// 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 main import ( "bytes" "fmt" "go/ast" "go/build" "go/doc" "go/format" "go/parser" "go/token" "io" "log" "os" "path/filepath" "strings" "unicode" "unicode/utf8" ) const ( punchedCardWidth = 80 // These things just won't leave us alone. indentedWidth = punchedCardWidth - len(indent) 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 bytes.Buffer } type PackageError string // type returned by pkg.Fatalf. func (p PackageError) Error() string { return string(p) } // prettyPath returns a version of the package path that is suitable for an // error message. It obeys the import comment if present. Also, since // pkg.build.ImportPath is sometimes the unhelpful "" or ".", it looks for a // directory name in GOROOT or GOPATH if that happens. func (pkg *Package) prettyPath() string { path := pkg.build.ImportComment if path == "" { path = pkg.build.ImportPath } if path != "." && path != "" { return path } // Convert the source directory into a more useful path. // Also convert everything to slash-separated paths for uniform handling. path = filepath.Clean(filepath.ToSlash(pkg.build.Dir)) // Can we find a decent prefix? goroot := filepath.Join(build.Default.GOROOT, "src") if p, ok := trim(path, filepath.ToSlash(goroot)); ok { return p } for _, gopath := range splitGopath() { if p, ok := trim(path, filepath.ToSlash(gopath)); ok { return p } } return path } // trim trims the directory prefix from the path, paying attention // to the path separator. If they are the same string or the prefix // is not present the original is returned. The boolean reports whether // the prefix is present. That path and prefix have slashes for separators. func trim(path, prefix string) (string, bool) { if !strings.HasPrefix(path, prefix) { return path, false } if path == prefix { return path, true } if path[len(prefix)] == '/' { return path[len(prefix)+1:], true } return path, false // Textual prefix but not a path prefix. } // pkg.Fatalf is like log.Fatalf, but panics so it can be recovered in the // main do function, so it doesn't cause an exit. Allows testing to work // without running a subprocess. The log prefix will be added when // logged in main; it is not added here. func (pkg *Package) Fatalf(format string, args ...interface{}) { panic(PackageError(fmt.Sprintf(format, args...))) } // 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 { fs := token.NewFileSet() // 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 os.FileInfo) bool { for _, name := range pkg.GoFiles { if name == info.Name() { return true } } for _, name := range pkg.CgoFiles { if name == info.Name() { return true } } return false } pkgs, err := parser.ParseDir(fs, pkg.Dir, include, parser.ParseComments) if err != nil { log.Fatal(err) } // Make sure they are all in one package. 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. docPkg := doc.New(astPkg, pkg.ImportPath, doc.AllDecls) for _, typ := range docPkg.Types { docPkg.Consts = append(docPkg.Consts, typ.Consts...) docPkg.Vars = append(docPkg.Vars, typ.Vars...) docPkg.Funcs = append(docPkg.Funcs, typ.Funcs...) } return &Package{ writer: writer, name: pkg.Name, userPath: userPath, pkg: astPkg, file: ast.MergePackageFiles(astPkg, 0), doc: docPkg, build: pkg, fs: fs, } } func (pkg *Package) Printf(format string, args ...interface{}) { 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') } } // emit prints the node. func (pkg *Package) emit(comment string, node ast.Node) { if node != nil { err := format.Node(&pkg.buf, pkg.fs, node) if err != nil { log.Fatal(err) } if comment != "" { pkg.newlines(1) doc.ToText(&pkg.buf, comment, " ", indent, indentedWidth) pkg.newlines(2) // Blank line after comment to separate from next item. } else { pkg.newlines(1) } } } // oneLineNode returns a one-line summary of the given input node. func (pkg *Package) oneLineNode(node ast.Node) string { const maxDepth = 10 return pkg.oneLineNodeDepth(node, maxDepth) } // oneLineNodeDepth returns a one-line summary of the given input node. // The depth specifies the maximum depth when traversing the AST. func (pkg *Package) oneLineNodeDepth(node ast.Node, depth int) string { const dotDotDot = "..." if depth == 0 { return dotDotDot } depth-- switch n := node.(type) { case nil: return "" case *ast.GenDecl: // Formats const and var declarations. trailer := "" if len(n.Specs) > 1 { trailer = " " + dotDotDot } // Find the first relevant spec. typ := "" for i, spec := range n.Specs { valueSpec := spec.(*ast.ValueSpec) // Must succeed; we can't mix types in one GenDecl. // The type name may carry over from a previous specification in the // case of constants and iota. if valueSpec.Type != nil { typ = fmt.Sprintf(" %s", pkg.oneLineNodeDepth(valueSpec.Type, depth)) } else if len(valueSpec.Values) > 0 { typ = "" } if !isExported(valueSpec.Names[0].Name) { continue } val := "" if i < len(valueSpec.Values) && valueSpec.Values[i] != nil { val = fmt.Sprintf(" = %s", pkg.oneLineNodeDepth(valueSpec.Values[i], depth)) } return fmt.Sprintf("%s %s%s%s%s", n.Tok, valueSpec.Names[0], typ, val, trailer) } return "" case *ast.FuncDecl: // Formats func declarations. name := n.Name.Name recv := pkg.oneLineNodeDepth(n.Recv, depth) if len(recv) > 0 { recv = "(" + recv + ") " } fnc := pkg.oneLineNodeDepth(n.Type, depth) if strings.Index(fnc, "func") == 0 { fnc = fnc[4:] } return fmt.Sprintf("func %s%s%s", recv, name, fnc) case *ast.TypeSpec: return fmt.Sprintf("type %s %s", n.Name.Name, pkg.oneLineNodeDepth(n.Type, depth)) case *ast.FuncType: var params []string if n.Params != nil { for _, field := range n.Params.List { params = append(params, pkg.oneLineField(field, depth)) } } needParens := false var results []string if n.Results != nil { needParens = needParens || len(n.Results.List) > 1 for _, field := range n.Results.List { needParens = needParens || len(field.Names) > 0 results = append(results, pkg.oneLineField(field, depth)) } } param := strings.Join(params, ", ") if len(results) == 0 { return fmt.Sprintf("func(%s)", param) } result := strings.Join(results, ", ") if !needParens { return fmt.Sprintf("func(%s) %s", param, result) } return fmt.Sprintf("func(%s) (%s)", param, result) case *ast.StructType: if n.Fields == nil || len(n.Fields.List) == 0 { return "struct{}" } return "struct{ ... }" case *ast.InterfaceType: if n.Methods == nil || len(n.Methods.List) == 0 { return "interface{}" } return "interface{ ... }" case *ast.FieldList: if n == nil || len(n.List) == 0 { return "" } if len(n.List) == 1 { return pkg.oneLineField(n.List[0], depth) } return dotDotDot case *ast.FuncLit: return pkg.oneLineNodeDepth(n.Type, depth) + " { ... }" case *ast.CompositeLit: typ := pkg.oneLineNodeDepth(n.Type, depth) if len(n.Elts) == 0 { return fmt.Sprintf("%s{}", typ) } return fmt.Sprintf("%s{ %s }", typ, dotDotDot) case *ast.ArrayType: length := pkg.oneLineNodeDepth(n.Len, depth) element := pkg.oneLineNodeDepth(n.Elt, depth) return fmt.Sprintf("[%s]%s", length, element) case *ast.MapType: key := pkg.oneLineNodeDepth(n.Key, depth) value := pkg.oneLineNodeDepth(n.Value, depth) return fmt.Sprintf("map[%s]%s", key, value) case *ast.CallExpr: fnc := pkg.oneLineNodeDepth(n.Fun, depth) var args []string for _, arg := range n.Args { args = append(args, pkg.oneLineNodeDepth(arg, depth)) } return fmt.Sprintf("%s(%s)", fnc, strings.Join(args, ", ")) case *ast.UnaryExpr: return fmt.Sprintf("%s%s", n.Op, pkg.oneLineNodeDepth(n.X, depth)) case *ast.Ident: return n.Name default: // As a fallback, use default formatter for all unknown node types. buf := new(bytes.Buffer) format.Node(buf, pkg.fs, node) s := buf.String() if strings.Contains(s, "\n") { return dotDotDot } return s } } // oneLineField returns a one-line summary of the field. func (pkg *Package) oneLineField(field *ast.Field, depth int) string { var names []string for _, name := range field.Names { names = append(names, name.Name) } if len(names) == 0 { return pkg.oneLineNodeDepth(field.Type, depth) } return strings.Join(names, ", ") + " " + pkg.oneLineNodeDepth(field.Type, depth) } // packageDoc prints the docs for the package (package doc plus one-liners of the rest). func (pkg *Package) packageDoc() { defer pkg.flush() if pkg.showInternals() { pkg.packageClause(false) } doc.ToText(&pkg.buf, pkg.doc.Doc, "", indent, indentedWidth) pkg.newlines(1) if !pkg.showInternals() { // Show only package docs for commands. return } pkg.newlines(2) // Guarantee blank line before the components. pkg.valueSummary(pkg.doc.Consts, false) pkg.valueSummary(pkg.doc.Vars, false) pkg.funcSummary(pkg.doc.Funcs, false) pkg.typeSummary() pkg.bugs() } // showInternals reports whether we should show the internals // of a package as opposed to just the package docs. // Used to decide whether to suppress internals for commands. // Called only by Package.packageDoc. func (pkg *Package) showInternals() bool { return pkg.pkg.Name != "main" || showCmd } // packageClause prints the package clause. // The argument boolean, if true, suppresses the output if the // user's argument is identical to the actual package path or // is empty, meaning it's the current directory. func (pkg *Package) packageClause(checkUserPath bool) { if checkUserPath { if pkg.userPath == "" || pkg.userPath == pkg.build.ImportPath { return } } importPath := pkg.build.ImportComment if importPath == "" { importPath = pkg.build.ImportPath } pkg.Printf("package %s // import %q\n\n", pkg.name, importPath) if importPath != pkg.build.ImportPath { pkg.Printf("WARNING: package source is installed in %q\n", pkg.build.ImportPath) } } // valueSummary prints a one-line summary for each set of values and constants. // If all the types in a constant or variable declaration belong to the same // type they can be printed by typeSummary, and so can be suppressed here. func (pkg *Package) valueSummary(values []*doc.Value, showGrouped bool) { var isGrouped map[*doc.Value]bool if !showGrouped { isGrouped = make(map[*doc.Value]bool) for _, typ := range pkg.doc.Types { if !isExported(typ.Name) { continue } for _, c := range typ.Consts { isGrouped[c] = true } for _, v := range typ.Vars { isGrouped[v] = true } } } for _, value := range values { if !isGrouped[value] { if decl := pkg.oneLineNode(value.Decl); decl != "" { pkg.Printf("%s\n", decl) } } } } // funcSummary prints a one-line summary for each function. Constructors // are printed by typeSummary, below, and so can be suppressed here. func (pkg *Package) funcSummary(funcs []*doc.Func, showConstructors bool) { // First, identify the constructors. Don't bother figuring out if they're exported. var isConstructor map[*doc.Func]bool if !showConstructors { isConstructor = make(map[*doc.Func]bool) for _, typ := range pkg.doc.Types { if isExported(typ.Name) { for _, f := range typ.Funcs { isConstructor[f] = true } } } } for _, fun := range funcs { // Exported functions only. The go/doc package does not include methods here. if isExported(fun.Name) { if !isConstructor[fun] { pkg.Printf("%s\n", pkg.oneLineNode(fun.Decl)) } } } } // typeSummary prints a one-line summary for each type, followed by its constructors. func (pkg *Package) typeSummary() { for _, typ := range pkg.doc.Types { for _, spec := range typ.Decl.Specs { typeSpec := spec.(*ast.TypeSpec) // Must succeed. if isExported(typeSpec.Name.Name) { pkg.Printf("%s\n", pkg.oneLineNode(typeSpec)) // Now print the consts, vars, and constructors. for _, c := range typ.Consts { if decl := pkg.oneLineNode(c.Decl); decl != "" { pkg.Printf(indent+"%s\n", decl) } } for _, v := range typ.Vars { if decl := pkg.oneLineNode(v.Decl); decl != "" { pkg.Printf(indent+"%s\n", decl) } } for _, constructor := range typ.Funcs { if isExported(constructor.Name) { pkg.Printf(indent+"%s\n", pkg.oneLineNode(constructor.Decl)) } } } } } } // 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) } } // findValues finds the doc.Values that describe the symbol. func (pkg *Package) findValues(symbol string, docValues []*doc.Value) (values []*doc.Value) { for _, value := range docValues { for _, name := range value.Names { if match(symbol, name) { values = append(values, value) } } } return } // findFuncs finds the doc.Funcs that describes the symbol. func (pkg *Package) findFuncs(symbol string) (funcs []*doc.Func) { for _, fun := range pkg.doc.Funcs { if match(symbol, fun.Name) { funcs = append(funcs, fun) } } return } // findTypes finds the doc.Types that describes the symbol. // If symbol is empty, it finds all exported types. func (pkg *Package) findTypes(symbol string) (types []*doc.Type) { for _, typ := range pkg.doc.Types { if symbol == "" && isExported(typ.Name) || match(symbol, typ.Name) { types = append(types, typ) } } return } // findTypeSpec returns the ast.TypeSpec within the declaration that defines the symbol. // The name must match exactly. func (pkg *Package) findTypeSpec(decl *ast.GenDecl, symbol string) *ast.TypeSpec { for _, spec := range decl.Specs { typeSpec := spec.(*ast.TypeSpec) // Must succeed. if symbol == typeSpec.Name.Name { return typeSpec } } return nil } // symbolDoc prints the docs for symbol. There may be multiple matches. // If symbol matches a type, output includes its methods factories and associated constants. // If there is no top-level symbol, symbolDoc looks for methods that match. func (pkg *Package) symbolDoc(symbol string) bool { defer pkg.flush() found := false // Functions. for _, fun := range pkg.findFuncs(symbol) { if !found { pkg.packageClause(true) } // Symbol is a function. decl := fun.Decl decl.Body = nil pkg.emit(fun.Doc, decl) found = true } // Constants and variables behave the same. values := pkg.findValues(symbol, pkg.doc.Consts) values = append(values, pkg.findValues(symbol, pkg.doc.Vars)...) for _, value := range values { // Print each spec only if there is at least one exported symbol in it. // (See issue 11008.) // TODO: Should we elide unexported symbols from a single spec? // It's an unlikely scenario, probably not worth the trouble. // TODO: Would be nice if go/doc did this for us. specs := make([]ast.Spec, 0, len(value.Decl.Specs)) var typ ast.Expr for _, spec := range value.Decl.Specs { vspec := spec.(*ast.ValueSpec) // The type name may carry over from a previous specification in the // case of constants and iota. if vspec.Type != nil { typ = vspec.Type } for _, ident := range vspec.Names { if isExported(ident.Name) { if vspec.Type == nil && vspec.Values == nil && typ != nil { // This a standalone identifier, as in the case of iota usage. // Thus, assume the type comes from the previous type. vspec.Type = &ast.Ident{ Name: string(pkg.oneLineNode(typ)), NamePos: vspec.End() - 1, } } specs = append(specs, vspec) typ = nil // Only inject type on first exported identifier break } } } if len(specs) == 0 { continue } value.Decl.Specs = specs if !found { pkg.packageClause(true) } pkg.emit(value.Doc, value.Decl) found = true } // Types. for _, typ := range pkg.findTypes(symbol) { if !found { pkg.packageClause(true) } decl := typ.Decl spec := pkg.findTypeSpec(decl, typ.Name) trimUnexportedElems(spec) // If there are multiple types defined, reduce to just this one. if len(decl.Specs) > 1 { decl.Specs = []ast.Spec{spec} } pkg.emit(typ.Doc, decl) // Show associated methods, constants, etc. if len(typ.Consts) > 0 || len(typ.Vars) > 0 || len(typ.Funcs) > 0 || len(typ.Methods) > 0 { pkg.Printf("\n") } pkg.valueSummary(typ.Consts, true) pkg.valueSummary(typ.Vars, true) pkg.funcSummary(typ.Funcs, true) pkg.funcSummary(typ.Methods, true) found = true } if !found { // See if there are methods. if !pkg.printMethodDoc("", symbol) { return false } } return true } // trimUnexportedElems modifies spec in place to elide unexported fields from // structs and methods from interfaces (unless the unexported flag is set). func trimUnexportedElems(spec *ast.TypeSpec) { if unexported { return } switch typ := spec.Type.(type) { case *ast.StructType: typ.Fields = trimUnexportedFields(typ.Fields, false) case *ast.InterfaceType: typ.Methods = trimUnexportedFields(typ.Methods, true) } } // trimUnexportedFields returns the field list trimmed of unexported fields. func trimUnexportedFields(fields *ast.FieldList, isInterface bool) *ast.FieldList { what := "methods" if !isInterface { what = "fields" } trimmed := false list := make([]*ast.Field, 0, len(fields.List)) for _, field := range fields.List { names := field.Names if len(names) == 0 { // Embedded type. Use the name of the type. It must be of type ident or *ident. // Nothing else is allowed. switch ident := field.Type.(type) { case *ast.Ident: if isInterface && ident.Name == "error" && ident.Obj == nil { // For documentation purposes, we consider the builtin error // type special when embedded in an interface, such that it // always gets shown publicly. list = append(list, field) continue } names = []*ast.Ident{ident} case *ast.StarExpr: // Must have the form *identifier. // This is only valid on embedded types in structs. if ident, ok := ident.X.(*ast.Ident); ok && !isInterface { names = []*ast.Ident{ident} } case *ast.SelectorExpr: // An embedded type may refer to a type in another package. names = []*ast.Ident{ident.Sel} } if names == nil { // Can only happen if AST is incorrect. Safe to continue with a nil list. log.Print("invalid program: unexpected type for embedded field") } } // Trims if any is unexported. Good enough in practice. ok := true for _, name := range names { if !isExported(name.Name) { trimmed = true ok = false break } } if ok { list = append(list, field) } } if !trimmed { return fields } unexportedField := &ast.Field{ Type: &ast.Ident{ // Hack: printer will treat this as a field with a named type. // Setting Name and NamePos to ("", fields.Closing-1) ensures that // when Pos and End are called on this field, they return the // position right before closing '}' character. Name: "", NamePos: fields.Closing - 1, }, Comment: &ast.CommentGroup{ List: []*ast.Comment{{Text: fmt.Sprintf("// Has unexported %s.\n", what)}}, }, } return &ast.FieldList{ Opening: fields.Opening, List: append(list, unexportedField), Closing: fields.Closing, } } // printMethodDoc prints the docs for matches of symbol.method. // If symbol is empty, it prints all methods that match the name. // It reports whether it found any methods. func (pkg *Package) printMethodDoc(symbol, method string) bool { defer pkg.flush() types := pkg.findTypes(symbol) if types == nil { if symbol == "" { return false } pkg.Fatalf("symbol %s is not a type in package %s installed in %q", symbol, pkg.name, pkg.build.ImportPath) } found := false for _, typ := range types { if len(typ.Methods) > 0 { for _, meth := range typ.Methods { if match(method, meth.Name) { decl := meth.Decl decl.Body = nil pkg.emit(meth.Doc, decl) found = true } } continue } // Type may be an interface. The go/doc package does not attach // an interface's methods to the doc.Type. We need to dig around. spec := pkg.findTypeSpec(typ.Decl, typ.Name) inter, ok := spec.Type.(*ast.InterfaceType) if !ok { // Not an interface type. // TODO? Maybe handle struct fields here. continue } for _, iMethod := range inter.Methods.List { // This is an interface, so there can be only one name. // TODO: Anonymous methods (embedding) if len(iMethod.Names) == 0 { continue } name := iMethod.Names[0].Name if match(method, name) { // pkg.oneLineField(iMethod, 0) if iMethod.Doc != nil { for _, comment := range iMethod.Doc.List { doc.ToText(&pkg.buf, comment.Text, "", indent, indentedWidth) } } s := pkg.oneLineNode(iMethod.Type) // Hack: s starts "func" but there is no name present. // We could instead build a FuncDecl but it's not worthwhile. lineComment := "" if iMethod.Comment != nil { lineComment = fmt.Sprintf(" %s", iMethod.Comment.List[0].Text) } pkg.Printf("func %s%s%s\n", name, s[4:], lineComment) found = true } } } return found } // methodDoc prints the docs for matches of symbol.method. func (pkg *Package) methodDoc(symbol, method string) bool { defer pkg.flush() return pkg.printMethodDoc(symbol, method) } // match reports whether the user's symbol matches the program's. // A lower-case character in the user's string matches either case in the program's. // The program string must be exported. func match(user, program string) bool { if !isExported(program) { return false } if matchCase { return user == program } for _, u := range user { p, w := utf8.DecodeRuneInString(program) program = program[w:] if u == p { continue } if unicode.IsLower(u) && simpleFold(u) == simpleFold(p) { continue } return false } return program == "" } // simpleFold returns the minimum rune equivalent to r // under Unicode-defined simple case folding. func simpleFold(r rune) rune { for { r1 := unicode.SimpleFold(r) if r1 <= r { return r1 // wrapped around, found min } r = r1 } }