--- /dev/null
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pointer
+
+import (
+ "bytes"
+ "fmt"
+ "go/types"
+ "log"
+ "os"
+ "os/exec"
+ "runtime"
+ "time"
+
+ "golang.org/x/tools/container/intsets"
+)
+
+// CanPoint reports whether the type T is pointerlike,
+// for the purposes of this analysis.
+func CanPoint(T types.Type) bool {
+ switch T := T.(type) {
+ case *types.Named:
+ if obj := T.Obj(); obj.Name() == "Value" && obj.Pkg().Path() == "reflect" {
+ return true // treat reflect.Value like interface{}
+ }
+ return CanPoint(T.Underlying())
+ case *types.Pointer, *types.Interface, *types.Map, *types.Chan, *types.Signature, *types.Slice:
+ return true
+ }
+
+ return false // array struct tuple builtin basic
+}
+
+// CanHaveDynamicTypes reports whether the type T can "hold" dynamic types,
+// i.e. is an interface (incl. reflect.Type) or a reflect.Value.
+//
+func CanHaveDynamicTypes(T types.Type) bool {
+ switch T := T.(type) {
+ case *types.Named:
+ if obj := T.Obj(); obj.Name() == "Value" && obj.Pkg().Path() == "reflect" {
+ return true // reflect.Value
+ }
+ return CanHaveDynamicTypes(T.Underlying())
+ case *types.Interface:
+ return true
+ }
+ return false
+}
+
+func isInterface(T types.Type) bool { return types.IsInterface(T) }
+
+// mustDeref returns the element type of its argument, which must be a
+// pointer; panic ensues otherwise.
+func mustDeref(typ types.Type) types.Type {
+ return typ.Underlying().(*types.Pointer).Elem()
+}
+
+// deref returns a pointer's element type; otherwise it returns typ.
+func deref(typ types.Type) types.Type {
+ if p, ok := typ.Underlying().(*types.Pointer); ok {
+ return p.Elem()
+ }
+ return typ
+}
+
+// A fieldInfo describes one subelement (node) of the flattening-out
+// of a type T: the subelement's type and its path from the root of T.
+//
+// For example, for this type:
+// type line struct{ points []struct{x, y int} }
+// flatten() of the inner struct yields the following []fieldInfo:
+// struct{ x, y int } ""
+// int ".x"
+// int ".y"
+// and flatten(line) yields:
+// struct{ points []struct{x, y int} } ""
+// struct{ x, y int } ".points[*]"
+// int ".points[*].x
+// int ".points[*].y"
+//
+type fieldInfo struct {
+ typ types.Type
+
+ // op and tail describe the path to the element (e.g. ".a#2.b[*].c").
+ op interface{} // *Array: true; *Tuple: int; *Struct: *types.Var; *Named: nil
+ tail *fieldInfo
+}
+
+// path returns a user-friendly string describing the subelement path.
+//
+func (fi *fieldInfo) path() string {
+ var buf bytes.Buffer
+ for p := fi; p != nil; p = p.tail {
+ switch op := p.op.(type) {
+ case bool:
+ fmt.Fprintf(&buf, "[*]")
+ case int:
+ fmt.Fprintf(&buf, "#%d", op)
+ case *types.Var:
+ fmt.Fprintf(&buf, ".%s", op.Name())
+ }
+ }
+ return buf.String()
+}
+
+// flatten returns a list of directly contained fields in the preorder
+// traversal of the type tree of t. The resulting elements are all
+// scalars (basic types or pointerlike types), except for struct/array
+// "identity" nodes, whose type is that of the aggregate.
+//
+// reflect.Value is considered pointerlike, similar to interface{}.
+//
+// Callers must not mutate the result.
+//
+func (a *analysis) flatten(t types.Type) []*fieldInfo {
+ fl, ok := a.flattenMemo[t]
+ if !ok {
+ switch t := t.(type) {
+ case *types.Named:
+ u := t.Underlying()
+ if isInterface(u) {
+ // Debuggability hack: don't remove
+ // the named type from interfaces as
+ // they're very verbose.
+ fl = append(fl, &fieldInfo{typ: t})
+ } else {
+ fl = a.flatten(u)
+ }
+
+ case *types.Basic,
+ *types.Signature,
+ *types.Chan,
+ *types.Map,
+ *types.Interface,
+ *types.Slice,
+ *types.Pointer:
+ fl = append(fl, &fieldInfo{typ: t})
+
+ case *types.Array:
+ fl = append(fl, &fieldInfo{typ: t}) // identity node
+ for _, fi := range a.flatten(t.Elem()) {
+ fl = append(fl, &fieldInfo{typ: fi.typ, op: true, tail: fi})
+ }
+
+ case *types.Struct:
+ fl = append(fl, &fieldInfo{typ: t}) // identity node
+ for i, n := 0, t.NumFields(); i < n; i++ {
+ f := t.Field(i)
+ for _, fi := range a.flatten(f.Type()) {
+ fl = append(fl, &fieldInfo{typ: fi.typ, op: f, tail: fi})
+ }
+ }
+
+ case *types.Tuple:
+ // No identity node: tuples are never address-taken.
+ n := t.Len()
+ if n == 1 {
+ // Don't add a fieldInfo link for singletons,
+ // e.g. in params/results.
+ fl = append(fl, a.flatten(t.At(0).Type())...)
+ } else {
+ for i := 0; i < n; i++ {
+ f := t.At(i)
+ for _, fi := range a.flatten(f.Type()) {
+ fl = append(fl, &fieldInfo{typ: fi.typ, op: i, tail: fi})
+ }
+ }
+ }
+
+ default:
+ panic(fmt.Sprintf("cannot flatten unsupported type %T", t))
+ }
+
+ a.flattenMemo[t] = fl
+ }
+
+ return fl
+}
+
+// sizeof returns the number of pointerlike abstractions (nodes) in the type t.
+func (a *analysis) sizeof(t types.Type) uint32 {
+ return uint32(len(a.flatten(t)))
+}
+
+// shouldTrack reports whether object type T contains (recursively)
+// any fields whose addresses should be tracked.
+func (a *analysis) shouldTrack(T types.Type) bool {
+ if a.track == trackAll {
+ return true // fast path
+ }
+ track, ok := a.trackTypes[T]
+ if !ok {
+ a.trackTypes[T] = true // break cycles conservatively
+ // NB: reflect.Value, reflect.Type are pre-populated to true.
+ for _, fi := range a.flatten(T) {
+ switch ft := fi.typ.Underlying().(type) {
+ case *types.Interface, *types.Signature:
+ track = true // needed for callgraph
+ case *types.Basic:
+ // no-op
+ case *types.Chan:
+ track = a.track&trackChan != 0 || a.shouldTrack(ft.Elem())
+ case *types.Map:
+ track = a.track&trackMap != 0 || a.shouldTrack(ft.Key()) || a.shouldTrack(ft.Elem())
+ case *types.Slice:
+ track = a.track&trackSlice != 0 || a.shouldTrack(ft.Elem())
+ case *types.Pointer:
+ track = a.track&trackPtr != 0 || a.shouldTrack(ft.Elem())
+ case *types.Array, *types.Struct:
+ // No need to look at field types since they will follow (flattened).
+ default:
+ // Includes *types.Tuple, which are never address-taken.
+ panic(ft)
+ }
+ if track {
+ break
+ }
+ }
+ a.trackTypes[T] = track
+ if !track && a.log != nil {
+ fmt.Fprintf(a.log, "\ttype not tracked: %s\n", T)
+ }
+ }
+ return track
+}
+
+// offsetOf returns the (abstract) offset of field index within struct
+// or tuple typ.
+func (a *analysis) offsetOf(typ types.Type, index int) uint32 {
+ var offset uint32
+ switch t := typ.Underlying().(type) {
+ case *types.Tuple:
+ for i := 0; i < index; i++ {
+ offset += a.sizeof(t.At(i).Type())
+ }
+ case *types.Struct:
+ offset++ // the node for the struct itself
+ for i := 0; i < index; i++ {
+ offset += a.sizeof(t.Field(i).Type())
+ }
+ default:
+ panic(fmt.Sprintf("offsetOf(%s : %T)", typ, typ))
+ }
+ return offset
+}
+
+// sliceToArray returns the type representing the arrays to which
+// slice type slice points.
+func sliceToArray(slice types.Type) *types.Array {
+ return types.NewArray(slice.Underlying().(*types.Slice).Elem(), 1)
+}
+
+// Node set -------------------------------------------------------------------
+
+type nodeset struct {
+ intsets.Sparse
+}
+
+func (ns *nodeset) String() string {
+ var buf bytes.Buffer
+ buf.WriteRune('{')
+ var space [50]int
+ for i, n := range ns.AppendTo(space[:0]) {
+ if i > 0 {
+ buf.WriteString(", ")
+ }
+ buf.WriteRune('n')
+ fmt.Fprintf(&buf, "%d", n)
+ }
+ buf.WriteRune('}')
+ return buf.String()
+}
+
+func (ns *nodeset) add(n nodeid) bool {
+ return ns.Sparse.Insert(int(n))
+}
+
+func (ns *nodeset) addAll(y *nodeset) bool {
+ return ns.UnionWith(&y.Sparse)
+}
+
+// Profiling & debugging -------------------------------------------------------
+
+var timers = make(map[string]time.Time)
+
+func start(name string) {
+ if debugTimers {
+ timers[name] = time.Now()
+ log.Printf("%s...\n", name)
+ }
+}
+
+func stop(name string) {
+ if debugTimers {
+ log.Printf("%s took %s\n", name, time.Since(timers[name]))
+ }
+}
+
+// diff runs the command "diff a b" and reports its success.
+func diff(a, b string) bool {
+ var cmd *exec.Cmd
+ switch runtime.GOOS {
+ case "plan9":
+ cmd = exec.Command("/bin/diff", "-c", a, b)
+ default:
+ cmd = exec.Command("/usr/bin/diff", "-u", a, b)
+ }
+ cmd.Stdout = os.Stderr
+ cmd.Stderr = os.Stderr
+ return cmd.Run() == nil
+}
projects / dotfiles / .git / blobdiff