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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 pkgdoc serves package documentation.
//
// The only API for Go programs is NewServer.
// The exported data structures are consumed by the templates
// in _content/lib/godoc/package*.html.
package pkgdoc
import (
"bytes"
"go/ast"
"go/build"
"go/doc"
"go/token"
"io"
"io/ioutil"
"log"
"net/http"
"net/url"
"os"
"path"
"path/filepath"
"sort"
"strings"
"unicode"
"unicode/utf8"
"golang.org/x/website/internal/api"
"golang.org/x/website/internal/backport/io/fs"
"golang.org/x/website/internal/web"
)
type docs struct {
fs fs.FS
api api.DB
site *web.Site
root *Dir
forceOld func(*http.Request) bool
}
// NewServer returns an HTTP handler serving package docs
// for packages loaded from fsys (a tree in GOROOT layout),
// styled according to site.
// If forceOld is not nil and returns true for a given request,
// NewServer will serve docs itself instead of redirecting to pkg.go.dev
// (forcing the ?m=old behavior).
func NewServer(fsys fs.FS, site *web.Site, forceOld func(*http.Request) bool) (http.Handler, error) {
apiDB, err := api.Load(fsys)
if err != nil {
return nil, err
}
var dirs []*Dir
if src := newDir(fsys, token.NewFileSet(), "src"); src != nil {
dirs = []*Dir{src}
}
root := &Dir{
Path: ".",
Dirs: dirs,
}
docs := &docs{
fs: fsys,
api: apiDB,
site: site,
root: root,
forceOld: forceOld,
}
return docs, nil
}
type Page struct {
docs *docs // outer doc collection
OldDocs bool // use ?m=old in doc links
Dirname string // directory containing the package
Err error // error or nil
mode mode // display metadata from query string
// package info
fset *token.FileSet // nil if no package documentation
PDoc *doc.Package // nil if no package documentation
Examples []*doc.Example // nil if no example code
Bugs []*doc.Note // nil if no BUG comments
IsMain bool // true for package main
IsFiltered bool // true if results were filtered
// directory info
Dirs []DirEntry // nil if no directory information
DirFlat bool // if set, show directory in a flat (non-indented) manner
}
type mode uint
const (
modeAll mode = 1 << iota // do not filter exports
modeFlat // show directory in a flat (non-indented) manner
modeMethods // show all embedded methods
modeOld // do not redirect to pkg.go.dev
modeBuiltin // don't associate consts, vars, and factory functions with types (not exposed via ?m= query parameter, used for package builtin, see issue 6645)
)
// modeNames defines names for each mode flag.
// The order here must match the order of the constants above.
var modeNames = []string{
"all",
"flat",
"methods",
"old",
}
// generate a query string for persisting the mode m between pages.
func (m mode) String() string {
s := ""
for i, name := range modeNames {
if m&(1<<i) != 0 && name != "" {
if s != "" {
s += ","
}
s += name
}
}
return s
}
// parseMode computes the mode flags by analyzing the request URL form value "m".
// Its value is a comma-separated list of mode names (for example, "all,flat").
func parseMode(text string) mode {
var mode mode
for _, k := range strings.Split(text, ",") {
k = strings.TrimSpace(k)
for i, name := range modeNames {
if name == k {
mode |= 1 << i
}
}
}
return mode
}
// open returns the Page for a package directory dir.
// Package documentation (Page.PDoc) is extracted from the AST.
// If there is no corresponding package in the
// directory, Page.PDoc is nil. If there are no sub-
// directories, Page.Dirs is nil. If an error occurred, PageInfo.Err is
// set to the respective error but the error is not logged.
func (d *docs) open(dir string, mode mode, goos, goarch string) *Page {
dir = path.Clean(dir)
info := &Page{docs: d, Dirname: dir, mode: mode}
// Restrict to the package files that would be used when building
// the package on this system. This makes sure that if there are
// separate implementations for, say, Windows vs Unix, we don't
// jumble them all together.
// Note: If goos/goarch aren't set, the current binary's GOOS/GOARCH
// are used.
ctxt := build.Default
ctxt.IsAbsPath = path.IsAbs
ctxt.IsDir = func(path string) bool {
fi, err := fs.Stat(d.fs, filepath.ToSlash(path))
return err == nil && fi.IsDir()
}
ctxt.ReadDir = func(dir string) ([]os.FileInfo, error) {
f, err := fs.ReadDir(d.fs, filepath.ToSlash(dir))
filtered := make([]os.FileInfo, 0, len(f))
for _, i := range f {
if mode&modeAll != 0 || i.Name() != "internal" {
info, err := i.Info()
if err == nil {
filtered = append(filtered, info)
}
}
}
return filtered, err
}
ctxt.OpenFile = func(name string) (r io.ReadCloser, err error) {
data, err := fs.ReadFile(d.fs, filepath.ToSlash(name))
if err != nil {
return nil, err
}
return ioutil.NopCloser(bytes.NewReader(data)), nil
}
// Make the syscall/js package always visible by default.
// It defaults to the host's GOOS/GOARCH, and golang.org's
// linux/amd64 means the wasm syscall/js package was blank.
// And you can't run godoc on js/wasm anyway, so host defaults
// don't make sense here.
if goos == "" && goarch == "" && dir == "syscall/js" {
goos, goarch = "js", "wasm"
}
if goos != "" {
ctxt.GOOS = goos
}
if goarch != "" {
ctxt.GOARCH = goarch
}
pkginfo, err := ctxt.ImportDir(dir, 0)
// continue if there are no Go source files; we still want the directory info
if _, nogo := err.(*build.NoGoError); err != nil && !nogo {
info.Err = err
return info
}
// collect package files
pkgname := pkginfo.Name
pkgfiles := append(pkginfo.GoFiles, pkginfo.CgoFiles...)
if len(pkgfiles) == 0 {
// Commands written in C have no .go files in the build.
// Instead, documentation may be found in an ignored file.
// The file may be ignored via an explicit +build ignore
// constraint (recommended), or by defining the package
// documentation (historic).
pkgname = "main" // assume package main since pkginfo.Name == ""
pkgfiles = pkginfo.IgnoredGoFiles
}
// get package information, if any
if len(pkgfiles) > 0 {
// build package AST
fset := token.NewFileSet()
files, err := parseFiles(d.fs, fset, dir, pkgfiles)
if err != nil {
info.Err = err
return info
}
// ignore any errors - they are due to unresolved identifiers
pkg, _ := ast.NewPackage(fset, files, simpleImporter, nil)
// extract package documentation
info.fset = fset
info.IsMain = pkgname == "main"
// show extracted documentation
var m doc.Mode
if mode&modeAll != 0 {
m |= doc.AllDecls
}
if mode&modeMethods != 0 {
m |= doc.AllMethods
}
info.PDoc = doc.New(pkg, strings.TrimPrefix(dir, "src/"), m)
if mode&modeBuiltin != 0 {
for _, t := range info.PDoc.Types {
info.PDoc.Consts = append(info.PDoc.Consts, t.Consts...)
info.PDoc.Vars = append(info.PDoc.Vars, t.Vars...)
info.PDoc.Funcs = append(info.PDoc.Funcs, t.Funcs...)
t.Consts = nil
t.Vars = nil
t.Funcs = nil
}
// for now we cannot easily sort consts and vars since
// go/doc.Value doesn't export the order information
sort.Sort(funcsByName(info.PDoc.Funcs))
}
// collect examples
testfiles := append(pkginfo.TestGoFiles, pkginfo.XTestGoFiles...)
files, err = parseFiles(d.fs, fset, dir, testfiles)
if err != nil {
log.Println("parsing examples:", err)
}
info.Examples = collectExamples(pkg, files)
info.Bugs = info.PDoc.Notes["BUG"]
}
info.Dirs = d.root.lookup(dir).list(func(path string) bool { return d.includePath(path, mode) })
info.DirFlat = mode&modeFlat != 0
return info
}
func (d *docs) includePath(path string, mode mode) (r bool) {
// if the path includes 'internal', don't list unless we are in the NoFiltering mode.
if mode&modeAll != 0 {
return true
}
if strings.Contains(path, "internal") || strings.Contains(path, "vendor") {
for _, c := range strings.Split(filepath.Clean(path), string(os.PathSeparator)) {
if c == "internal" || c == "vendor" {
return false
}
}
}
return true
}
// simpleImporter returns a (dummy) package object named
// by the last path component of the provided package path
// (as is the convention for packages). This is sufficient
// to resolve package identifiers without doing an actual
// import. It never returns an error.
//
func simpleImporter(imports map[string]*ast.Object, path string) (*ast.Object, error) {
pkg := imports[path]
if pkg == nil {
// note that strings.LastIndex returns -1 if there is no "/"
pkg = ast.NewObj(ast.Pkg, path[strings.LastIndex(path, "/")+1:])
pkg.Data = ast.NewScope(nil) // required by ast.NewPackage for dot-import
imports[path] = pkg
}
return pkg, nil
}
// packageExports is a local implementation of ast.PackageExports
// which correctly updates each package file's comment list.
// (The ast.PackageExports signature is frozen, hence the local
// implementation).
//
func packageExports(fset *token.FileSet, pkg *ast.Package) {
for _, src := range pkg.Files {
cmap := ast.NewCommentMap(fset, src, src.Comments)
ast.FileExports(src)
src.Comments = cmap.Filter(src).Comments()
}
}
type funcsByName []*doc.Func
func (s funcsByName) Len() int { return len(s) }
func (s funcsByName) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s funcsByName) Less(i, j int) bool { return s[i].Name < s[j].Name }
// collectExamples collects examples for pkg from testfiles.
func collectExamples(pkg *ast.Package, testfiles map[string]*ast.File) []*doc.Example {
var files []*ast.File
for _, f := range testfiles {
files = append(files, f)
}
var examples []*doc.Example
globals := globalNames(pkg)
for _, e := range doc.Examples(files...) {
name := trimExampleSuffix(e.Name)
if name == "" || globals[name] {
examples = append(examples, e)
}
}
return examples
}
// globalNames returns a set of the names declared by all package-level
// declarations. Method names are returned in the form Receiver_Method.
func globalNames(pkg *ast.Package) map[string]bool {
names := make(map[string]bool)
for _, file := range pkg.Files {
for _, decl := range file.Decls {
addNames(names, decl)
}
}
return names
}
// addNames adds the names declared by decl to the names set.
// Method names are added in the form ReceiverTypeName_Method.
func addNames(names map[string]bool, decl ast.Decl) {
switch d := decl.(type) {
case *ast.FuncDecl:
name := d.Name.Name
if d.Recv != nil {
var typeName string
switch r := d.Recv.List[0].Type.(type) {
case *ast.StarExpr:
typeName = r.X.(*ast.Ident).Name
case *ast.Ident:
typeName = r.Name
}
name = typeName + "_" + name
}
names[name] = true
case *ast.GenDecl:
for _, spec := range d.Specs {
switch s := spec.(type) {
case *ast.TypeSpec:
names[s.Name.Name] = true
case *ast.ValueSpec:
for _, id := range s.Names {
names[id.Name] = true
}
}
}
}
}
func splitExampleName(s string) (name, suffix string) {
i := strings.LastIndex(s, "_")
if 0 <= i && i < len(s)-1 && !startsWithUppercase(s[i+1:]) {
name = s[:i]
suffix = " (" + strings.Title(s[i+1:]) + ")"
return
}
name = s
return
}
// trimExampleSuffix strips lowercase braz in Foo_braz or Foo_Bar_braz from name
// while keeping uppercase Braz in Foo_Braz.
func trimExampleSuffix(name string) string {
if i := strings.LastIndex(name, "_"); i != -1 {
if i < len(name)-1 && !startsWithUppercase(name[i+1:]) {
name = name[:i]
}
}
return name
}
func startsWithUppercase(s string) bool {
r, _ := utf8.DecodeRuneInString(s)
return unicode.IsUpper(r)
}
func (d *docs) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if maybeRedirect(w, r) {
return
}
// TODO(rsc): URL should be clean already.
relpath := path.Clean(strings.TrimPrefix(r.URL.Path, "/pkg"))
relpath = strings.TrimPrefix(relpath, "/")
mode := parseMode(r.FormValue("m"))
// Redirect to pkg.go.dev.
// We provide two overrides for the redirect.
// First, the request can set ?m=old to get the old pages.
// Second, the request can come from China:
// since pkg.go.dev is not available in China, we serve the docs directly.
if mode&modeOld == 0 && (d.forceOld == nil || !d.forceOld(r)) {
if relpath == "" {
relpath = "std"
}
suffix := ""
if r.Host == "tip.golang.org" {
suffix = "@master"
}
if goos, goarch := r.FormValue("GOOS"), r.FormValue("GOARCH"); goos != "" || goarch != "" {
suffix += "?"
if goos != "" {
suffix += "GOOS=" + url.QueryEscape(goos)
}
if goarch != "" {
if goos != "" {
suffix += "&"
}
suffix += "GOARCH=" + url.QueryEscape(goarch)
}
}
http.Redirect(w, r, "https://pkg.go.dev/"+relpath+suffix, http.StatusTemporaryRedirect)
return
}
if relpath == "builtin" {
// The fake built-in package contains unexported identifiers,
// but we want to show them. Also, disable type association,
// since it's not helpful for this fake package (see issue 6645).
mode |= modeAll | modeBuiltin
}
info := d.open("src/"+relpath, mode, r.FormValue("GOOS"), r.FormValue("GOARCH"))
if info.Err != nil {
log.Print(info.Err)
d.site.ServeError(w, r, info.Err)
return
}
info.OldDocs = mode&modeOld != 0
var tabtitle, title, subtitle string
switch {
case info.PDoc != nil:
tabtitle = info.PDoc.Name
default:
tabtitle = info.Dirname
title = "Directory "
}
if title == "" {
if info.IsMain {
// assume that the directory name is the command name
_, tabtitle = path.Split(relpath)
title = "Command "
} else {
title = "Package "
}
}
title += tabtitle
// special cases for top-level package/command directories
switch tabtitle {
case "/src":
title = "Packages"
tabtitle = "Packages"
case "/src/cmd":
title = "Commands"
tabtitle = "Commands"
}
layout := "pkg"
if info.Dirname == "src" {
layout = "pkgroot"
}
d.site.ServePage(w, r, web.Page{
"title": title,
"tabTitle": tabtitle,
"subtitle": subtitle,
"layout": layout,
"pkg": info,
})
}
// ModeQuery returns the "?m=..." query for the current page.
func (p *Page) ModeQuery() string {
m := p.mode
s := m.String()
if s == "" {
return ""
}
return "?m=" + s
}
func maybeRedirect(w http.ResponseWriter, r *http.Request) (redirected bool) {
canonical := path.Clean(r.URL.Path)
if !strings.HasSuffix(canonical, "/") {
canonical += "/"
}
if r.URL.Path != canonical {
url := *r.URL
url.Path = canonical
http.Redirect(w, r, url.String(), http.StatusMovedPermanently)
redirected = true
}
return
}