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// 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 imports
import (
"bytes"
"context"
"fmt"
"go/ast"
"go/build"
"go/parser"
"go/token"
"io/ioutil"
"os"
"path"
"path/filepath"
"reflect"
"sort"
"strconv"
"strings"
"sync"
"unicode"
"unicode/utf8"
"golang.org/x/tools/go/ast/astutil"
"golang.org/x/tools/internal/gocommand"
"golang.org/x/tools/internal/gopathwalk"
)
// importToGroup is a list of functions which map from an import path to
// a group number.
var importToGroup = []func(env *ProcessEnv, importPath string) (num int, ok bool){
func(env *ProcessEnv, importPath string) (num int, ok bool) {
if env.LocalPrefix == "" {
return
}
for _, p := range strings.Split(env.LocalPrefix, ",") {
if strings.HasPrefix(importPath, p) || strings.TrimSuffix(p, "/") == importPath {
return 3, true
}
}
return
},
func(_ *ProcessEnv, importPath string) (num int, ok bool) {
if strings.HasPrefix(importPath, "appengine") {
return 2, true
}
return
},
func(_ *ProcessEnv, importPath string) (num int, ok bool) {
if strings.Contains(importPath, ".") {
return 1, true
}
return
},
}
func importGroup(env *ProcessEnv, importPath string) int {
for _, fn := range importToGroup {
if n, ok := fn(env, importPath); ok {
return n
}
}
return 0
}
type ImportFixType int
const (
AddImport ImportFixType = iota
DeleteImport
SetImportName
)
type ImportFix struct {
// StmtInfo represents the import statement this fix will add, remove, or change.
StmtInfo ImportInfo
// IdentName is the identifier that this fix will add or remove.
IdentName string
// FixType is the type of fix this is (AddImport, DeleteImport, SetImportName).
FixType ImportFixType
Relevance int // see pkg
}
// An ImportInfo represents a single import statement.
type ImportInfo struct {
ImportPath string // import path, e.g. "crypto/rand".
Name string // import name, e.g. "crand", or "" if none.
}
// A packageInfo represents what's known about a package.
type packageInfo struct {
name string // real package name, if known.
exports map[string]bool // known exports.
}
// parseOtherFiles parses all the Go files in srcDir except filename, including
// test files if filename looks like a test.
func parseOtherFiles(fset *token.FileSet, srcDir, filename string) []*ast.File {
// This could use go/packages but it doesn't buy much, and it fails
// with https://golang.org/issue/26296 in LoadFiles mode in some cases.
considerTests := strings.HasSuffix(filename, "_test.go")
fileBase := filepath.Base(filename)
packageFileInfos, err := ioutil.ReadDir(srcDir)
if err != nil {
return nil
}
var files []*ast.File
for _, fi := range packageFileInfos {
if fi.Name() == fileBase || !strings.HasSuffix(fi.Name(), ".go") {
continue
}
if !considerTests && strings.HasSuffix(fi.Name(), "_test.go") {
continue
}
f, err := parser.ParseFile(fset, filepath.Join(srcDir, fi.Name()), nil, 0)
if err != nil {
continue
}
files = append(files, f)
}
return files
}
// addGlobals puts the names of package vars into the provided map.
func addGlobals(f *ast.File, globals map[string]bool) {
for _, decl := range f.Decls {
genDecl, ok := decl.(*ast.GenDecl)
if !ok {
continue
}
for _, spec := range genDecl.Specs {
valueSpec, ok := spec.(*ast.ValueSpec)
if !ok {
continue
}
globals[valueSpec.Names[0].Name] = true
}
}
}
// collectReferences builds a map of selector expressions, from
// left hand side (X) to a set of right hand sides (Sel).
func collectReferences(f *ast.File) references {
refs := references{}
var visitor visitFn
visitor = func(node ast.Node) ast.Visitor {
if node == nil {
return visitor
}
switch v := node.(type) {
case *ast.SelectorExpr:
xident, ok := v.X.(*ast.Ident)
if !ok {
break
}
if xident.Obj != nil {
// If the parser can resolve it, it's not a package ref.
break
}
if !ast.IsExported(v.Sel.Name) {
// Whatever this is, it's not exported from a package.
break
}
pkgName := xident.Name
r := refs[pkgName]
if r == nil {
r = make(map[string]bool)
refs[pkgName] = r
}
r[v.Sel.Name] = true
}
return visitor
}
ast.Walk(visitor, f)
return refs
}
// collectImports returns all the imports in f.
// Unnamed imports (., _) and "C" are ignored.
func collectImports(f *ast.File) []*ImportInfo {
var imports []*ImportInfo
for _, imp := range f.Imports {
var name string
if imp.Name != nil {
name = imp.Name.Name
}
if imp.Path.Value == `"C"` || name == "_" || name == "." {
continue
}
path := strings.Trim(imp.Path.Value, `"`)
imports = append(imports, &ImportInfo{
Name: name,
ImportPath: path,
})
}
return imports
}
// findMissingImport searches pass's candidates for an import that provides
// pkg, containing all of syms.
func (p *pass) findMissingImport(pkg string, syms map[string]bool) *ImportInfo {
for _, candidate := range p.candidates {
pkgInfo, ok := p.knownPackages[candidate.ImportPath]
if !ok {
continue
}
if p.importIdentifier(candidate) != pkg {
continue
}
allFound := true
for right := range syms {
if !pkgInfo.exports[right] {
allFound = false
break
}
}
if allFound {
return candidate
}
}
return nil
}
// references is set of references found in a Go file. The first map key is the
// left hand side of a selector expression, the second key is the right hand
// side, and the value should always be true.
type references map[string]map[string]bool
// A pass contains all the inputs and state necessary to fix a file's imports.
// It can be modified in some ways during use; see comments below.
type pass struct {
// Inputs. These must be set before a call to load, and not modified after.
fset *token.FileSet // fset used to parse f and its siblings.
f *ast.File // the file being fixed.
srcDir string // the directory containing f.
env *ProcessEnv // the environment to use for go commands, etc.
loadRealPackageNames bool // if true, load package names from disk rather than guessing them.
otherFiles []*ast.File // sibling files.
// Intermediate state, generated by load.
existingImports map[string]*ImportInfo
allRefs references
missingRefs references
// Inputs to fix. These can be augmented between successive fix calls.
lastTry bool // indicates that this is the last call and fix should clean up as best it can.
candidates []*ImportInfo // candidate imports in priority order.
knownPackages map[string]*packageInfo // information about all known packages.
}
// loadPackageNames saves the package names for everything referenced by imports.
func (p *pass) loadPackageNames(imports []*ImportInfo) error {
if p.env.Logf != nil {
p.env.Logf("loading package names for %v packages", len(imports))
defer func() {
p.env.Logf("done loading package names for %v packages", len(imports))
}()
}
var unknown []string
for _, imp := range imports {
if _, ok := p.knownPackages[imp.ImportPath]; ok {
continue
}
unknown = append(unknown, imp.ImportPath)
}
names, err := p.env.GetResolver().loadPackageNames(unknown, p.srcDir)
if err != nil {
return err
}
for path, name := range names {
p.knownPackages[path] = &packageInfo{
name: name,
exports: map[string]bool{},
}
}
return nil
}
// importIdentifier returns the identifier that imp will introduce. It will
// guess if the package name has not been loaded, e.g. because the source
// is not available.
func (p *pass) importIdentifier(imp *ImportInfo) string {
if imp.Name != "" {
return imp.Name
}
known := p.knownPackages[imp.ImportPath]
if known != nil && known.name != "" {
return known.name
}
return ImportPathToAssumedName(imp.ImportPath)
}
// load reads in everything necessary to run a pass, and reports whether the
// file already has all the imports it needs. It fills in p.missingRefs with the
// file's missing symbols, if any, or removes unused imports if not.
func (p *pass) load() ([]*ImportFix, bool) {
p.knownPackages = map[string]*packageInfo{}
p.missingRefs = references{}
p.existingImports = map[string]*ImportInfo{}
// Load basic information about the file in question.
p.allRefs = collectReferences(p.f)
// Load stuff from other files in the same package:
// global variables so we know they don't need resolving, and imports
// that we might want to mimic.
globals := map[string]bool{}
for _, otherFile := range p.otherFiles {
// Don't load globals from files that are in the same directory
// but a different package. Using them to suggest imports is OK.
if p.f.Name.Name == otherFile.Name.Name {
addGlobals(otherFile, globals)
}
p.candidates = append(p.candidates, collectImports(otherFile)...)
}
// Resolve all the import paths we've seen to package names, and store
// f's imports by the identifier they introduce.
imports := collectImports(p.f)
if p.loadRealPackageNames {
err := p.loadPackageNames(append(imports, p.candidates...))
if err != nil {
if p.env.Logf != nil {
p.env.Logf("loading package names: %v", err)
}
return nil, false
}
}
for _, imp := range imports {
p.existingImports[p.importIdentifier(imp)] = imp
}
// Find missing references.
for left, rights := range p.allRefs {
if globals[left] {
continue
}
_, ok := p.existingImports[left]
if !ok {
p.missingRefs[left] = rights
continue
}
}
if len(p.missingRefs) != 0 {
return nil, false
}
return p.fix()
}
// fix attempts to satisfy missing imports using p.candidates. If it finds
// everything, or if p.lastTry is true, it updates fixes to add the imports it found,
// delete anything unused, and update import names, and returns true.
func (p *pass) fix() ([]*ImportFix, bool) {
// Find missing imports.
var selected []*ImportInfo
for left, rights := range p.missingRefs {
if imp := p.findMissingImport(left, rights); imp != nil {
selected = append(selected, imp)
}
}
if !p.lastTry && len(selected) != len(p.missingRefs) {
return nil, false
}
// Found everything, or giving up. Add the new imports and remove any unused.
var fixes []*ImportFix
for _, imp := range p.existingImports {
// We deliberately ignore globals here, because we can't be sure
// they're in the same package. People do things like put multiple
// main packages in the same directory, and we don't want to
// remove imports if they happen to have the same name as a var in
// a different package.
if _, ok := p.allRefs[p.importIdentifier(imp)]; !ok {
fixes = append(fixes, &ImportFix{
StmtInfo: *imp,
IdentName: p.importIdentifier(imp),
FixType: DeleteImport,
})
continue
}
// An existing import may need to update its import name to be correct.
if name := p.importSpecName(imp); name != imp.Name {
fixes = append(fixes, &ImportFix{
StmtInfo: ImportInfo{
Name: name,
ImportPath: imp.ImportPath,
},
IdentName: p.importIdentifier(imp),
FixType: SetImportName,
})
}
}
for _, imp := range selected {
fixes = append(fixes, &ImportFix{
StmtInfo: ImportInfo{
Name: p.importSpecName(imp),
ImportPath: imp.ImportPath,
},
IdentName: p.importIdentifier(imp),
FixType: AddImport,
})
}
return fixes, true
}
// importSpecName gets the import name of imp in the import spec.
//
// When the import identifier matches the assumed import name, the import name does
// not appear in the import spec.
func (p *pass) importSpecName(imp *ImportInfo) string {
// If we did not load the real package names, or the name is already set,
// we just return the existing name.
if !p.loadRealPackageNames || imp.Name != "" {
return imp.Name
}
ident := p.importIdentifier(imp)
if ident == ImportPathToAssumedName(imp.ImportPath) {
return "" // ident not needed since the assumed and real names are the same.
}
return ident
}
// apply will perform the fixes on f in order.
func apply(fset *token.FileSet, f *ast.File, fixes []*ImportFix) {
for _, fix := range fixes {
switch fix.FixType {
case DeleteImport:
astutil.DeleteNamedImport(fset, f, fix.StmtInfo.Name, fix.StmtInfo.ImportPath)
case AddImport:
astutil.AddNamedImport(fset, f, fix.StmtInfo.Name, fix.StmtInfo.ImportPath)
case SetImportName:
// Find the matching import path and change the name.
for _, spec := range f.Imports {
path := strings.Trim(spec.Path.Value, `"`)
if path == fix.StmtInfo.ImportPath {
spec.Name = &ast.Ident{
Name: fix.StmtInfo.Name,
NamePos: spec.Pos(),
}
}
}
}
}
}
// assumeSiblingImportsValid assumes that siblings' use of packages is valid,
// adding the exports they use.
func (p *pass) assumeSiblingImportsValid() {
for _, f := range p.otherFiles {
refs := collectReferences(f)
imports := collectImports(f)
importsByName := map[string]*ImportInfo{}
for _, imp := range imports {
importsByName[p.importIdentifier(imp)] = imp
}
for left, rights := range refs {
if imp, ok := importsByName[left]; ok {
if m, ok := stdlib[imp.ImportPath]; ok {
// We have the stdlib in memory; no need to guess.
rights = copyExports(m)
}
p.addCandidate(imp, &packageInfo{
// no name; we already know it.
exports: rights,
})
}
}
}
}
// addCandidate adds a candidate import to p, and merges in the information
// in pkg.
func (p *pass) addCandidate(imp *ImportInfo, pkg *packageInfo) {
p.candidates = append(p.candidates, imp)
if existing, ok := p.knownPackages[imp.ImportPath]; ok {
if existing.name == "" {
existing.name = pkg.name
}
for export := range pkg.exports {
existing.exports[export] = true
}
} else {
p.knownPackages[imp.ImportPath] = pkg
}
}
// fixImports adds and removes imports from f so that all its references are
// satisfied and there are no unused imports.
//
// This is declared as a variable rather than a function so goimports can
// easily be extended by adding a file with an init function.
var fixImports = fixImportsDefault
func fixImportsDefault(fset *token.FileSet, f *ast.File, filename string, env *ProcessEnv) error {
fixes, err := getFixes(fset, f, filename, env)
if err != nil {
return err
}
apply(fset, f, fixes)
return err
}
// getFixes gets the import fixes that need to be made to f in order to fix the imports.
// It does not modify the ast.
func getFixes(fset *token.FileSet, f *ast.File, filename string, env *ProcessEnv) ([]*ImportFix, error) {
abs, err := filepath.Abs(filename)
if err != nil {
return nil, err
}
srcDir := filepath.Dir(abs)
if env.Logf != nil {
env.Logf("fixImports(filename=%q), abs=%q, srcDir=%q ...", filename, abs, srcDir)
}
// First pass: looking only at f, and using the naive algorithm to
// derive package names from import paths, see if the file is already
// complete. We can't add any imports yet, because we don't know
// if missing references are actually package vars.
p := &pass{fset: fset, f: f, srcDir: srcDir, env: env}
if fixes, done := p.load(); done {
return fixes, nil
}
otherFiles := parseOtherFiles(fset, srcDir, filename)
// Second pass: add information from other files in the same package,
// like their package vars and imports.
p.otherFiles = otherFiles
if fixes, done := p.load(); done {
return fixes, nil
}
// Now we can try adding imports from the stdlib.
p.assumeSiblingImportsValid()
addStdlibCandidates(p, p.missingRefs)
if fixes, done := p.fix(); done {
return fixes, nil
}
// Third pass: get real package names where we had previously used
// the naive algorithm.
p = &pass{fset: fset, f: f, srcDir: srcDir, env: env}
p.loadRealPackageNames = true
p.otherFiles = otherFiles
if fixes, done := p.load(); done {
return fixes, nil
}
addStdlibCandidates(p, p.missingRefs)
p.assumeSiblingImportsValid()
if fixes, done := p.fix(); done {
return fixes, nil
}
// Go look for candidates in $GOPATH, etc. We don't necessarily load
// the real exports of sibling imports, so keep assuming their contents.
if err := addExternalCandidates(p, p.missingRefs, filename); err != nil {
return nil, err
}
p.lastTry = true
fixes, _ := p.fix()
return fixes, nil
}
// Highest relevance, used for the standard library. Chosen arbitrarily to
// match pre-existing gopls code.
const MaxRelevance = 7
// getCandidatePkgs works with the passed callback to find all acceptable packages.
// It deduplicates by import path, and uses a cached stdlib rather than reading
// from disk.
func getCandidatePkgs(ctx context.Context, wrappedCallback *scanCallback, filename, filePkg string, env *ProcessEnv) error {
notSelf := func(p *pkg) bool {
return p.packageName != filePkg || p.dir != filepath.Dir(filename)
}
// Start off with the standard library.
for importPath, exports := range stdlib {
p := &pkg{
dir: filepath.Join(env.GOROOT, "src", importPath),
importPathShort: importPath,
packageName: path.Base(importPath),
relevance: MaxRelevance,
}
if notSelf(p) && wrappedCallback.packageNameLoaded(p) {
wrappedCallback.exportsLoaded(p, exports)
}
}
var mu sync.Mutex
dupCheck := map[string]struct{}{}
scanFilter := &scanCallback{
rootFound: func(root gopathwalk.Root) bool {
// Exclude goroot results -- getting them is relatively expensive, not cached,
// and generally redundant with the in-memory version.
return root.Type != gopathwalk.RootGOROOT && wrappedCallback.rootFound(root)
},
dirFound: wrappedCallback.dirFound,
packageNameLoaded: func(pkg *pkg) bool {
mu.Lock()
defer mu.Unlock()
if _, ok := dupCheck[pkg.importPathShort]; ok {
return false
}
dupCheck[pkg.importPathShort] = struct{}{}
return notSelf(pkg) && wrappedCallback.packageNameLoaded(pkg)
},
exportsLoaded: func(pkg *pkg, exports []string) {
// If we're an x_test, load the package under test's test variant.
if strings.HasSuffix(filePkg, "_test") && pkg.dir == filepath.Dir(filename) {
var err error
_, exports, err = loadExportsFromFiles(ctx, env, pkg.dir, true)
if err != nil {
return
}
}
wrappedCallback.exportsLoaded(pkg, exports)
},
}
return env.GetResolver().scan(ctx, scanFilter)
}
func ScoreImportPaths(ctx context.Context, env *ProcessEnv, paths []string) map[string]int {
result := make(map[string]int)
for _, path := range paths {
result[path] = env.GetResolver().scoreImportPath(ctx, path)
}
return result
}
func PrimeCache(ctx context.Context, env *ProcessEnv) error {
// Fully scan the disk for directories, but don't actually read any Go files.
callback := &scanCallback{
rootFound: func(gopathwalk.Root) bool {
return true
},
dirFound: func(pkg *pkg) bool {
return false
},
packageNameLoaded: func(pkg *pkg) bool {
return false
},
}
return getCandidatePkgs(ctx, callback, "", "", env)
}
func candidateImportName(pkg *pkg) string {
if ImportPathToAssumedName(pkg.importPathShort) != pkg.packageName {
return pkg.packageName
}
return ""
}
// getAllCandidates gets all of the candidates to be imported, regardless of if they are needed.
func getAllCandidates(ctx context.Context, wrapped func(ImportFix), searchPrefix, filename, filePkg string, env *ProcessEnv) error {
callback := &scanCallback{
rootFound: func(gopathwalk.Root) bool {
return true
},
dirFound: func(pkg *pkg) bool {
if !canUse(filename, pkg.dir) {
return false
}
// Try the assumed package name first, then a simpler path match
// in case of packages named vN, which are not uncommon.
return strings.HasPrefix(ImportPathToAssumedName(pkg.importPathShort), searchPrefix) ||
strings.HasPrefix(path.Base(pkg.importPathShort), searchPrefix)
},
packageNameLoaded: func(pkg *pkg) bool {
if !strings.HasPrefix(pkg.packageName, searchPrefix) {
return false
}
wrapped(ImportFix{
StmtInfo: ImportInfo{
ImportPath: pkg.importPathShort,
Name: candidateImportName(pkg),
},
IdentName: pkg.packageName,
FixType: AddImport,
Relevance: pkg.relevance,
})
return false
},
}
return getCandidatePkgs(ctx, callback, filename, filePkg, env)
}
// A PackageExport is a package and its exports.
type PackageExport struct {
Fix *ImportFix
Exports []string
}
func getPackageExports(ctx context.Context, wrapped func(PackageExport), searchPkg, filename, filePkg string, env *ProcessEnv) error {
callback := &scanCallback{
rootFound: func(gopathwalk.Root) bool {
return true
},
dirFound: func(pkg *pkg) bool {
return pkgIsCandidate(filename, references{searchPkg: nil}, pkg)
},
packageNameLoaded: func(pkg *pkg) bool {
return pkg.packageName == searchPkg
},
exportsLoaded: func(pkg *pkg, exports []string) {
sort.Strings(exports)
wrapped(PackageExport{
Fix: &ImportFix{
StmtInfo: ImportInfo{
ImportPath: pkg.importPathShort,
Name: candidateImportName(pkg),
},
IdentName: pkg.packageName,
FixType: AddImport,
Relevance: pkg.relevance,
},
Exports: exports,
})
},
}
return getCandidatePkgs(ctx, callback, filename, filePkg, env)
}
// ProcessEnv contains environment variables and settings that affect the use of
// the go command, the go/build package, etc.
type ProcessEnv struct {
LocalPrefix string
BuildFlags []string
// If non-empty, these will be used instead of the
// process-wide values.
GOPATH, GOROOT, GO111MODULE, GOPROXY, GOFLAGS, GOSUMDB string
WorkingDir string
// If Logf is non-nil, debug logging is enabled through this function.
Logf func(format string, args ...interface{})
resolver Resolver
}
// CopyConfig copies the env's configuration into a new env.
func (e *ProcessEnv) CopyConfig() *ProcessEnv {
copy := *e
copy.resolver = nil
return &copy
}
func (e *ProcessEnv) env() []string {
env := os.Environ()
add := func(k, v string) {
if v != "" {
env = append(env, k+"="+v)
}
}
add("GOPATH", e.GOPATH)
add("GOROOT", e.GOROOT)
add("GO111MODULE", e.GO111MODULE)
add("GOPROXY", e.GOPROXY)
add("GOFLAGS", e.GOFLAGS)
add("GOSUMDB", e.GOSUMDB)
if e.WorkingDir != "" {
add("PWD", e.WorkingDir)
}
return env
}
func (e *ProcessEnv) GetResolver() Resolver {
if e.resolver != nil {
return e.resolver
}
out, err := e.invokeGo(context.TODO(), "env", "GOMOD")
if err != nil || len(bytes.TrimSpace(out.Bytes())) == 0 {
e.resolver = newGopathResolver(e)
return e.resolver
}
e.resolver = newModuleResolver(e)
return e.resolver
}
func (e *ProcessEnv) buildContext() *build.Context {
ctx := build.Default
ctx.GOROOT = e.GOROOT
ctx.GOPATH = e.GOPATH
// As of Go 1.14, build.Context has a Dir field
// (see golang.org/issue/34860).
// Populate it only if present.
rc := reflect.ValueOf(&ctx).Elem()
dir := rc.FieldByName("Dir")
if !dir.IsValid() {
// Working drafts of Go 1.14 named the field "WorkingDir" instead.
// TODO(bcmills): Remove this case after the Go 1.14 beta has been released.
dir = rc.FieldByName("WorkingDir")
}
if dir.IsValid() && dir.Kind() == reflect.String {
dir.SetString(e.WorkingDir)
}
return &ctx
}
func (e *ProcessEnv) invokeGo(ctx context.Context, verb string, args ...string) (*bytes.Buffer, error) {
inv := gocommand.Invocation{
Verb: verb,
Args: args,
BuildFlags: e.BuildFlags,
Env: e.env(),
Logf: e.Logf,
WorkingDir: e.WorkingDir,
}
return inv.Run(ctx)
}
func addStdlibCandidates(pass *pass, refs references) {
add := func(pkg string) {
// Prevent self-imports.
if path.Base(pkg) == pass.f.Name.Name && filepath.Join(pass.env.GOROOT, "src", pkg) == pass.srcDir {
return
}
exports := copyExports(stdlib[pkg])
pass.addCandidate(
&ImportInfo{ImportPath: pkg},
&packageInfo{name: path.Base(pkg), exports: exports})
}
for left := range refs {
if left == "rand" {
// Make sure we try crypto/rand before math/rand.
add("crypto/rand")
add("math/rand")
continue
}
for importPath := range stdlib {
if path.Base(importPath) == left {
add(importPath)
}
}
}
}
// A Resolver does the build-system-specific parts of goimports.
type Resolver interface {
// loadPackageNames loads the package names in importPaths.
loadPackageNames(importPaths []string, srcDir string) (map[string]string, error)
// scan works with callback to search for packages. See scanCallback for details.
scan(ctx context.Context, callback *scanCallback) error
// loadExports returns the set of exported symbols in the package at dir.
// loadExports may be called concurrently.
loadExports(ctx context.Context, pkg *pkg, includeTest bool) (string, []string, error)
// scoreImportPath returns the relevance for an import path.
scoreImportPath(ctx context.Context, path string) int
ClearForNewScan()
}
// A scanCallback controls a call to scan and receives its results.
// In general, minor errors will be silently discarded; a user should not
// expect to receive a full series of calls for everything.
type scanCallback struct {
// rootFound is called before scanning a new root dir. If it returns true,
// the root will be scanned. Returning false will not necessarily prevent
// directories from that root making it to dirFound.
rootFound func(gopathwalk.Root) bool
// dirFound is called when a directory is found that is possibly a Go package.
// pkg will be populated with everything except packageName.
// If it returns true, the package's name will be loaded.
dirFound func(pkg *pkg) bool
// packageNameLoaded is called when a package is found and its name is loaded.
// If it returns true, the package's exports will be loaded.
packageNameLoaded func(pkg *pkg) bool
// exportsLoaded is called when a package's exports have been loaded.
exportsLoaded func(pkg *pkg, exports []string)
}
func addExternalCandidates(pass *pass, refs references, filename string) error {
var mu sync.Mutex
found := make(map[string][]pkgDistance)
callback := &scanCallback{
rootFound: func(gopathwalk.Root) bool {
return true // We want everything.
},
dirFound: func(pkg *pkg) bool {
return pkgIsCandidate(filename, refs, pkg)
},
packageNameLoaded: func(pkg *pkg) bool {
if _, want := refs[pkg.packageName]; !want {
return false
}
if pkg.dir == pass.srcDir && pass.f.Name.Name == pkg.packageName {
// The candidate is in the same directory and has the
// same package name. Don't try to import ourselves.
return false
}
if !canUse(filename, pkg.dir) {
return false
}
mu.Lock()
defer mu.Unlock()
found[pkg.packageName] = append(found[pkg.packageName], pkgDistance{pkg, distance(pass.srcDir, pkg.dir)})
return false // We'll do our own loading after we sort.
},
}
err := pass.env.GetResolver().scan(context.Background(), callback)
if err != nil {
return err
}
// Search for imports matching potential package references.
type result struct {
imp *ImportInfo
pkg *packageInfo
}
results := make(chan result, len(refs))
ctx, cancel := context.WithCancel(context.TODO())
var wg sync.WaitGroup
defer func() {
cancel()
wg.Wait()
}()
var (
firstErr error
firstErrOnce sync.Once
)
for pkgName, symbols := range refs {
wg.Add(1)
go func(pkgName string, symbols map[string]bool) {
defer wg.Done()
found, err := findImport(ctx, pass, found[pkgName], pkgName, symbols, filename)
if err != nil {
firstErrOnce.Do(func() {
firstErr = err
cancel()
})
return
}
if found == nil {
return // No matching package.
}
imp := &ImportInfo{
ImportPath: found.importPathShort,
}
pkg := &packageInfo{
name: pkgName,
exports: symbols,
}
results <- result{imp, pkg}
}(pkgName, symbols)
}
go func() {
wg.Wait()
close(results)
}()
for result := range results {
pass.addCandidate(result.imp, result.pkg)
}
return firstErr
}
// notIdentifier reports whether ch is an invalid identifier character.
func notIdentifier(ch rune) bool {
return !('a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' ||
'0' <= ch && ch <= '9' ||
ch == '_' ||
ch >= utf8.RuneSelf && (unicode.IsLetter(ch) || unicode.IsDigit(ch)))
}
// ImportPathToAssumedName returns the assumed package name of an import path.
// It does this using only string parsing of the import path.
// It picks the last element of the path that does not look like a major
// version, and then picks the valid identifier off the start of that element.
// It is used to determine if a local rename should be added to an import for
// clarity.
// This function could be moved to a standard package and exported if we want
// for use in other tools.
func ImportPathToAssumedName(importPath string) string {
base := path.Base(importPath)
if strings.HasPrefix(base, "v") {
if _, err := strconv.Atoi(base[1:]); err == nil {
dir := path.Dir(importPath)
if dir != "." {
base = path.Base(dir)
}
}
}
base = strings.TrimPrefix(base, "go-")
if i := strings.IndexFunc(base, notIdentifier); i >= 0 {
base = base[:i]
}
return base
}
// gopathResolver implements resolver for GOPATH workspaces.
type gopathResolver struct {
env *ProcessEnv
walked bool
cache *dirInfoCache
scanSema chan struct{} // scanSema prevents concurrent scans.
}
func newGopathResolver(env *ProcessEnv) *gopathResolver {
r := &gopathResolver{
env: env,
cache: &dirInfoCache{
dirs: map[string]*directoryPackageInfo{},
listeners: map[*int]cacheListener{},
},
scanSema: make(chan struct{}, 1),
}
r.scanSema <- struct{}{}
return r
}
func (r *gopathResolver) ClearForNewScan() {
<-r.scanSema
r.cache = &dirInfoCache{
dirs: map[string]*directoryPackageInfo{},
listeners: map[*int]cacheListener{},
}
r.walked = false
r.scanSema <- struct{}{}
}
func (r *gopathResolver) loadPackageNames(importPaths []string, srcDir string) (map[string]string, error) {
names := map[string]string{}
for _, path := range importPaths {
names[path] = importPathToName(r.env, path, srcDir)
}
return names, nil
}
// importPathToName finds out the actual package name, as declared in its .go files.
// If there's a problem, it returns "".
func importPathToName(env *ProcessEnv, importPath, srcDir string) (packageName string) {
// Fast path for standard library without going to disk.
if _, ok := stdlib[importPath]; ok {
return path.Base(importPath) // stdlib packages always match their paths.
}
buildPkg, err := env.buildContext().Import(importPath, srcDir, build.FindOnly)
if err != nil {
return ""
}
pkgName, err := packageDirToName(buildPkg.Dir)
if err != nil {
return ""
}
return pkgName
}
// packageDirToName is a faster version of build.Import if
// the only thing desired is the package name. Given a directory,
// packageDirToName then only parses one file in the package,
// trusting that the files in the directory are consistent.
func packageDirToName(dir string) (packageName string, err error) {
d, err := os.Open(dir)
if err != nil {
return "", err
}
names, err := d.Readdirnames(-1)
d.Close()
if err != nil {
return "", err
}
sort.Strings(names) // to have predictable behavior
var lastErr error
var nfile int
for _, name := range names {
if !strings.HasSuffix(name, ".go") {
continue
}
if strings.HasSuffix(name, "_test.go") {
continue
}
nfile++
fullFile := filepath.Join(dir, name)
fset := token.NewFileSet()
f, err := parser.ParseFile(fset, fullFile, nil, parser.PackageClauseOnly)
if err != nil {
lastErr = err
continue
}
pkgName := f.Name.Name
if pkgName == "documentation" {
// Special case from go/build.ImportDir, not
// handled by ctx.MatchFile.
continue
}
if pkgName == "main" {
// Also skip package main, assuming it's a +build ignore generator or example.
// Since you can't import a package main anyway, there's no harm here.
continue
}
return pkgName, nil
}
if lastErr != nil {
return "", lastErr
}
return "", fmt.Errorf("no importable package found in %d Go files", nfile)
}
type pkg struct {
dir string // absolute file path to pkg directory ("/usr/lib/go/src/net/http")
importPathShort string // vendorless import path ("net/http", "a/b")
packageName string // package name loaded from source if requested
relevance int // a weakly-defined score of how relevant a package is. 0 is most relevant.
}
type pkgDistance struct {
pkg *pkg
distance int // relative distance to target
}
// byDistanceOrImportPathShortLength sorts by relative distance breaking ties
// on the short import path length and then the import string itself.
type byDistanceOrImportPathShortLength []pkgDistance
func (s byDistanceOrImportPathShortLength) Len() int { return len(s) }
func (s byDistanceOrImportPathShortLength) Less(i, j int) bool {
di, dj := s[i].distance, s[j].distance
if di == -1 {
return false
}
if dj == -1 {
return true
}
if di != dj {
return di < dj
}
vi, vj := s[i].pkg.importPathShort, s[j].pkg.importPathShort
if len(vi) != len(vj) {
return len(vi) < len(vj)
}
return vi < vj
}
func (s byDistanceOrImportPathShortLength) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func distance(basepath, targetpath string) int {
p, err := filepath.Rel(basepath, targetpath)
if err != nil {
return -1
}
if p == "." {
return 0
}
return strings.Count(p, string(filepath.Separator)) + 1
}
func (r *gopathResolver) scan(ctx context.Context, callback *scanCallback) error {
add := func(root gopathwalk.Root, dir string) {
// We assume cached directories have not changed. We can skip them and their
// children.
if _, ok := r.cache.Load(dir); ok {
return
}
importpath := filepath.ToSlash(dir[len(root.Path)+len("/"):])
info := directoryPackageInfo{
status: directoryScanned,
dir: dir,
rootType: root.Type,
nonCanonicalImportPath: VendorlessPath(importpath),
}
r.cache.Store(dir, info)
}
processDir := func(info directoryPackageInfo) {
// Skip this directory if we were not able to get the package information successfully.
if scanned, err := info.reachedStatus(directoryScanned); !scanned || err != nil {
return
}
p := &pkg{
importPathShort: info.nonCanonicalImportPath,
dir: info.dir,
relevance: MaxRelevance - 1,
}
if info.rootType == gopathwalk.RootGOROOT {
p.relevance = MaxRelevance
}
if !callback.dirFound(p) {
return
}
var err error
p.packageName, err = r.cache.CachePackageName(info)
if err != nil {
return
}
if !callback.packageNameLoaded(p) {
return
}
if _, exports, err := r.loadExports(ctx, p, false); err == nil {
callback.exportsLoaded(p, exports)
}
}
stop := r.cache.ScanAndListen(ctx, processDir)
defer stop()
// The callback is not necessarily safe to use in the goroutine below. Process roots eagerly.
roots := filterRoots(gopathwalk.SrcDirsRoots(r.env.buildContext()), callback.rootFound)
// We can't cancel walks, because we need them to finish to have a usable
// cache. Instead, run them in a separate goroutine and detach.
scanDone := make(chan struct{})
go func() {
select {
case <-ctx.Done():
return
case <-r.scanSema:
}
defer func() { r.scanSema <- struct{}{} }()
gopathwalk.Walk(roots, add, gopathwalk.Options{Logf: r.env.Logf, ModulesEnabled: false})
close(scanDone)
}()
select {
case <-ctx.Done():
case <-scanDone:
}
return nil
}
func (r *gopathResolver) scoreImportPath(ctx context.Context, path string) int {
if _, ok := stdlib[path]; ok {
return MaxRelevance
}
return MaxRelevance - 1
}
func filterRoots(roots []gopathwalk.Root, include func(gopathwalk.Root) bool) []gopathwalk.Root {
var result []gopathwalk.Root
for _, root := range roots {
if !include(root) {
continue
}
result = append(result, root)
}
return result
}
func (r *gopathResolver) loadExports(ctx context.Context, pkg *pkg, includeTest bool) (string, []string, error) {
if info, ok := r.cache.Load(pkg.dir); ok && !includeTest {
return r.cache.CacheExports(ctx, r.env, info)
}
return loadExportsFromFiles(ctx, r.env, pkg.dir, includeTest)
}
// VendorlessPath returns the devendorized version of the import path ipath.
// For example, VendorlessPath("foo/bar/vendor/a/b") returns "a/b".
func VendorlessPath(ipath string) string {
// Devendorize for use in import statement.
if i := strings.LastIndex(ipath, "/vendor/"); i >= 0 {
return ipath[i+len("/vendor/"):]
}
if strings.HasPrefix(ipath, "vendor/") {
return ipath[len("vendor/"):]
}
return ipath
}
func loadExportsFromFiles(ctx context.Context, env *ProcessEnv, dir string, includeTest bool) (string, []string, error) {
var exports []string
// Look for non-test, buildable .go files which could provide exports.
all, err := ioutil.ReadDir(dir)
if err != nil {
return "", nil, err
}
var files []os.FileInfo
for _, fi := range all {
name := fi.Name()
if !strings.HasSuffix(name, ".go") || (!includeTest && strings.HasSuffix(name, "_test.go")) {
continue
}
match, err := env.buildContext().MatchFile(dir, fi.Name())
if err != nil || !match {
continue
}
files = append(files, fi)
}
if len(files) == 0 {
return "", nil, fmt.Errorf("dir %v contains no buildable, non-test .go files", dir)
}
var pkgName string
fset := token.NewFileSet()
for _, fi := range files {
select {
case <-ctx.Done():
return "", nil, ctx.Err()
default:
}
fullFile := filepath.Join(dir, fi.Name())
f, err := parser.ParseFile(fset, fullFile, nil, 0)
if err != nil {
return "", nil, fmt.Errorf("parsing %s: %v", fullFile, err)
}
if f.Name.Name == "documentation" {
// Special case from go/build.ImportDir, not
// handled by MatchFile above.
continue
}
if includeTest && strings.HasSuffix(f.Name.Name, "_test") {
// x_test package. We want internal test files only.
continue
}
pkgName = f.Name.Name
for name := range f.Scope.Objects {
if ast.IsExported(name) {
exports = append(exports, name)
}
}
}
if env.Logf != nil {
sortedExports := append([]string(nil), exports...)
sort.Strings(sortedExports)
env.Logf("loaded exports in dir %v (package %v): %v", dir, pkgName, strings.Join(sortedExports, ", "))
}
return pkgName, exports, nil
}
// findImport searches for a package with the given symbols.
// If no package is found, findImport returns ("", false, nil)
func findImport(ctx context.Context, pass *pass, candidates []pkgDistance, pkgName string, symbols map[string]bool, filename string) (*pkg, error) {
// Sort the candidates by their import package length,
// assuming that shorter package names are better than long
// ones. Note that this sorts by the de-vendored name, so
// there's no "penalty" for vendoring.
sort.Sort(byDistanceOrImportPathShortLength(candidates))
if pass.env.Logf != nil {
for i, c := range candidates {
pass.env.Logf("%s candidate %d/%d: %v in %v", pkgName, i+1, len(candidates), c.pkg.importPathShort, c.pkg.dir)
}
}
// Collect exports for packages with matching names.
rescv := make([]chan *pkg, len(candidates))
for i := range candidates {
rescv[i] = make(chan *pkg, 1)
}
const maxConcurrentPackageImport = 4
loadExportsSem := make(chan struct{}, maxConcurrentPackageImport)
ctx, cancel := context.WithCancel(ctx)
var wg sync.WaitGroup
defer func() {
cancel()
wg.Wait()
}()
wg.Add(1)
go func() {
defer wg.Done()
for i, c := range candidates {
select {
case loadExportsSem <- struct{}{}:
case <-ctx.Done():
return
}
wg.Add(1)
go func(c pkgDistance, resc chan<- *pkg) {
defer func() {
<-loadExportsSem
wg.Done()
}()
if pass.env.Logf != nil {
pass.env.Logf("loading exports in dir %s (seeking package %s)", c.pkg.dir, pkgName)
}
// If we're an x_test, load the package under test's test variant.
includeTest := strings.HasSuffix(pass.f.Name.Name, "_test") && c.pkg.dir == pass.srcDir
_, exports, err := pass.env.GetResolver().loadExports(ctx, c.pkg, includeTest)
if err != nil {
if pass.env.Logf != nil {
pass.env.Logf("loading exports in dir %s (seeking package %s): %v", c.pkg.dir, pkgName, err)
}
resc <- nil
return
}
exportsMap := make(map[string]bool, len(exports))
for _, sym := range exports {
exportsMap[sym] = true
}
// If it doesn't have the right
// symbols, send nil to mean no match.
for symbol := range symbols {
if !exportsMap[symbol] {
resc <- nil
return
}
}
resc <- c.pkg
}(c, rescv[i])
}
}()
for _, resc := range rescv {
pkg := <-resc
if pkg == nil {
continue
}
return pkg, nil
}
return nil, nil
}
// pkgIsCandidate reports whether pkg is a candidate for satisfying the
// finding which package pkgIdent in the file named by filename is trying
// to refer to.
//
// This check is purely lexical and is meant to be as fast as possible
// because it's run over all $GOPATH directories to filter out poor
// candidates in order to limit the CPU and I/O later parsing the
// exports in candidate packages.
//
// filename is the file being formatted.
// pkgIdent is the package being searched for, like "client" (if
// searching for "client.New")
func pkgIsCandidate(filename string, refs references, pkg *pkg) bool {
// Check "internal" and "vendor" visibility:
if !canUse(filename, pkg.dir) {
return false
}
// Speed optimization to minimize disk I/O:
// the last two components on disk must contain the
// package name somewhere.
//
// This permits mismatch naming like directory
// "go-foo" being package "foo", or "pkg.v3" being "pkg",
// or directory "google.golang.org/api/cloudbilling/v1"
// being package "cloudbilling", but doesn't
// permit a directory "foo" to be package
// "bar", which is strongly discouraged
// anyway. There's no reason goimports needs
// to be slow just to accommodate that.
for pkgIdent := range refs {
lastTwo := lastTwoComponents(pkg.importPathShort)
if strings.Contains(lastTwo, pkgIdent) {
return true
}
if hasHyphenOrUpperASCII(lastTwo) && !hasHyphenOrUpperASCII(pkgIdent) {
lastTwo = lowerASCIIAndRemoveHyphen(lastTwo)
if strings.Contains(lastTwo, pkgIdent) {
return true
}
}
}
return false
}
func hasHyphenOrUpperASCII(s string) bool {
for i := 0; i < len(s); i++ {
b := s[i]
if b == '-' || ('A' <= b && b <= 'Z') {
return true
}
}
return false
}
func lowerASCIIAndRemoveHyphen(s string) (ret string) {
buf := make([]byte, 0, len(s))
for i := 0; i < len(s); i++ {
b := s[i]
switch {
case b == '-':
continue
case 'A' <= b && b <= 'Z':
buf = append(buf, b+('a'-'A'))
default:
buf = append(buf, b)
}
}
return string(buf)
}
// canUse reports whether the package in dir is usable from filename,
// respecting the Go "internal" and "vendor" visibility rules.
func canUse(filename, dir string) bool {
// Fast path check, before any allocations. If it doesn't contain vendor
// or internal, it's not tricky:
// Note that this can false-negative on directories like "notinternal",
// but we check it correctly below. This is just a fast path.
if !strings.Contains(dir, "vendor") && !strings.Contains(dir, "internal") {
return true
}
dirSlash := filepath.ToSlash(dir)
if !strings.Contains(dirSlash, "/vendor/") && !strings.Contains(dirSlash, "/internal/") && !strings.HasSuffix(dirSlash, "/internal") {
return true
}
// Vendor or internal directory only visible from children of parent.
// That means the path from the current directory to the target directory
// can contain ../vendor or ../internal but not ../foo/vendor or ../foo/internal
// or bar/vendor or bar/internal.
// After stripping all the leading ../, the only okay place to see vendor or internal
// is at the very beginning of the path.
absfile, err := filepath.Abs(filename)
if err != nil {
return false
}
absdir, err := filepath.Abs(dir)
if err != nil {
return false
}
rel, err := filepath.Rel(absfile, absdir)
if err != nil {
return false
}
relSlash := filepath.ToSlash(rel)
if i := strings.LastIndex(relSlash, "../"); i >= 0 {
relSlash = relSlash[i+len("../"):]
}
return !strings.Contains(relSlash, "/vendor/") && !strings.Contains(relSlash, "/internal/") && !strings.HasSuffix(relSlash, "/internal")
}
// lastTwoComponents returns at most the last two path components
// of v, using either / or \ as the path separator.
func lastTwoComponents(v string) string {
nslash := 0
for i := len(v) - 1; i >= 0; i-- {
if v[i] == '/' || v[i] == '\\' {
nslash++
if nslash == 2 {
return v[i:]
}
}
}
return v
}
type visitFn func(node ast.Node) ast.Visitor
func (fn visitFn) Visit(node ast.Node) ast.Visitor {
return fn(node)
}
func copyExports(pkg []string) map[string]bool {
m := make(map[string]bool, len(pkg))
for _, v := range pkg {
m[v] = true
}
return m
}