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cmd/cloner: simplify code

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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>
josh/immutable-views
Josh Bleecher Snyder 3 years ago committed by Josh Bleecher Snyder
parent d5ab18b2e6
commit 081be3e96b
1 changed files with 79 additions and 77 deletions
Show Stats Download Patch File Download Diff File

156
cmd/cloner/cloner.go
Unescape Escape View File

@ -85,7 +85,7 @@ func main() {
continue
}
pkg := typeNameObj.Pkg()
gen(buf, imports, typeName, typ, pkg)
gen(buf, imports, typ, pkg)
found = true
}
}
@ -150,7 +150,7 @@ package %s
`
func gen(buf *bytes.Buffer, imports map[string]struct{}, name string, typ *types.Named, thisPkg *types.Package) {
func gen(buf *bytes.Buffer, imports map[string]struct{}, typ *types.Named, thisPkg *types.Package) {
pkgQual := func(pkg *types.Package) string {
if thisPkg == pkg {
return ""
@ -162,89 +162,91 @@ func gen(buf *bytes.Buffer, imports map[string]struct{}, name string, typ *types
return types.TypeString(t, pkgQual)
}
switch t := typ.Underlying().(type) {
case *types.Struct:
name := typ.Obj().Name()
fmt.Fprintf(buf, "// Clone makes a deep copy of %s.\n", name)
fmt.Fprintf(buf, "// The result aliases no memory with the original.\n")
fmt.Fprintf(buf, "func (src *%s) Clone() *%s {\n", name, name)
writef := func(format string, args ...interface{}) {
fmt.Fprintf(buf, "\t"+format+"\n", args...)
t, ok := typ.Underlying().(*types.Struct)
if !ok {
return
}
name := typ.Obj().Name()
fmt.Fprintf(buf, "// Clone makes a deep copy of %s.\n", name)
fmt.Fprintf(buf, "// The result aliases no memory with the original.\n")
fmt.Fprintf(buf, "func (src *%s) Clone() *%s {\n", name, name)
writef := func(format string, args ...interface{}) {
fmt.Fprintf(buf, "\t"+format+"\n", args...)
}
writef("if src == nil {")
writef("\treturn nil")
writef("}")
writef("dst := new(%s)", name)
writef("*dst = *src")
for i := 0; i < t.NumFields(); i++ {
fname := t.Field(i).Name()
ft := t.Field(i).Type()
if !containsPointers(ft) {
continue
}
writef("if src == nil {")
writef("\treturn nil")
writef("}")
writef("dst := new(%s)", name)
writef("*dst = *src")
for i := 0; i < t.NumFields(); i++ {
fname := t.Field(i).Name()
ft := t.Field(i).Type()
if !containsPointers(ft) {
continue
}
if named, _ := ft.(*types.Named); named != nil && !hasBasicUnderlying(ft) {
writef("dst.%s = *src.%s.Clone()", fname, fname)
continue
}
switch ft := ft.Underlying().(type) {
case *types.Slice:
if 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)
if _, isPtr := ft.Elem().(*types.Pointer); isPtr {
writef("\tdst.%s[i] = src.%s[i].Clone()", fname, fname)
} else {
writef("\tdst.%s[i] = *src.%s[i].Clone()", fname, fname)
}
writef("}")
} else {
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()) {
writef("dst.%s = src.%s.Clone()", fname, fname)
continue
}
if named, _ := ft.(*types.Named); named != nil && !hasBasicUnderlying(ft) {
writef("dst.%s = *src.%s.Clone()", fname, fname)
continue
}
switch ft := ft.Underlying().(type) {
case *types.Slice:
if containsPointers(ft.Elem()) {
n := importedName(ft.Elem())
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()) {
writef("\t" + `panic("TODO pointers in pointers")`)
}
writef("}")
case *types.Map:
writef("if dst.%s != nil {", fname)
writef("\tdst.%s = map[%s]%s{}", fname, importedName(ft.Key()), importedName(ft.Elem()))
if sliceType, isSlice := ft.Elem().(*types.Slice); isSlice {
n := importedName(sliceType.Elem())
writef("\tfor k := range src.%s {", fname)
// use zero-length slice instead of nil to ensure
// 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()) {
writef("\tfor k, v := range src.%s {", fname)
writef("\t\tdst.%s[k] = v.Clone()", fname)
writef("\t}")
writef("dst.%s = make([]%s, len(src.%s))", fname, n, fname)
writef("for i := range dst.%s {", fname)
if _, isPtr := ft.Elem().(*types.Pointer); isPtr {
writef("\tdst.%s[i] = src.%s[i].Clone()", fname, fname)
} else {
writef("\tfor k, v := range src.%s {", fname)
writef("\t\tdst.%s[k] = v", fname)
writef("\t}")
writef("\tdst.%s[i] = *src.%s[i].Clone()", fname, fname)
}
writef("}")
case *types.Struct:
writef(`panic("TODO struct %s")`, fname)
default:
writef(`panic(fmt.Sprintf("TODO: %T", ft))`)
} else {
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()) {
writef("dst.%s = src.%s.Clone()", fname, fname)
continue
}
n := importedName(ft.Elem())
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()) {
writef("\t" + `panic("TODO pointers in pointers")`)
}
writef("}")
case *types.Map:
writef("if dst.%s != nil {", fname)
writef("\tdst.%s = map[%s]%s{}", fname, importedName(ft.Key()), importedName(ft.Elem()))
if sliceType, isSlice := ft.Elem().(*types.Slice); isSlice {
n := importedName(sliceType.Elem())
writef("\tfor k := range src.%s {", fname)
// use zero-length slice instead of nil to ensure
// 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()) {
writef("\tfor k, v := range src.%s {", fname)
writef("\t\tdst.%s[k] = v.Clone()", fname)
writef("\t}")
} else {
writef("\tfor k, v := range src.%s {", fname)
writef("\t\tdst.%s[k] = v", fname)
writef("\t}")
}
writef("}")
case *types.Struct:
writef(`panic("TODO struct %s")`, fname)
default:
writef(`panic(fmt.Sprintf("TODO: %T", ft))`)
}
writef("return dst")
fmt.Fprintf(buf, "}\n\n")
buf.Write(codegen.AssertStructUnchanged(t, name, "Clone", thisPkg, imports))
}
writef("return dst")
fmt.Fprintf(buf, "}\n\n")
buf.Write(codegen.AssertStructUnchanged(t, name, "Clone", thisPkg, imports))
}
func hasBasicUnderlying(typ types.Type) bool {

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