go/ast: simplify walking lists with generics

Change-Id: Ib6e3fd9c5788400420555b2889e6dba0853446bc
Reviewed-on: https://go-review.googlesource.com/c/go/+/582495
Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

diff --git a/src/go/ast/walk.go b/src/go/ast/walk.go
index 87e190f08adaae55319fb788fa98269536a16d5c..59e6fc174d6eb5f4248a6023acb5b2eeb293b275 100644 (file)
--- a/src/go/ast/walk.go
+++ b/src/go/ast/walk.go
@@ -13,29 +13,9 @@ type Visitor interface {
        Visit(node Node) (w Visitor)
 }
 
-// Helper functions for common node lists. They may be empty.
-
-func walkIdentList(v Visitor, list []*Ident) {
-       for _, x := range list {
-               Walk(v, x)
-       }
-}
-
-func walkExprList(v Visitor, list []Expr) {
-       for _, x := range list {
-               Walk(v, x)
-       }
-}
-
-func walkStmtList(v Visitor, list []Stmt) {
-       for _, x := range list {
-               Walk(v, x)
-       }
-}
-
-func walkDeclList(v Visitor, list []Decl) {
-       for _, x := range list {
-               Walk(v, x)
+func walkList[N Node](v Visitor, list []N) {
+       for _, node := range list {
+               Walk(v, node)
        }
 }
 
@@ -61,15 +41,13 @@ func Walk(v Visitor, node Node) {
                // nothing to do
 
        case *CommentGroup:
-               for _, c := range n.List {
-                       Walk(v, c)
-               }
+               walkList(v, n.List)
 
        case *Field:
                if n.Doc != nil {
                        Walk(v, n.Doc)
                }
-               walkIdentList(v, n.Names)
+               walkList(v, n.Names)
                if n.Type != nil {
                        Walk(v, n.Type)
                }
@@ -81,9 +59,7 @@ func Walk(v Visitor, node Node) {
                }
 
        case *FieldList:
-               for _, f := range n.List {
-                       Walk(v, f)
-               }
+               walkList(v, n.List)
 
        // Expressions
        case *BadExpr, *Ident, *BasicLit:
@@ -102,7 +78,7 @@ func Walk(v Visitor, node Node) {
                if n.Type != nil {
                        Walk(v, n.Type)
                }
-               walkExprList(v, n.Elts)
+               walkList(v, n.Elts)
 
        case *ParenExpr:
                Walk(v, n.X)
@@ -117,9 +93,7 @@ func Walk(v Visitor, node Node) {
 
        case *IndexListExpr:
                Walk(v, n.X)
-               for _, index := range n.Indices {
-                       Walk(v, index)
-               }
+               walkList(v, n.Indices)
 
        case *SliceExpr:
                Walk(v, n.X)
@@ -141,7 +115,7 @@ func Walk(v Visitor, node Node) {
 
        case *CallExpr:
                Walk(v, n.Fun)
-               walkExprList(v, n.Args)
+               walkList(v, n.Args)
 
        case *StarExpr:
                Walk(v, n.X)
@@ -213,8 +187,8 @@ func Walk(v Visitor, node Node) {
                Walk(v, n.X)
 
        case *AssignStmt:
-               walkExprList(v, n.Lhs)
-               walkExprList(v, n.Rhs)
+               walkList(v, n.Lhs)
+               walkList(v, n.Rhs)
 
        case *GoStmt:
                Walk(v, n.Call)
@@ -223,7 +197,7 @@ func Walk(v Visitor, node Node) {
                Walk(v, n.Call)
 
        case *ReturnStmt:
-               walkExprList(v, n.Results)
+               walkList(v, n.Results)
 
        case *BranchStmt:
                if n.Label != nil {
@@ -231,7 +205,7 @@ func Walk(v Visitor, node Node) {
                }
 
        case *BlockStmt:
-               walkStmtList(v, n.List)
+               walkList(v, n.List)
 
        case *IfStmt:
                if n.Init != nil {
@@ -244,8 +218,8 @@ func Walk(v Visitor, node Node) {
                }
 
        case *CaseClause:
-               walkExprList(v, n.List)
-               walkStmtList(v, n.Body)
+               walkList(v, n.List)
+               walkList(v, n.Body)
 
        case *SwitchStmt:
                if n.Init != nil {
@@ -267,7 +241,7 @@ func Walk(v Visitor, node Node) {
                if n.Comm != nil {
                        Walk(v, n.Comm)
                }
-               walkStmtList(v, n.Body)
+               walkList(v, n.Body)
 
        case *SelectStmt:
                Walk(v, n.Body)
@@ -311,11 +285,11 @@ func Walk(v Visitor, node Node) {
                if n.Doc != nil {
                        Walk(v, n.Doc)
                }
-               walkIdentList(v, n.Names)
+               walkList(v, n.Names)
                if n.Type != nil {
                        Walk(v, n.Type)
                }
-               walkExprList(v, n.Values)
+               walkList(v, n.Values)
                if n.Comment != nil {
                        Walk(v, n.Comment)
                }
@@ -340,9 +314,7 @@ func Walk(v Visitor, node Node) {
                if n.Doc != nil {
                        Walk(v, n.Doc)
                }
-               for _, s := range n.Specs {
-                       Walk(v, s)
-               }
+               walkList(v, n.Specs)
 
        case *FuncDecl:
                if n.Doc != nil {
@@ -363,7 +335,7 @@ func Walk(v Visitor, node Node) {
                        Walk(v, n.Doc)
                }
                Walk(v, n.Name)
-               walkDeclList(v, n.Decls)
+               walkList(v, n.Decls)
                // don't walk n.Comments - they have been
                // visited already through the individual
                // nodes