @"\s+";

// =======================
//   Grammatik / Semantik
// =======================

// mehrere Statements; Result ist uns egal -> null
Start -> (Statement)* EOF
{

	string output = ""; 
	int i = 0; 

	while ($Statement[i] != null) { 

		if ($Statement[i] != null) { 
			if (output.Length > 0) 
				output += "\r\n"; 
			output += $Statement[i].ToString(); 
		} 
		i++;
	} 
	
	return output;

};

Statement -> AssignStmt | PrintStmt | ExprStmt
{
    if ($AssignStmt != null) return $AssignStmt;
    if ($PrintStmt  != null) return $PrintStmt;
    return $ExprStmt;
};

// a = 12  oder  a = "Hallo"  oder  a = 1+2*3
AssignStmt -> IDENT ASSIGN AddExpr
{
    // "Variables" kommt aus der partiellen Parser-Klasse (siehe unten)
    Variables[$IDENT.ToString()] = $AddExpr;
    return null;
};

// print( Ausdruck )
PrintStmt -> PRINT BROPEN AddExpr BRCLOSE
{
    Console.WriteLine($AddExpr);
    return null;
};

// nackter Ausdruck als Statement
ExprStmt -> AddExpr
{
    return $AddExpr;
};

// Addition / Subtraktion
// +: Zahlen addieren ODER Strings konkatenieren
AddExpr -> MultExpr (PLUSMINUS MultExpr)*
{ 
    object value = $MultExpr;
    int i = 1;

    while ($MultExpr[i] != null)
    {
        string sign = $PLUSMINUS[i-1].ToString();
        object rhs = $MultExpr[i++];

        if (sign == "+")
        {
            if (value is string || rhs is string)
                value = value.ToString() + rhs.ToString();
            else
                value = Convert.ToInt32(value) + Convert.ToInt32(rhs);
        }
        else // "-"
        {
            value = Convert.ToInt32(value) - Convert.ToInt32(rhs);
        }
    }

    return value; 
};

// Multiplikation / Division (nur numerisch)
MultExpr -> Atom (MULTDIV Atom)*
{ 
    object value = $Atom;
    int i = 1;

    while ($Atom[i] != null)
    {
        string sign = $MULTDIV[i-1].ToString();
        object rhs = $Atom[i++];

        if (sign == "*")
        {
            value = Convert.ToInt32(value) * Convert.ToInt32(rhs);
        }
        else // "/"
        {
            value = Convert.ToInt32(value) / Convert.ToInt32(rhs);
        }
    }
    return value; 
};

// Atome: Zahl, String, Variable oder (Ausdruck)
Atom -> NUMBER | STRING | IDENT | BROPEN AddExpr BRCLOSE
{
    if ($NUMBER != null)
    {
        return Convert.ToInt32($NUMBER.ToString());
    }
    else if ($STRING != null)
    {
        string s = $STRING.ToString();
        if (s.Length >= 2 && s[0] == '"' && s[s.Length - 1] == '"')
            s = s.Substring(1, s.Length - 2);
        return s;
    }
    else if ($IDENT != null)
    {
        // Variable lesen
        object v;
        string name = $IDENT.ToString();
        if (!Variables.TryGetValue(name, out v))
            throw new Exception("Variable '" + name + "' ist nicht definiert.");
        return name;
    }
    else
    {
        // ( Ausdruck )
        return $AddExpr;
    }
};