cmd/viewer,types/views: add support for views of maps

Updates #4635

Signed-off-by: Maisem Ali <maisem@tailscale.com>

7 files changed, 314 insertions, 21 deletions

diff --git a/cmd/viewer/tests/tests.go b/cmd/viewer/tests/tests.go
index 18115ea0f..ec202ccde 100644
--- a/cmd/viewer/tests/tests.go
+++ b/cmd/viewer/tests/tests.go
@@ -19,7 +19,18 @@ type StructWithoutPtrs struct {
 }
 
 type Map struct {
-	M map[string]int
+	Int                 map[string]int
+	SliceInt            map[string][]int
+	StructWithPtr       map[string]*StructWithPtrs
+	StructWithoutPtr    map[string]*StructWithoutPtrs
+	SlicesWithPtrs      map[string][]*StructWithPtrs
+	SlicesWithoutPtrs   map[string][]*StructWithoutPtrs
+	StructWithoutPtrKey map[StructWithoutPtrs]int `json:"-"`
+
+	// Unsupported.
+	SliceIntPtr      map[string][]*int
+	PointerKey       map[*string]int        `json:"-"`
+	StructWithPtrKey map[StructWithPtrs]int `json:"-"`
 }
 
 type StructWithPtrs struct {
diff --git a/cmd/viewer/tests/tests_clone.go b/cmd/viewer/tests/tests_clone.go
index 1fb12746f..357fa20a5 100644
--- a/cmd/viewer/tests/tests_clone.go
+++ b/cmd/viewer/tests/tests_clone.go
@@ -61,10 +61,64 @@ func (src *Map) Clone() *Map {
 	}
 	dst := new(Map)
 	*dst = *src
-	if dst.M != nil {
-		dst.M = map[string]int{}
-		for k, v := range src.M {
-			dst.M[k] = v
+	if dst.Int != nil {
+		dst.Int = map[string]int{}
+		for k, v := range src.Int {
+			dst.Int[k] = v
+		}
+	}
+	if dst.SliceInt != nil {
+		dst.SliceInt = map[string][]int{}
+		for k := range src.SliceInt {
+			dst.SliceInt[k] = append([]int{}, src.SliceInt[k]...)
+		}
+	}
+	if dst.StructWithPtr != nil {
+		dst.StructWithPtr = map[string]*StructWithPtrs{}
+		for k, v := range src.StructWithPtr {
+			dst.StructWithPtr[k] = v.Clone()
+		}
+	}
+	if dst.StructWithoutPtr != nil {
+		dst.StructWithoutPtr = map[string]*StructWithoutPtrs{}
+		for k, v := range src.StructWithoutPtr {
+			dst.StructWithoutPtr[k] = v.Clone()
+		}
+	}
+	if dst.SlicesWithPtrs != nil {
+		dst.SlicesWithPtrs = map[string][]*StructWithPtrs{}
+		for k := range src.SlicesWithPtrs {
+			dst.SlicesWithPtrs[k] = append([]*StructWithPtrs{}, src.SlicesWithPtrs[k]...)
+		}
+	}
+	if dst.SlicesWithoutPtrs != nil {
+		dst.SlicesWithoutPtrs = map[string][]*StructWithoutPtrs{}
+		for k := range src.SlicesWithoutPtrs {
+			dst.SlicesWithoutPtrs[k] = append([]*StructWithoutPtrs{}, src.SlicesWithoutPtrs[k]...)
+		}
+	}
+	if dst.StructWithoutPtrKey != nil {
+		dst.StructWithoutPtrKey = map[StructWithoutPtrs]int{}
+		for k, v := range src.StructWithoutPtrKey {
+			dst.StructWithoutPtrKey[k] = v
+		}
+	}
+	if dst.SliceIntPtr != nil {
+		dst.SliceIntPtr = map[string][]*int{}
+		for k := range src.SliceIntPtr {
+			dst.SliceIntPtr[k] = append([]*int{}, src.SliceIntPtr[k]...)
+		}
+	}
+	if dst.PointerKey != nil {
+		dst.PointerKey = map[*string]int{}
+		for k, v := range src.PointerKey {
+			dst.PointerKey[k] = v
+		}
+	}
+	if dst.StructWithPtrKey != nil {
+		dst.StructWithPtrKey = map[StructWithPtrs]int{}
+		for k, v := range src.StructWithPtrKey {
+			dst.StructWithPtrKey[k] = v
 		}
 	}
 	return dst
@@ -72,7 +126,16 @@ func (src *Map) Clone() *Map {
 
 // A compilation failure here means this code must be regenerated, with the command at the top of this file.
 var _MapCloneNeedsRegeneration = Map(struct {
-	M map[string]int
+	Int                 map[string]int
+	SliceInt            map[string][]int
+	StructWithPtr       map[string]*StructWithPtrs
+	StructWithoutPtr    map[string]*StructWithoutPtrs
+	SlicesWithPtrs      map[string][]*StructWithPtrs
+	SlicesWithoutPtrs   map[string][]*StructWithoutPtrs
+	StructWithoutPtrKey map[StructWithoutPtrs]int
+	SliceIntPtr         map[string][]*int
+	PointerKey          map[*string]int
+	StructWithPtrKey    map[StructWithPtrs]int
 }{})
 
 // Clone makes a deep copy of StructWithSlices.
diff --git a/cmd/viewer/tests/tests_view.go b/cmd/viewer/tests/tests_view.go
index a3abe6f1e..30d6b1af3 100644
--- a/cmd/viewer/tests/tests_view.go
+++ b/cmd/viewer/tests/tests_view.go
@@ -188,9 +188,57 @@ func (v *MapView) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
+func (v MapView) Int() views.Map[string, int] { return views.MapOf(v.ж.Int) }
+
+func (v MapView) SliceInt() views.MapFn[string, []int, views.Slice[int]] {
+	return views.MapFnOf(v.ж.SliceInt, func(t []int) views.Slice[int] {
+		return views.SliceOf(t)
+	})
+}
+
+func (v MapView) StructWithPtr() views.MapFn[string, *StructWithPtrs, StructWithPtrsView] {
+	return views.MapFnOf(v.ж.StructWithPtr, func(t *StructWithPtrs) StructWithPtrsView {
+		return t.View()
+	})
+}
+
+func (v MapView) StructWithoutPtr() views.MapFn[string, *StructWithoutPtrs, StructWithoutPtrsView] {
+	return views.MapFnOf(v.ж.StructWithoutPtr, func(t *StructWithoutPtrs) StructWithoutPtrsView {
+		return t.View()
+	})
+}
+
+func (v MapView) SlicesWithPtrs() views.MapFn[string, []*StructWithPtrs, views.SliceView[*StructWithPtrs, StructWithPtrsView]] {
+	return views.MapFnOf(v.ж.SlicesWithPtrs, func(t []*StructWithPtrs) views.SliceView[*StructWithPtrs, StructWithPtrsView] {
+		return views.SliceOfViews[*StructWithPtrs, StructWithPtrsView](t)
+	})
+}
+
+func (v MapView) SlicesWithoutPtrs() views.MapFn[string, []*StructWithoutPtrs, views.SliceView[*StructWithoutPtrs, StructWithoutPtrsView]] {
+	return views.MapFnOf(v.ж.SlicesWithoutPtrs, func(t []*StructWithoutPtrs) views.SliceView[*StructWithoutPtrs, StructWithoutPtrsView] {
+		return views.SliceOfViews[*StructWithoutPtrs, StructWithoutPtrsView](t)
+	})
+}
+
+func (v MapView) StructWithoutPtrKey() views.Map[StructWithoutPtrs, int] {
+	return views.MapOf(v.ж.StructWithoutPtrKey)
+}
+func (v MapView) SliceIntPtr() map[string][]*int           { panic("unsupported") }
+func (v MapView) PointerKey() map[*string]int              { panic("unsupported") }
+func (v MapView) StructWithPtrKey() map[StructWithPtrs]int { panic("unsupported") }
+
 // A compilation failure here means this code must be regenerated, with the command at the top of this file.
 var _MapViewNeedsRegeneration = Map(struct {
-	M map[string]int
+	Int                 map[string]int
+	SliceInt            map[string][]int
+	StructWithPtr       map[string]*StructWithPtrs
+	StructWithoutPtr    map[string]*StructWithoutPtrs
+	SlicesWithPtrs      map[string][]*StructWithPtrs
+	SlicesWithoutPtrs   map[string][]*StructWithoutPtrs
+	StructWithoutPtrKey map[StructWithoutPtrs]int
+	SliceIntPtr         map[string][]*int
+	PointerKey          map[*string]int
+	StructWithPtrKey    map[StructWithPtrs]int
 }{})
 
 // View returns a readonly view of StructWithSlices.
diff --git a/cmd/viewer/viewer.go b/cmd/viewer/viewer.go
index ad3f02696..c9909453a 100644
--- a/cmd/viewer/viewer.go
+++ b/cmd/viewer/viewer.go
@@ -88,8 +88,12 @@ func (v *{{.ViewName}}) UnmarshalJSON(b []byte) error {
 
 {{end}}
 {{define "mapField"}}
-// Unsupported, panics.
-func(v {{.ViewName}}) {{.FieldName}}() {{.FieldType}} {panic("unsupported")}
+func(v {{.ViewName}}) {{.FieldName}}() views.Map[{{.MapKeyType}},{{.MapValueType}}] { return views.MapOf(v.ж.{{.FieldName}})}
+{{end}}
+{{define "mapFnField"}}
+func(v {{.ViewName}}) {{.FieldName}}() views.MapFn[{{.MapKeyType}},{{.MapValueType}},{{.MapValueView}}] { return views.MapFnOf(v.ж.{{.FieldName}}, func (t {{.MapValueType}}) {{.MapValueView}} {
+	return {{.MapFn}}
+})}
 {{end}}
 {{define "unsupportedField"}}func(v {{.ViewName}}) {{.FieldName}}() {{.FieldType}} {panic("unsupported")}
 {{end}}
@@ -132,6 +136,11 @@ func genView(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, thi
 		FieldName     string
 		FieldType     string
 		FieldViewName string
+
+		MapKeyType   string
+		MapValueType string
+		MapValueView string
+		MapFn        string
 	}{
 		StructName: typ.Obj().Name(),
 		ViewName:   typ.Obj().Name() + "View",
@@ -194,7 +203,7 @@ func genView(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, thi
 				writeTemplate("sliceField")
 			}
 			continue
-		case *types.Struct:
+		case *types.Struct, *types.Named:
 			strucT := underlying
 			args.FieldType = it.QualifiedName(fieldType)
 			if codegen.ContainsPointers(strucT) {
@@ -204,9 +213,62 @@ func genView(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, thi
 			writeTemplate("valueField")
 			continue
 		case *types.Map:
-			// TODO(maisem): support this.
-			// args.FieldType = importedName(ft)
-			// writeTemplate("mapField")
+			m := underlying
+			args.FieldType = it.QualifiedName(fieldType)
+			shallow, deep, key := requiresCloning(m.Key())
+			if shallow || deep {
+				writeTemplate("unsupportedField")
+				continue
+			}
+			args.MapKeyType = it.QualifiedName(key)
+			mElem := m.Elem()
+			var template string
+			switch u := mElem.(type) {
+			case *types.Basic:
+				template = "mapField"
+				args.MapValueType = it.QualifiedName(mElem)
+			case *types.Slice:
+				slice := u
+				sElem := slice.Elem()
+				switch x := sElem.(type) {
+				case *types.Basic:
+					args.MapValueView = fmt.Sprintf("views.Slice[%v]", sElem)
+					args.MapValueType = "[]" + sElem.String()
+					args.MapFn = "views.SliceOf(t)"
+					template = "mapFnField"
+				case *types.Pointer:
+					ptr := x
+					pElem := ptr.Elem()
+					switch pElem.(type) {
+					case *types.Struct, *types.Named:
+						ptrType := it.QualifiedName(ptr)
+						viewType := it.QualifiedName(pElem) + "View"
+						args.MapFn = fmt.Sprintf("views.SliceOfViews[%v,%v](t)", ptrType, viewType)
+						args.MapValueView = fmt.Sprintf("views.SliceView[%v,%v]", ptrType, viewType)
+						args.MapValueType = "[]" + ptrType
+						template = "mapFnField"
+					default:
+						template = "unsupportedField"
+					}
+				default:
+					template = "unsupportedField"
+				}
+			case *types.Pointer:
+				ptr := u
+				pElem := ptr.Elem()
+				switch pElem.(type) {
+				case *types.Struct, *types.Named:
+					args.MapValueType = it.QualifiedName(ptr)
+					args.MapValueView = it.QualifiedName(pElem) + "View"
+					args.MapFn = "t.View()"
+					template = "mapFnField"
+				default:
+					template = "unsupportedField"
+				}
+			default:
+				template = "unsupportedField"
+			}
+			writeTemplate(template)
 			continue
 		case *types.Pointer:
 			ptr := underlying
diff --git a/tailcfg/tailcfg.go b/tailcfg/tailcfg.go
index b313a5ca9..b7ddb9dec 100644
--- a/tailcfg/tailcfg.go
+++ b/tailcfg/tailcfg.go
@@ -531,13 +531,6 @@ type NetInfo struct {
 	// Update BasicallyEqual when adding fields.
 }
 
-// DERPLatencyForEach calls fn for each value in the DERPLatency map.
-func (v NetInfoView) DERPLatencyForEach(fn func(k string, v float64)) {
-	for k, v := range v.ж.DERPLatency {
-		fn(k, v)
-	}
-}
-
 func (ni *NetInfo) String() string {
 	if ni == nil {
 		return "NetInfo(nil)"
diff --git a/tailcfg/tailcfg_view.go b/tailcfg/tailcfg_view.go
index a5f95457b..be466d41b 100644
--- a/tailcfg/tailcfg_view.go
+++ b/tailcfg/tailcfg_view.go
@@ -343,7 +343,9 @@ func (v NetInfoView) PMP() opt.Bool                   { return v.ж.PMP }
 func (v NetInfoView) PCP() opt.Bool                   { return v.ж.PCP }
 func (v NetInfoView) PreferredDERP() int              { return v.ж.PreferredDERP }
 func (v NetInfoView) LinkType() string                { return v.ж.LinkType }
-func (v NetInfoView) String() string                  { return v.ж.String() }
+
+func (v NetInfoView) DERPLatency() views.Map[string, float64] { return views.MapOf(v.ж.DERPLatency) }
+func (v NetInfoView) String() string                          { return v.ж.String() }
 
 // A compilation failure here means this code must be regenerated, with the command at the top of this file.
 var _NetInfoViewNeedsRegeneration = NetInfo(struct {
@@ -471,6 +473,12 @@ func (v *DNSConfigView) UnmarshalJSON(b []byte) error {
 func (v DNSConfigView) Resolvers() views.SliceView[*dnstype.Resolver, dnstype.ResolverView] {
 	return views.SliceOfViews[*dnstype.Resolver, dnstype.ResolverView](v.ж.Resolvers)
 }
+
+func (v DNSConfigView) Routes() views.MapFn[string, []*dnstype.Resolver, views.SliceView[*dnstype.Resolver, dnstype.ResolverView]] {
+	return views.MapFnOf(v.ж.Routes, func(t []*dnstype.Resolver) views.SliceView[*dnstype.Resolver, dnstype.ResolverView] {
+		return views.SliceOfViews[*dnstype.Resolver, dnstype.ResolverView](t)
+	})
+}
 func (v DNSConfigView) FallbackResolvers() views.SliceView[*dnstype.Resolver, dnstype.ResolverView] {
 	return views.SliceOfViews[*dnstype.Resolver, dnstype.ResolverView](v.ж.FallbackResolvers)
 }
@@ -667,6 +675,11 @@ func (v *DERPMapView) UnmarshalJSON(b []byte) error {
 	return nil
 }
 
+func (v DERPMapView) Regions() views.MapFn[int, *DERPRegion, DERPRegionView] {
+	return views.MapFnOf(v.ж.Regions, func(t *DERPRegion) DERPRegionView {
+		return t.View()
+	})
+}
 func (v DERPMapView) OmitDefaultRegions() bool { return v.ж.OmitDefaultRegions }
 
 // A compilation failure here means this code must be regenerated, with the command at the top of this file.
diff --git a/types/views/views.go b/types/views/views.go
index af037f0a0..466462460 100644
--- a/types/views/views.go
+++ b/types/views/views.go
@@ -53,6 +53,8 @@ func SliceOfViews[T ViewCloner[T, V], V StructView[T]](x []T) SliceView[T, V] {
 // 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
@@ -88,6 +90,8 @@ func (v SliceView[T, V]) AsSlice() []V {
 
 // 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
@@ -181,3 +185,102 @@ func (v IPPrefixSlice) MarshalJSON() ([]byte, error) {
 func (v *IPPrefixSlice) UnmarshalJSON(b []byte) error {
 	return v.ж.UnmarshalJSON(b)
 }
+
+// MapOf returns 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 read-only accessor 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
+}
+
+// ForEach calls f for every k,v pair in the underlying map.
+func (m Map[K, V]) ForEach(f func(k K, v V)) {
+	for k, v := range m.ж {
+		f(k, v)
+	}
+}
+
+// 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
+}
+
+// ForEach calls f for every k,v pair in the underlying map.
+func (m MapFn[K, T, V]) ForEach(f func(k K, v V)) {
+	for k, v := range m.ж {
+		f(k, m.wrapv(v))
+	}
+}