Large map<srting,string> Initialization

[Stefan Strasser]

Tom Browder schrieb:
> I need a map with many string pairs and I instantiate it like this:
> 
>   map<const string,const string> mymap;

first const is not required, key type of a map is always const.

>   mymap.insert(make_pair("long_string1", "long_string_val1"));
>   ...
>   mymap.insert(make_pair("long_string10000", "long_string_val10000"));
> 
> The strings generally are about 30-40 characters in length.
> 
> The source file is very long and g++ (4.0) takes a very long time (and a
> large amount of memory) to compile it.

GCC does not have a very good algorithm complexity in this case it seems.
(I tried, doubling the "insert" statements quintupled compilation time).

this is compiled much faster(and will run faster):

std::pair<std::string,std::string> a[]={
	std::make_pair("asdklfj","kljsfd"),
	// ...
};

std::map<std::string,std::string> b(a,a + (sizeof(a) / sizeof(*a)));

> 
> I have broken the file into smaller pieces (which helps with memory usage)
> but the total compile time is about the same.
> 
> Note that the map is never modified after the initial load, it is merely
> used for looking up the values.
> 
> Several questions:
> 
> 1.  Is there a better way to initialize such a map?
> 
> 2.  Are there g++ options that would help?
> 
> 3.  Are there linker/loader tricks that would help?
> 
> Thanks.
> 
> Tom Browder
> 
> 
> 



-- 
Stefan Strasser