go/ast: consider anonymous fields and set Incomplete bit when filtering ASTs

Also:
- fieldListExports: don't require internal pointer to StructType/InterfaceType node
- filterFieldLists: make structure match fieldListExports

R=rsc
CC=golang-dev
https://golang.org/cl/4527050

src/pkg/go/ast/filter.go

@@ -21,24 +21,26 @@ func identListExports(list []*Ident) []*Ident {
 }
 
 
-// isExportedType assumes that typ is a correct type.
-func isExportedType(typ Expr) bool {
-	switch t := typ.(type) {
+// fieldName assumes that x is the type of an anonymous field and
+// returns the corresponding field name. If x is not an acceptable
+// anonymous field, the result is nil.
+//
+func fieldName(x Expr) *Ident {
+	switch t := x.(type) {
 	case *Ident:
-		return t.IsExported()
-	case *ParenExpr:
-		return isExportedType(t.X)
+		return t
 	case *SelectorExpr:
-		// assume t.X is a typename
-		return t.Sel.IsExported()
+		if _, ok := t.X.(*Ident); ok {
+			return t.Sel
+		}
 	case *StarExpr:
-		return isExportedType(t.X)
+		return fieldName(t.X)
 	}
-	return false
+	return nil
 }
 
 
-func fieldListExports(fields *FieldList, incomplete *bool) {
+func fieldListExports(fields *FieldList) (removedFields bool) {
 	if fields == nil {
 		return
 	}
@@ -53,12 +55,13 @@ func fieldListExports(fields *FieldList, incomplete *bool) {
 			// fields, so this is not absolutely correct.
 			// However, this cannot be done w/o complete
 			// type information.)
-			exported = isExportedType(f.Type)
+			name := fieldName(f.Type)
+			exported = name != nil && name.IsExported()
 		} else {
 			n := len(f.Names)
 			f.Names = identListExports(f.Names)
 			if len(f.Names) < n {
-				*incomplete = true
+				removedFields = true
 			}
 			exported = len(f.Names) > 0
 		}
@@ -69,9 +72,10 @@ func fieldListExports(fields *FieldList, incomplete *bool) {
 		}
 	}
 	if j < len(list) {
-		*incomplete = true
+		removedFields = true
 	}
 	fields.List = list[0:j]
+	return
 }
 
 
@@ -90,12 +94,16 @@ func typeExports(typ Expr) {
 	case *ArrayType:
 		typeExports(t.Elt)
 	case *StructType:
-		fieldListExports(t.Fields, &t.Incomplete)
+		if fieldListExports(t.Fields) {
+			t.Incomplete = true
+		}
 	case *FuncType:
 		paramListExports(t.Params)
 		paramListExports(t.Results)
 	case *InterfaceType:
-		fieldListExports(t.Methods, &t.Incomplete)
+		if fieldListExports(t.Methods) {
+			t.Incomplete = true
+		}
 	case *MapType:
 		typeExports(t.Key)
 		typeExports(t.Value)
@@ -206,25 +214,36 @@ func filterIdentList(list []*Ident, f Filter) []*Ident {
 }
 
 
-func filterFieldList(list []*Field, f Filter) []*Field {
-	j := 0
-	for _, field := range list {
-		field.Names = filterIdentList(field.Names, f)
-		if len(field.Names) > 0 {
-			list[j] = field
-			j++
-		}
-	}
-	return list[0:j]
-}
-
-
-func filterFields(fields *FieldList, f Filter) bool {
+func filterFieldList(fields *FieldList, filter Filter) (removedFields bool) {
 	if fields == nil {
 		return false
 	}
-	fields.List = filterFieldList(fields.List, f)
-	return len(fields.List) > 0
+	list := fields.List
+	j := 0
+	for _, f := range list {
+		keepField := false
+		if len(f.Names) == 0 {
+			// anonymous field
+			name := fieldName(f.Type)
+			keepField = name != nil && filter(name.Name)
+		} else {
+			n := len(f.Names)
+			f.Names = filterIdentList(f.Names, filter)
+			if len(f.Names) < n {
+				removedFields = true
+			}
+			keepField = len(f.Names) > 0
+		}
+		if keepField {
+			list[j] = f
+			j++
+		}
+	}
+	if j < len(list) {
+		removedFields = true
+	}
+	fields.List = list[0:j]
+	return
 }
 
 
@@ -239,9 +258,15 @@ func filterSpec(spec Spec, f Filter) bool {
 		}
 		switch t := s.Type.(type) {
 		case *StructType:
-			return filterFields(t.Fields, f)
+			if filterFieldList(t.Fields, f) {
+				t.Incomplete = true
+			}
+			return len(t.Fields.List) > 0
 		case *InterfaceType:
-			return filterFields(t.Methods, f)
+			if filterFieldList(t.Methods, f) {
+				t.Incomplete = true
+			}
+			return len(t.Methods.List) > 0
 		}
 	}
 	return false