cue: add function for Value.Attributes()

cue/types.go

@@ -2151,11 +2151,45 @@ func (v Value) Attribute(key string) Attribute {
 	return Attribute{internal.NewNonExisting(key)}
 }
 
+// Attributes reports all field attributes for the Value.
+func (v Value) Attributes() []Attribute {
+	attrs := []Attribute{}
+
+	// return empty when vertex is nil
+	if v.v == nil {
+		return attrs
+	}
+
+	// collect attribues
+	for _, a := range export.ExtractFieldAttrs(v.v.Conjuncts) {
+		key, body := a.Split()
+		A := Attribute{internal.ParseAttrBody(token.NoPos, body)}
+		A.attr.Name = key
+		attrs = append(attrs, A)
+	}
+
+	return attrs
+}
+
 // An Attribute contains meta data about a field.
 type Attribute struct {
 	attr internal.Attr
 }
 
+// Name returns the '@name(...)' for the Attribute.
+func (a *Attribute) Name() string {
+	return a.attr.Name
+}
+
+// Map returns all key/value pairs for the attribute as a map
+func (a *Attribute) Map() map[string]string {
+	ret := map[string]string{}
+	for _, F := range a.attr.Fields {
+		ret[F.Key()] = F.Value()
+	}
+	return ret
+}
+
 // Err returns the error associated with this Attribute or nil if this
 // attribute is valid.
 func (a *Attribute) Err() error {

internal/attrs.go

@@ -26,6 +26,7 @@ import (
 
 // Attr holds positional information for a single Attr.
 type Attr struct {
+	Name   string
 	Fields []keyValue
 	Err    error
 }
@@ -42,8 +43,16 @@ type keyValue struct {
 }
 
 func (kv *keyValue) Text() string { return kv.data }
-func (kv *keyValue) Key() string  { return kv.data[:kv.equal] }
+func (kv *keyValue) Key() string  {
+	if kv.equal == 0 {
+		return kv.data
+	}
+	return kv.data[:kv.equal]
+}
 func (kv *keyValue) Value() string {
+	if kv.equal == 0 {
+		return ""
+	}
 	return strings.TrimSpace(kv.data[kv.equal+1:])
 }