How to get equivalent Share Object Name from given Object API Name ?

I have complex requirement where I need to use Apex sharing for both standard & custom object. Share Object and its fields are different for Standard and Custom Obect. 

For example, 

for Lead, its share object is  LeadShare (fields: LeadAccessLevel, LeadId ...)

for Custom__c, its share object is Custom__Share (fields: AccessLevel, ParentId...)

Trying to make this dynamic in nature. and So  I need to find equivalent Share object for given object,  Is there any way to get this ?  Like using Schema or something else 

Thanks & Regards