Re: Using Lua's string interning for faster compares?

[dcharno <dcharno@...>]

On 01/18/2012 01:07 AM, Philipp Janda wrote:
> Hi!
>
> On 17.01.2012 08:12, HyperHacker wrote:
> > When I write modules to wrap C++ objects, they usually have a __index
> > method that does a lot of string comparing, like:
> > if(!strcmp(key, "foo")) lua_pushcfunction(L, obj_method_foo);
> > else if(!strcmp(key, "bar")) lua_pushcfunction(L, obj_method_bar);
> > etc... I'm not sure if compilers can optimize this, but doing all
> > those strcmp()s every time a method/field is looked up seems terribly
> > inefficient.
>
> Try Ragel[1].
>
> [1]: http://www.complang.org/ragel/
>
> I've attached the template I use for such occasions.

What about gperf?

http://www.gnu.org/software/gperf/


%includes
struct str2id_s { const char *name; int id; };
%%
"foo",    0
"bar",    1
"baz",    2
"foobar", 3
"hello",  4
"bye",    5
%%

#include <stdio.h>

int str2id(const char *s)
{
	struct str2id_s *p = in_word_set(s, strlen(s));
	return p ? p->id : -1;
}

int main(int argc, char *argv[])
{
	printf( "%d \n", str2id("foo") );
	printf( "%d \n", str2id("bar") );
	printf( "%d \n", str2id("baz") );
}