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 // 192 // NewFromFiles uses all provided files when computing documentation, 193 // so it is the caller's responsibility to provide only the files that 194 // match the desired build context. "go/build".Context.MatchFile can 195 // be used for determining whether a file matches a build context with 196 // the desired GOOS and GOARCH values, and other build constraints. 197 // The import path of the package is specified by importPath. 198 // 199 // Examples found in _test.go files are associated with the corresponding 200 // type, function, method, or the package, based on their name. 201 // If the example has a suffix in its name, it is set in the 202 // [Example.Suffix] field. [Examples] with malformed names are skipped. 203 // 204 // Optionally, a single extra argument of type [Mode] can be provided to 205 // control low-level aspects of the documentation extraction behavior. 206 // 207 // NewFromFiles takes ownership of the AST files and may edit them, 208 // unless the PreserveAST Mode bit is on. 209 func NewFromFiles(fset *token.FileSet, files []*ast.File, importPath string, opts ...any) (*Package, error) { 210 // Check for invalid API usage. 211 if fset == nil { 212 panic(fmt.Errorf("doc.NewFromFiles: no token.FileSet provided (fset == nil)")) 213 } 214 var mode Mode 215 switch len(opts) { // There can only be 0 or 1 options, so a simple switch works for now. 216 case 0: 217 // Nothing to do. 218 case 1: 219 m, ok := opts[0].(Mode) 220 if !ok { 221 panic(fmt.Errorf("doc.NewFromFiles: option argument type must be doc.Mode")) 222 } 223 mode = m 224 default: 225 panic(fmt.Errorf("doc.NewFromFiles: there must not be more than 1 option argument")) 226 } 227 228 // Collect .go and _test.go files. 229 var ( 230 pkgName string 231 goFiles = make(map[string]*ast.File) 232 testGoFiles []*ast.File 233 ) 234 for i, file := range files { 235 f := fset.File(file.Pos()) 236 if f == nil { 237 return nil, fmt.Errorf("file files[%d] is not found in the provided file set", i) 238 } 239 switch filename := f.Name(); { 240 case strings.HasSuffix(filename, "_test.go"): 241 testGoFiles = append(testGoFiles, file) 242 case strings.HasSuffix(filename, ".go"): 243 pkgName = file.Name.Name 244 goFiles[filename] = file 245 default: 246 return nil, fmt.Errorf("file files[%d] filename %q does not have a .go extension", i, filename) 247 } 248 } 249 250 // Compute package documentation. 251 // 252 // Since this package doesn't need Package.{Scope,Imports}, or 253 // handle errors, and ast.File's Scope field is unset in files 254 // parsed with parser.SkipObjectResolution, we construct the 255 // Package directly instead of calling [ast.NewPackage]. 256 pkg := &ast.Package{Name: pkgName, Files: goFiles} 257 p := New(pkg, importPath, mode) 258 classifyExamples(p, Examples(testGoFiles...)) 259 return p, nil 260 } 261 262 // lookupSym reports whether the package has a given symbol or method. 263 // 264 // If recv == "", HasSym reports whether the package has a top-level 265 // const, func, type, or var named name. 266 // 267 // If recv != "", HasSym reports whether the package has a type 268 // named recv with a method named name. 269 func (p *Package) lookupSym(recv, name string) bool { 270 if recv != "" { 271 return p.syms[recv+"."+name] 272 } 273 return p.syms[name] 274 } 275 276 // lookupPackage returns the import path identified by name 277 // in the given package. If name uniquely identifies a single import, 278 // then lookupPackage returns that import. 279 // If multiple packages are imported as name, importPath returns "", false. 280 // Otherwise, if name is the name of p itself, importPath returns "", true, 281 // to signal a reference to p. 282 // Otherwise, importPath returns "", false. 283 func (p *Package) lookupPackage(name string) (importPath string, ok bool) { 284 if path, ok := p.importByName[name]; ok { 285 if path == "" { 286 return "", false // multiple imports used the name 287 } 288 return path, true // found import 289 } 290 if p.Name == name { 291 return "", true // allow reference to this package 292 } 293 return "", false // unknown name 294 } 295 296 // Parser returns a doc comment parser configured 297 // for parsing doc comments from package p. 298 // Each call returns a new parser, so that the caller may 299 // customize it before use. 300 func (p *Package) Parser() *comment.Parser { 301 return &comment.Parser{ 302 LookupPackage: p.lookupPackage, 303 LookupSym: p.lookupSym, 304 } 305 } 306 307 // Printer returns a doc comment printer configured 308 // for printing doc comments from package p. 309 // Each call returns a new printer, so that the caller may 310 // customize it before use. 311 func (p *Package) Printer() *comment.Printer { 312 // No customization today, but having p.Printer() 313 // gives us flexibility in the future, and it is convenient for callers. 314 return &comment.Printer{} 315 } 316 317 // HTML returns formatted HTML for the doc comment text. 318 // 319 // To customize details of the HTML, use [Package.Printer] 320 // to obtain a [comment.Printer], and configure it 321 // before calling its HTML method. 322 func (p *Package) HTML(text string) []byte { 323 return p.Printer().HTML(p.Parser().Parse(text)) 324 } 325 326 // Markdown returns formatted Markdown for the doc comment text. 327 // 328 // To customize details of the Markdown, use [Package.Printer] 329 // to obtain a [comment.Printer], and configure it 330 // before calling its Markdown method. 331 func (p *Package) Markdown(text string) []byte { 332 return p.Printer().Markdown(p.Parser().Parse(text)) 333 } 334 335 // Text returns formatted text for the doc comment text, 336 // wrapped to 80 Unicode code points and using tabs for 337 // code block indentation. 338 // 339 // To customize details of the formatting, use [Package.Printer] 340 // to obtain a [comment.Printer], and configure it 341 // before calling its Text method. 342 func (p *Package) Text(text string) []byte { 343 return p.Printer().Text(p.Parser().Parse(text)) 344 } 345