Package doc

Overview ▾

Package doc extracts source code documentation from a Go AST.

Variables

IllegalPrefixes is a list of lower-case prefixes that identify a comment as not being a doc comment. This helps to avoid misinterpreting the common mistake of a copyright notice immediately before a package statement as being a doc comment.

var IllegalPrefixes = []string{
    "copyright",
    "all rights",
    "author",
}

func IsPredeclared 1.8

func IsPredeclared(s string) bool

IsPredeclared reports whether s is a predeclared identifier.

func Synopsis

func Synopsis(text string) string

Synopsis returns a cleaned version of the first sentence in text.

Deprecated: New programs should use Package.Synopsis instead, which handles links in text properly.

func ToHTML

func ToHTML(w io.Writer, text string, words map[string]string)

ToHTML converts comment text to formatted HTML.

Deprecated: ToHTML cannot identify documentation links in the doc comment, because they depend on knowing what package the text came from, which is not included in this API.

Given the *doc.Package p where text was found, ToHTML(w, text, nil) can be replaced by:

w.Write(p.HTML(text))

which is in turn shorthand for:

w.Write(p.Printer().HTML(p.Parser().Parse(text)))

If words may be non-nil, the longer replacement is:

parser := p.Parser()
parser.Words = words
w.Write(p.Printer().HTML(parser.Parse(d)))

func ToText

func ToText(w io.Writer, text string, prefix, codePrefix string, width int)

ToText converts comment text to formatted text.

Deprecated: ToText cannot identify documentation links in the doc comment, because they depend on knowing what package the text came from, which is not included in this API.

Given the *doc.Package p where text was found, ToText(w, text, "", "\t", 80) can be replaced by:

w.Write(p.Text(text))

In the general case, ToText(w, text, prefix, codePrefix, width) can be replaced by:

d := p.Parser().Parse(text)
pr := p.Printer()
pr.TextPrefix = prefix
pr.TextCodePrefix = codePrefix
pr.TextWidth = width
w.Write(pr.Text(d))

See the documentation for Package.Text and comment.Printer.Text for more details.

type Example

An Example represents an example function found in a test source file.

type Example struct {
    Name        string // name of the item being exemplified (including optional suffix)
    Suffix      string // example suffix, without leading '_' (only populated by NewFromFiles); added in Go 1.14
    Doc         string // example function doc string
    Code        ast.Node
    Play        *ast.File // a whole program version of the example; added in Go 1.1
    Comments    []*ast.CommentGroup
    Output      string // expected output
    Unordered   bool // Go 1.7
    EmptyOutput bool // expect empty output; added in Go 1.1
    Order       int  // original source code order; added in Go 1.1
}

func Examples

func Examples(testFiles ...*ast.File) []*Example

Examples returns the examples found in testFiles, sorted by Name field. The Order fields record the order in which the examples were encountered. The Suffix field is not populated when Examples is called directly, it is only populated by NewFromFiles for examples it finds in _test.go files.

Playable Examples must be in a package whose name ends in "_test". An Example is "playable" (the Play field is non-nil) in either of these circumstances:

type Filter

type Filter func(string) bool

type Func

Func is the documentation for a func declaration.

type Func struct {
    Doc  string
    Name string
    Decl *ast.FuncDecl

    // methods
    // (for functions, these fields have the respective zero value)
    Recv  string // actual   receiver "T" or "*T"
    Orig  string // original receiver "T" or "*T"
    Level int    // embedding level; 0 means not embedded

    // Examples is a sorted list of examples associated with this
    // function or method. Examples are extracted from _test.go files
    // provided to NewFromFiles.
    Examples []*Example // Go 1.14
}

type Mode

Mode values control the operation of New and NewFromFiles.

type Mode int
const (
    // AllDecls says to extract documentation for all package-level
    // declarations, not just exported ones.
    AllDecls Mode = 1 << iota

    // AllMethods says to show all embedded methods, not just the ones of
    // invisible (unexported) anonymous fields.
    AllMethods

    // PreserveAST says to leave the AST unmodified. Originally, pieces of
    // the AST such as function bodies were nil-ed out to save memory in
    // godoc, but not all programs want that behavior.
    PreserveAST
)

type Note 1.1

A Note represents a marked comment starting with "MARKER(uid): note body". Any note with a marker of 2 or more upper case [A-Z] letters and a uid of at least one character is recognized. The ":" following the uid is optional. Notes are collected in the Package.Notes map indexed by the notes marker.

type Note struct {
    Pos, End token.Pos // position range of the comment containing the marker
    UID      string    // uid found with the marker
    Body     string    // note body text
}

type Package

Package is the documentation for an entire package.

type Package struct {
    Doc        string
    Name       string
    ImportPath string
    Imports    []string
    Filenames  []string
    Notes      map[string][]*Note // Go 1.1

    // Deprecated: For backward compatibility Bugs is still populated,
    // but all new code should use Notes instead.
    Bugs []string

    // declarations
    Consts []*Value
    Types  []*Type
    Vars   []*Value
    Funcs  []*Func

    // Examples is a sorted list of examples associated with
    // the package. Examples are extracted from _test.go files
    // provided to NewFromFiles.
    Examples []*Example // Go 1.14
    // contains filtered or unexported fields
}

func New

func New(pkg *ast.Package, importPath string, mode Mode) *Package

New computes the package documentation for the given package AST. New takes ownership of the AST pkg and may edit or overwrite it. To have the Examples fields populated, use NewFromFiles and include the package's _test.go files.

func NewFromFiles 1.14

func NewFromFiles(fset *token.FileSet, files []*ast.File, importPath string, opts ...any) (*Package, error)

NewFromFiles computes documentation for a package.

The package is specified by a list of *ast.Files and corresponding file set, which must not be nil. NewFromFiles uses all provided files when computing documentation, so it is the caller's responsibility to provide only the files that match the desired build context. "go/build".Context.MatchFile can be used for determining whether a file matches a build context with the desired GOOS and GOARCH values, and other build constraints. The import path of the package is specified by importPath.

Examples found in _test.go files are associated with the corresponding type, function, method, or the package, based on their name. If the example has a suffix in its name, it is set in the Example.Suffix field. Examples with malformed names are skipped.

Optionally, a single extra argument of type Mode can be provided to control low-level aspects of the documentation extraction behavior.

NewFromFiles takes ownership of the AST files and may edit them, unless the PreserveAST Mode bit is on.

Example

This example illustrates how to use NewFromFiles to compute package documentation with examples.

package p - This is the package comment.
func Greet - This comment is associated with the Greet function.
 ⤷ example with suffix "world" - This comment is associated with the ExampleGreet_world example.

func (*Package) Filter

func (p *Package) Filter(f Filter)

Filter eliminates documentation for names that don't pass through the filter f. TODO(gri): Recognize "Type.Method" as a name.

func (*Package) HTML 1.19

func (p *Package) HTML(text string) []byte

HTML returns formatted HTML for the doc comment text.

To customize details of the HTML, use Package.Printer to obtain a comment.Printer, and configure it before calling its HTML method.

func (*Package) Markdown 1.19

func (p *Package) Markdown(text string) []byte

Markdown returns formatted Markdown for the doc comment text.

To customize details of the Markdown, use Package.Printer to obtain a comment.Printer, and configure it before calling its Markdown method.

func (*Package) Parser 1.19

func (p *Package) Parser() *comment.Parser

Parser returns a doc comment parser configured for parsing doc comments from package p. Each call returns a new parser, so that the caller may customize it before use.

func (*Package) Printer 1.19

func (p *Package) Printer() *comment.Printer

Printer returns a doc comment printer configured for printing doc comments from package p. Each call returns a new printer, so that the caller may customize it before use.

func (*Package) Synopsis 1.19

func (p *Package) Synopsis(text string) string

Synopsis returns a cleaned version of the first sentence in text. That sentence ends after the first period followed by space and not preceded by exactly one uppercase letter, or at the first paragraph break. The result string has no \n, \r, or \t characters and uses only single spaces between words. If text starts with any of the IllegalPrefixes, the result is the empty string.

func (*Package) Text 1.19

func (p *Package) Text(text string) []byte

Text returns formatted text for the doc comment text, wrapped to 80 Unicode code points and using tabs for code block indentation.

To customize details of the formatting, use Package.Printer to obtain a comment.Printer, and configure it before calling its Text method.

type Type

Type is the documentation for a type declaration.

type Type struct {
    Doc  string
    Name string
    Decl *ast.GenDecl

    // associated declarations
    Consts  []*Value // sorted list of constants of (mostly) this type
    Vars    []*Value // sorted list of variables of (mostly) this type
    Funcs   []*Func  // sorted list of functions returning this type
    Methods []*Func  // sorted list of methods (including embedded ones) of this type

    // Examples is a sorted list of examples associated with
    // this type. Examples are extracted from _test.go files
    // provided to NewFromFiles.
    Examples []*Example // Go 1.14
}

type Value

Value is the documentation for a (possibly grouped) var or const declaration.

type Value struct {
    Doc   string
    Names []string // var or const names in declaration order
    Decl  *ast.GenDecl
    // contains filtered or unexported fields
}

Subdirectories

Name Synopsis
..
comment Package comment implements parsing and reformatting of Go doc comments, (documentation comments), which are comments that immediately precede a top-level declaration of a package, const, func, type, or var.