Check in the vendor directory

Travis seems to be having issues pulling deps, so we'll have to check in
the vendor directory and prevent the makefile from trying to regenerate
it normally.

vendor/k8s.io/apimachinery/third_party/forked/golang/json/OWNERS

@@ -0,0 +1,5 @@
+approvers:
+- pwittrock
+reviewers:
+- mengqiy
+- apelisse

vendor/k8s.io/apimachinery/third_party/forked/golang/json/fields.go

@@ -0,0 +1,513 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package json is forked from the Go standard library to enable us to find the
+// field of a struct that a given JSON key maps to.
+package json
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"sort"
+	"strings"
+	"sync"
+	"unicode"
+	"unicode/utf8"
+)
+
+const (
+	patchStrategyTagKey = "patchStrategy"
+	patchMergeKeyTagKey = "patchMergeKey"
+)
+
+// Finds the patchStrategy and patchMergeKey struct tag fields on a given
+// struct field given the struct type and the JSON name of the field.
+// It returns field type, a slice of patch strategies, merge key and error.
+// TODO: fix the returned errors to be introspectable.
+func LookupPatchMetadataForStruct(t reflect.Type, jsonField string) (
+	elemType reflect.Type, patchStrategies []string, patchMergeKey string, e error) {
+	if t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+
+	if t.Kind() != reflect.Struct {
+		e = fmt.Errorf("merging an object in json but data type is not struct, instead is: %s",
+			t.Kind().String())
+		return
+	}
+	jf := []byte(jsonField)
+	// Find the field that the JSON library would use.
+	var f *field
+	fields := cachedTypeFields(t)
+	for i := range fields {
+		ff := &fields[i]
+		if bytes.Equal(ff.nameBytes, jf) {
+			f = ff
+			break
+		}
+		// Do case-insensitive comparison.
+		if f == nil && ff.equalFold(ff.nameBytes, jf) {
+			f = ff
+		}
+	}
+	if f != nil {
+		// Find the reflect.Value of the most preferential struct field.
+		tjf := t.Field(f.index[0])
+		// we must navigate down all the anonymously included structs in the chain
+		for i := 1; i < len(f.index); i++ {
+			tjf = tjf.Type.Field(f.index[i])
+		}
+		patchStrategy := tjf.Tag.Get(patchStrategyTagKey)
+		patchMergeKey = tjf.Tag.Get(patchMergeKeyTagKey)
+		patchStrategies = strings.Split(patchStrategy, ",")
+		elemType = tjf.Type
+		return
+	}
+	e = fmt.Errorf("unable to find api field in struct %s for the json field %q", t.Name(), jsonField)
+	return
+}
+
+// A field represents a single field found in a struct.
+type field struct {
+	name      string
+	nameBytes []byte                 // []byte(name)
+	equalFold func(s, t []byte) bool // bytes.EqualFold or equivalent
+
+	tag bool
+	// index is the sequence of indexes from the containing type fields to this field.
+	// it is a slice because anonymous structs will need multiple navigation steps to correctly
+	// resolve the proper fields
+	index     []int
+	typ       reflect.Type
+	omitEmpty bool
+	quoted    bool
+}
+
+func (f field) String() string {
+	return fmt.Sprintf("{name: %s, type: %v, tag: %v, index: %v, omitEmpty: %v, quoted: %v}", f.name, f.typ, f.tag, f.index, f.omitEmpty, f.quoted)
+}
+
+func fillField(f field) field {
+	f.nameBytes = []byte(f.name)
+	f.equalFold = foldFunc(f.nameBytes)
+	return f
+}
+
+// byName sorts field by name, breaking ties with depth,
+// then breaking ties with "name came from json tag", then
+// breaking ties with index sequence.
+type byName []field
+
+func (x byName) Len() int { return len(x) }
+
+func (x byName) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
+
+func (x byName) Less(i, j int) bool {
+	if x[i].name != x[j].name {
+		return x[i].name < x[j].name
+	}
+	if len(x[i].index) != len(x[j].index) {
+		return len(x[i].index) < len(x[j].index)
+	}
+	if x[i].tag != x[j].tag {
+		return x[i].tag
+	}
+	return byIndex(x).Less(i, j)
+}
+
+// byIndex sorts field by index sequence.
+type byIndex []field
+
+func (x byIndex) Len() int { return len(x) }
+
+func (x byIndex) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
+
+func (x byIndex) Less(i, j int) bool {
+	for k, xik := range x[i].index {
+		if k >= len(x[j].index) {
+			return false
+		}
+		if xik != x[j].index[k] {
+			return xik < x[j].index[k]
+		}
+	}
+	return len(x[i].index) < len(x[j].index)
+}
+
+// typeFields returns a list of fields that JSON should recognize for the given type.
+// The algorithm is breadth-first search over the set of structs to include - the top struct
+// and then any reachable anonymous structs.
+func typeFields(t reflect.Type) []field {
+	// Anonymous fields to explore at the current level and the next.
+	current := []field{}
+	next := []field{{typ: t}}
+
+	// Count of queued names for current level and the next.
+	count := map[reflect.Type]int{}
+	nextCount := map[reflect.Type]int{}
+
+	// Types already visited at an earlier level.
+	visited := map[reflect.Type]bool{}
+
+	// Fields found.
+	var fields []field
+
+	for len(next) > 0 {
+		current, next = next, current[:0]
+		count, nextCount = nextCount, map[reflect.Type]int{}
+
+		for _, f := range current {
+			if visited[f.typ] {
+				continue
+			}
+			visited[f.typ] = true
+
+			// Scan f.typ for fields to include.
+			for i := 0; i < f.typ.NumField(); i++ {
+				sf := f.typ.Field(i)
+				if sf.PkgPath != "" { // unexported
+					continue
+				}
+				tag := sf.Tag.Get("json")
+				if tag == "-" {
+					continue
+				}
+				name, opts := parseTag(tag)
+				if !isValidTag(name) {
+					name = ""
+				}
+				index := make([]int, len(f.index)+1)
+				copy(index, f.index)
+				index[len(f.index)] = i
+
+				ft := sf.Type
+				if ft.Name() == "" && ft.Kind() == reflect.Ptr {
+					// Follow pointer.
+					ft = ft.Elem()
+				}
+
+				// Record found field and index sequence.
+				if name != "" || !sf.Anonymous || ft.Kind() != reflect.Struct {
+					tagged := name != ""
+					if name == "" {
+						name = sf.Name
+					}
+					fields = append(fields, fillField(field{
+						name:      name,
+						tag:       tagged,
+						index:     index,
+						typ:       ft,
+						omitEmpty: opts.Contains("omitempty"),
+						quoted:    opts.Contains("string"),
+					}))
+					if count[f.typ] > 1 {
+						// If there were multiple instances, add a second,
+						// so that the annihilation code will see a duplicate.
+						// It only cares about the distinction between 1 or 2,
+						// so don't bother generating any more copies.
+						fields = append(fields, fields[len(fields)-1])
+					}
+					continue
+				}
+
+				// Record new anonymous struct to explore in next round.
+				nextCount[ft]++
+				if nextCount[ft] == 1 {
+					next = append(next, fillField(field{name: ft.Name(), index: index, typ: ft}))
+				}
+			}
+		}
+	}
+
+	sort.Sort(byName(fields))
+
+	// Delete all fields that are hidden by the Go rules for embedded fields,
+	// except that fields with JSON tags are promoted.
+
+	// The fields are sorted in primary order of name, secondary order
+	// of field index length. Loop over names; for each name, delete
+	// hidden fields by choosing the one dominant field that survives.
+	out := fields[:0]
+	for advance, i := 0, 0; i < len(fields); i += advance {
+		// One iteration per name.
+		// Find the sequence of fields with the name of this first field.
+		fi := fields[i]
+		name := fi.name
+		for advance = 1; i+advance < len(fields); advance++ {
+			fj := fields[i+advance]
+			if fj.name != name {
+				break
+			}
+		}
+		if advance == 1 { // Only one field with this name
+			out = append(out, fi)
+			continue
+		}
+		dominant, ok := dominantField(fields[i : i+advance])
+		if ok {
+			out = append(out, dominant)
+		}
+	}
+
+	fields = out
+	sort.Sort(byIndex(fields))
+
+	return fields
+}
+
+// dominantField looks through the fields, all of which are known to
+// have the same name, to find the single field that dominates the
+// others using Go's embedding rules, modified by the presence of
+// JSON tags. If there are multiple top-level fields, the boolean
+// will be false: This condition is an error in Go and we skip all
+// the fields.
+func dominantField(fields []field) (field, bool) {
+	// The fields are sorted in increasing index-length order. The winner
+	// must therefore be one with the shortest index length. Drop all
+	// longer entries, which is easy: just truncate the slice.
+	length := len(fields[0].index)
+	tagged := -1 // Index of first tagged field.
+	for i, f := range fields {
+		if len(f.index) > length {
+			fields = fields[:i]
+			break
+		}
+		if f.tag {
+			if tagged >= 0 {
+				// Multiple tagged fields at the same level: conflict.
+				// Return no field.
+				return field{}, false
+			}
+			tagged = i
+		}
+	}
+	if tagged >= 0 {
+		return fields[tagged], true
+	}
+	// All remaining fields have the same length. If there's more than one,
+	// we have a conflict (two fields named "X" at the same level) and we
+	// return no field.
+	if len(fields) > 1 {
+		return field{}, false
+	}
+	return fields[0], true
+}
+
+var fieldCache struct {
+	sync.RWMutex
+	m map[reflect.Type][]field
+}
+
+// cachedTypeFields is like typeFields but uses a cache to avoid repeated work.
+func cachedTypeFields(t reflect.Type) []field {
+	fieldCache.RLock()
+	f := fieldCache.m[t]
+	fieldCache.RUnlock()
+	if f != nil {
+		return f
+	}
+
+	// Compute fields without lock.
+	// Might duplicate effort but won't hold other computations back.
+	f = typeFields(t)
+	if f == nil {
+		f = []field{}
+	}
+
+	fieldCache.Lock()
+	if fieldCache.m == nil {
+		fieldCache.m = map[reflect.Type][]field{}
+	}
+	fieldCache.m[t] = f
+	fieldCache.Unlock()
+	return f
+}
+
+func isValidTag(s string) bool {
+	if s == "" {
+		return false
+	}
+	for _, c := range s {
+		switch {
+		case strings.ContainsRune("!#$%&()*+-./:<=>?@[]^_{|}~ ", c):
+			// Backslash and quote chars are reserved, but
+			// otherwise any punctuation chars are allowed
+			// in a tag name.
+		default:
+			if !unicode.IsLetter(c) && !unicode.IsDigit(c) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+const (
+	caseMask     = ^byte(0x20) // Mask to ignore case in ASCII.
+	kelvin       = '\u212a'
+	smallLongEss = '\u017f'
+)
+
+// foldFunc returns one of four different case folding equivalence
+// functions, from most general (and slow) to fastest:
+//
+// 1) bytes.EqualFold, if the key s contains any non-ASCII UTF-8
+// 2) equalFoldRight, if s contains special folding ASCII ('k', 'K', 's', 'S')
+// 3) asciiEqualFold, no special, but includes non-letters (including _)
+// 4) simpleLetterEqualFold, no specials, no non-letters.
+//
+// The letters S and K are special because they map to 3 runes, not just 2:
+//  * S maps to s and to U+017F 'ſ' Latin small letter long s
+//  * k maps to K and to U+212A 'K' Kelvin sign
+// See http://play.golang.org/p/tTxjOc0OGo
+//
+// The returned function is specialized for matching against s and
+// should only be given s. It's not curried for performance reasons.
+func foldFunc(s []byte) func(s, t []byte) bool {
+	nonLetter := false
+	special := false // special letter
+	for _, b := range s {
+		if b >= utf8.RuneSelf {
+			return bytes.EqualFold
+		}
+		upper := b & caseMask
+		if upper < 'A' || upper > 'Z' {
+			nonLetter = true
+		} else if upper == 'K' || upper == 'S' {
+			// See above for why these letters are special.
+			special = true
+		}
+	}
+	if special {
+		return equalFoldRight
+	}
+	if nonLetter {
+		return asciiEqualFold
+	}
+	return simpleLetterEqualFold
+}
+
+// equalFoldRight is a specialization of bytes.EqualFold when s is
+// known to be all ASCII (including punctuation), but contains an 's',
+// 'S', 'k', or 'K', requiring a Unicode fold on the bytes in t.
+// See comments on foldFunc.
+func equalFoldRight(s, t []byte) bool {
+	for _, sb := range s {
+		if len(t) == 0 {
+			return false
+		}
+		tb := t[0]
+		if tb < utf8.RuneSelf {
+			if sb != tb {
+				sbUpper := sb & caseMask
+				if 'A' <= sbUpper && sbUpper <= 'Z' {
+					if sbUpper != tb&caseMask {
+						return false
+					}
+				} else {
+					return false
+				}
+			}
+			t = t[1:]
+			continue
+		}
+		// sb is ASCII and t is not. t must be either kelvin
+		// sign or long s; sb must be s, S, k, or K.
+		tr, size := utf8.DecodeRune(t)
+		switch sb {
+		case 's', 'S':
+			if tr != smallLongEss {
+				return false
+			}
+		case 'k', 'K':
+			if tr != kelvin {
+				return false
+			}
+		default:
+			return false
+		}
+		t = t[size:]
+
+	}
+	if len(t) > 0 {
+		return false
+	}
+	return true
+}
+
+// asciiEqualFold is a specialization of bytes.EqualFold for use when
+// s is all ASCII (but may contain non-letters) and contains no
+// special-folding letters.
+// See comments on foldFunc.
+func asciiEqualFold(s, t []byte) bool {
+	if len(s) != len(t) {
+		return false
+	}
+	for i, sb := range s {
+		tb := t[i]
+		if sb == tb {
+			continue
+		}
+		if ('a' <= sb && sb <= 'z') || ('A' <= sb && sb <= 'Z') {
+			if sb&caseMask != tb&caseMask {
+				return false
+			}
+		} else {
+			return false
+		}
+	}
+	return true
+}
+
+// simpleLetterEqualFold is a specialization of bytes.EqualFold for
+// use when s is all ASCII letters (no underscores, etc) and also
+// doesn't contain 'k', 'K', 's', or 'S'.
+// See comments on foldFunc.
+func simpleLetterEqualFold(s, t []byte) bool {
+	if len(s) != len(t) {
+		return false
+	}
+	for i, b := range s {
+		if b&caseMask != t[i]&caseMask {
+			return false
+		}
+	}
+	return true
+}
+
+// tagOptions is the string following a comma in a struct field's "json"
+// tag, or the empty string. It does not include the leading comma.
+type tagOptions string
+
+// parseTag splits a struct field's json tag into its name and
+// comma-separated options.
+func parseTag(tag string) (string, tagOptions) {
+	if idx := strings.Index(tag, ","); idx != -1 {
+		return tag[:idx], tagOptions(tag[idx+1:])
+	}
+	return tag, tagOptions("")
+}
+
+// Contains reports whether a comma-separated list of options
+// contains a particular substr flag. substr must be surrounded by a
+// string boundary or commas.
+func (o tagOptions) Contains(optionName string) bool {
+	if len(o) == 0 {
+		return false
+	}
+	s := string(o)
+	for s != "" {
+		var next string
+		i := strings.Index(s, ",")
+		if i >= 0 {
+			s, next = s[:i], s[i+1:]
+		}
+		if s == optionName {
+			return true
+		}
+		s = next
+	}
+	return false
+}

vendor/k8s.io/apimachinery/third_party/forked/golang/reflect/deep_equal.go

@@ -0,0 +1,388 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package reflect is a fork of go's standard library reflection package, which
+// allows for deep equal with equality functions defined.
+package reflect
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+// Equalities is a map from type to a function comparing two values of
+// that type.
+type Equalities map[reflect.Type]reflect.Value
+
+// For convenience, panics on errrors
+func EqualitiesOrDie(funcs ...interface{}) Equalities {
+	e := Equalities{}
+	if err := e.AddFuncs(funcs...); err != nil {
+		panic(err)
+	}
+	return e
+}
+
+// AddFuncs is a shortcut for multiple calls to AddFunc.
+func (e Equalities) AddFuncs(funcs ...interface{}) error {
+	for _, f := range funcs {
+		if err := e.AddFunc(f); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// AddFunc uses func as an equality function: it must take
+// two parameters of the same type, and return a boolean.
+func (e Equalities) AddFunc(eqFunc interface{}) error {
+	fv := reflect.ValueOf(eqFunc)
+	ft := fv.Type()
+	if ft.Kind() != reflect.Func {
+		return fmt.Errorf("expected func, got: %v", ft)
+	}
+	if ft.NumIn() != 2 {
+		return fmt.Errorf("expected two 'in' params, got: %v", ft)
+	}
+	if ft.NumOut() != 1 {
+		return fmt.Errorf("expected one 'out' param, got: %v", ft)
+	}
+	if ft.In(0) != ft.In(1) {
+		return fmt.Errorf("expected arg 1 and 2 to have same type, but got %v", ft)
+	}
+	var forReturnType bool
+	boolType := reflect.TypeOf(forReturnType)
+	if ft.Out(0) != boolType {
+		return fmt.Errorf("expected bool return, got: %v", ft)
+	}
+	e[ft.In(0)] = fv
+	return nil
+}
+
+// Below here is forked from go's reflect/deepequal.go
+
+// During deepValueEqual, must keep track of checks that are
+// in progress.  The comparison algorithm assumes that all
+// checks in progress are true when it reencounters them.
+// Visited comparisons are stored in a map indexed by visit.
+type visit struct {
+	a1  uintptr
+	a2  uintptr
+	typ reflect.Type
+}
+
+// unexportedTypePanic is thrown when you use this DeepEqual on something that has an
+// unexported type. It indicates a programmer error, so should not occur at runtime,
+// which is why it's not public and thus impossible to catch.
+type unexportedTypePanic []reflect.Type
+
+func (u unexportedTypePanic) Error() string { return u.String() }
+func (u unexportedTypePanic) String() string {
+	strs := make([]string, len(u))
+	for i, t := range u {
+		strs[i] = fmt.Sprintf("%v", t)
+	}
+	return "an unexported field was encountered, nested like this: " + strings.Join(strs, " -> ")
+}
+
+func makeUsefulPanic(v reflect.Value) {
+	if x := recover(); x != nil {
+		if u, ok := x.(unexportedTypePanic); ok {
+			u = append(unexportedTypePanic{v.Type()}, u...)
+			x = u
+		}
+		panic(x)
+	}
+}
+
+// Tests for deep equality using reflected types. The map argument tracks
+// comparisons that have already been seen, which allows short circuiting on
+// recursive types.
+func (e Equalities) deepValueEqual(v1, v2 reflect.Value, visited map[visit]bool, depth int) bool {
+	defer makeUsefulPanic(v1)
+
+	if !v1.IsValid() || !v2.IsValid() {
+		return v1.IsValid() == v2.IsValid()
+	}
+	if v1.Type() != v2.Type() {
+		return false
+	}
+	if fv, ok := e[v1.Type()]; ok {
+		return fv.Call([]reflect.Value{v1, v2})[0].Bool()
+	}
+
+	hard := func(k reflect.Kind) bool {
+		switch k {
+		case reflect.Array, reflect.Map, reflect.Slice, reflect.Struct:
+			return true
+		}
+		return false
+	}
+
+	if v1.CanAddr() && v2.CanAddr() && hard(v1.Kind()) {
+		addr1 := v1.UnsafeAddr()
+		addr2 := v2.UnsafeAddr()
+		if addr1 > addr2 {
+			// Canonicalize order to reduce number of entries in visited.
+			addr1, addr2 = addr2, addr1
+		}
+
+		// Short circuit if references are identical ...
+		if addr1 == addr2 {
+			return true
+		}
+
+		// ... or already seen
+		typ := v1.Type()
+		v := visit{addr1, addr2, typ}
+		if visited[v] {
+			return true
+		}
+
+		// Remember for later.
+		visited[v] = true
+	}
+
+	switch v1.Kind() {
+	case reflect.Array:
+		// We don't need to check length here because length is part of
+		// an array's type, which has already been filtered for.
+		for i := 0; i < v1.Len(); i++ {
+			if !e.deepValueEqual(v1.Index(i), v2.Index(i), visited, depth+1) {
+				return false
+			}
+		}
+		return true
+	case reflect.Slice:
+		if (v1.IsNil() || v1.Len() == 0) != (v2.IsNil() || v2.Len() == 0) {
+			return false
+		}
+		if v1.IsNil() || v1.Len() == 0 {
+			return true
+		}
+		if v1.Len() != v2.Len() {
+			return false
+		}
+		if v1.Pointer() == v2.Pointer() {
+			return true
+		}
+		for i := 0; i < v1.Len(); i++ {
+			if !e.deepValueEqual(v1.Index(i), v2.Index(i), visited, depth+1) {
+				return false
+			}
+		}
+		return true
+	case reflect.Interface:
+		if v1.IsNil() || v2.IsNil() {
+			return v1.IsNil() == v2.IsNil()
+		}
+		return e.deepValueEqual(v1.Elem(), v2.Elem(), visited, depth+1)
+	case reflect.Ptr:
+		return e.deepValueEqual(v1.Elem(), v2.Elem(), visited, depth+1)
+	case reflect.Struct:
+		for i, n := 0, v1.NumField(); i < n; i++ {
+			if !e.deepValueEqual(v1.Field(i), v2.Field(i), visited, depth+1) {
+				return false
+			}
+		}
+		return true
+	case reflect.Map:
+		if (v1.IsNil() || v1.Len() == 0) != (v2.IsNil() || v2.Len() == 0) {
+			return false
+		}
+		if v1.IsNil() || v1.Len() == 0 {
+			return true
+		}
+		if v1.Len() != v2.Len() {
+			return false
+		}
+		if v1.Pointer() == v2.Pointer() {
+			return true
+		}
+		for _, k := range v1.MapKeys() {
+			if !e.deepValueEqual(v1.MapIndex(k), v2.MapIndex(k), visited, depth+1) {
+				return false
+			}
+		}
+		return true
+	case reflect.Func:
+		if v1.IsNil() && v2.IsNil() {
+			return true
+		}
+		// Can't do better than this:
+		return false
+	default:
+		// Normal equality suffices
+		if !v1.CanInterface() || !v2.CanInterface() {
+			panic(unexportedTypePanic{})
+		}
+		return v1.Interface() == v2.Interface()
+	}
+}
+
+// DeepEqual is like reflect.DeepEqual, but focused on semantic equality
+// instead of memory equality.
+//
+// It will use e's equality functions if it finds types that match.
+//
+// An empty slice *is* equal to a nil slice for our purposes; same for maps.
+//
+// Unexported field members cannot be compared and will cause an imformative panic; you must add an Equality
+// function for these types.
+func (e Equalities) DeepEqual(a1, a2 interface{}) bool {
+	if a1 == nil || a2 == nil {
+		return a1 == a2
+	}
+	v1 := reflect.ValueOf(a1)
+	v2 := reflect.ValueOf(a2)
+	if v1.Type() != v2.Type() {
+		return false
+	}
+	return e.deepValueEqual(v1, v2, make(map[visit]bool), 0)
+}
+
+func (e Equalities) deepValueDerive(v1, v2 reflect.Value, visited map[visit]bool, depth int) bool {
+	defer makeUsefulPanic(v1)
+
+	if !v1.IsValid() || !v2.IsValid() {
+		return v1.IsValid() == v2.IsValid()
+	}
+	if v1.Type() != v2.Type() {
+		return false
+	}
+	if fv, ok := e[v1.Type()]; ok {
+		return fv.Call([]reflect.Value{v1, v2})[0].Bool()
+	}
+
+	hard := func(k reflect.Kind) bool {
+		switch k {
+		case reflect.Array, reflect.Map, reflect.Slice, reflect.Struct:
+			return true
+		}
+		return false
+	}
+
+	if v1.CanAddr() && v2.CanAddr() && hard(v1.Kind()) {
+		addr1 := v1.UnsafeAddr()
+		addr2 := v2.UnsafeAddr()
+		if addr1 > addr2 {
+			// Canonicalize order to reduce number of entries in visited.
+			addr1, addr2 = addr2, addr1
+		}
+
+		// Short circuit if references are identical ...
+		if addr1 == addr2 {
+			return true
+		}
+
+		// ... or already seen
+		typ := v1.Type()
+		v := visit{addr1, addr2, typ}
+		if visited[v] {
+			return true
+		}
+
+		// Remember for later.
+		visited[v] = true
+	}
+
+	switch v1.Kind() {
+	case reflect.Array:
+		// We don't need to check length here because length is part of
+		// an array's type, which has already been filtered for.
+		for i := 0; i < v1.Len(); i++ {
+			if !e.deepValueDerive(v1.Index(i), v2.Index(i), visited, depth+1) {
+				return false
+			}
+		}
+		return true
+	case reflect.Slice:
+		if v1.IsNil() || v1.Len() == 0 {
+			return true
+		}
+		if v1.Len() > v2.Len() {
+			return false
+		}
+		if v1.Pointer() == v2.Pointer() {
+			return true
+		}
+		for i := 0; i < v1.Len(); i++ {
+			if !e.deepValueDerive(v1.Index(i), v2.Index(i), visited, depth+1) {
+				return false
+			}
+		}
+		return true
+	case reflect.String:
+		if v1.Len() == 0 {
+			return true
+		}
+		if v1.Len() > v2.Len() {
+			return false
+		}
+		return v1.String() == v2.String()
+	case reflect.Interface:
+		if v1.IsNil() {
+			return true
+		}
+		return e.deepValueDerive(v1.Elem(), v2.Elem(), visited, depth+1)
+	case reflect.Ptr:
+		if v1.IsNil() {
+			return true
+		}
+		return e.deepValueDerive(v1.Elem(), v2.Elem(), visited, depth+1)
+	case reflect.Struct:
+		for i, n := 0, v1.NumField(); i < n; i++ {
+			if !e.deepValueDerive(v1.Field(i), v2.Field(i), visited, depth+1) {
+				return false
+			}
+		}
+		return true
+	case reflect.Map:
+		if v1.IsNil() || v1.Len() == 0 {
+			return true
+		}
+		if v1.Len() > v2.Len() {
+			return false
+		}
+		if v1.Pointer() == v2.Pointer() {
+			return true
+		}
+		for _, k := range v1.MapKeys() {
+			if !e.deepValueDerive(v1.MapIndex(k), v2.MapIndex(k), visited, depth+1) {
+				return false
+			}
+		}
+		return true
+	case reflect.Func:
+		if v1.IsNil() && v2.IsNil() {
+			return true
+		}
+		// Can't do better than this:
+		return false
+	default:
+		// Normal equality suffices
+		if !v1.CanInterface() || !v2.CanInterface() {
+			panic(unexportedTypePanic{})
+		}
+		return v1.Interface() == v2.Interface()
+	}
+}
+
+// DeepDerivative is similar to DeepEqual except that unset fields in a1 are
+// ignored (not compared). This allows us to focus on the fields that matter to
+// the semantic comparison.
+//
+// The unset fields include a nil pointer and an empty string.
+func (e Equalities) DeepDerivative(a1, a2 interface{}) bool {
+	if a1 == nil {
+		return true
+	}
+	v1 := reflect.ValueOf(a1)
+	v2 := reflect.ValueOf(a2)
+	if v1.Type() != v2.Type() {
+		return false
+	}
+	return e.deepValueDerive(v1, v2, make(map[visit]bool), 0)
+}