Source file src/go/doc/doc.go
1 // Copyright 2009 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 doc extracts source code documentation from a Go AST. 6 package doc 7 8 import ( 9 "fmt" 10 "go/ast" 11 "go/doc/comment" 12 "go/token" 13 "strings" 14 ) 15 16 // Package is the documentation for an entire package. 17 type Package struct { 18 Doc string 19 Name string 20 ImportPath string 21 Imports []string 22 Filenames []string 23 Notes map[string][]*Note 24 25 // Deprecated: For backward compatibility Bugs is still populated, 26 // but all new code should use Notes instead. 27 Bugs []string 28 29 // declarations 30 Consts []*Value 31 Types []*Type 32 Vars []*Value 33 Funcs []*Func 34 35 // Examples is a sorted list of examples associated with 36 // the package. Examples are extracted from _test.go files 37 // provided to NewFromFiles. 38 Examples []*Example 39 40 importByName map[string]string 41 syms map[string]bool 42 } 43 44 // Value is the documentation for a (possibly grouped) var or const declaration. 45 type Value struct { 46 Doc string 47 Names []string // var or const names in declaration order 48 Decl *ast.GenDecl 49 50 order int 51 } 52 53 // Type is the documentation for a type declaration. 54 type Type struct { 55 Doc string 56 Name string 57 Decl *ast.GenDecl 58 59 // associated declarations 60 Consts []*Value // sorted list of constants of (mostly) this type 61 Vars []*Value // sorted list of variables of (mostly) this type 62 Funcs []*Func // sorted list of functions returning this type 63 Methods []*Func // sorted list of methods (including embedded ones) of this type 64 65 // Examples is a sorted list of examples associated with 66 // this type. Examples are extracted from _test.go files 67 // provided to NewFromFiles. 68 Examples []*Example 69 } 70 71 // Func is the documentation for a func declaration. 72 type Func struct { 73 Doc string 74 Name string 75 Decl *ast.FuncDecl 76 77 // methods 78 // (for functions, these fields have the respective zero value) 79 Recv string // actual receiver "T" or "*T" possibly followed by type parameters [P1, ..., Pn] 80 Orig string // original receiver "T" or "*T" 81 Level int // embedding level; 0 means not embedded 82 83 // Examples is a sorted list of examples associated with this 84 // function or method. Examples are extracted from _test.go files 85 // provided to NewFromFiles. 86 Examples []*Example 87 } 88 89 // A Note represents a marked comment starting with "MARKER(uid): note body". 90 // Any note with a marker of 2 or more upper case [A-Z] letters and a uid of 91 // at least one character is recognized. The ":" following the uid is optional. 92 // Notes are collected in the Package.Notes map indexed by the notes marker. 93 type Note struct { 94 Pos, End token.Pos // position range of the comment containing the marker 95 UID string // uid found with the marker 96 Body string // note body text 97 } 98 99 // Mode values control the operation of [New] and [NewFromFiles]. 100 type Mode int 101 102 const ( 103 // AllDecls says to extract documentation for all package-level 104 // declarations, not just exported ones. 105 AllDecls Mode = 1 << iota 106 107 // AllMethods says to show all embedded methods, not just the ones of 108 // invisible (unexported) anonymous fields. 109 AllMethods 110 111 // PreserveAST says to leave the AST unmodified. Originally, pieces of 112 // the AST such as function bodies were nil-ed out to save memory in 113 // godoc, but not all programs want that behavior. 114 PreserveAST 115 ) 116 117 // New computes the package documentation for the given package AST. 118 // New takes ownership of the AST pkg and may edit or overwrite it. 119 // To have the [Examples] fields populated, use [NewFromFiles] and include 120 // the package's _test.go files. 121 func New(pkg *ast.Package, importPath string, mode Mode) *Package { 122 var r reader 123 r.readPackage(pkg, mode) 124 r.computeMethodSets() 125 r.cleanupTypes() 126 p := &Package{ 127 Doc: r.doc, 128 Name: pkg.Name, 129 ImportPath: importPath, 130 Imports: sortedKeys(r.imports), 131 Filenames: r.filenames, 132 Notes: r.notes, 133 Bugs: noteBodies(r.notes["BUG"]), 134 Consts: sortedValues(r.values, token.CONST), 135 Types: sortedTypes(r.types, mode&AllMethods != 0), 136 Vars: sortedValues(r.values, token.VAR), 137 Funcs: sortedFuncs(r.funcs, true), 138 139 importByName: r.importByName, 140 syms: make(map[string]bool), 141 } 142 143 p.collectValues(p.Consts) 144 p.collectValues(p.Vars) 145 p.collectTypes(p.Types) 146 p.collectFuncs(p.Funcs) 147 148 return p 149 } 150 151 func (p *Package) collectValues(values []*Value) { 152 for _, v := range values { 153 for _, name := range v.Names { 154 p.syms[name] = true 155 } 156 } 157 } 158 159 func (p *Package) collectTypes(types []*Type) { 160 for _, t := range types { 161 if p.syms[t.Name] { 162 // Shouldn't be any cycles but stop just in case. 163 continue 164 } 165 p.syms[t.Name] = true 166 p.collectValues(t.Consts) 167 p.collectValues(t.Vars) 168 p.collectFuncs(t.Funcs) 169 p.collectFuncs(t.Methods) 170 } 171 } 172 173 func (p *Package) collectFuncs(funcs []*Func) { 174 for _, f := range funcs { 175 if f.Recv != "" { 176 r := strings.TrimPrefix(f.Recv, "*") 177 if i := strings.IndexByte(r, '['); i >= 0 { 178 r = r[:i] // remove type parameters 179 } 180 p.syms[r+"."+f.Name] = true 181 } else { 182 p.syms[f.Name] = true 183 } 184 } 185 } 186 187 // NewFromFiles computes documentation for a package. 188 // 189 // The package is specified by a list of *ast.Files and corresponding 190 // file set, which must not be nil. 191 // NewFromFiles uses all provided files when computing documentation, 192 // so it is the caller's responsibility to provide only the files that 193 // match the desired build context. "go/build".Context.MatchFile can 194 // be used for determining whether a file matches a build context with 195 // the desired GOOS and GOARCH values, and other build constraints. 196 // The import path of the package is specified by importPath. 197 // 198 // Examples found in _test.go files are associated with the corresponding 199 // type, function, method, or the package, based on their name. 200 // If the example has a suffix in its name, it is set in the 201 // [Example.Suffix] field. [Examples] with malformed names are skipped. 202 // 203 // Optionally, a single extra argument of type [Mode] can be provided to 204 // control low-level aspects of the documentation extraction behavior. 205 // 206 // NewFromFiles takes ownership of the AST files and may edit them, 207 // unless the PreserveAST Mode bit is on. 208 func NewFromFiles(fset *token.FileSet, files []*ast.File, importPath string, opts ...any) (*Package, error) { 209 // Check for invalid API usage. 210 if fset == nil { 211 panic(fmt.Errorf("doc.NewFromFiles: no token.FileSet provided (fset == nil)")) 212 } 213 var mode Mode 214 switch len(opts) { // There can only be 0 or 1 options, so a simple switch works for now. 215 case 0: 216 // Nothing to do. 217 case 1: 218 m, ok := opts[0].(Mode) 219 if !ok { 220 panic(fmt.Errorf("doc.NewFromFiles: option argument type must be doc.Mode")) 221 } 222 mode = m 223 default: 224 panic(fmt.Errorf("doc.NewFromFiles: there must not be more than 1 option argument")) 225 } 226 227 // Collect .go and _test.go files. 228 var ( 229 goFiles = make(map[string]*ast.File) 230 testGoFiles []*ast.File 231 ) 232 for i := range files { 233 f := fset.File(files[i].Pos()) 234 if f == nil { 235 return nil, fmt.Errorf("file files[%d] is not found in the provided file set", i) 236 } 237 switch name := f.Name(); { 238 case strings.HasSuffix(name, ".go") && !strings.HasSuffix(name, "_test.go"): 239 goFiles[name] = files[i] 240 case strings.HasSuffix(name, "_test.go"): 241 testGoFiles = append(testGoFiles, files[i]) 242 default: 243 return nil, fmt.Errorf("file files[%d] filename %q does not have a .go extension", i, name) 244 } 245 } 246 247 // TODO(dmitshur,gri): A relatively high level call to ast.NewPackage with a simpleImporter 248 // ast.Importer implementation is made below. It might be possible to short-circuit and simplify. 249 250 // Compute package documentation. 251 pkg, _ := ast.NewPackage(fset, goFiles, simpleImporter, nil) // Ignore errors that can happen due to unresolved identifiers. 252 p := New(pkg, importPath, mode) 253 classifyExamples(p, Examples(testGoFiles...)) 254 return p, nil 255 } 256 257 // simpleImporter returns a (dummy) package object named by the last path 258 // component of the provided package path (as is the convention for packages). 259 // This is sufficient to resolve package identifiers without doing an actual 260 // import. It never returns an error. 261 func simpleImporter(imports map[string]*ast.Object, path string) (*ast.Object, error) { 262 pkg := imports[path] 263 if pkg == nil { 264 // note that strings.LastIndex returns -1 if there is no "/" 265 pkg = ast.NewObj(ast.Pkg, path[strings.LastIndex(path, "/")+1:]) 266 pkg.Data = ast.NewScope(nil) // required by ast.NewPackage for dot-import 267 imports[path] = pkg 268 } 269 return pkg, nil 270 } 271 272 // lookupSym reports whether the package has a given symbol or method. 273 // 274 // If recv == "", HasSym reports whether the package has a top-level 275 // const, func, type, or var named name. 276 // 277 // If recv != "", HasSym reports whether the package has a type 278 // named recv with a method named name. 279 func (p *Package) lookupSym(recv, name string) bool { 280 if recv != "" { 281 return p.syms[recv+"."+name] 282 } 283 return p.syms[name] 284 } 285 286 // lookupPackage returns the import path identified by name 287 // in the given package. If name uniquely identifies a single import, 288 // then lookupPackage returns that import. 289 // If multiple packages are imported as name, importPath returns "", false. 290 // Otherwise, if name is the name of p itself, importPath returns "", true, 291 // to signal a reference to p. 292 // Otherwise, importPath returns "", false. 293 func (p *Package) lookupPackage(name string) (importPath string, ok bool) { 294 if path, ok := p.importByName[name]; ok { 295 if path == "" { 296 return "", false // multiple imports used the name 297 } 298 return path, true // found import 299 } 300 if p.Name == name { 301 return "", true // allow reference to this package 302 } 303 return "", false // unknown name 304 } 305 306 // Parser returns a doc comment parser configured 307 // for parsing doc comments from package p. 308 // Each call returns a new parser, so that the caller may 309 // customize it before use. 310 func (p *Package) Parser() *comment.Parser { 311 return &comment.Parser{ 312 LookupPackage: p.lookupPackage, 313 LookupSym: p.lookupSym, 314 } 315 } 316 317 // Printer returns a doc comment printer configured 318 // for printing doc comments from package p. 319 // Each call returns a new printer, so that the caller may 320 // customize it before use. 321 func (p *Package) Printer() *comment.Printer { 322 // No customization today, but having p.Printer() 323 // gives us flexibility in the future, and it is convenient for callers. 324 return &comment.Printer{} 325 } 326 327 // HTML returns formatted HTML for the doc comment text. 328 // 329 // To customize details of the HTML, use [Package.Printer] 330 // to obtain a [comment.Printer], and configure it 331 // before calling its HTML method. 332 func (p *Package) HTML(text string) []byte { 333 return p.Printer().HTML(p.Parser().Parse(text)) 334 } 335 336 // Markdown returns formatted Markdown for the doc comment text. 337 // 338 // To customize details of the Markdown, use [Package.Printer] 339 // to obtain a [comment.Printer], and configure it 340 // before calling its Markdown method. 341 func (p *Package) Markdown(text string) []byte { 342 return p.Printer().Markdown(p.Parser().Parse(text)) 343 } 344 345 // Text returns formatted text for the doc comment text, 346 // wrapped to 80 Unicode code points and using tabs for 347 // code block indentation. 348 // 349 // To customize details of the formatting, use [Package.Printer] 350 // to obtain a [comment.Printer], and configure it 351 // before calling its Text method. 352 func (p *Package) Text(text string) []byte { 353 return p.Printer().Text(p.Parser().Parse(text)) 354 } 355