RNGScope.hpp

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#ifndef RAIIGRAPH_RNG_SCOPE_HPP
#define RAIIGRAPH_RNG_SCOPE_HPP
 
#include "igraph.h"
#include "error.hpp"
 
namespace raiigraph {
 
class RNGScope {
public:
    RNGScope(igraph_uint_t seed) : RNGScope(seed, &igraph_rngtype_pcg32) {}
 
    RNGScope(igraph_uint_t seed, const igraph_rng_type_t* type) {
        check_code(igraph_rng_init(&current, type));
 
        auto errcode = igraph_rng_seed(&current, seed);
        if (errcode != IGRAPH_SUCCESS) {
            igraph_rng_destroy(&current);
            throw IgraphError(errcode);
        }
 
        previous = *(igraph_rng_default());
        igraph_rng_set_default(&current);
    }
 
    RNGScope(const igraph_rng_type_t* type) {
        check_code(igraph_rng_init(&current, type));
        previous = *(igraph_rng_default());
        igraph_rng_set_default(&current);
    }
 
    RNGScope() : RNGScope(&igraph_rngtype_pcg32) {}
 
public:
    // We shouldn't be copying or moving an RNGscope object, as this defeats the logic provided by scoping.
    RNGScope(const RNGScope&) = delete;
    RNGScope& operator=(const RNGScope&) = delete;
    RNGScope(RNGScope&&) = delete;
    RNGScope& operator=(RNGScope&&) = delete;
 
    ~RNGScope() {
        igraph_rng_set_default(&previous);
        igraph_rng_destroy(&current);
    }
private:
    igraph_rng_t previous;
    igraph_rng_t current;
};
 
}
 
#endif