reactnative调研

/**
	* This function parses the exported methods inside RCTBridgeModules and
	* generates an array of arrays of RCTModuleMethod objects, keyed
	* by module index.
	*/
	static RCTSparseArray *RCTExportedMethodsByModuleID(void)
	{
	static RCTSparseArray *methodsByModuleID;
	static dispatch_once_t onceToken;
	dispatch_once(&onceToken, ^{
	Dl_info info;
	dladdr(&RCTExportedMethodsByModuleID, &info);
	#ifdef __LP64__
	typedef uint64_t RCTExportValue;
	typedef struct section_64 RCTExportSection;
	#define RCTGetSectByNameFromHeader getsectbynamefromheader_64
	#else
	typedef uint32_t RCTExportValue;
	typedef struct section RCTExportSection;
	#define RCTGetSectByNameFromHeader getsectbynamefromheader
	#endif
	const RCTExportValue mach_header = (RCTExportValue)info.dli_fbase;
	const RCTExportSection *section = RCTGetSectByNameFromHeader((void *)mach_header, "__DATA", "RCTExport");
	if (section == NULL) {
	return;
	}
	NSArray *classes = RCTBridgeModuleClassesByModuleID();
	NSMutableDictionary *methodsByModuleClassName = [NSMutableDictionary dictionaryWithCapacity:[classes count]];
	for (RCTExportValue addr = section->offset;
	addr < section->offset + section->size;
	addr += sizeof(const char **) * 2) {
	// Get data entry
	const char **entries = (const char **)(mach_header + addr);
	// Create method
	RCTModuleMethod *moduleMethod =
	[[RCTModuleMethod alloc] initWithMethodName:@(entries[0])
	JSMethodName:strlen(entries[1]) ? @(entries[1]) : nil];
	// Cache method
	NSArray *methods = methodsByModuleClassName[moduleMethod.moduleClassName];
	methodsByModuleClassName[moduleMethod.moduleClassName] =
	methods ? [methods arrayByAddingObject:moduleMethod] : @[moduleMethod];
	}
	methodsByModuleID = [[RCTSparseArray alloc] initWithCapacity:[classes count]];
	[classes enumerateObjectsUsingBlock:^(Class moduleClass, NSUInteger moduleID, BOOL *stop) {
	methodsByModuleID[moduleID] = methodsByModuleClassName[NSStringFromClass(moduleClass)];
	}];
	});
	return methodsByModuleID;
	}