An index for facilitating fast lookup of common abstractions inside parsed binary policy data
structures. Typically, data is indexed by an enum that describes a well-known value and the
index stores the offset of the data in the binary policy to avoid scanning a collection to find
an element that contains a matching string. For example, the policy contains a collection of
classes that are identified by string names included in each collection entry. However,
policy_index.classes(KernelClass::Process).unwrap() yields the offset in the policy’s
collection of classes where the “process” class resides.