// Print a Markdown report of which AWS services use which AWS protocols
func main() {
	_, reverseImports, _ := importgraph.Build(&build.Default)
	u := usage.GetShortUsage(reverseImports)

	markdown := ToMarkdown(u)

	fmt.Println(markdown)
}

func (u *Unexporter) loadProgram(pkgPath string) (err error) {
	wd, err := os.Getwd()
	if err != nil {
		return err
	}

	bpkg, err := u.ctxt.Import(pkgPath, wd, build.ImportComment)
	if err != nil {
		return err
	}

	_, rev, _ := importgraph.Build(u.ctxt)
	pkgs := rev.Search(bpkg.ImportPath)

	conf := loader.Config{
		Build:       u.ctxt,
		ParserMode:  parser.ParseComments,
		AllowErrors: false,
	}

	// Optimization: don't type-check the bodies of functions in our
	// dependencies, since we only need exported package members.
	conf.TypeCheckFuncBodies = func(p string) bool {
		return pkgs[p] || pkgs[strings.TrimSuffix(p, "_test")]
	}
	for pkg := range pkgs {
		conf.ImportWithTests(pkg)
	}

	u.prog, err = conf.Load()
	if err != nil {
		return
	}
	for p, info := range u.prog.AllPackages {
		if p.Path() == bpkg.ImportPath {
			u.pkgInfo = info
			break
		}
	}

	return
}

func scanWorkspace(ctxt *build.Context, path string) []string {
	// Scan the workspace and build the import graph.
	_, rev, errors := importgraph.Build(ctxt)
	if len(errors) > 0 {
		// With a large GOPATH tree, errors are inevitable.
		// Report them but proceed.
		log.Printf("While scanning Go workspace:\n")
		for path, err := range errors {
			log.Printf("Package %q: %s.\n", path, err)
		}
	}

	// Enumerate the set of potentially affected packages.
	var affectedPackages []string
	// External test packages are never imported,
	// so they will never appear in the graph.
	for pkg := range rev.Search(path) {
		affectedPackages = append(affectedPackages, pkg)
	}
	return affectedPackages
}

func Main(ctxt *build.Context, offsetFlag, fromFlag, to string) error {
	// -- Parse the -from or -offset specifier ----------------------------

	if (offsetFlag == "") == (fromFlag == "") {
		return fmt.Errorf("exactly one of the -from and -offset flags must be specified")
	}

	if !isValidIdentifier(to) {
		return fmt.Errorf("-to %q: not a valid identifier", to)
	}

	var spec *spec
	var err error
	if fromFlag != "" {
		spec, err = parseFromFlag(ctxt, fromFlag)
	} else {
		spec, err = parseOffsetFlag(ctxt, offsetFlag)
	}
	if err != nil {
		return err
	}

	if spec.fromName == to {
		return fmt.Errorf("the old and new names are the same: %s", to)
	}

	// -- Load the program consisting of the initial package  -------------

	iprog, err := loadProgram(ctxt, map[string]bool{spec.pkg: true})
	if err != nil {
		return err
	}

	fromObjects, err := findFromObjects(iprog, spec)
	if err != nil {
		return err
	}

	// -- Load a larger program, for global renamings ---------------------

	if requiresGlobalRename(fromObjects, to) {
		// For a local refactoring, we needn't load more
		// packages, but if the renaming affects the package's
		// API, we we must load all packages that depend on the
		// package defining the object, plus their tests.

		if Verbose {
			fmt.Fprintln(os.Stderr, "Potentially global renaming; scanning workspace...")
		}

		// Scan the workspace and build the import graph.
		_, rev, errors := importgraph.Build(ctxt)
		if len(errors) > 0 {
			fmt.Fprintf(os.Stderr, "While scanning Go workspace:\n")
			for path, err := range errors {
				fmt.Fprintf(os.Stderr, "Package %q: %s.\n", path, err)
			}
		}

		// Enumerate the set of potentially affected packages.
		affectedPackages := make(map[string]bool)
		for _, obj := range fromObjects {
			// External test packages are never imported,
			// so they will never appear in the graph.
			for path := range rev.Search(obj.Pkg().Path()) {
				affectedPackages[path] = true
			}
		}

		// TODO(adonovan): allow the user to specify the scope,
		// or -ignore patterns?  Computing the scope when we
		// don't (yet) support inputs containing errors can make
		// the tool rather brittle.

		// Re-load the larger program.
		iprog, err = loadProgram(ctxt, affectedPackages)
		if err != nil {
			return err
		}

		fromObjects, err = findFromObjects(iprog, spec)
		if err != nil {
			return err
		}
	}

	// -- Do the renaming -------------------------------------------------

	r := renamer{
		iprog:        iprog,
		objsToUpdate: make(map[types.Object]bool),
		to:           to,
		packages:     make(map[*types.Package]*loader.PackageInfo),
	}

	// A renaming initiated at an interface method indicates the
	// intention to rename abstract and concrete methods as needed
	// to preserve assignability.
	for _, obj := range fromObjects {
		if obj, ok := obj.(*types.Func); ok {
//.........这里部分代码省略.........

// Implements displays the "implements" relation as it pertains to the
// selected type.
// If the selection is a method, 'implements' displays
// the corresponding methods of the types that would have been reported
// by an implements query on the receiver type.
//
func implements(q *Query) error {
	lconf := loader.Config{Build: q.Build}
	allowErrors(&lconf)

	qpkg, err := importQueryPackage(q.Pos, &lconf)
	if err != nil {
		return err
	}

	// Set the packages to search.
	if len(q.Scope) > 0 {
		// Inspect all packages in the analysis scope, if specified.
		if err := setPTAScope(&lconf, q.Scope); err != nil {
			return err
		}
	} else {
		// Otherwise inspect the forward and reverse
		// transitive closure of the selected package.
		// (In theory even this is incomplete.)
		_, rev, _ := importgraph.Build(q.Build)
		for path := range rev.Search(qpkg) {
			lconf.ImportWithTests(path)
		}

		// TODO(adonovan): for completeness, we should also
		// type-check and inspect function bodies in all
		// imported packages.  This would be expensive, but we
		// could optimize by skipping functions that do not
		// contain type declarations.  This would require
		// changing the loader's TypeCheckFuncBodies hook to
		// provide the []*ast.File.
	}

	// Load/parse/type-check the program.
	lprog, err := lconf.Load()
	if err != nil {
		return err
	}
	q.Fset = lprog.Fset

	qpos, err := parseQueryPos(lprog, q.Pos, false)
	if err != nil {
		return err
	}

	// Find the selected type.
	path, action := findInterestingNode(qpos.info, qpos.path)

	var method *types.Func
	var T types.Type // selected type (receiver if method != nil)

	switch action {
	case actionExpr:
		// method?
		if id, ok := path[0].(*ast.Ident); ok {
			if obj, ok := qpos.info.ObjectOf(id).(*types.Func); ok {
				recv := obj.Type().(*types.Signature).Recv()
				if recv == nil {
					return fmt.Errorf("this function is not a method")
				}
				method = obj
				T = recv.Type()
			}
		}
	case actionType:
		T = qpos.info.TypeOf(path[0].(ast.Expr))
	}
	if T == nil {
		return fmt.Errorf("no type or method here")
	}

	// Find all named types, even local types (which can have
	// methods via promotion) and the built-in "error".
	var allNamed []types.Type
	for _, info := range lprog.AllPackages {
		for _, obj := range info.Defs {
			if obj, ok := obj.(*types.TypeName); ok {
				allNamed = append(allNamed, obj.Type())
			}
		}
	}
	allNamed = append(allNamed, types.Universe.Lookup("error").Type())

	var msets typeutil.MethodSetCache

	// Test each named type.
	var to, from, fromPtr []types.Type
	for _, U := range allNamed {
		if isInterface(T) {
			if msets.MethodSet(T).Len() == 0 {
				continue // empty interface
			}
			if isInterface(U) {
				if msets.MethodSet(U).Len() == 0 {
//.........这里部分代码省略.........

// globalReferrers reports references throughout the entire workspace to the
// object at the specified source position.  Its defining package is defpkg,
// and the query package is qpkg.  isPkgLevel indicates whether the object
// is defined at package-level.
func globalReferrers(q *Query, qpkg, defpkg string, objposn token.Position, isPkgLevel bool) error {
	// Scan the workspace and build the import graph.
	// Ignore broken packages.
	_, rev, _ := importgraph.Build(q.Build)

	// Find the set of packages that depend on defpkg.
	// Only function bodies in those packages need type-checking.
	var users map[string]bool
	if isPkgLevel {
		users = rev[defpkg] // direct importers
		if users == nil {
			users = make(map[string]bool)
		}
		users[defpkg] = true // plus the defining package itself
	} else {
		users = rev.Search(defpkg) // transitive importers
	}

	// Prepare to load the larger program.
	fset := token.NewFileSet()
	lconf := loader.Config{
		Fset:  fset,
		Build: q.Build,
		TypeCheckFuncBodies: func(p string) bool {
			return users[strings.TrimSuffix(p, "_test")]
		},
	}
	allowErrors(&lconf)

	// The importgraph doesn't treat external test packages
	// as separate nodes, so we must use ImportWithTests.
	for path := range users {
		lconf.ImportWithTests(path)
	}

	// The remainder of this function is somewhat tricky because it
	// operates on the concurrent stream of packages observed by the
	// loader's AfterTypeCheck hook.  Most of guru's helper
	// functions assume the entire program has already been loaded,
	// so we can't use them here.
	// TODO(adonovan): smooth things out once the other changes have landed.

	// Results are reported concurrently from within the
	// AfterTypeCheck hook.  The program may provide a useful stream
	// of information even if the user doesn't let the program run
	// to completion.

	var (
		mu    sync.Mutex
		qobj  types.Object
		qinfo *loader.PackageInfo // info for qpkg
	)

	// For efficiency, we scan each package for references
	// just after it has been type-checked.  The loader calls
	// AfterTypeCheck (concurrently), providing us with a stream of
	// packages.
	lconf.AfterTypeCheck = func(info *loader.PackageInfo, files []*ast.File) {
		// AfterTypeCheck may be called twice for the same package due to augmentation.

		// Only inspect packages that depend on the declaring package
		// (and thus were type-checked).
		if lconf.TypeCheckFuncBodies(info.Pkg.Path()) {
			// Record the query object and its package when we see it.
			mu.Lock()
			if qobj == nil && info.Pkg.Path() == defpkg {
				// Find the object by its position (slightly ugly).
				qobj = findObject(fset, &info.Info, objposn)
				if qobj == nil {
					// It really ought to be there;
					// we found it once already.
					log.Fatalf("object at %s not found in package %s",
						objposn, defpkg)
				}

				// Object found.
				qinfo = info
				q.Output(fset, &referrersInitialResult{
					qinfo: qinfo,
					obj:   qobj,
				})
			}
			obj := qobj
			mu.Unlock()

			// Look for references to the query object.
			if obj != nil {
				outputUses(q, fset, usesOf(obj, info), info.Pkg)
			}
		}

		clearInfoFields(info) // save memory
	}

	lconf.Load() // ignore error

//.........这里部分代码省略.........

// packageReferrers reports all references to the specified package
// throughout the workspace.
func packageReferrers(q *Query, path string) error {
	// Scan the workspace and build the import graph.
	// Ignore broken packages.
	_, rev, _ := importgraph.Build(q.Build)

	// Find the set of packages that directly import the query package.
	// Only those packages need typechecking of function bodies.
	users := rev[path]

	// Load the larger program.
	fset := token.NewFileSet()
	lconf := loader.Config{
		Fset:  fset,
		Build: q.Build,
		TypeCheckFuncBodies: func(p string) bool {
			return users[strings.TrimSuffix(p, "_test")]
		},
	}
	allowErrors(&lconf)

	// The importgraph doesn't treat external test packages
	// as separate nodes, so we must use ImportWithTests.
	for path := range users {
		lconf.ImportWithTests(path)
	}

	// Subtle!  AfterTypeCheck needs no mutex for qpkg because the
	// topological import order gives us the necessary happens-before edges.
	// TODO(adonovan): what about import cycles?
	var qpkg *types.Package

	// For efficiency, we scan each package for references
	// just after it has been type-checked.  The loader calls
	// AfterTypeCheck (concurrently), providing us with a stream of
	// packages.
	lconf.AfterTypeCheck = func(info *loader.PackageInfo, files []*ast.File) {
		// AfterTypeCheck may be called twice for the same package due to augmentation.

		if info.Pkg.Path() == path && qpkg == nil {
			// Found the package of interest.
			qpkg = info.Pkg
			fakepkgname := types.NewPkgName(token.NoPos, qpkg, qpkg.Name(), qpkg)
			q.Output(fset, &referrersInitialResult{
				qinfo: info,
				obj:   fakepkgname, // bogus
			})
		}

		// Only inspect packages that directly import the
		// declaring package (and thus were type-checked).
		if lconf.TypeCheckFuncBodies(info.Pkg.Path()) {
			// Find PkgNames that refer to qpkg.
			// TODO(adonovan): perhaps more useful would be to show imports
			// of the package instead of qualified identifiers.
			var refs []*ast.Ident
			for id, obj := range info.Uses {
				if obj, ok := obj.(*types.PkgName); ok && obj.Imported() == qpkg {
					refs = append(refs, id)
				}
			}
			outputUses(q, fset, refs, info.Pkg)
		}

		clearInfoFields(info) // save memory
	}

	lconf.Load() // ignore error

	if qpkg == nil {
		log.Fatalf("query package %q not found during reloading", path)
	}

	return nil
}

// Referrers reports all identifiers that resolve to the same object
// as the queried identifier, within any package in the analysis scope.
func referrers(q *Query) error {
	lconf := loader.Config{Build: q.Build}
	allowErrors(&lconf)

	if _, err := importQueryPackage(q.Pos, &lconf); err != nil {
		return err
	}

	var id *ast.Ident
	var obj types.Object
	var lprog *loader.Program
	var pass2 bool
	var qpos *queryPos
	for {
		// Load/parse/type-check the program.
		var err error
		lprog, err = lconf.Load()
		if err != nil {
			return err
		}
		q.Fset = lprog.Fset

		qpos, err = parseQueryPos(lprog, q.Pos, false)
		if err != nil {
			return err
		}

		id, _ = qpos.path[0].(*ast.Ident)
		if id == nil {
			return fmt.Errorf("no identifier here")
		}

		obj = qpos.info.ObjectOf(id)
		if obj == nil {
			// Happens for y in "switch y := x.(type)",
			// the package declaration,
			// and unresolved identifiers.
			if _, ok := qpos.path[1].(*ast.File); ok { // package decl?
				pkg := qpos.info.Pkg
				obj = types.NewPkgName(id.Pos(), pkg, pkg.Name(), pkg)
			} else {
				return fmt.Errorf("no object for identifier: %T", qpos.path[1])
			}
		}

		if pass2 {
			break
		}

		// If the identifier is exported, we must load all packages that
		// depend transitively upon the package that defines it.
		// Treat PkgNames as exported, even though they're lowercase.
		if _, isPkg := obj.(*types.PkgName); !(isPkg || obj.Exported()) {
			break // not exported
		}

		// Scan the workspace and build the import graph.
		// Ignore broken packages.
		_, rev, _ := importgraph.Build(q.Build)

		// Re-load the larger program.
		// Create a new file set so that ...
		// External test packages are never imported,
		// so they will never appear in the graph.
		// (We must reset the Config here, not just reset the Fset field.)
		lconf = loader.Config{
			Fset:  token.NewFileSet(),
			Build: q.Build,
		}
		allowErrors(&lconf)
		for path := range rev.Search(obj.Pkg().Path()) {
			lconf.ImportWithTests(path)
		}
		pass2 = true
	}

	// Iterate over all go/types' Uses facts for the entire program.
	var refs []*ast.Ident
	for _, info := range lprog.AllPackages {
		for id2, obj2 := range info.Uses {
			if sameObj(obj, obj2) {
				refs = append(refs, id2)
			}
		}
	}
	sort.Sort(byNamePos{q.Fset, refs})

	q.result = &referrersResult{
		qpos:  qpos,
		query: id,
		obj:   obj,
		refs:  refs,
	}
	return nil
}

// Move, given a package path and a destination package path, will try
// to move the given package to the new path. The Move function will
// first check for any conflicts preventing the move, such as a
// package already existing at the destination package path. If the
// move can proceed, it builds an import graph to find all imports of
// the packages whose paths need to be renamed. This includes uses of
// the subpackages of the package to be moved as those packages will
// also need to be moved. It then renames all imports to point to the
// new paths, and then moves the packages to their new paths.
func Move(ctxt *build.Context, from, to, moveTmpl string) error {
	srcDir, err := srcDir(ctxt, from)
	if err != nil {
		return err
	}

	// This should be the only place in the program that constructs
	// file paths.
	// TODO(matloob): test on Microsoft Windows.
	fromDir := buildutil.JoinPath(ctxt, srcDir, filepath.FromSlash(from))
	toDir := buildutil.JoinPath(ctxt, srcDir, filepath.FromSlash(to))
	toParent := filepath.Dir(toDir)
	if !buildutil.IsDir(ctxt, toParent) {
		return fmt.Errorf("parent directory does not exist for path %s", toDir)
	}

	// Build the import graph and figure out which packages to update.
	fwd, rev, errors := importgraph.Build(ctxt)
	if len(errors) > 0 {
		fmt.Fprintf(os.Stderr, "While scanning Go workspace:\n")
		for path, err := range errors {
			fmt.Fprintf(os.Stderr, "Package %q: %s.\n", path, err)
		}
		return fmt.Errorf("failed to construct import graph")
	}

	// Determine the affected packages---the set of packages whose import
	// statements need updating.
	affectedPackages := map[string]bool{from: true}
	destinations := map[string]string{} // maps old dir to new dir
	for pkg := range subpackages(ctxt, srcDir, from) {
		for r := range rev[pkg] {
			affectedPackages[r] = true
		}
		destinations[pkg] = strings.Replace(pkg,
			// Ensure directories have a trailing "/".
			filepath.Join(from, ""), filepath.Join(to, ""), 1)
	}

	// Load all the affected packages.
	iprog, err := loadProgram(ctxt, affectedPackages)
	if err != nil {
		return err
	}

	// Prepare the move command, if one was supplied.
	var cmd string
	if moveTmpl != "" {
		if cmd, err = moveCmd(moveTmpl, fromDir, toDir); err != nil {
			return err
		}
	}

	m := mover{
		ctxt:             ctxt,
		fwd:              fwd,
		rev:              rev,
		iprog:            iprog,
		from:             from,
		to:               to,
		fromDir:          fromDir,
		toDir:            toDir,
		affectedPackages: affectedPackages,
		destinations:     destinations,
		cmd:              cmd,
	}

	if err := m.checkValid(); err != nil {
		return err
	}

	m.move()

	return nil
}

func TestBuild(t *testing.T) {
	forward, reverse, errors := importgraph.Build(&build.Default)

	// Test direct edges.
	// We throw in crypto/hmac to prove that external test files
	// (such as this one) are inspected.
	for _, p := range []string{"go/build", "testing", "crypto/hmac"} {
		if !forward[this][p] {
			t.Errorf("forward[importgraph][%s] not found", p)
		}
		if !reverse[p][this] {
			t.Errorf("reverse[%s][importgraph] not found", p)
		}
	}

	// Test non-existent direct edges
	for _, p := range []string{"errors", "reflect"} {
		if forward[this][p] {
			t.Errorf("unexpected: forward[importgraph][%s] found", p)
		}
		if reverse[p][this] {
			t.Errorf("unexpected: reverse[%s][importgraph] found", p)
		}
	}

	// Test Search is reflexive.
	if !forward.Search(this)[this] {
		t.Errorf("irreflexive: forward.Search(importgraph)[importgraph] not found")
	}
	if !reverse.Search(this)[this] {
		t.Errorf("irrefexive: reverse.Search(importgraph)[importgraph] not found")
	}

	// Test Search is transitive.  (There is no direct edge to these packages.)
	for _, p := range []string{"errors", "reflect", "unsafe"} {
		if !forward.Search(this)[p] {
			t.Errorf("intransitive: forward.Search(importgraph)[%s] not found", p)
		}
		if !reverse.Search(p)[this] {
			t.Errorf("intransitive: reverse.Search(%s)[importgraph] not found", p)
		}
	}

	// Test strongly-connected components.  Because A's external
	// test package can depend on B, and vice versa, most of the
	// standard libraries are mutually dependent when their external
	// tests are considered.
	//
	// For any nodes x, y in the same SCC, y appears in the results
	// of both forward and reverse searches starting from x
	if !forward.Search("fmt")["io"] ||
		!forward.Search("io")["fmt"] ||
		!reverse.Search("fmt")["io"] ||
		!reverse.Search("io")["fmt"] {
		t.Errorf("fmt and io are not mutually reachable despite being in the same SCC")
	}

	// debugging
	if false {
		for path, err := range errors {
			t.Logf("%s: %s", path, err)
		}
		printSorted := func(direction string, g importgraph.Graph, start string) {
			t.Log(direction)
			var pkgs []string
			for pkg := range g.Search(start) {
				pkgs = append(pkgs, pkg)
			}
			sort.Strings(pkgs)
			for _, pkg := range pkgs {
				t.Logf("\t%s", pkg)
			}
		}
		printSorted("forward", forward, this)
		printSorted("reverse", reverse, this)
	}
}

// runMain runs the actual command. It's an helper function so we can easily
// calls defers or return errors.  most of the functionality can be seen in
// `gorename` code source. Actually unexport is something that probably
// gorename can do for us.
//
// TODO(arslan): add tests
// TODO(arslan): add vim-go integration ;)
// TODO(arslan): check how this is acting for internal/ folders
// TODO(arslan): check how this is acting for vendor/ folders
func runMain(conf *config) error {
	if conf.importPath == "" {
		return errors.New("import path of the package must be given")
	}

	path := conf.importPath

	prog, err := loadProgram(conf.buildContext, map[string]bool{path: true})
	if err != nil {
		return err
	}

	_, rev, errors := importgraph.Build(conf.buildContext)
	if len(errors) > 0 {
		// With a large GOPATH tree, errors are inevitable.
		// Report them but proceed.
		log.Printf("while scanning Go workspace:\n")
		for path, err := range errors {
			log.Printf("Package %q: %s.\n", path, err)
		}
	}

	// Enumerate the set of potentially affected packages.
	possiblePackages := make(map[string]bool)
	for _, obj := range findExportedObjects(prog, path) {
		for path := range rev.Search(obj.Pkg().Path()) {
			possiblePackages[path] = true
		}
	}

	if conf.verbose {
		log.Println("Possible affected packages:")
		for pkg := range possiblePackages {
			log.Println("\t", pkg)
		}
	}

	// reload the program with all possible packages to fetch the packageinfo's
	globalProg, err := loadProgram(conf.buildContext, possiblePackages)
	if err != nil {
		return err
	}

	objsToUpdate := make(map[types.Object]bool, 0)
	objects := findExportedObjects(globalProg, path)

	if conf.verbose {
		log.Println("Exported identififers are:")
		for _, obj := range objects {
			log.Println("\t", obj)
		}
	}

	// filter safeObjects check which exported identifiers are used by other packages
	var safeObjects map[*ast.Ident]types.Object
	for _, info := range globalProg.Imported {
		// we only check for packages other than ours
		if info.Pkg.Path() == path {
			continue
		}

		safeObjects = filterObjects(info, objects, conf.identifiers)
	}

	// filter out identifiers which can't be renamed due any collision in our package
	for _, info := range globalProg.Imported {
		// we don't care about other packages anymore
		if info.Pkg.Path() != path {
			continue
		}

		for _, obj := range safeObjects {
			// don't include collisions
			newName := toLowerCase(obj.Name())
			if info.Pkg.Path() == obj.Pkg().Path() && hasObject(info, newName) {
				log.Printf("WARNING! can't unexport %q due collision. Identifier %q already exists.\n",
					obj.Name(), newName)
				continue
			}

			objsToUpdate[obj] = true
		}
	}

	if conf.verbose {
		log.Println("Safe to unexport identifiers are:")
		for obj := range objsToUpdate {
			log.Println("\t", obj)
		}
	}

//.........这里部分代码省略.........