kubernetes/vendor/github.com/google/go-cmp/cmp/cmpopts/struct_filter.go

// filterField returns a new Option where opt is only evaluated on paths that
// include a specific exported field on a single struct type.
// The struct type is specified by passing in a value of that type.
//
// The name may be a dot-delimited string (e.g., "Foo.Bar") to select a
// specific sub-field that is embedded or nested within the parent struct.
func filterField(typ interface{ … }

type structFilter …

func newStructFilter(typ interface{ … }

func (sf structFilter) filter(p cmp.Path) bool { … }

type fieldTree …

// insert inserts a sequence of field accesses into the tree.
func (ft *fieldTree) insert(cname []string) { … }

// matchPrefix reports whether any selector in the fieldTree matches
// the start of path p.
func (ft fieldTree) matchPrefix(p cmp.Path) bool { … }

// canonicalName returns a list of identifiers where any struct field access
// through an embedded field is expanded to include the names of the embedded
// types themselves.
//
// For example, suppose field "Foo" is not directly in the parent struct,
// but actually from an embedded struct of type "Bar". Then, the canonical name
// of "Foo" is actually "Bar.Foo".
//
// Suppose field "Foo" is not directly in the parent struct, but actually
// a field in two different embedded structs of types "Bar" and "Baz".
// Then the selector "Foo" causes a panic since it is ambiguous which one it
// refers to. The user must specify either "Bar.Foo" or "Baz.Foo".
func canonicalName(t reflect.Type, sel string) ([]string, error) { … }