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import "go/doc"
Package doc extracts source code documentation from a Go AST.
var IllegalPrefixes = []string{
"copyright",
"all rights",
"author",
}
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.
func IsPredeclared(s string) bool
IsPredeclared reports whether s is a predeclared identifier.
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(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(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 struct {
Name string // name of the item being exemplified (including optional suffix)
Suffix string // example suffix, without leading '_' (only populated by NewFromFiles)
Doc string // example function doc string
Code ast.Node
Play *ast.File // a whole program version of the example
Comments []*ast.CommentGroup
Output string // expected output
Unordered bool
EmptyOutput bool // expect empty output
Order int // original source code order
}
An Example represents an example function found in a test source file.
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 func(string) bool
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" possibly followed by type parameters [P1, ..., Pn]
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
}
Func is the documentation for a func declaration.
type Mode int
Mode values control the operation of New and NewFromFiles.
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 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
}
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 Package struct {
Doc string
Name string
ImportPath string
Imports []string
Filenames []string
Notes map[string][]*Note
// 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
// contains filtered or unexported fields
}
Package is the documentation for an entire package.
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(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.
This example illustrates how to use NewFromFiles to compute package documentation with examples.
Code:
package main
import (
"fmt"
"go/ast"
"go/doc"
"go/parser"
"go/token"
)
func main() {
// src and test are two source files that make up
// a package whose documentation will be computed.
const src = `
// This is the package comment.
package p
import "fmt"
// This comment is associated with the Greet function.
func Greet(who string) {
fmt.Printf("Hello, %s!\n", who)
}
`
const test = `
package p_test
// This comment is associated with the ExampleGreet_world example.
func ExampleGreet_world() {
Greet("world")
}
`
// Create the AST by parsing src and test.
fset := token.NewFileSet()
files := []*ast.File{
mustParse(fset, "src.go", src),
mustParse(fset, "src_test.go", test),
}
// Compute package documentation with examples.
p, err := doc.NewFromFiles(fset, files, "example.com/p")
if err != nil {
panic(err)
}
fmt.Printf("package %s - %s", p.Name, p.Doc)
fmt.Printf("func %s - %s", p.Funcs[0].Name, p.Funcs[0].Doc)
fmt.Printf(" ⤷ example with suffix %q - %s", p.Funcs[0].Examples[0].Suffix, p.Funcs[0].Examples[0].Doc)
}
func mustParse(fset *token.FileSet, filename, src string) *ast.File {
f, err := parser.ParseFile(fset, filename, src, parser.ParseComments)
if err != nil {
panic(err)
}
return f
}
Output:
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 (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 (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 (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 (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 (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 (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 (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 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
}
Type is the documentation for a type declaration.
type Value struct {
Doc string
Names []string // var or const names in declaration order
Decl *ast.GenDecl
// contains filtered or unexported fields
}
Value is the documentation for a (possibly grouped) var or const declaration.
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.