type FileSet struct {
Package string// package name Specs map[string]ast.Expr// type specs in file Identities map[string]gen.Elem// processed from specs Directives []string// raw preprocessor directives}
A FileSet is the in-memory representation of a
parsed file.
File parses a file at the relative path
provided and produces a new *FileSet.
(No exported structs is considered an error.)
If you pass in a path to a directory, the entire
directory will be parsed.