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tailscale/types/views/views.go

386 lines
11 KiB
Go

// Copyright (c) 2022 Tailscale Inc & 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 views provides read-only accessors for commonly used
// value types.
package views
import (
"encoding/json"
"errors"
"net/netip"
"golang.org/x/exp/slices"
"tailscale.com/net/tsaddr"
)
func unmarshalJSON[T any](b []byte, x *[]T) error {
if *x != nil {
return errors.New("already initialized")
}
if len(b) == 0 {
return nil
}
return json.Unmarshal(b, x)
}
// StructView represents the corresponding StructView of a Viewable. The concrete types are
// typically generated by tailscale.com/cmd/viewer.
type StructView[T any] interface {
// Valid reports whether the underlying Viewable is nil.
Valid() bool
// AsStruct returns a deep-copy of the underlying value.
// It returns nil, if Valid() is false.
AsStruct() T
}
// ViewCloner is any type that has had View and Clone funcs generated using
// tailscale.com/cmd/viewer.
type ViewCloner[T any, V StructView[T]] interface {
// View returns a read-only view of Viewable.
// If Viewable is nil, View().Valid() reports false.
View() V
// Clone returns a deep-clone of Viewable.
// It returns nil, when Viewable is nil.
Clone() T
}
// SliceOfViews returns a ViewSlice for x.
func SliceOfViews[T ViewCloner[T, V], V StructView[T]](x []T) SliceView[T, V] {
return SliceView[T, V]{x}
}
// SliceView is a read-only wrapper around a struct which should only be exposed
// as a View.
type SliceView[T ViewCloner[T, V], V StructView[T]] struct {
// ж is the underlying mutable value, named with a hard-to-type
// character that looks pointy like a pointer.
// It is named distinctively to make you think of how dangerous it is to escape
// to callers. You must not let callers be able to mutate it.
ж []T
}
// MarshalJSON implements json.Marshaler.
func (v SliceView[T, V]) MarshalJSON() ([]byte, error) { return json.Marshal(v.ж) }
// UnmarshalJSON implements json.Unmarshaler.
func (v *SliceView[T, V]) UnmarshalJSON(b []byte) error { return unmarshalJSON(b, &v.ж) }
// IsNil reports whether the underlying slice is nil.
func (v SliceView[T, V]) IsNil() bool { return v.ж == nil }
// Len returns the length of the slice.
func (v SliceView[T, V]) Len() int { return len(v.ж) }
// At returns a View of the element at index `i` of the slice.
func (v SliceView[T, V]) At(i int) V { return v.ж[i].View() }
// AppendTo appends the underlying slice values to dst.
func (v SliceView[T, V]) AppendTo(dst []V) []V {
for _, x := range v.ж {
dst = append(dst, x.View())
}
return dst
}
// AsSlice returns a copy of underlying slice.
func (v SliceView[T, V]) AsSlice() []V {
return v.AppendTo(nil)
}
// Slice is a read-only accessor for a slice.
type Slice[T any] struct {
// ж is the underlying mutable value, named with a hard-to-type
// character that looks pointy like a pointer.
// It is named distinctively to make you think of how dangerous it is to escape
// to callers. You must not let callers be able to mutate it.
ж []T
}
// SliceOf returns a Slice for the provided slice for immutable values.
// It is the caller's responsibility to make sure V is immutable.
func SliceOf[T any](x []T) Slice[T] {
return Slice[T]{x}
}
// MarshalJSON implements json.Marshaler.
func (v Slice[T]) MarshalJSON() ([]byte, error) {
return json.Marshal(v.ж)
}
// UnmarshalJSON implements json.Unmarshaler.
func (v *Slice[T]) UnmarshalJSON(b []byte) error {
return unmarshalJSON(b, &v.ж)
}
// IsNil reports whether the underlying slice is nil.
func (v Slice[T]) IsNil() bool { return v.ж == nil }
// Len returns the length of the slice.
func (v Slice[T]) Len() int { return len(v.ж) }
// At returns the element at index `i` of the slice.
func (v Slice[T]) At(i int) T { return v.ж[i] }
// AppendTo appends the underlying slice values to dst.
func (v Slice[T]) AppendTo(dst []T) []T {
return append(dst, v.ж...)
}
// AsSlice returns a copy of underlying slice.
func (v Slice[T]) AsSlice() []T {
return v.AppendTo(v.ж[:0:0])
}
// IndexFunc returns the first index of an element in v satisfying f(e),
// or -1 if none do.
//
// As it runs in O(n) time, use with care.
func (v Slice[T]) IndexFunc(f func(T) bool) int {
for i := 0; i < v.Len(); i++ {
if f(v.At(i)) {
return i
}
}
return -1
}
// ContainsFunc reports whether any element in v satisfies f(e).
//
// As it runs in O(n) time, use with care.
func (v Slice[T]) ContainsFunc(f func(T) bool) bool {
for i := 0; i < v.Len(); i++ {
if f(v.At(i)) {
return true
}
}
return false
}
// SliceContains reports whether v contains element e.
//
// As it runs in O(n) time, use with care.
func SliceContains[T comparable](v Slice[T], e T) bool {
for i := 0; i < v.Len(); i++ {
if v.At(i) == e {
return true
}
}
return false
}
// SliceEqualAnyOrder reports whether a and b contain the same elements, regardless of order.
// The underlying slices for a and b can be nil.
func SliceEqualAnyOrder[T comparable](a, b Slice[T]) bool {
if a.Len() != b.Len() {
return false
}
var diffStart int // beginning index where a and b differ
for n := a.Len(); diffStart < n; diffStart++ {
if a.At(diffStart) != b.At(diffStart) {
break
}
}
if diffStart == a.Len() {
return true
}
// count the occurrences of remaining values and compare
valueCount := make(map[T]int)
for i, n := diffStart, a.Len(); i < n; i++ {
valueCount[a.At(i)]++
valueCount[b.At(i)]--
}
for _, count := range valueCount {
if count != 0 {
return false
}
}
return true
}
// IPPrefixSlice is a read-only accessor for a slice of netip.Prefix.
type IPPrefixSlice struct {
ж Slice[netip.Prefix]
}
// IPPrefixSliceOf returns a IPPrefixSlice for the provided slice.
func IPPrefixSliceOf(x []netip.Prefix) IPPrefixSlice { return IPPrefixSlice{SliceOf(x)} }
// IsNil reports whether the underlying slice is nil.
func (v IPPrefixSlice) IsNil() bool { return v.ж.IsNil() }
// Len returns the length of the slice.
func (v IPPrefixSlice) Len() int { return v.ж.Len() }
// At returns the IPPrefix at index `i` of the slice.
func (v IPPrefixSlice) At(i int) netip.Prefix { return v.ж.At(i) }
// AppendTo appends the underlying slice values to dst.
func (v IPPrefixSlice) AppendTo(dst []netip.Prefix) []netip.Prefix {
return v.ж.AppendTo(dst)
}
// Unwrap returns the underlying Slice[netip.Prefix].
func (v IPPrefixSlice) Unwrap() Slice[netip.Prefix] {
return v.ж
}
// AsSlice returns a copy of underlying slice.
func (v IPPrefixSlice) AsSlice() []netip.Prefix {
return v.ж.AsSlice()
}
// Filter returns a new slice, containing elements of v that match f.
func (v IPPrefixSlice) Filter(f func(netip.Prefix) bool) []netip.Prefix {
return tsaddr.FilterPrefixesCopy(v.ж.ж, f)
}
// PrefixesContainsIP reports whether any IPPrefix contains IP.
func (v IPPrefixSlice) ContainsIP(ip netip.Addr) bool {
return tsaddr.PrefixesContainsIP(v.ж.ж, ip)
}
// PrefixesContainsFunc reports whether f is true for any IPPrefix in the slice.
func (v IPPrefixSlice) ContainsFunc(f func(netip.Prefix) bool) bool {
return slices.ContainsFunc(v.ж.ж, f)
}
// ContainsExitRoutes reports whether v contains ExitNode Routes.
func (v IPPrefixSlice) ContainsExitRoutes() bool {
return tsaddr.ContainsExitRoutes(v.ж.ж)
}
// ContainsNonExitSubnetRoutes reports whether v contains Subnet
// Routes other than ExitNode Routes.
func (v IPPrefixSlice) ContainsNonExitSubnetRoutes() bool {
for i := 0; i < v.Len(); i++ {
if v.At(i).Bits() != 0 {
return true
}
}
return false
}
// MarshalJSON implements json.Marshaler.
func (v IPPrefixSlice) MarshalJSON() ([]byte, error) {
return v.ж.MarshalJSON()
}
// UnmarshalJSON implements json.Unmarshaler.
func (v *IPPrefixSlice) UnmarshalJSON(b []byte) error {
return v.ж.UnmarshalJSON(b)
}
// MapOf returns a view over m. It is the caller's responsibility to make sure K
// and V is immutable, if this is being used to provide a read-only view over m.
func MapOf[K comparable, V comparable](m map[K]V) Map[K, V] {
return Map[K, V]{m}
}
// Map is a view over a map whose values are immutable.
type Map[K comparable, V any] struct {
// ж is the underlying mutable value, named with a hard-to-type
// character that looks pointy like a pointer.
// It is named distinctively to make you think of how dangerous it is to escape
// to callers. You must not let callers be able to mutate it.
ж map[K]V
}
// Has reports whether k has an entry in the map.
func (m Map[K, V]) Has(k K) bool {
_, ok := m.ж[k]
return ok
}
// IsNil reports whether the underlying map is nil.
func (m Map[K, V]) IsNil() bool {
return m.ж == nil
}
// Len returns the number of elements in the map.
func (m Map[K, V]) Len() int { return len(m.ж) }
// Get returns the element with key k.
func (m Map[K, V]) Get(k K) V {
return m.ж[k]
}
// GetOk returns the element with key k and a bool representing whether the key
// is in map.
func (m Map[K, V]) GetOk(k K) (V, bool) {
v, ok := m.ж[k]
return v, ok
}
// MapRangeFn is the func called from a Map.Range call.
// Implementations should return false to stop range.
type MapRangeFn[K comparable, V any] func(k K, v V) (cont bool)
// Range calls f for every k,v pair in the underlying map.
// It stops iteration immediately if f returns false.
func (m Map[K, V]) Range(f MapRangeFn[K, V]) {
for k, v := range m.ж {
if !f(k, v) {
return
}
}
}
// MapFnOf returns a MapFn for m.
func MapFnOf[K comparable, T any, V any](m map[K]T, f func(T) V) MapFn[K, T, V] {
return MapFn[K, T, V]{
ж: m,
wrapv: f,
}
}
// MapFn is like Map but with a func to convert values from T to V.
// It is used to provide map of slices and views.
type MapFn[K comparable, T any, V any] struct {
// ж is the underlying mutable value, named with a hard-to-type
// character that looks pointy like a pointer.
// It is named distinctively to make you think of how dangerous it is to escape
// to callers. You must not let callers be able to mutate it.
ж map[K]T
wrapv func(T) V
}
// Has reports whether k has an entry in the map.
func (m MapFn[K, T, V]) Has(k K) bool {
_, ok := m.ж[k]
return ok
}
// Get returns the element with key k.
func (m MapFn[K, T, V]) Get(k K) V {
return m.wrapv(m.ж[k])
}
// IsNil reports whether the underlying map is nil.
func (m MapFn[K, T, V]) IsNil() bool {
return m.ж == nil
}
// Len returns the number of elements in the map.
func (m MapFn[K, T, V]) Len() int { return len(m.ж) }
// GetOk returns the element with key k and a bool representing whether the key
// is in map.
func (m MapFn[K, T, V]) GetOk(k K) (V, bool) {
v, ok := m.ж[k]
return m.wrapv(v), ok
}
// Range calls f for every k,v pair in the underlying map.
// It stops iteration immediately if f returns false.
func (m MapFn[K, T, V]) Range(f MapRangeFn[K, V]) {
for k, v := range m.ж {
if !f(k, m.wrapv(v)) {
return
}
}
}