blob: 194797bd822b49fc6337d7b3a7e6c1ba0315fb8e [file] [log] [blame]
// Copyright 2015 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.
// Bundle creates a single-source-file version of a source package
// suitable for inclusion in a particular target package.
//
// Usage:
//
// bundle [-o file] [-dst path] [-pkg name] [-prefix p] [-import old=new] [-tags build_constraints] <src>
//
// The src argument specifies the import path of the package to bundle.
// The bundling of a directory of source files into a single source file
// necessarily imposes a number of constraints.
// The package being bundled must not use cgo; must not use conditional
// file compilation, whether with build tags or system-specific file names
// like code_amd64.go; must not depend on any special comments, which
// may not be preserved; must not use any assembly sources;
// must not use renaming imports; and must not use reflection-based APIs
// that depend on the specific names of types or struct fields.
//
// By default, bundle writes the bundled code to standard output.
// If the -o argument is given, bundle writes to the named file
// and also includes a “//go:generate” comment giving the exact
// command line used, for regenerating the file with “go generate.”
//
// Bundle customizes its output for inclusion in a particular package, the destination package.
// By default bundle assumes the destination is the package in the current directory,
// but the destination package can be specified explicitly using the -dst option,
// which takes an import path as its argument.
// If the source package imports the destination package, bundle will remove
// those imports and rewrite any references to use direct references to the
// corresponding symbols.
// Bundle also must write a package declaration in the output and must
// choose a name to use in that declaration.
// If the -pkg option is given, bundle uses that name.
// Otherwise, the name of the destination package is used.
// Build constraints for the generated file can be specified using the -tags option.
//
// To avoid collisions, bundle inserts a prefix at the beginning of
// every package-level const, func, type, and var identifier in src's code,
// updating references accordingly. The default prefix is the package name
// of the source package followed by an underscore. The -prefix option
// specifies an alternate prefix.
//
// Occasionally it is necessary to rewrite imports during the bundling
// process. The -import option, which may be repeated, specifies that
// an import of "old" should be rewritten to import "new" instead.
//
// # Example
//
// Bundle archive/zip for inclusion in cmd/dist:
//
// cd $GOROOT/src/cmd/dist
// bundle -o zip.go archive/zip
//
// Bundle golang.org/x/net/http2 for inclusion in net/http,
// prefixing all identifiers by "http2" instead of "http2_", and
// including a "!nethttpomithttp2" build constraint:
//
// cd $GOROOT/src/net/http
// bundle -o h2_bundle.go -prefix http2 -tags '!nethttpomithttp2' golang.org/x/net/http2
//
// Update the http2 bundle in net/http:
//
// go generate net/http
//
// Update all bundles in the standard library:
//
// go generate -run bundle std
package main
import (
"bytes"
"flag"
"fmt"
"go/ast"
"go/format"
"go/printer"
"go/token"
"go/types"
"io/ioutil"
"log"
"os"
"strconv"
"strings"
"unicode"
"golang.org/x/tools/go/packages"
)
var (
outputFile = flag.String("o", "", "write output to `file` (default standard output)")
dstPath = flag.String("dst", ".", "set destination import `path`")
pkgName = flag.String("pkg", "", "set destination package `name`")
prefix = flag.String("prefix", "&_", "set bundled identifier prefix to `p` (default is \"&_\", where & stands for the original name)")
buildTags = flag.String("tags", "", "the build constraints to be inserted into the generated file")
importMap = map[string]string{}
)
func init() {
flag.Var(flagFunc(addImportMap), "import", "rewrite import using `map`, of form old=new (can be repeated)")
}
func addImportMap(s string) {
if strings.Count(s, "=") != 1 {
log.Fatal("-import argument must be of the form old=new")
}
i := strings.Index(s, "=")
old, new := s[:i], s[i+1:]
if old == "" || new == "" {
log.Fatal("-import argument must be of the form old=new; old and new must be non-empty")
}
importMap[old] = new
}
func usage() {
fmt.Fprintf(os.Stderr, "Usage: bundle [options] <src>\n")
flag.PrintDefaults()
}
func main() {
log.SetPrefix("bundle: ")
log.SetFlags(0)
flag.Usage = usage
flag.Parse()
args := flag.Args()
if len(args) != 1 {
usage()
os.Exit(2)
}
cfg := &packages.Config{Mode: packages.NeedName}
pkgs, err := packages.Load(cfg, *dstPath)
if err != nil {
log.Fatalf("cannot load destination package: %v", err)
}
if packages.PrintErrors(pkgs) > 0 || len(pkgs) != 1 {
log.Fatalf("failed to load destination package")
}
if *pkgName == "" {
*pkgName = pkgs[0].Name
}
code, err := bundle(args[0], pkgs[0].PkgPath, *pkgName, *prefix, *buildTags)
if err != nil {
log.Fatal(err)
}
if *outputFile != "" {
err := ioutil.WriteFile(*outputFile, code, 0666)
if err != nil {
log.Fatal(err)
}
} else {
_, err := os.Stdout.Write(code)
if err != nil {
log.Fatal(err)
}
}
}
// isStandardImportPath is copied from cmd/go in the standard library.
func isStandardImportPath(path string) bool {
i := strings.Index(path, "/")
if i < 0 {
i = len(path)
}
elem := path[:i]
return !strings.Contains(elem, ".")
}
var testingOnlyPackagesConfig *packages.Config
func bundle(src, dst, dstpkg, prefix, buildTags string) ([]byte, error) {
// Load the initial package.
cfg := &packages.Config{}
if testingOnlyPackagesConfig != nil {
*cfg = *testingOnlyPackagesConfig
} else {
// Bypass default vendor mode, as we need a package not available in the
// std module vendor folder.
cfg.Env = append(os.Environ(), "GOFLAGS=-mod=mod")
}
cfg.Mode = packages.NeedTypes | packages.NeedSyntax | packages.NeedTypesInfo
pkgs, err := packages.Load(cfg, src)
if err != nil {
return nil, err
}
if packages.PrintErrors(pkgs) > 0 || len(pkgs) != 1 {
return nil, fmt.Errorf("failed to load source package")
}
pkg := pkgs[0]
if strings.Contains(prefix, "&") {
prefix = strings.Replace(prefix, "&", pkg.Syntax[0].Name.Name, -1)
}
objsToUpdate := make(map[types.Object]bool)
var rename func(from types.Object)
rename = func(from types.Object) {
if !objsToUpdate[from] {
objsToUpdate[from] = true
// Renaming a type that is used as an embedded field
// requires renaming the field too. e.g.
// type T int // if we rename this to U..
// var s struct {T}
// print(s.T) // ...this must change too
if _, ok := from.(*types.TypeName); ok {
for id, obj := range pkg.TypesInfo.Uses {
if obj == from {
if field := pkg.TypesInfo.Defs[id]; field != nil {
rename(field)
}
}
}
}
}
}
// Rename each package-level object.
scope := pkg.Types.Scope()
for _, name := range scope.Names() {
rename(scope.Lookup(name))
}
var out bytes.Buffer
if buildTags != "" {
fmt.Fprintf(&out, "//go:build %s\n", buildTags)
fmt.Fprintf(&out, "// +build %s\n\n", buildTags)
}
fmt.Fprintf(&out, "// Code generated by golang.org/x/tools/cmd/bundle. DO NOT EDIT.\n")
if *outputFile != "" && buildTags == "" {
fmt.Fprintf(&out, "//go:generate bundle %s\n", strings.Join(quoteArgs(os.Args[1:]), " "))
} else {
fmt.Fprintf(&out, "// $ bundle %s\n", strings.Join(os.Args[1:], " "))
}
fmt.Fprintf(&out, "\n")
// Concatenate package comments from all files...
for _, f := range pkg.Syntax {
if doc := f.Doc.Text(); strings.TrimSpace(doc) != "" {
for _, line := range strings.Split(doc, "\n") {
fmt.Fprintf(&out, "// %s\n", line)
}
}
}
// ...but don't let them become the actual package comment.
fmt.Fprintln(&out)
fmt.Fprintf(&out, "package %s\n\n", dstpkg)
// BUG(adonovan,shurcooL): bundle may generate incorrect code
// due to shadowing between identifiers and imported package names.
//
// The generated code will either fail to compile or
// (unlikely) compile successfully but have different behavior
// than the original package. The risk of this happening is higher
// when the original package has renamed imports (they're typically
// renamed in order to resolve a shadow inside that particular .go file).
// TODO(adonovan,shurcooL):
// - detect shadowing issues, and either return error or resolve them
// - preserve comments from the original import declarations.
// pkgStd and pkgExt are sets of printed import specs. This is done
// to deduplicate instances of the same import name and path.
var pkgStd = make(map[string]bool)
var pkgExt = make(map[string]bool)
for _, f := range pkg.Syntax {
for _, imp := range f.Imports {
path, err := strconv.Unquote(imp.Path.Value)
if err != nil {
log.Fatalf("invalid import path string: %v", err) // Shouldn't happen here since packages.Load succeeded.
}
if path == dst {
continue
}
if newPath, ok := importMap[path]; ok {
path = newPath
}
var name string
if imp.Name != nil {
name = imp.Name.Name
}
spec := fmt.Sprintf("%s %q", name, path)
if isStandardImportPath(path) {
pkgStd[spec] = true
} else {
pkgExt[spec] = true
}
}
}
// Print a single declaration that imports all necessary packages.
fmt.Fprintln(&out, "import (")
for p := range pkgStd {
fmt.Fprintf(&out, "\t%s\n", p)
}
if len(pkgExt) > 0 {
fmt.Fprintln(&out)
}
for p := range pkgExt {
fmt.Fprintf(&out, "\t%s\n", p)
}
fmt.Fprint(&out, ")\n\n")
// Modify and print each file.
for _, f := range pkg.Syntax {
// Update renamed identifiers.
for id, obj := range pkg.TypesInfo.Defs {
if objsToUpdate[obj] {
id.Name = prefix + obj.Name()
}
}
for id, obj := range pkg.TypesInfo.Uses {
if objsToUpdate[obj] {
id.Name = prefix + obj.Name()
}
}
// For each qualified identifier that refers to the
// destination package, remove the qualifier.
// The "@@@." strings are removed in postprocessing.
ast.Inspect(f, func(n ast.Node) bool {
if sel, ok := n.(*ast.SelectorExpr); ok {
if id, ok := sel.X.(*ast.Ident); ok {
if obj, ok := pkg.TypesInfo.Uses[id].(*types.PkgName); ok {
if obj.Imported().Path() == dst {
id.Name = "@@@"
}
}
}
}
return true
})
last := f.Package
if len(f.Imports) > 0 {
imp := f.Imports[len(f.Imports)-1]
last = imp.End()
if imp.Comment != nil {
if e := imp.Comment.End(); e > last {
last = e
}
}
}
// Pretty-print package-level declarations.
// but no package or import declarations.
var buf bytes.Buffer
for _, decl := range f.Decls {
if decl, ok := decl.(*ast.GenDecl); ok && decl.Tok == token.IMPORT {
continue
}
beg, end := sourceRange(decl)
printComments(&out, f.Comments, last, beg)
buf.Reset()
format.Node(&buf, pkg.Fset, &printer.CommentedNode{Node: decl, Comments: f.Comments})
// Remove each "@@@." in the output.
// TODO(adonovan): not hygienic.
out.Write(bytes.Replace(buf.Bytes(), []byte("@@@."), nil, -1))
last = printSameLineComment(&out, f.Comments, pkg.Fset, end)
out.WriteString("\n\n")
}
printLastComments(&out, f.Comments, last)
}
// Now format the entire thing.
result, err := format.Source(out.Bytes())
if err != nil {
log.Fatalf("formatting failed: %v", err)
}
return result, nil
}
// sourceRange returns the [beg, end) interval of source code
// belonging to decl (incl. associated comments).
func sourceRange(decl ast.Decl) (beg, end token.Pos) {
beg = decl.Pos()
end = decl.End()
var doc, com *ast.CommentGroup
switch d := decl.(type) {
case *ast.GenDecl:
doc = d.Doc
if len(d.Specs) > 0 {
switch spec := d.Specs[len(d.Specs)-1].(type) {
case *ast.ValueSpec:
com = spec.Comment
case *ast.TypeSpec:
com = spec.Comment
}
}
case *ast.FuncDecl:
doc = d.Doc
}
if doc != nil {
beg = doc.Pos()
}
if com != nil && com.End() > end {
end = com.End()
}
return beg, end
}
func printComments(out *bytes.Buffer, comments []*ast.CommentGroup, pos, end token.Pos) {
for _, cg := range comments {
if pos <= cg.Pos() && cg.Pos() < end {
for _, c := range cg.List {
fmt.Fprintln(out, c.Text)
}
fmt.Fprintln(out)
}
}
}
const infinity = 1 << 30
func printLastComments(out *bytes.Buffer, comments []*ast.CommentGroup, pos token.Pos) {
printComments(out, comments, pos, infinity)
}
func printSameLineComment(out *bytes.Buffer, comments []*ast.CommentGroup, fset *token.FileSet, pos token.Pos) token.Pos {
tf := fset.File(pos)
for _, cg := range comments {
if pos <= cg.Pos() && tf.Line(cg.Pos()) == tf.Line(pos) {
for _, c := range cg.List {
fmt.Fprintln(out, c.Text)
}
return cg.End()
}
}
return pos
}
func quoteArgs(ss []string) []string {
// From go help generate:
//
// > The arguments to the directive are space-separated tokens or
// > double-quoted strings passed to the generator as individual
// > arguments when it is run.
//
// > Quoted strings use Go syntax and are evaluated before execution; a
// > quoted string appears as a single argument to the generator.
//
var qs []string
for _, s := range ss {
if s == "" || containsSpace(s) {
s = strconv.Quote(s)
}
qs = append(qs, s)
}
return qs
}
func containsSpace(s string) bool {
for _, r := range s {
if unicode.IsSpace(r) {
return true
}
}
return false
}
type flagFunc func(string)
func (f flagFunc) Set(s string) error {
f(s)
return nil
}
func (f flagFunc) String() string { return "" }