add std::string grb::toString(const grb::Backend) (#269)

Adds facilities to convert a backend identifier to a human-readable (`std::`)string.

include/graphblas/backends.hpp

@@ -29,6 +29,9 @@
 #ifndef _H_GRB_BACKENDS
 #define _H_GRB_BACKENDS
 
+#include <string>
+#include <iostream>
+
 
 namespace grb {
 
@@ -218,6 +221,42 @@ namespace grb {
 
 	};
 
+	/**
+	 * Converts a backend identifier to a human-readable string.
+	 *
+	 * @param[in] backend The backend whose string to return.
+	 *
+	 * @return The name of the given \a backend as a C++ string.
+	 */
+	static inline std::string toString( const enum grb::Backend backend ) {
+		switch( backend ) {
+			case grb::Backend::reference:     return "reference";
+			case grb::Backend::reference_omp: return "reference_omp";
+			case grb::Backend::hyperdags:     return "hyperdags";
+			case grb::Backend::nonblocking:   return "nonblocking";
+			case grb::Backend::shmem1D:       return "shmem1D";
+			case grb::Backend::NUMA1D:        return "NUMA1D";
+			case grb::Backend::GENERIC_BSP:   return "GENERIC_BSP";
+			case grb::Backend::BSP1D:         return "BSP1D";
+			case grb::Backend::doublyBSP1D:   return "doublyBSP1D";
+			case grb::Backend::BSP2D:         return "BSP2D";
+			case grb::Backend::autoBSP:       return "autoBSP";
+			case grb::Backend::optBSP:        return "optBSP";
+			case grb::Backend::hybrid:        return "hybrid";
+			case grb::Backend::hybridSmall:   return "hybridSmall";
+			case grb::Backend::hybridMid:     return "hybridMid";
+			case grb::Backend::hybridLarge:   return "hybridLarge";
+			case grb::Backend::minFootprint:  return "minFootprint";
+			case grb::Backend::banshee:       return "banshee";
+			case grb::Backend::banshee_ssr:   return "banshee_ssr";
+			default:
+				const int backend_id = static_cast< int >( backend );
+				std::cerr << "Warning, std::string( const grb::Backend ): unknown backend "
+					<< backend_id << " encountered, please submit a bug report.\n";
+				return "unknown_backend(id=" + std::to_string( backend_id ) + ")";
+		}
+	}
+
 } // namespace grb
 
 #endif