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// 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.
// Package pkgdoc is a library-ified fork of Go's cmd/doc program
// that only does what we need for misc/genreadme.
package pkgdoc
import (
"bytes"
"errors"
"fmt"
"go/ast"
"go/build"
"go/doc"
"go/parser"
"go/token"
"io"
"io/fs"
"log"
"slices"
)
const (
punchedCardWidth = 80
indent = " "
)
type Package struct {
writer io.Writer // Destination for output.
name string // Package name, json for encoding/json.
userPath string // String the user used to find this package.
pkg *ast.Package // Parsed package.
file *ast.File // Merged from all files in the package
doc *doc.Package
build *build.Package
fs *token.FileSet // Needed for printing.
buf pkgBuffer
}
func (pkg *Package) ToText(w io.Writer, text, prefix, codePrefix string) {
d := pkg.doc.Parser().Parse(text)
pr := pkg.doc.Printer()
pr.TextPrefix = prefix
pr.TextCodePrefix = codePrefix
w.Write(pr.Text(d))
}
// pkgBuffer is a wrapper for bytes.Buffer that prints a package clause the
// first time Write is called.
type pkgBuffer struct {
pkg *Package
printed bool // Prevent repeated package clauses.
bytes.Buffer
}
func (pb *pkgBuffer) Write(p []byte) (int, error) {
pb.packageClause()
return pb.Buffer.Write(p)
}
func (pb *pkgBuffer) packageClause() {
if !pb.printed {
pb.printed = true
// Only show package clause for commands if requested explicitly.
if pb.pkg.pkg.Name != "main" {
pb.pkg.packageClause()
}
}
}
type PackageError string // type returned by pkg.Fatalf.
func (p PackageError) Error() string {
return string(p)
}
// parsePackage turns the build package we found into a parsed package
// we can then use to generate documentation.
func parsePackage(writer io.Writer, pkg *build.Package, userPath string) *Package {
// include tells parser.ParseDir which files to include.
// That means the file must be in the build package's GoFiles or CgoFiles
// list only (no tag-ignored files, tests, swig or other non-Go files).
include := func(info fs.FileInfo) bool {
return slices.Contains(pkg.GoFiles, info.Name()) || slices.Contains(pkg.CgoFiles, info.Name())
}
fset := token.NewFileSet()
pkgs, err := parser.ParseDir(fset, pkg.Dir, include, parser.ParseComments|parser.ImportsOnly)
if err != nil {
log.Fatal(err)
}
// Make sure they are all in one package.
if len(pkgs) == 0 {
log.Fatalf("no source-code package in directory %s", pkg.Dir)
}
if len(pkgs) > 1 {
log.Fatalf("multiple packages in directory %s", pkg.Dir)
}
astPkg := pkgs[pkg.Name]
// TODO: go/doc does not include typed constants in the constants
// list, which is what we want. For instance, time.Sunday is of type
// time.Weekday, so it is defined in the type but not in the
// Consts list for the package. This prevents
// go doc time.Sunday
// from finding the symbol. Work around this for now, but we
// should fix it in go/doc.
// A similar story applies to factory functions.
mode := doc.AllDecls
docPkg := doc.New(astPkg, pkg.ImportPath, mode)
p := &Package{
writer: writer,
name: pkg.Name,
userPath: userPath,
pkg: astPkg,
file: ast.MergePackageFiles(astPkg, 0),
doc: docPkg,
build: pkg,
fs: fset,
}
p.buf.pkg = p
return p
}
func (pkg *Package) Printf(format string, args ...any) {
fmt.Fprintf(&pkg.buf, format, args...)
}
func (pkg *Package) flush() {
_, err := pkg.writer.Write(pkg.buf.Bytes())
if err != nil {
log.Fatal(err)
}
pkg.buf.Reset() // Not needed, but it's a flush.
}
var newlineBytes = []byte("\n\n") // We never ask for more than 2.
// newlines guarantees there are n newlines at the end of the buffer.
func (pkg *Package) newlines(n int) {
for !bytes.HasSuffix(pkg.buf.Bytes(), newlineBytes[:n]) {
pkg.buf.WriteRune('\n')
}
}
// packageDoc prints the docs for the package.
func (pkg *Package) packageDoc() {
pkg.Printf("") // Trigger the package clause; we know the package exists.
pkg.ToText(&pkg.buf, pkg.doc.Doc, "", indent)
pkg.newlines(1)
pkg.bugs()
}
// packageClause prints the package clause.
func (pkg *Package) packageClause() {
importPath := pkg.build.ImportComment
if importPath == "" {
importPath = pkg.build.ImportPath
}
pkg.Printf("package %s // import %q\n\n", pkg.name, importPath)
}
// bugs prints the BUGS information for the package.
// TODO: Provide access to TODOs and NOTEs as well (very noisy so off by default)?
func (pkg *Package) bugs() {
if pkg.doc.Notes["BUG"] == nil {
return
}
pkg.Printf("\n")
for _, note := range pkg.doc.Notes["BUG"] {
pkg.Printf("%s: %v\n", "BUG", note.Body)
}
}
// PackageDoc generates documentation for a package in the given directory.
func PackageDoc(dir string) ([]byte, error) {
var buf bytes.Buffer
var writer io.Writer = &buf
buildPackage, err := build.ImportDir(dir, build.ImportComment)
if err != nil {
var noGoError *build.NoGoError
if errors.As(err, &noGoError) {
return nil, nil
}
return nil, err
}
userPath := dir
pkg := parsePackage(writer, buildPackage, userPath)
pkg.packageDoc()
pkg.flush()
return buf.Bytes(), nil
}
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