/// <summary>
/// Expression ::= ["+" | "-"] Term {("+"|"-") Term}.
/// </summary>
/// <returns></returns>
private EXPRESSION parseExpression()
{
bool sign = true; // positive
Token token = lexer.get();
if ( token.code == TokenCode.PLUS ) { lexer.forget(); }
else if ( token.code == TokenCode.MINUS ) { sign = false; lexer.forget(); }
EXPRESSION result = new EXPRESSION();
result.positive = sign;
result.term = parseTerm();
while ( true )
{
token = lexer.get();
switch ( token.code )
{
case TokenCode.PLUS :
case TokenCode.MINUS :
lexer.forget();
result.ops.Add(token.code);
result.terms.Add(parseTerm());
break;
default :
// Don't forget()
return result;
}
}
}
/// <summary>
/// Expression ::= ["+" | "-"] Term {("+"|"-") Term}.
/// </summary>
private void generateExpression(ILGenerator il, EXPRESSION expression)
{
generateTerm(il,expression.term);
if ( !expression.positive ) il.Emit(OpCodes.Neg);
for ( int i=0; i<expression.terms.Count; i++ )
{
generateTerm(il,expression.terms[i]);
switch ( expression.ops[i] )
{
case TokenCode.PLUS : il.Emit(OpCodes.Add); break;
case TokenCode.MINUS : il.Emit(OpCodes.Sub); break;
}
}
}
