Track the key of any named group objects.

As part of #380 we allowed names
and groups tags/options to co-exist to ultimately support Fx feature
request uber-go/fx#998.

We now intend to support Map value groups as per
uber-go/fx#1036. We will do this in 2 steps.

1. This PR will begin tracking any names passed into value groups with
out changing any external facing functionality.

2. a subsequent PR will exploit this structure to support Map value
groups.

constructor.go

@@ -181,15 +181,15 @@ func (n *constructorNode) Call(c containerStore) (err error) {
 // would be made to a containerWriter and defers them until Commit is called.
 type stagingContainerWriter struct {
 	values map[key]reflect.Value
-	groups map[key][]reflect.Value
+	groups map[key][]keyedGroupValue
 }
 
 var _ containerWriter = (*stagingContainerWriter)(nil)
 
 func newStagingContainerWriter() *stagingContainerWriter {
 	return &stagingContainerWriter{
 		values: make(map[key]reflect.Value),
-		groups: make(map[key][]reflect.Value),
+		groups: make(map[key][]keyedGroupValue),
 	}
 }
 
@@ -201,12 +201,12 @@ func (sr *stagingContainerWriter) setDecoratedValue(_ string, _ reflect.Type, _
 	digerror.BugPanicf("stagingContainerWriter.setDecoratedValue must never be called")
 }
 
-func (sr *stagingContainerWriter) submitGroupedValue(group string, t reflect.Type, v reflect.Value) {
+func (sr *stagingContainerWriter) submitGroupedValue(group, mapKey string, t reflect.Type, v reflect.Value) {
 	k := key{t: t, group: group}
-	sr.groups[k] = append(sr.groups[k], v)
+	sr.groups[k] = append(sr.groups[k], keyedGroupValue{key: mapKey, value: v})
 }
 
-func (sr *stagingContainerWriter) submitDecoratedGroupedValue(_ string, _ reflect.Type, _ reflect.Value) {
+func (sr *stagingContainerWriter) submitDecoratedGroupedValue(_, _ string, _ reflect.Type, _ reflect.Value) {
 	digerror.BugPanicf("stagingContainerWriter.submitDecoratedGroupedValue must never be called")
 }
 
@@ -216,9 +216,9 @@ func (sr *stagingContainerWriter) Commit(cw containerWriter) {
 		cw.setValue(k.name, k.t, v)
 	}
 
-	for k, vs := range sr.groups {
-		for _, v := range vs {
-			cw.submitGroupedValue(k.group, k.t, v)
+	for k, kgvs := range sr.groups {
+		for _, kgv := range kgvs {
+			cw.submitGroupedValue(k.group, kgv.key, k.t, kgv.value)
 		}
 	}
 }

container.go

@@ -81,12 +81,12 @@ type containerWriter interface {
 	setDecoratedValue(name string, t reflect.Type, v reflect.Value)
 
 	// submitGroupedValue submits a value to the value group with the provided
-	// name.
-	submitGroupedValue(name string, t reflect.Type, v reflect.Value)
+	// name and optional map key.
+	submitGroupedValue(name, mapKey string, t reflect.Type, v reflect.Value)
 
 	// submitDecoratedGroupedValue submits a decorated value to the value group
-	// with the provided name.
-	submitDecoratedGroupedValue(name string, t reflect.Type, v reflect.Value)
+	// with the provided name and optional map key.
+	submitDecoratedGroupedValue(name, mapKey string, t reflect.Type, v reflect.Value)
 }
 
 // containerStore provides access to the Container's underlying data store.
@@ -108,7 +108,7 @@ type containerStore interface {
 	// Retrieves all values for the provided group and type.
 	//
 	// The order in which the values are returned is undefined.
-	getValueGroup(name string, t reflect.Type) []reflect.Value
+	getValueGroup(name string, t reflect.Type) []keyedGroupValue
 
 	// Retrieves all decorated values for the provided group and type, if any.
 	getDecoratedValueGroup(name string, t reflect.Type) (reflect.Value, bool)
@@ -273,8 +273,8 @@ func (bs byTypeName) Swap(i int, j int) {
 	bs[i], bs[j] = bs[j], bs[i]
 }
 
-func shuffledCopy(rand *rand.Rand, items []reflect.Value) []reflect.Value {
-	newItems := make([]reflect.Value, len(items))
+func shuffledCopy(rand *rand.Rand, items []keyedGroupValue) []keyedGroupValue {
+	newItems := make([]keyedGroupValue, len(items))
 	for i, j := range rand.Perm(len(items)) {
 		newItems[i] = items[j]
 	}

param.go

@@ -627,6 +627,7 @@ func (pt paramGroupedSlice) Build(c containerStore) (reflect.Value, error) {
 	}
 
 	// Check if we have decorated values
+	// qjeremy(how to handle this with maps?)
 	if decoratedItems, ok := pt.getDecoratedValues(c); ok {
 		return decoratedItems, nil
 	}
@@ -645,7 +646,10 @@ func (pt paramGroupedSlice) Build(c containerStore) (reflect.Value, error) {
 	stores := c.storesToRoot()
 	result := reflect.MakeSlice(pt.Type, 0, itemCount)
 	for _, c := range stores {
-		result = reflect.Append(result, c.getValueGroup(pt.Group, pt.Type.Elem())...)
+		kgvs := c.getValueGroup(pt.Group, pt.Type.Elem())
+		for _, kgv := range kgvs {
+			result = reflect.Append(result, kgv.value)
+		}
 	}
 	return result, nil
 }

result.go

@@ -491,6 +491,9 @@ type resultGrouped struct {
 	// Name of the group as specified in the `group:".."` tag.
 	Group string
 
+	// Key if a name tag or option was provided, for populating maps
+	Key string
+
 	// Type of value produced.
 	Type reflect.Type
 
@@ -527,8 +530,10 @@ func newResultGrouped(f reflect.StructField) (resultGrouped, error) {
 	if err != nil {
 		return resultGrouped{}, err
 	}
+	name := f.Tag.Get(_nameTag)
 	rg := resultGrouped{
 		Group:   g.Name,
+		Key:     name,
 		Flatten: g.Flatten,
 		Type:    f.Type,
 	}
@@ -553,18 +558,19 @@ func newResultGrouped(f reflect.StructField) (resultGrouped, error) {
 func (rt resultGrouped) Extract(cw containerWriter, decorated bool, v reflect.Value) {
 	// Decorated values are always flattened.
 	if !decorated && !rt.Flatten {
-		cw.submitGroupedValue(rt.Group, rt.Type, v)
+		cw.submitGroupedValue(rt.Group, rt.Key, rt.Type, v)
 		for _, asType := range rt.As {
-			cw.submitGroupedValue(rt.Group, asType, v)
+			cw.submitGroupedValue(rt.Group, rt.Key, asType, v)
 		}
 		return
 	}
 
 	if decorated {
-		cw.submitDecoratedGroupedValue(rt.Group, rt.Type, v)
+		cw.submitDecoratedGroupedValue(rt.Group, rt.Key, rt.Type, v)
 		return
 	}
+	// it's not possible to provide a key for the flattening case
 	for i := 0; i < v.Len(); i++ {
-		cw.submitGroupedValue(rt.Group, rt.Type, v.Index(i))
+		cw.submitGroupedValue(rt.Group, "", rt.Type, v.Index(i))
 	}
 }

result_test.go

@@ -196,7 +196,7 @@ func TestNewResultObject(t *testing.T) {
 					FieldName:  "Writer",
 					FieldIndex: 1,
 					Results: []result{
-						resultGrouped{Group: "writers", Type: typeOfWriter},
+						resultGrouped{Group: "writers", Key: "writer1", Type: typeOfWriter},
 						resultSingle{Name: "writer1", Type: typeOfWriter},
 					},
 				},

scope.go

@@ -35,6 +35,11 @@ type ScopeOption interface {
 	noScopeOption() //yet
 }
 
+type keyedGroupValue struct {
+	key   string
+	value reflect.Value
+}
+
 // Scope is a scoped DAG of types and their dependencies.
 // A Scope may also have one or more child Scopes that inherit
 // from it.
@@ -61,10 +66,10 @@ type Scope struct {
 	values map[key]reflect.Value
 
 	// Values groups that generated directly in the Scope.
-	groups map[key][]reflect.Value
+	groups map[key][]keyedGroupValue
 
 	// Values groups that generated via decoraters in the Scope.
-	decoratedGroups map[key]reflect.Value
+	decoratedGroups map[key]keyedGroupValue
 
 	// Source of randomness.
 	rand *rand.Rand
@@ -98,8 +103,8 @@ func newScope() *Scope {
 		decorators:      make(map[key]*decoratorNode),
 		values:          make(map[key]reflect.Value),
 		decoratedValues: make(map[key]reflect.Value),
-		groups:          make(map[key][]reflect.Value),
-		decoratedGroups: make(map[key]reflect.Value),
+		groups:          make(map[key][]keyedGroupValue),
+		decoratedGroups: make(map[key]keyedGroupValue),
 		invokerFn:       defaultInvoker,
 		rand:            rand.New(rand.NewSource(time.Now().UnixNano())),
 	}
@@ -190,25 +195,25 @@ func (s *Scope) setDecoratedValue(name string, t reflect.Type, v reflect.Value)
 	s.decoratedValues[key{name: name, t: t}] = v
 }
 
-func (s *Scope) getValueGroup(name string, t reflect.Type) []reflect.Value {
+func (s *Scope) getValueGroup(name string, t reflect.Type) []keyedGroupValue {
 	items := s.groups[key{group: name, t: t}]
 	// shuffle the list so users don't rely on the ordering of grouped values
 	return shuffledCopy(s.rand, items)
 }
 
 func (s *Scope) getDecoratedValueGroup(name string, t reflect.Type) (reflect.Value, bool) {
 	items, ok := s.decoratedGroups[key{group: name, t: t}]
-	return items, ok
+	return items.value, ok
 }
 
-func (s *Scope) submitGroupedValue(name string, t reflect.Type, v reflect.Value) {
+func (s *Scope) submitGroupedValue(name, mapKey string, t reflect.Type, v reflect.Value) {
 	k := key{group: name, t: t}
-	s.groups[k] = append(s.groups[k], v)
+	s.groups[k] = append(s.groups[k], keyedGroupValue{key: mapKey, value: v})
 }
 
-func (s *Scope) submitDecoratedGroupedValue(name string, t reflect.Type, v reflect.Value) {
+func (s *Scope) submitDecoratedGroupedValue(name, mapKey string, t reflect.Type, v reflect.Value) {
 	k := key{group: name, t: t}
-	s.decoratedGroups[k] = v
+	s.decoratedGroups[k] = keyedGroupValue{key: mapKey, value: v}
 }
 
 func (s *Scope) getValueProviders(name string, t reflect.Type) []provider {
@@ -310,9 +315,9 @@ func (s *Scope) String() string {
 	for k, v := range s.values {
 		fmt.Fprintln(b, "\t", k, "=>", v)
 	}
-	for k, vs := range s.groups {
-		for _, v := range vs {
-			fmt.Fprintln(b, "\t", k, "=>", v)
+	for k, kgvs := range s.groups {
+		for _, kgv := range kgvs {
+			fmt.Fprintln(b, "\t", k, "=>", kgv.value)
 		}
 	}
 	fmt.Fprintln(b, "}")