pkg.go

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package main
     6  
     7  import (
     8  	"bufio"
     9  	"bytes"
    10  	"fmt"
    11  	"go/ast"
    12  	"go/build"
    13  	"go/doc"
    14  	"go/format"
    15  	"go/parser"
    16  	"go/printer"
    17  	"go/token"
    18  	"io"
    19  	"io/fs"
    20  	"log"
    21  	"path/filepath"
    22  	"strings"
    23  	"unicode"
    24  	"unicode/utf8"
    25  )
    26  
    27  const (
    28  	punchedCardWidth = 80
    29  	indent           = "    "
    30  )
    31  
    32  type Package struct {
    33  	writer      io.Writer    // Destination for output.
    34  	name        string       // Package name, json for encoding/json.
    35  	userPath    string       // String the user used to find this package.
    36  	pkg         *ast.Package // Parsed package.
    37  	file        *ast.File    // Merged from all files in the package
    38  	doc         *doc.Package
    39  	build       *build.Package
    40  	typedValue  map[*doc.Value]bool // Consts and vars related to types.
    41  	constructor map[*doc.Func]bool  // Constructors.
    42  	fs          *token.FileSet      // Needed for printing.
    43  	buf         pkgBuffer
    44  }
    45  
    46  func (pkg *Package) ToText(w io.Writer, text, prefix, codePrefix string) {
    47  	d := pkg.doc.Parser().Parse(text)
    48  	pr := pkg.doc.Printer()
    49  	pr.TextPrefix = prefix
    50  	pr.TextCodePrefix = codePrefix
    51  	w.Write(pr.Text(d))
    52  }
    53  
    54  // pkgBuffer is a wrapper for bytes.Buffer that prints a package clause the
    55  // first time Write is called.
    56  type pkgBuffer struct {
    57  	pkg     *Package
    58  	printed bool // Prevent repeated package clauses.
    59  	bytes.Buffer
    60  }
    61  
    62  func (pb *pkgBuffer) Write(p []byte) (int, error) {
    63  	pb.packageClause()
    64  	return pb.Buffer.Write(p)
    65  }
    66  
    67  func (pb *pkgBuffer) packageClause() {
    68  	if !pb.printed {
    69  		pb.printed = true
    70  		// Only show package clause for commands if requested explicitly.
    71  		if pb.pkg.pkg.Name != "main" || showCmd {
    72  			pb.pkg.packageClause()
    73  		}
    74  	}
    75  }
    76  
    77  type PackageError string // type returned by pkg.Fatalf.
    78  
    79  func (p PackageError) Error() string {
    80  	return string(p)
    81  }
    82  
    83  // prettyPath returns a version of the package path that is suitable for an
    84  // error message. It obeys the import comment if present. Also, since
    85  // pkg.build.ImportPath is sometimes the unhelpful "" or ".", it looks for a
    86  // directory name in GOROOT or GOPATH if that happens.
    87  func (pkg *Package) prettyPath() string {
    88  	path := pkg.build.ImportComment
    89  	if path == "" {
    90  		path = pkg.build.ImportPath
    91  	}
    92  	if path != "." && path != "" {
    93  		return path
    94  	}
    95  	// Convert the source directory into a more useful path.
    96  	// Also convert everything to slash-separated paths for uniform handling.
    97  	path = filepath.Clean(filepath.ToSlash(pkg.build.Dir))
    98  	// Can we find a decent prefix?
    99  	if buildCtx.GOROOT != "" {
   100  		goroot := filepath.Join(buildCtx.GOROOT, "src")
   101  		if p, ok := trim(path, filepath.ToSlash(goroot)); ok {
   102  			return p
   103  		}
   104  	}
   105  	for _, gopath := range splitGopath() {
   106  		if p, ok := trim(path, filepath.ToSlash(gopath)); ok {
   107  			return p
   108  		}
   109  	}
   110  	return path
   111  }
   112  
   113  // trim trims the directory prefix from the path, paying attention
   114  // to the path separator. If they are the same string or the prefix
   115  // is not present the original is returned. The boolean reports whether
   116  // the prefix is present. That path and prefix have slashes for separators.
   117  func trim(path, prefix string) (string, bool) {
   118  	if !strings.HasPrefix(path, prefix) {
   119  		return path, false
   120  	}
   121  	if path == prefix {
   122  		return path, true
   123  	}
   124  	if path[len(prefix)] == '/' {
   125  		return path[len(prefix)+1:], true
   126  	}
   127  	return path, false // Textual prefix but not a path prefix.
   128  }
   129  
   130  // pkg.Fatalf is like log.Fatalf, but panics so it can be recovered in the
   131  // main do function, so it doesn't cause an exit. Allows testing to work
   132  // without running a subprocess. The log prefix will be added when
   133  // logged in main; it is not added here.
   134  func (pkg *Package) Fatalf(format string, args ...any) {
   135  	panic(PackageError(fmt.Sprintf(format, args...)))
   136  }
   137  
   138  // parsePackage turns the build package we found into a parsed package
   139  // we can then use to generate documentation.
   140  func parsePackage(writer io.Writer, pkg *build.Package, userPath string) *Package {
   141  	// include tells parser.ParseDir which files to include.
   142  	// That means the file must be in the build package's GoFiles or CgoFiles
   143  	// list only (no tag-ignored files, tests, swig or other non-Go files).
   144  	include := func(info fs.FileInfo) bool {
   145  		for _, name := range pkg.GoFiles {
   146  			if name == info.Name() {
   147  				return true
   148  			}
   149  		}
   150  		for _, name := range pkg.CgoFiles {
   151  			if name == info.Name() {
   152  				return true
   153  			}
   154  		}
   155  		return false
   156  	}
   157  	fset := token.NewFileSet()
   158  	pkgs, err := parser.ParseDir(fset, pkg.Dir, include, parser.ParseComments)
   159  	if err != nil {
   160  		log.Fatal(err)
   161  	}
   162  	// Make sure they are all in one package.
   163  	if len(pkgs) == 0 {
   164  		log.Fatalf("no source-code package in directory %s", pkg.Dir)
   165  	}
   166  	if len(pkgs) > 1 {
   167  		log.Fatalf("multiple packages in directory %s", pkg.Dir)
   168  	}
   169  	astPkg := pkgs[pkg.Name]
   170  
   171  	// TODO: go/doc does not include typed constants in the constants
   172  	// list, which is what we want. For instance, time.Sunday is of type
   173  	// time.Weekday, so it is defined in the type but not in the
   174  	// Consts list for the package. This prevents
   175  	//	go doc time.Sunday
   176  	// from finding the symbol. Work around this for now, but we
   177  	// should fix it in go/doc.
   178  	// A similar story applies to factory functions.
   179  	mode := doc.AllDecls
   180  	if showSrc {
   181  		mode |= doc.PreserveAST // See comment for Package.emit.
   182  	}
   183  	docPkg := doc.New(astPkg, pkg.ImportPath, mode)
   184  	typedValue := make(map[*doc.Value]bool)
   185  	constructor := make(map[*doc.Func]bool)
   186  	for _, typ := range docPkg.Types {
   187  		docPkg.Consts = append(docPkg.Consts, typ.Consts...)
   188  		docPkg.Vars = append(docPkg.Vars, typ.Vars...)
   189  		docPkg.Funcs = append(docPkg.Funcs, typ.Funcs...)
   190  		if isExported(typ.Name) {
   191  			for _, value := range typ.Consts {
   192  				typedValue[value] = true
   193  			}
   194  			for _, value := range typ.Vars {
   195  				typedValue[value] = true
   196  			}
   197  			for _, fun := range typ.Funcs {
   198  				// We don't count it as a constructor bound to the type
   199  				// if the type itself is not exported.
   200  				constructor[fun] = true
   201  			}
   202  		}
   203  	}
   204  
   205  	p := &Package{
   206  		writer:      writer,
   207  		name:        pkg.Name,
   208  		userPath:    userPath,
   209  		pkg:         astPkg,
   210  		file:        ast.MergePackageFiles(astPkg, 0),
   211  		doc:         docPkg,
   212  		typedValue:  typedValue,
   213  		constructor: constructor,
   214  		build:       pkg,
   215  		fs:          fset,
   216  	}
   217  	p.buf.pkg = p
   218  	return p
   219  }
   220  
   221  func (pkg *Package) Printf(format string, args ...any) {
   222  	fmt.Fprintf(&pkg.buf, format, args...)
   223  }
   224  
   225  func (pkg *Package) flush() {
   226  	_, err := pkg.writer.Write(pkg.buf.Bytes())
   227  	if err != nil {
   228  		log.Fatal(err)
   229  	}
   230  	pkg.buf.Reset() // Not needed, but it's a flush.
   231  }
   232  
   233  var newlineBytes = []byte("\n\n") // We never ask for more than 2.
   234  
   235  // newlines guarantees there are n newlines at the end of the buffer.
   236  func (pkg *Package) newlines(n int) {
   237  	for !bytes.HasSuffix(pkg.buf.Bytes(), newlineBytes[:n]) {
   238  		pkg.buf.WriteRune('\n')
   239  	}
   240  }
   241  
   242  // emit prints the node. If showSrc is true, it ignores the provided comment,
   243  // assuming the comment is in the node itself. Otherwise, the go/doc package
   244  // clears the stuff we don't want to print anyway. It's a bit of a magic trick.
   245  func (pkg *Package) emit(comment string, node ast.Node) {
   246  	if node != nil {
   247  		var arg any = node
   248  		if showSrc {
   249  			// Need an extra little dance to get internal comments to appear.
   250  			arg = &printer.CommentedNode{
   251  				Node:     node,
   252  				Comments: pkg.file.Comments,
   253  			}
   254  		}
   255  		err := format.Node(&pkg.buf, pkg.fs, arg)
   256  		if err != nil {
   257  			log.Fatal(err)
   258  		}
   259  		if comment != "" && !showSrc {
   260  			pkg.newlines(1)
   261  			pkg.ToText(&pkg.buf, comment, indent, indent+indent)
   262  			pkg.newlines(2) // Blank line after comment to separate from next item.
   263  		} else {
   264  			pkg.newlines(1)
   265  		}
   266  	}
   267  }
   268  
   269  // oneLineNode returns a one-line summary of the given input node.
   270  func (pkg *Package) oneLineNode(node ast.Node) string {
   271  	const maxDepth = 10
   272  	return pkg.oneLineNodeDepth(node, maxDepth)
   273  }
   274  
   275  // oneLineNodeDepth returns a one-line summary of the given input node.
   276  // The depth specifies the maximum depth when traversing the AST.
   277  func (pkg *Package) oneLineNodeDepth(node ast.Node, depth int) string {
   278  	const dotDotDot = "..."
   279  	if depth == 0 {
   280  		return dotDotDot
   281  	}
   282  	depth--
   283  
   284  	switch n := node.(type) {
   285  	case nil:
   286  		return ""
   287  
   288  	case *ast.GenDecl:
   289  		// Formats const and var declarations.
   290  		trailer := ""
   291  		if len(n.Specs) > 1 {
   292  			trailer = " " + dotDotDot
   293  		}
   294  
   295  		// Find the first relevant spec.
   296  		typ := ""
   297  		for i, spec := range n.Specs {
   298  			valueSpec := spec.(*ast.ValueSpec) // Must succeed; we can't mix types in one GenDecl.
   299  
   300  			// The type name may carry over from a previous specification in the
   301  			// case of constants and iota.
   302  			if valueSpec.Type != nil {
   303  				typ = fmt.Sprintf(" %s", pkg.oneLineNodeDepth(valueSpec.Type, depth))
   304  			} else if len(valueSpec.Values) > 0 {
   305  				typ = ""
   306  			}
   307  
   308  			if !isExported(valueSpec.Names[0].Name) {
   309  				continue
   310  			}
   311  			val := ""
   312  			if i < len(valueSpec.Values) && valueSpec.Values[i] != nil {
   313  				val = fmt.Sprintf(" = %s", pkg.oneLineNodeDepth(valueSpec.Values[i], depth))
   314  			}
   315  			return fmt.Sprintf("%s %s%s%s%s", n.Tok, valueSpec.Names[0], typ, val, trailer)
   316  		}
   317  		return ""
   318  
   319  	case *ast.FuncDecl:
   320  		// Formats func declarations.
   321  		name := n.Name.Name
   322  		recv := pkg.oneLineNodeDepth(n.Recv, depth)
   323  		if len(recv) > 0 {
   324  			recv = "(" + recv + ") "
   325  		}
   326  		fnc := pkg.oneLineNodeDepth(n.Type, depth)
   327  		fnc = strings.TrimPrefix(fnc, "func")
   328  		return fmt.Sprintf("func %s%s%s", recv, name, fnc)
   329  
   330  	case *ast.TypeSpec:
   331  		sep := " "
   332  		if n.Assign.IsValid() {
   333  			sep = " = "
   334  		}
   335  		tparams := pkg.formatTypeParams(n.TypeParams, depth)
   336  		return fmt.Sprintf("type %s%s%s%s", n.Name.Name, tparams, sep, pkg.oneLineNodeDepth(n.Type, depth))
   337  
   338  	case *ast.FuncType:
   339  		var params []string
   340  		if n.Params != nil {
   341  			for _, field := range n.Params.List {
   342  				params = append(params, pkg.oneLineField(field, depth))
   343  			}
   344  		}
   345  		needParens := false
   346  		var results []string
   347  		if n.Results != nil {
   348  			needParens = needParens || len(n.Results.List) > 1
   349  			for _, field := range n.Results.List {
   350  				needParens = needParens || len(field.Names) > 0
   351  				results = append(results, pkg.oneLineField(field, depth))
   352  			}
   353  		}
   354  
   355  		tparam := pkg.formatTypeParams(n.TypeParams, depth)
   356  		param := joinStrings(params)
   357  		if len(results) == 0 {
   358  			return fmt.Sprintf("func%s(%s)", tparam, param)
   359  		}
   360  		result := joinStrings(results)
   361  		if !needParens {
   362  			return fmt.Sprintf("func%s(%s) %s", tparam, param, result)
   363  		}
   364  		return fmt.Sprintf("func%s(%s) (%s)", tparam, param, result)
   365  
   366  	case *ast.StructType:
   367  		if n.Fields == nil || len(n.Fields.List) == 0 {
   368  			return "struct{}"
   369  		}
   370  		return "struct{ ... }"
   371  
   372  	case *ast.InterfaceType:
   373  		if n.Methods == nil || len(n.Methods.List) == 0 {
   374  			return "interface{}"
   375  		}
   376  		return "interface{ ... }"
   377  
   378  	case *ast.FieldList:
   379  		if n == nil || len(n.List) == 0 {
   380  			return ""
   381  		}
   382  		if len(n.List) == 1 {
   383  			return pkg.oneLineField(n.List[0], depth)
   384  		}
   385  		return dotDotDot
   386  
   387  	case *ast.FuncLit:
   388  		return pkg.oneLineNodeDepth(n.Type, depth) + " { ... }"
   389  
   390  	case *ast.CompositeLit:
   391  		typ := pkg.oneLineNodeDepth(n.Type, depth)
   392  		if len(n.Elts) == 0 {
   393  			return fmt.Sprintf("%s{}", typ)
   394  		}
   395  		return fmt.Sprintf("%s{ %s }", typ, dotDotDot)
   396  
   397  	case *ast.ArrayType:
   398  		length := pkg.oneLineNodeDepth(n.Len, depth)
   399  		element := pkg.oneLineNodeDepth(n.Elt, depth)
   400  		return fmt.Sprintf("[%s]%s", length, element)
   401  
   402  	case *ast.MapType:
   403  		key := pkg.oneLineNodeDepth(n.Key, depth)
   404  		value := pkg.oneLineNodeDepth(n.Value, depth)
   405  		return fmt.Sprintf("map[%s]%s", key, value)
   406  
   407  	case *ast.CallExpr:
   408  		fnc := pkg.oneLineNodeDepth(n.Fun, depth)
   409  		var args []string
   410  		for _, arg := range n.Args {
   411  			args = append(args, pkg.oneLineNodeDepth(arg, depth))
   412  		}
   413  		return fmt.Sprintf("%s(%s)", fnc, joinStrings(args))
   414  
   415  	case *ast.UnaryExpr:
   416  		return fmt.Sprintf("%s%s", n.Op, pkg.oneLineNodeDepth(n.X, depth))
   417  
   418  	case *ast.Ident:
   419  		return n.Name
   420  
   421  	default:
   422  		// As a fallback, use default formatter for all unknown node types.
   423  		buf := new(strings.Builder)
   424  		format.Node(buf, pkg.fs, node)
   425  		s := buf.String()
   426  		if strings.Contains(s, "\n") {
   427  			return dotDotDot
   428  		}
   429  		return s
   430  	}
   431  }
   432  
   433  func (pkg *Package) formatTypeParams(list *ast.FieldList, depth int) string {
   434  	if list.NumFields() == 0 {
   435  		return ""
   436  	}
   437  	var tparams []string
   438  	for _, field := range list.List {
   439  		tparams = append(tparams, pkg.oneLineField(field, depth))
   440  	}
   441  	return "[" + joinStrings(tparams) + "]"
   442  }
   443  
   444  // oneLineField returns a one-line summary of the field.
   445  func (pkg *Package) oneLineField(field *ast.Field, depth int) string {
   446  	var names []string
   447  	for _, name := range field.Names {
   448  		names = append(names, name.Name)
   449  	}
   450  	if len(names) == 0 {
   451  		return pkg.oneLineNodeDepth(field.Type, depth)
   452  	}
   453  	return joinStrings(names) + " " + pkg.oneLineNodeDepth(field.Type, depth)
   454  }
   455  
   456  // joinStrings formats the input as a comma-separated list,
   457  // but truncates the list at some reasonable length if necessary.
   458  func joinStrings(ss []string) string {
   459  	var n int
   460  	for i, s := range ss {
   461  		n += len(s) + len(", ")
   462  		if n > punchedCardWidth {
   463  			ss = append(ss[:i:i], "...")
   464  			break
   465  		}
   466  	}
   467  	return strings.Join(ss, ", ")
   468  }
   469  
   470  // printHeader prints a header for the section named s, adding a blank line on each side.
   471  func (pkg *Package) printHeader(s string) {
   472  	pkg.Printf("\n%s\n\n", s)
   473  }
   474  
   475  // constsDoc prints all const documentation, if any, including a header.
   476  // The one argument is the valueDoc registry.
   477  func (pkg *Package) constsDoc(printed map[*ast.GenDecl]bool) {
   478  	var header bool
   479  	for _, value := range pkg.doc.Consts {
   480  		// Constants and variables come in groups, and valueDoc prints
   481  		// all the items in the group. We only need to find one exported symbol.
   482  		for _, name := range value.Names {
   483  			if isExported(name) && !pkg.typedValue[value] {
   484  				if !header {
   485  					pkg.printHeader("CONSTANTS")
   486  					header = true
   487  				}
   488  				pkg.valueDoc(value, printed)
   489  				break
   490  			}
   491  		}
   492  	}
   493  }
   494  
   495  // varsDoc prints all var documentation, if any, including a header.
   496  // Printed is the valueDoc registry.
   497  func (pkg *Package) varsDoc(printed map[*ast.GenDecl]bool) {
   498  	var header bool
   499  	for _, value := range pkg.doc.Vars {
   500  		// Constants and variables come in groups, and valueDoc prints
   501  		// all the items in the group. We only need to find one exported symbol.
   502  		for _, name := range value.Names {
   503  			if isExported(name) && !pkg.typedValue[value] {
   504  				if !header {
   505  					pkg.printHeader("VARIABLES")
   506  					header = true
   507  				}
   508  				pkg.valueDoc(value, printed)
   509  				break
   510  			}
   511  		}
   512  	}
   513  }
   514  
   515  // funcsDoc prints all func documentation, if any, including a header.
   516  func (pkg *Package) funcsDoc() {
   517  	var header bool
   518  	for _, fun := range pkg.doc.Funcs {
   519  		if isExported(fun.Name) && !pkg.constructor[fun] {
   520  			if !header {
   521  				pkg.printHeader("FUNCTIONS")
   522  				header = true
   523  			}
   524  			pkg.emit(fun.Doc, fun.Decl)
   525  		}
   526  	}
   527  }
   528  
   529  // funcsDoc prints all type documentation, if any, including a header.
   530  func (pkg *Package) typesDoc() {
   531  	var header bool
   532  	for _, typ := range pkg.doc.Types {
   533  		if isExported(typ.Name) {
   534  			if !header {
   535  				pkg.printHeader("TYPES")
   536  				header = true
   537  			}
   538  			pkg.typeDoc(typ)
   539  		}
   540  	}
   541  }
   542  
   543  // packageDoc prints the docs for the package.
   544  func (pkg *Package) packageDoc() {
   545  	pkg.Printf("") // Trigger the package clause; we know the package exists.
   546  	if showAll || !short {
   547  		pkg.ToText(&pkg.buf, pkg.doc.Doc, "", indent)
   548  		pkg.newlines(1)
   549  	}
   550  
   551  	switch {
   552  	case showAll:
   553  		printed := make(map[*ast.GenDecl]bool) // valueDoc registry
   554  		pkg.constsDoc(printed)
   555  		pkg.varsDoc(printed)
   556  		pkg.funcsDoc()
   557  		pkg.typesDoc()
   558  
   559  	case pkg.pkg.Name == "main" && !showCmd:
   560  		// Show only package docs for commands.
   561  		return
   562  
   563  	default:
   564  		if !short {
   565  			pkg.newlines(2) // Guarantee blank line before the components.
   566  		}
   567  		pkg.valueSummary(pkg.doc.Consts, false)
   568  		pkg.valueSummary(pkg.doc.Vars, false)
   569  		pkg.funcSummary(pkg.doc.Funcs, false)
   570  		pkg.typeSummary()
   571  	}
   572  
   573  	if !short {
   574  		pkg.bugs()
   575  	}
   576  }
   577  
   578  // packageClause prints the package clause.
   579  func (pkg *Package) packageClause() {
   580  	if short {
   581  		return
   582  	}
   583  	importPath := pkg.build.ImportComment
   584  	if importPath == "" {
   585  		importPath = pkg.build.ImportPath
   586  	}
   587  
   588  	// If we're using modules, the import path derived from module code locations wins.
   589  	// If we did a file system scan, we knew the import path when we found the directory.
   590  	// But if we started with a directory name, we never knew the import path.
   591  	// Either way, we don't know it now, and it's cheap to (re)compute it.
   592  	if usingModules {
   593  		for _, root := range codeRoots() {
   594  			if pkg.build.Dir == root.dir {
   595  				importPath = root.importPath
   596  				break
   597  			}
   598  			if strings.HasPrefix(pkg.build.Dir, root.dir+string(filepath.Separator)) {
   599  				suffix := filepath.ToSlash(pkg.build.Dir[len(root.dir)+1:])
   600  				if root.importPath == "" {
   601  					importPath = suffix
   602  				} else {
   603  					importPath = root.importPath + "/" + suffix
   604  				}
   605  				break
   606  			}
   607  		}
   608  	}
   609  
   610  	pkg.Printf("package %s // import %q\n\n", pkg.name, importPath)
   611  	if !usingModules && importPath != pkg.build.ImportPath {
   612  		pkg.Printf("WARNING: package source is installed in %q\n", pkg.build.ImportPath)
   613  	}
   614  }
   615  
   616  // valueSummary prints a one-line summary for each set of values and constants.
   617  // If all the types in a constant or variable declaration belong to the same
   618  // type they can be printed by typeSummary, and so can be suppressed here.
   619  func (pkg *Package) valueSummary(values []*doc.Value, showGrouped bool) {
   620  	var isGrouped map[*doc.Value]bool
   621  	if !showGrouped {
   622  		isGrouped = make(map[*doc.Value]bool)
   623  		for _, typ := range pkg.doc.Types {
   624  			if !isExported(typ.Name) {
   625  				continue
   626  			}
   627  			for _, c := range typ.Consts {
   628  				isGrouped[c] = true
   629  			}
   630  			for _, v := range typ.Vars {
   631  				isGrouped[v] = true
   632  			}
   633  		}
   634  	}
   635  
   636  	for _, value := range values {
   637  		if !isGrouped[value] {
   638  			if decl := pkg.oneLineNode(value.Decl); decl != "" {
   639  				pkg.Printf("%s\n", decl)
   640  			}
   641  		}
   642  	}
   643  }
   644  
   645  // funcSummary prints a one-line summary for each function. Constructors
   646  // are printed by typeSummary, below, and so can be suppressed here.
   647  func (pkg *Package) funcSummary(funcs []*doc.Func, showConstructors bool) {
   648  	for _, fun := range funcs {
   649  		// Exported functions only. The go/doc package does not include methods here.
   650  		if isExported(fun.Name) {
   651  			if showConstructors || !pkg.constructor[fun] {
   652  				pkg.Printf("%s\n", pkg.oneLineNode(fun.Decl))
   653  			}
   654  		}
   655  	}
   656  }
   657  
   658  // typeSummary prints a one-line summary for each type, followed by its constructors.
   659  func (pkg *Package) typeSummary() {
   660  	for _, typ := range pkg.doc.Types {
   661  		for _, spec := range typ.Decl.Specs {
   662  			typeSpec := spec.(*ast.TypeSpec) // Must succeed.
   663  			if isExported(typeSpec.Name.Name) {
   664  				pkg.Printf("%s\n", pkg.oneLineNode(typeSpec))
   665  				// Now print the consts, vars, and constructors.
   666  				for _, c := range typ.Consts {
   667  					if decl := pkg.oneLineNode(c.Decl); decl != "" {
   668  						pkg.Printf(indent+"%s\n", decl)
   669  					}
   670  				}
   671  				for _, v := range typ.Vars {
   672  					if decl := pkg.oneLineNode(v.Decl); decl != "" {
   673  						pkg.Printf(indent+"%s\n", decl)
   674  					}
   675  				}
   676  				for _, constructor := range typ.Funcs {
   677  					if isExported(constructor.Name) {
   678  						pkg.Printf(indent+"%s\n", pkg.oneLineNode(constructor.Decl))
   679  					}
   680  				}
   681  			}
   682  		}
   683  	}
   684  }
   685  
   686  // bugs prints the BUGS information for the package.
   687  // TODO: Provide access to TODOs and NOTEs as well (very noisy so off by default)?
   688  func (pkg *Package) bugs() {
   689  	if pkg.doc.Notes["BUG"] == nil {
   690  		return
   691  	}
   692  	pkg.Printf("\n")
   693  	for _, note := range pkg.doc.Notes["BUG"] {
   694  		pkg.Printf("%s: %v\n", "BUG", note.Body)
   695  	}
   696  }
   697  
   698  // findValues finds the doc.Values that describe the symbol.
   699  func (pkg *Package) findValues(symbol string, docValues []*doc.Value) (values []*doc.Value) {
   700  	for _, value := range docValues {
   701  		for _, name := range value.Names {
   702  			if match(symbol, name) {
   703  				values = append(values, value)
   704  			}
   705  		}
   706  	}
   707  	return
   708  }
   709  
   710  // findFuncs finds the doc.Funcs that describes the symbol.
   711  func (pkg *Package) findFuncs(symbol string) (funcs []*doc.Func) {
   712  	for _, fun := range pkg.doc.Funcs {
   713  		if match(symbol, fun.Name) {
   714  			funcs = append(funcs, fun)
   715  		}
   716  	}
   717  	return
   718  }
   719  
   720  // findTypes finds the doc.Types that describes the symbol.
   721  // If symbol is empty, it finds all exported types.
   722  func (pkg *Package) findTypes(symbol string) (types []*doc.Type) {
   723  	for _, typ := range pkg.doc.Types {
   724  		if symbol == "" && isExported(typ.Name) || match(symbol, typ.Name) {
   725  			types = append(types, typ)
   726  		}
   727  	}
   728  	return
   729  }
   730  
   731  // findTypeSpec returns the ast.TypeSpec within the declaration that defines the symbol.
   732  // The name must match exactly.
   733  func (pkg *Package) findTypeSpec(decl *ast.GenDecl, symbol string) *ast.TypeSpec {
   734  	for _, spec := range decl.Specs {
   735  		typeSpec := spec.(*ast.TypeSpec) // Must succeed.
   736  		if symbol == typeSpec.Name.Name {
   737  			return typeSpec
   738  		}
   739  	}
   740  	return nil
   741  }
   742  
   743  // symbolDoc prints the docs for symbol. There may be multiple matches.
   744  // If symbol matches a type, output includes its methods factories and associated constants.
   745  // If there is no top-level symbol, symbolDoc looks for methods that match.
   746  func (pkg *Package) symbolDoc(symbol string) bool {
   747  	found := false
   748  	// Functions.
   749  	for _, fun := range pkg.findFuncs(symbol) {
   750  		// Symbol is a function.
   751  		decl := fun.Decl
   752  		pkg.emit(fun.Doc, decl)
   753  		found = true
   754  	}
   755  	// Constants and variables behave the same.
   756  	values := pkg.findValues(symbol, pkg.doc.Consts)
   757  	values = append(values, pkg.findValues(symbol, pkg.doc.Vars)...)
   758  	printed := make(map[*ast.GenDecl]bool) // valueDoc registry
   759  	for _, value := range values {
   760  		pkg.valueDoc(value, printed)
   761  		found = true
   762  	}
   763  	// Types.
   764  	for _, typ := range pkg.findTypes(symbol) {
   765  		pkg.typeDoc(typ)
   766  		found = true
   767  	}
   768  	if !found {
   769  		// See if there are methods.
   770  		if !pkg.printMethodDoc("", symbol) {
   771  			return false
   772  		}
   773  	}
   774  	return true
   775  }
   776  
   777  // valueDoc prints the docs for a constant or variable. The printed map records
   778  // which values have been printed already to avoid duplication. Otherwise, a
   779  // declaration like:
   780  //
   781  //	const ( c = 1; C = 2 )
   782  //
   783  // … could be printed twice if the -u flag is set, as it matches twice.
   784  func (pkg *Package) valueDoc(value *doc.Value, printed map[*ast.GenDecl]bool) {
   785  	if printed[value.Decl] {
   786  		return
   787  	}
   788  	// Print each spec only if there is at least one exported symbol in it.
   789  	// (See issue 11008.)
   790  	// TODO: Should we elide unexported symbols from a single spec?
   791  	// It's an unlikely scenario, probably not worth the trouble.
   792  	// TODO: Would be nice if go/doc did this for us.
   793  	specs := make([]ast.Spec, 0, len(value.Decl.Specs))
   794  	var typ ast.Expr
   795  	for _, spec := range value.Decl.Specs {
   796  		vspec := spec.(*ast.ValueSpec)
   797  
   798  		// The type name may carry over from a previous specification in the
   799  		// case of constants and iota.
   800  		if vspec.Type != nil {
   801  			typ = vspec.Type
   802  		}
   803  
   804  		for _, ident := range vspec.Names {
   805  			if showSrc || isExported(ident.Name) {
   806  				if vspec.Type == nil && vspec.Values == nil && typ != nil {
   807  					// This a standalone identifier, as in the case of iota usage.
   808  					// Thus, assume the type comes from the previous type.
   809  					vspec.Type = &ast.Ident{
   810  						Name:    pkg.oneLineNode(typ),
   811  						NamePos: vspec.End() - 1,
   812  					}
   813  				}
   814  
   815  				specs = append(specs, vspec)
   816  				typ = nil // Only inject type on first exported identifier
   817  				break
   818  			}
   819  		}
   820  	}
   821  	if len(specs) == 0 {
   822  		return
   823  	}
   824  	value.Decl.Specs = specs
   825  	pkg.emit(value.Doc, value.Decl)
   826  	printed[value.Decl] = true
   827  }
   828  
   829  // typeDoc prints the docs for a type, including constructors and other items
   830  // related to it.
   831  func (pkg *Package) typeDoc(typ *doc.Type) {
   832  	decl := typ.Decl
   833  	spec := pkg.findTypeSpec(decl, typ.Name)
   834  	trimUnexportedElems(spec)
   835  	// If there are multiple types defined, reduce to just this one.
   836  	if len(decl.Specs) > 1 {
   837  		decl.Specs = []ast.Spec{spec}
   838  	}
   839  	pkg.emit(typ.Doc, decl)
   840  	pkg.newlines(2)
   841  	// Show associated methods, constants, etc.
   842  	if showAll {
   843  		printed := make(map[*ast.GenDecl]bool) // valueDoc registry
   844  		// We can use append here to print consts, then vars. Ditto for funcs and methods.
   845  		values := typ.Consts
   846  		values = append(values, typ.Vars...)
   847  		for _, value := range values {
   848  			for _, name := range value.Names {
   849  				if isExported(name) {
   850  					pkg.valueDoc(value, printed)
   851  					break
   852  				}
   853  			}
   854  		}
   855  		funcs := typ.Funcs
   856  		funcs = append(funcs, typ.Methods...)
   857  		for _, fun := range funcs {
   858  			if isExported(fun.Name) {
   859  				pkg.emit(fun.Doc, fun.Decl)
   860  				if fun.Doc == "" {
   861  					pkg.newlines(2)
   862  				}
   863  			}
   864  		}
   865  	} else {
   866  		pkg.valueSummary(typ.Consts, true)
   867  		pkg.valueSummary(typ.Vars, true)
   868  		pkg.funcSummary(typ.Funcs, true)
   869  		pkg.funcSummary(typ.Methods, true)
   870  	}
   871  }
   872  
   873  // trimUnexportedElems modifies spec in place to elide unexported fields from
   874  // structs and methods from interfaces (unless the unexported flag is set or we
   875  // are asked to show the original source).
   876  func trimUnexportedElems(spec *ast.TypeSpec) {
   877  	if showSrc {
   878  		return
   879  	}
   880  	switch typ := spec.Type.(type) {
   881  	case *ast.StructType:
   882  		typ.Fields = trimUnexportedFields(typ.Fields, false)
   883  	case *ast.InterfaceType:
   884  		typ.Methods = trimUnexportedFields(typ.Methods, true)
   885  	}
   886  }
   887  
   888  // trimUnexportedFields returns the field list trimmed of unexported fields.
   889  func trimUnexportedFields(fields *ast.FieldList, isInterface bool) *ast.FieldList {
   890  	what := "methods"
   891  	if !isInterface {
   892  		what = "fields"
   893  	}
   894  
   895  	trimmed := false
   896  	list := make([]*ast.Field, 0, len(fields.List))
   897  	for _, field := range fields.List {
   898  		// When printing fields we normally print field.Doc.
   899  		// Here we are going to pass the AST to go/format,
   900  		// which will print the comments from the AST,
   901  		// not field.Doc which is from go/doc.
   902  		// The two are similar but not identical;
   903  		// for example, field.Doc does not include directives.
   904  		// In order to consistently print field.Doc,
   905  		// we replace the comment in the AST with field.Doc.
   906  		// That will cause go/format to print what we want.
   907  		// See issue #56592.
   908  		if field.Doc != nil {
   909  			doc := field.Doc
   910  			text := doc.Text()
   911  
   912  			trailingBlankLine := len(doc.List[len(doc.List)-1].Text) == 2
   913  			if !trailingBlankLine {
   914  				// Remove trailing newline.
   915  				lt := len(text)
   916  				if lt > 0 && text[lt-1] == '\n' {
   917  					text = text[:lt-1]
   918  				}
   919  			}
   920  
   921  			start := doc.List[0].Slash
   922  			doc.List = doc.List[:0]
   923  			for _, line := range strings.Split(text, "\n") {
   924  				prefix := "// "
   925  				if len(line) > 0 && line[0] == '\t' {
   926  					prefix = "//"
   927  				}
   928  				doc.List = append(doc.List, &ast.Comment{
   929  					Text: prefix + line,
   930  				})
   931  			}
   932  			doc.List[0].Slash = start
   933  		}
   934  
   935  		names := field.Names
   936  		if len(names) == 0 {
   937  			// Embedded type. Use the name of the type. It must be of the form ident or
   938  			// pkg.ident (for structs and interfaces), or *ident or *pkg.ident (structs only).
   939  			// Or a type embedded in a constraint.
   940  			// Nothing else is allowed.
   941  			ty := field.Type
   942  			if se, ok := field.Type.(*ast.StarExpr); !isInterface && ok {
   943  				// The form *ident or *pkg.ident is only valid on
   944  				// embedded types in structs.
   945  				ty = se.X
   946  			}
   947  			constraint := false
   948  			switch ident := ty.(type) {
   949  			case *ast.Ident:
   950  				if isInterface && ident.Name == "error" && ident.Obj == nil {
   951  					// For documentation purposes, we consider the builtin error
   952  					// type special when embedded in an interface, such that it
   953  					// always gets shown publicly.
   954  					list = append(list, field)
   955  					continue
   956  				}
   957  				names = []*ast.Ident{ident}
   958  			case *ast.SelectorExpr:
   959  				// An embedded type may refer to a type in another package.
   960  				names = []*ast.Ident{ident.Sel}
   961  			default:
   962  				// An approximation or union or type
   963  				// literal in an interface.
   964  				constraint = true
   965  			}
   966  			if names == nil && !constraint {
   967  				// Can only happen if AST is incorrect. Safe to continue with a nil list.
   968  				log.Print("invalid program: unexpected type for embedded field")
   969  			}
   970  		}
   971  		// Trims if any is unexported. Good enough in practice.
   972  		ok := true
   973  		if !unexported {
   974  			for _, name := range names {
   975  				if !isExported(name.Name) {
   976  					trimmed = true
   977  					ok = false
   978  					break
   979  				}
   980  			}
   981  		}
   982  		if ok {
   983  			list = append(list, field)
   984  		}
   985  	}
   986  	if !trimmed {
   987  		return fields
   988  	}
   989  	unexportedField := &ast.Field{
   990  		Type: &ast.Ident{
   991  			// Hack: printer will treat this as a field with a named type.
   992  			// Setting Name and NamePos to ("", fields.Closing-1) ensures that
   993  			// when Pos and End are called on this field, they return the
   994  			// position right before closing '}' character.
   995  			Name:    "",
   996  			NamePos: fields.Closing - 1,
   997  		},
   998  		Comment: &ast.CommentGroup{
   999  			List: []*ast.Comment{{Text: fmt.Sprintf("// Has unexported %s.\n", what)}},
  1000  		},
  1001  	}
  1002  	return &ast.FieldList{
  1003  		Opening: fields.Opening,
  1004  		List:    append(list, unexportedField),
  1005  		Closing: fields.Closing,
  1006  	}
  1007  }
  1008  
  1009  // printMethodDoc prints the docs for matches of symbol.method.
  1010  // If symbol is empty, it prints all methods for any concrete type
  1011  // that match the name. It reports whether it found any methods.
  1012  func (pkg *Package) printMethodDoc(symbol, method string) bool {
  1013  	types := pkg.findTypes(symbol)
  1014  	if types == nil {
  1015  		if symbol == "" {
  1016  			return false
  1017  		}
  1018  		pkg.Fatalf("symbol %s is not a type in package %s installed in %q", symbol, pkg.name, pkg.build.ImportPath)
  1019  	}
  1020  	found := false
  1021  	for _, typ := range types {
  1022  		if len(typ.Methods) > 0 {
  1023  			for _, meth := range typ.Methods {
  1024  				if match(method, meth.Name) {
  1025  					decl := meth.Decl
  1026  					pkg.emit(meth.Doc, decl)
  1027  					found = true
  1028  				}
  1029  			}
  1030  			continue
  1031  		}
  1032  		if symbol == "" {
  1033  			continue
  1034  		}
  1035  		// Type may be an interface. The go/doc package does not attach
  1036  		// an interface's methods to the doc.Type. We need to dig around.
  1037  		spec := pkg.findTypeSpec(typ.Decl, typ.Name)
  1038  		inter, ok := spec.Type.(*ast.InterfaceType)
  1039  		if !ok {
  1040  			// Not an interface type.
  1041  			continue
  1042  		}
  1043  
  1044  		// Collect and print only the methods that match.
  1045  		var methods []*ast.Field
  1046  		for _, iMethod := range inter.Methods.List {
  1047  			// This is an interface, so there can be only one name.
  1048  			// TODO: Anonymous methods (embedding)
  1049  			if len(iMethod.Names) == 0 {
  1050  				continue
  1051  			}
  1052  			name := iMethod.Names[0].Name
  1053  			if match(method, name) {
  1054  				methods = append(methods, iMethod)
  1055  				found = true
  1056  			}
  1057  		}
  1058  		if found {
  1059  			pkg.Printf("type %s ", spec.Name)
  1060  			inter.Methods.List, methods = methods, inter.Methods.List
  1061  			err := format.Node(&pkg.buf, pkg.fs, inter)
  1062  			if err != nil {
  1063  				log.Fatal(err)
  1064  			}
  1065  			pkg.newlines(1)
  1066  			// Restore the original methods.
  1067  			inter.Methods.List = methods
  1068  		}
  1069  	}
  1070  	return found
  1071  }
  1072  
  1073  // printFieldDoc prints the docs for matches of symbol.fieldName.
  1074  // It reports whether it found any field.
  1075  // Both symbol and fieldName must be non-empty or it returns false.
  1076  func (pkg *Package) printFieldDoc(symbol, fieldName string) bool {
  1077  	if symbol == "" || fieldName == "" {
  1078  		return false
  1079  	}
  1080  	types := pkg.findTypes(symbol)
  1081  	if types == nil {
  1082  		pkg.Fatalf("symbol %s is not a type in package %s installed in %q", symbol, pkg.name, pkg.build.ImportPath)
  1083  	}
  1084  	found := false
  1085  	numUnmatched := 0
  1086  	for _, typ := range types {
  1087  		// Type must be a struct.
  1088  		spec := pkg.findTypeSpec(typ.Decl, typ.Name)
  1089  		structType, ok := spec.Type.(*ast.StructType)
  1090  		if !ok {
  1091  			// Not a struct type.
  1092  			continue
  1093  		}
  1094  		for _, field := range structType.Fields.List {
  1095  			// TODO: Anonymous fields.
  1096  			for _, name := range field.Names {
  1097  				if !match(fieldName, name.Name) {
  1098  					numUnmatched++
  1099  					continue
  1100  				}
  1101  				if !found {
  1102  					pkg.Printf("type %s struct {\n", typ.Name)
  1103  				}
  1104  				if field.Doc != nil {
  1105  					// To present indented blocks in comments correctly, process the comment as
  1106  					// a unit before adding the leading // to each line.
  1107  					docBuf := new(bytes.Buffer)
  1108  					pkg.ToText(docBuf, field.Doc.Text(), "", indent)
  1109  					scanner := bufio.NewScanner(docBuf)
  1110  					for scanner.Scan() {
  1111  						fmt.Fprintf(&pkg.buf, "%s// %s\n", indent, scanner.Bytes())
  1112  					}
  1113  				}
  1114  				s := pkg.oneLineNode(field.Type)
  1115  				lineComment := ""
  1116  				if field.Comment != nil {
  1117  					lineComment = fmt.Sprintf("  %s", field.Comment.List[0].Text)
  1118  				}
  1119  				pkg.Printf("%s%s %s%s\n", indent, name, s, lineComment)
  1120  				found = true
  1121  			}
  1122  		}
  1123  	}
  1124  	if found {
  1125  		if numUnmatched > 0 {
  1126  			pkg.Printf("\n    // ... other fields elided ...\n")
  1127  		}
  1128  		pkg.Printf("}\n")
  1129  	}
  1130  	return found
  1131  }
  1132  
  1133  // match reports whether the user's symbol matches the program's.
  1134  // A lower-case character in the user's string matches either case in the program's.
  1135  // The program string must be exported.
  1136  func match(user, program string) bool {
  1137  	if !isExported(program) {
  1138  		return false
  1139  	}
  1140  	if matchCase {
  1141  		return user == program
  1142  	}
  1143  	for _, u := range user {
  1144  		p, w := utf8.DecodeRuneInString(program)
  1145  		program = program[w:]
  1146  		if u == p {
  1147  			continue
  1148  		}
  1149  		if unicode.IsLower(u) && simpleFold(u) == simpleFold(p) {
  1150  			continue
  1151  		}
  1152  		return false
  1153  	}
  1154  	return program == ""
  1155  }
  1156  
  1157  // simpleFold returns the minimum rune equivalent to r
  1158  // under Unicode-defined simple case folding.
  1159  func simpleFold(r rune) rune {
  1160  	for {
  1161  		r1 := unicode.SimpleFold(r)
  1162  		if r1 <= r {
  1163  			return r1 // wrapped around, found min
  1164  		}
  1165  		r = r1
  1166  	}
  1167  }
  1168
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