| // The doc command prints the doc comment of a package-level object. |
| package main |
| |
| import ( |
| "fmt" |
| "go/ast" |
| "go/parser" |
| "log" |
| "os" |
| |
| // TODO: these will use std go/types after Feb 2016 |
| "golang.org/x/tools/go/loader" |
| "golang.org/x/tools/go/types/typeutil" |
| ) |
| |
| func main() { |
| if len(os.Args) != 3 { |
| log.Fatal("Usage: doc <package> <object>") |
| } |
| //!+part1 |
| pkgpath, name := os.Args[1], os.Args[2] |
| |
| // The loader loads a complete Go program from source code. |
| conf := loader.Config{ParserMode: parser.ParseComments} |
| conf.Import(pkgpath) |
| lprog, err := conf.Load() |
| if err != nil { |
| log.Fatal(err) // load error |
| } |
| |
| // Find the package and package-level object. |
| pkg := lprog.Package(pkgpath).Pkg |
| obj := pkg.Scope().Lookup(name) |
| if obj == nil { |
| log.Fatalf("%s.%s not found", pkg.Path(), name) |
| } |
| //!-part1 |
| //!+part2 |
| |
| // Print the object and its methods (incl. location of definition). |
| fmt.Println(obj) |
| for _, sel := range typeutil.IntuitiveMethodSet(obj.Type(), nil) { |
| fmt.Printf("%s: %s\n", lprog.Fset.Position(sel.Obj().Pos()), sel) |
| } |
| |
| // Find the path from the root of the AST to the object's position. |
| // Walk up to the enclosing ast.Decl for the doc comment. |
| _, path, _ := lprog.PathEnclosingInterval(obj.Pos(), obj.Pos()) |
| for _, n := range path { |
| switch n := n.(type) { |
| case *ast.GenDecl: |
| fmt.Println("\n", n.Doc.Text()) |
| return |
| case *ast.FuncDecl: |
| fmt.Println("\n", n.Doc.Text()) |
| return |
| } |
| } |
| //!-part2 |
| } |
| |
| /* |
| //!+output |
| $ ./doc net/http File |
| type net/http.File interface{Readdir(count int) ([]os.FileInfo, error); Seek(offset int64, whence int) (int64, error); Stat() (os.FileInfo, error); io.Closer; io.Reader} |
| /go/src/io/io.go:92:2: method (net/http.File) Close() error |
| /go/src/io/io.go:71:2: method (net/http.File) Read(p []byte) (n int, err error) |
| /go/src/net/http/fs.go:65:2: method (net/http.File) Readdir(count int) ([]os.FileInfo, error) |
| /go/src/net/http/fs.go:66:2: method (net/http.File) Seek(offset int64, whence int) (int64, error) |
| /go/src/net/http/fs.go:67:2: method (net/http.File) Stat() (os.FileInfo, error) |
| |
| A File is returned by a FileSystem's Open method and can be |
| served by the FileServer implementation. |
| |
| The methods should behave the same as those on an *os.File. |
| //!-output |
| */ |