cmd/cloner: simplify code
Change from a single-case type switch to a type assertion with an early return. That exposes that the name arg to gen is unneeded. Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
This commit is contained in:
Josh Bleecher Snyder
Josh Bleecher Snyder
parent
d5ab18b2e6
commit
081be3e96b
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@ -85,7 +85,7 @@ func main() {
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continue
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}
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pkg := typeNameObj.Pkg()
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gen(buf, imports, typeName, typ, pkg)
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gen(buf, imports, typ, pkg)
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found = true
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}
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}
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@ -150,7 +150,7 @@ package %s
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`
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func gen(buf *bytes.Buffer, imports map[string]struct{}, name string, typ *types.Named, thisPkg *types.Package) {
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func gen(buf *bytes.Buffer, imports map[string]struct{}, typ *types.Named, thisPkg *types.Package) {
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pkgQual := func(pkg *types.Package) string {
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if thisPkg == pkg {
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return ""
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@ -162,89 +162,91 @@ func gen(buf *bytes.Buffer, imports map[string]struct{}, name string, typ *types
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return types.TypeString(t, pkgQual)
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}
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switch t := typ.Underlying().(type) {
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case *types.Struct:
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name := typ.Obj().Name()
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fmt.Fprintf(buf, "// Clone makes a deep copy of %s.\n", name)
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fmt.Fprintf(buf, "// The result aliases no memory with the original.\n")
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fmt.Fprintf(buf, "func (src *%s) Clone() *%s {\n", name, name)
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writef := func(format string, args ...interface{}) {
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fmt.Fprintf(buf, "\t"+format+"\n", args...)
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}
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writef("if src == nil {")
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writef("\treturn nil")
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writef("}")
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writef("dst := new(%s)", name)
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writef("*dst = *src")
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for i := 0; i < t.NumFields(); i++ {
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fname := t.Field(i).Name()
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ft := t.Field(i).Type()
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if !containsPointers(ft) {
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continue
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}
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if named, _ := ft.(*types.Named); named != nil && !hasBasicUnderlying(ft) {
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writef("dst.%s = *src.%s.Clone()", fname, fname)
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continue
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}
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switch ft := ft.Underlying().(type) {
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case *types.Slice:
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if containsPointers(ft.Elem()) {
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n := importedName(ft.Elem())
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writef("dst.%s = make([]%s, len(src.%s))", fname, n, fname)
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writef("for i := range dst.%s {", fname)
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if _, isPtr := ft.Elem().(*types.Pointer); isPtr {
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writef("\tdst.%s[i] = src.%s[i].Clone()", fname, fname)
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} else {
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writef("\tdst.%s[i] = *src.%s[i].Clone()", fname, fname)
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}
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writef("}")
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} else {
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writef("dst.%s = append(src.%s[:0:0], src.%s...)", fname, fname, fname)
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}
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case *types.Pointer:
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if named, _ := ft.Elem().(*types.Named); named != nil && containsPointers(ft.Elem()) {
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writef("dst.%s = src.%s.Clone()", fname, fname)
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continue
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}
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n := importedName(ft.Elem())
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writef("if dst.%s != nil {", fname)
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writef("\tdst.%s = new(%s)", fname, n)
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writef("\t*dst.%s = *src.%s", fname, fname)
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if containsPointers(ft.Elem()) {
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writef("\t" + `panic("TODO pointers in pointers")`)
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}
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writef("}")
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case *types.Map:
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writef("if dst.%s != nil {", fname)
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writef("\tdst.%s = map[%s]%s{}", fname, importedName(ft.Key()), importedName(ft.Elem()))
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if sliceType, isSlice := ft.Elem().(*types.Slice); isSlice {
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n := importedName(sliceType.Elem())
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writef("\tfor k := range src.%s {", fname)
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// use zero-length slice instead of nil to ensure
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// the key is always copied.
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writef("\t\tdst.%s[k] = append([]%s{}, src.%s[k]...)", fname, n, fname)
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writef("\t}")
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} else if containsPointers(ft.Elem()) {
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writef("\tfor k, v := range src.%s {", fname)
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writef("\t\tdst.%s[k] = v.Clone()", fname)
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writef("\t}")
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} else {
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writef("\tfor k, v := range src.%s {", fname)
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writef("\t\tdst.%s[k] = v", fname)
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writef("\t}")
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}
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writef("}")
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case *types.Struct:
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writef(`panic("TODO struct %s")`, fname)
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default:
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writef(`panic(fmt.Sprintf("TODO: %T", ft))`)
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}
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}
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writef("return dst")
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fmt.Fprintf(buf, "}\n\n")
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buf.Write(codegen.AssertStructUnchanged(t, name, "Clone", thisPkg, imports))
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t, ok := typ.Underlying().(*types.Struct)
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if !ok {
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return
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}
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name := typ.Obj().Name()
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fmt.Fprintf(buf, "// Clone makes a deep copy of %s.\n", name)
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fmt.Fprintf(buf, "// The result aliases no memory with the original.\n")
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fmt.Fprintf(buf, "func (src *%s) Clone() *%s {\n", name, name)
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writef := func(format string, args ...interface{}) {
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fmt.Fprintf(buf, "\t"+format+"\n", args...)
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}
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writef("if src == nil {")
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writef("\treturn nil")
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writef("}")
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writef("dst := new(%s)", name)
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writef("*dst = *src")
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for i := 0; i < t.NumFields(); i++ {
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fname := t.Field(i).Name()
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ft := t.Field(i).Type()
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if !containsPointers(ft) {
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continue
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}
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if named, _ := ft.(*types.Named); named != nil && !hasBasicUnderlying(ft) {
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writef("dst.%s = *src.%s.Clone()", fname, fname)
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continue
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}
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switch ft := ft.Underlying().(type) {
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case *types.Slice:
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if containsPointers(ft.Elem()) {
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n := importedName(ft.Elem())
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writef("dst.%s = make([]%s, len(src.%s))", fname, n, fname)
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writef("for i := range dst.%s {", fname)
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if _, isPtr := ft.Elem().(*types.Pointer); isPtr {
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writef("\tdst.%s[i] = src.%s[i].Clone()", fname, fname)
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} else {
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writef("\tdst.%s[i] = *src.%s[i].Clone()", fname, fname)
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}
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writef("}")
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} else {
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writef("dst.%s = append(src.%s[:0:0], src.%s...)", fname, fname, fname)
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}
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case *types.Pointer:
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if named, _ := ft.Elem().(*types.Named); named != nil && containsPointers(ft.Elem()) {
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writef("dst.%s = src.%s.Clone()", fname, fname)
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continue
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}
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n := importedName(ft.Elem())
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writef("if dst.%s != nil {", fname)
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writef("\tdst.%s = new(%s)", fname, n)
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writef("\t*dst.%s = *src.%s", fname, fname)
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if containsPointers(ft.Elem()) {
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writef("\t" + `panic("TODO pointers in pointers")`)
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}
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writef("}")
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case *types.Map:
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writef("if dst.%s != nil {", fname)
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writef("\tdst.%s = map[%s]%s{}", fname, importedName(ft.Key()), importedName(ft.Elem()))
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if sliceType, isSlice := ft.Elem().(*types.Slice); isSlice {
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n := importedName(sliceType.Elem())
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writef("\tfor k := range src.%s {", fname)
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// use zero-length slice instead of nil to ensure
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// the key is always copied.
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writef("\t\tdst.%s[k] = append([]%s{}, src.%s[k]...)", fname, n, fname)
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writef("\t}")
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} else if containsPointers(ft.Elem()) {
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writef("\tfor k, v := range src.%s {", fname)
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writef("\t\tdst.%s[k] = v.Clone()", fname)
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writef("\t}")
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} else {
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writef("\tfor k, v := range src.%s {", fname)
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writef("\t\tdst.%s[k] = v", fname)
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writef("\t}")
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}
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writef("}")
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case *types.Struct:
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writef(`panic("TODO struct %s")`, fname)
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default:
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writef(`panic(fmt.Sprintf("TODO: %T", ft))`)
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}
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}
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writef("return dst")
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fmt.Fprintf(buf, "}\n\n")
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buf.Write(codegen.AssertStructUnchanged(t, name, "Clone", thisPkg, imports))
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}
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func hasBasicUnderlying(typ types.Type) bool {
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