// - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
private static IExpression ParseAddExpression()
{
if (Check(FirstMultExp))
{
IExpression exp = ParseMultExpression();
while (Check(new TokenSet(TokenType.Plus | TokenType.Minus)))
{
TokenType opType = CurrentToken.type;
Eat(opType);
if (!Check(FirstMultExp))
{
throw new InvalidSyntaxException("Expected an expression after + or - operator");
}
IExpression right = ParseMultExpression();
switch (opType)
{
case TokenType.Plus:
exp = new AddExpression(exp, right);
break;
case TokenType.Minus:
exp = new SubExpression(exp, right);
break;
default:
throw new UnexpectedBehaviorException("Expected plus or minus, got: " + opType);
}
}
return(exp);
}
else
{
throw new InvalidSyntaxException("Invalid expression");
}
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
private static IExpression ParseAddExpression()
{
if ( Check( FirstMultExp ) )
{
IExpression exp = ParseMultExpression();
while ( Check( new TokenSet( TokenType.Plus | TokenType.Minus ) ) )
{
TokenType opType = CurrentToken.type;
Eat( opType );
if ( !Check( FirstMultExp ) )
{
throw new InvalidSyntaxException( "Expected an expression after + or - operator" );
}
IExpression right = ParseMultExpression();
switch ( opType )
{
case TokenType.Plus:
exp = new AddExpression( exp, right );
break;
case TokenType.Minus:
exp = new SubExpression( exp, right );
break;
default:
throw new UnexpectedBehaviorException( "Expected plus or minus, got: " + opType );
}
}
return exp;
}
else
{
throw new InvalidSyntaxException( "Invalid expression" );
}
}