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util/codegen: add ContainsPointers

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And use it in cmd/cloner.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
This commit is contained in:
Josh Bleecher Snyder 2021-09-17 11:29:17 -07:00 committed by Josh Bleecher Snyder
parent d5a0a4297e
commit 3cd85c0ca6
2 changed files with 40 additions and 36 deletions
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41
cmd/cloner/cloner.go
View File

@ -156,7 +156,7 @@ func gen(buf *bytes.Buffer, imports map[string]struct{}, typ *types.Named, thisP
for i := 0; i < t.NumFields(); i++ {
fname := t.Field(i).Name()
ft := t.Field(i).Type()
if !containsPointers(ft) {
if !codegen.ContainsPointers(ft) {
continue
}
if named, _ := ft.(*types.Named); named != nil && !hasBasicUnderlying(ft) {
@ -165,7 +165,7 @@ func gen(buf *bytes.Buffer, imports map[string]struct{}, typ *types.Named, thisP
}
switch ft := ft.Underlying().(type) {
case *types.Slice:
if containsPointers(ft.Elem()) {
if codegen.ContainsPointers(ft.Elem()) {
n := importedName(ft.Elem())
writef("dst.%s = make([]%s, len(src.%s))", fname, n, fname)
writef("for i := range dst.%s {", fname)
@ -179,7 +179,7 @@ func gen(buf *bytes.Buffer, imports map[string]struct{}, typ *types.Named, thisP
writef("dst.%s = append(src.%s[:0:0], src.%s...)", fname, fname, fname)
}
case *types.Pointer:
if named, _ := ft.Elem().(*types.Named); named != nil && containsPointers(ft.Elem()) {
if named, _ := ft.Elem().(*types.Named); named != nil && codegen.ContainsPointers(ft.Elem()) {
writef("dst.%s = src.%s.Clone()", fname, fname)
continue
}
@ -187,7 +187,7 @@ func gen(buf *bytes.Buffer, imports map[string]struct{}, typ *types.Named, thisP
writef("if dst.%s != nil {", fname)
writef("\tdst.%s = new(%s)", fname, n)
writef("\t*dst.%s = *src.%s", fname, fname)
if containsPointers(ft.Elem()) {
if codegen.ContainsPointers(ft.Elem()) {
writef("\t" + `panic("TODO pointers in pointers")`)
}
writef("}")
@ -201,7 +201,7 @@ func gen(buf *bytes.Buffer, imports map[string]struct{}, typ *types.Named, thisP
// the key is always copied.
writef("\t\tdst.%s[k] = append([]%s{}, src.%s[k]...)", fname, n, fname)
writef("\t}")
} else if containsPointers(ft.Elem()) {
} else if codegen.ContainsPointers(ft.Elem()) {
writef("\tfor k, v := range src.%s {", fname)
writef("\t\tdst.%s[k] = v.Clone()", fname)
writef("\t}")
@ -229,34 +229,3 @@ func hasBasicUnderlying(typ types.Type) bool {
return false
}
}
func containsPointers(typ types.Type) bool {
switch typ.String() {
case "time.Time":
// time.Time contains a pointer that does not need copying
return false
case "inet.af/netaddr.IP":
return false
}
switch ft := typ.Underlying().(type) {
case *types.Array:
return containsPointers(ft.Elem())
case *types.Chan:
return true
case *types.Interface:
return true // a little too broad
case *types.Map:
return true
case *types.Pointer:
return true
case *types.Slice:
return true
case *types.Struct:
for i := 0; i < ft.NumFields(); i++ {
if containsPointers(ft.Field(i).Type()) {
return true
}
}
}
return false
}

35
util/codegen/codegen.go
View File

@ -109,3 +109,38 @@ func importedName(t types.Type, thisPkg *types.Package) (qualifiedName, importPk
}
return types.TypeString(t, qual), importPkg
}
// ContainsPointers reports whether typ contains any pointers,
// either explicitly or implicitly.
// It has special handling for some types that contain pointers
// that we know are free from memory aliasing/mutation concerns.
func ContainsPointers(typ types.Type) bool {
switch typ.String() {
case "time.Time":
// time.Time contains a pointer that does not need copying
return false
case "inet.af/netaddr.IP":
return false
}
switch ft := typ.Underlying().(type) {
case *types.Array:
return ContainsPointers(ft.Elem())
case *types.Chan:
return true
case *types.Interface:
return true // a little too broad
case *types.Map:
return true
case *types.Pointer:
return true
case *types.Slice:
return true
case *types.Struct:
for i := 0; i < ft.NumFields(); i++ {
if ContainsPointers(ft.Field(i).Type()) {
return true
}
}
}
return false
}