Will I get a faster parser using spirit X3 when I use the expect operator

Question

In spirit X3 I can build a parser like this:

const auto p = ("Number:" >> x3::_int)
             | ("String:" >> +x3::alpha);

If I know after the string Number comes a int and after String a string all the time I can use the > to say after Number only comes a number and so on.

const auto p = ("Number:" > x3::_int)
             | ("String:" > +x3::alpha);

For me the difference is if the parser fails to parse the input an exception is throw.

Now my question is, should I use the > operater over the >> operater whenever possible? Is the parser which will be generated using > faster then the one only using the >> operator?

No – `>` is `>>` plus a `throw` if parsing fails. – ildjarn Aug 13 '16 at 14:47 — ildjarn, Aug 13 '16 at 14:47
If you ever wonder "What is faster", just measure it. – Baum mit Augen Aug 13 '16 at 14:52 — Baum mit Augen, Aug 13 '16 at 14:52

score 1 · Accepted Answer · answered Aug 13 '16 at 22:56

1

You should always just profile things.

Regardless:

Will I get a faster parser using spirit X3 when I use the expect operator

Only to the extent that it prevents backtracking alternatives, but if you needed that it's not doing the same anyways.

answered Aug 13 '16 at 22:56

sehe

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Will I get a faster parser using spirit X3 when I use the expect operator

1 Answers1