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// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package source
import (
"context"
"encoding/json"
"fmt"
"go/ast"
"go/doc"
"go/format"
"go/types"
"strings"
"golang.org/x/tools/internal/event"
"golang.org/x/tools/internal/lsp/protocol"
errors "golang.org/x/xerrors"
)
type HoverInformation struct {
// Signature is the symbol's signature.
Signature string `json:"signature"`
// SingleLine is a single line describing the symbol.
// This is recommended only for use in clients that show a single line for hover.
SingleLine string `json:"singleLine"`
// Synopsis is a single sentence synopsis of the symbol's documentation.
Synopsis string `json:"synopsis"`
// FullDocumentation is the symbol's full documentation.
FullDocumentation string `json:"fullDocumentation"`
// ImportPath is the import path for the package containing the given symbol.
ImportPath string
// Link is the pkg.go.dev anchor for the given symbol.
// For example, "go/ast#Node".
Link string `json:"link"`
// SymbolName is the types.Object.Name for the given symbol.
SymbolName string
source interface{}
comment *ast.CommentGroup
// isTypeName reports whether the identifier is a type name. In such cases,
// the hover has the prefix "type ".
isType bool
}
func Hover(ctx context.Context, snapshot Snapshot, fh FileHandle, position protocol.Position) (*protocol.Hover, error) {
ident, err := Identifier(ctx, snapshot, fh, position)
if err != nil {
return nil, nil
}
h, err := HoverIdentifier(ctx, ident)
if err != nil {
return nil, err
}
rng, err := ident.Range()
if err != nil {
return nil, err
}
// See golang/go#36998: don't link to modules matching GOPRIVATE.
if snapshot.View().IsGoPrivatePath(h.ImportPath) {
h.Link = ""
}
hover, err := FormatHover(h, snapshot.View().Options())
if err != nil {
return nil, err
}
return &protocol.Hover{
Contents: protocol.MarkupContent{
Kind: snapshot.View().Options().PreferredContentFormat,
Value: hover,
},
Range: rng,
}, nil
}
func HoverIdentifier(ctx context.Context, i *IdentifierInfo) (*HoverInformation, error) {
ctx, done := event.Start(ctx, "source.Hover")
defer done()
fset := i.Snapshot.FileSet()
h, err := HoverInfo(ctx, i.pkg, i.Declaration.obj, i.Declaration.node)
if err != nil {
return nil, err
}
// Determine the symbol's signature.
switch x := h.source.(type) {
case ast.Node:
var b strings.Builder
if err := format.Node(&b, fset, x); err != nil {
return nil, err
}
h.Signature = b.String()
if h.isType {
h.Signature = "type " + h.Signature
}
case types.Object:
// If the variable is implicitly declared in a type switch, we need to
// manually generate its object string.
if typ := i.Declaration.typeSwitchImplicit; typ != nil {
if v, ok := x.(*types.Var); ok {
h.Signature = fmt.Sprintf("var %s %s", v.Name(), types.TypeString(typ, i.qf))
break
}
}
h.Signature = objectString(x, i.qf)
}
if obj := i.Declaration.obj; obj != nil {
h.SingleLine = objectString(obj, i.qf)
}
h.ImportPath, h.Link, h.SymbolName = pathLinkAndSymbolName(i)
return h, nil
}
func pathLinkAndSymbolName(i *IdentifierInfo) (string, string, string) {
obj := i.Declaration.obj
if obj == nil {
return "", "", ""
}
switch obj := obj.(type) {
case *types.PkgName:
path := obj.Imported().Path()
link := path
if mod, version, ok := moduleAtVersion(path, i); ok {
link = strings.Replace(path, mod, mod+"@"+version, 1)
}
return path, link, obj.Name()
case *types.Builtin:
return "builtin", fmt.Sprintf("builtin#%s", obj.Name()), obj.Name()
}
// Check if the identifier is test-only (and is therefore not part of a
// package's API). This is true if the request originated in a test package,
// and if the declaration is also found in the same test package.
if i.pkg != nil && obj.Pkg() != nil && i.pkg.ForTest() != "" {
if _, err := i.pkg.File(i.Declaration.MappedRange[0].URI()); err == nil {
return "", "", ""
}
}
// Don't return links for other unexported types.
if !obj.Exported() {
return "", "", ""
}
var rTypeName string
switch obj := obj.(type) {
case *types.Var:
// If the object is a field, and we have an associated selector
// composite literal, or struct, we can determine the link.
if obj.IsField() {
if named, ok := i.enclosing.(*types.Named); ok {
rTypeName = named.Obj().Name()
}
}
case *types.Func:
typ, ok := obj.Type().(*types.Signature)
if !ok {
return "", "", ""
}
if r := typ.Recv(); r != nil {
switch rtyp := Deref(r.Type()).(type) {
case *types.Struct:
rTypeName = r.Name()
case *types.Named:
// If we have an unexported type, see if the enclosing type is
// exported (we may have an interface or struct we can link
// to). If not, don't show any link.
if !rtyp.Obj().Exported() {
if named, ok := i.enclosing.(*types.Named); ok && named.Obj().Exported() {
rTypeName = named.Obj().Name()
} else {
return "", "", ""
}
} else {
rTypeName = rtyp.Obj().Name()
}
}
}
}
path := obj.Pkg().Path()
link := path
if mod, version, ok := moduleAtVersion(path, i); ok {
link = strings.Replace(path, mod, mod+"@"+version, 1)
}
if rTypeName != "" {
link = fmt.Sprintf("%s#%s.%s", link, rTypeName, obj.Name())
symbol := fmt.Sprintf("(%s.%s).%s", obj.Pkg().Name(), rTypeName, obj.Name())
return path, link, symbol
}
// For most cases, the link is "package/path#symbol".
link = fmt.Sprintf("%s#%s", link, obj.Name())
symbolName := fmt.Sprintf("%s.%s", obj.Pkg().Name(), obj.Name())
return path, link, symbolName
}
func moduleAtVersion(path string, i *IdentifierInfo) (string, string, bool) {
if strings.ToLower(i.Snapshot.View().Options().LinkTarget) != "pkg.go.dev" {
return "", "", false
}
impPkg, err := i.pkg.GetImport(path)
if err != nil {
return "", "", false
}
if impPkg.Version() == nil {
return "", "", false
}
version, modpath := impPkg.Version().Version, impPkg.Version().Path
if modpath == "" || version == "" {
return "", "", false
}
return modpath, version, true
}
// objectString is a wrapper around the types.ObjectString function.
// It handles adding more information to the object string.
func objectString(obj types.Object, qf types.Qualifier) string {
str := types.ObjectString(obj, qf)
switch obj := obj.(type) {
case *types.Const:
str = fmt.Sprintf("%s = %s", str, obj.Val())
}
return str
}
// HoverInfo returns a HoverInformation struct for an ast node and its type
// object.
func HoverInfo(ctx context.Context, pkg Package, obj types.Object, node ast.Node) (*HoverInformation, error) {
var info *HoverInformation
switch node := node.(type) {
case *ast.Ident:
// The package declaration.
for _, f := range pkg.GetSyntax() {
if f.Name == node {
info = &HoverInformation{comment: f.Doc}
}
}
case *ast.ImportSpec:
// Try to find the package documentation for an imported package.
if pkgName, ok := obj.(*types.PkgName); ok {
imp, err := pkg.GetImport(pkgName.Imported().Path())
if err != nil {
return nil, err
}
// Assume that only one file will contain package documentation,
// so pick the first file that has a doc comment.
for _, file := range imp.GetSyntax() {
if file.Doc != nil {
info = &HoverInformation{source: obj, comment: file.Doc}
break
}
}
}
info = &HoverInformation{source: node}
case *ast.GenDecl:
switch obj := obj.(type) {
case *types.TypeName, *types.Var, *types.Const, *types.Func:
var err error
info, err = formatGenDecl(node, obj, obj.Type())
if err != nil {
return nil, err
}
_, info.isType = obj.(*types.TypeName)
}
case *ast.TypeSpec:
if obj.Parent() == types.Universe {
if obj.Name() == "error" {
info = &HoverInformation{source: node}
} else {
info = &HoverInformation{source: node.Name} // comments not needed for builtins
}
}
case *ast.FuncDecl:
switch obj.(type) {
case *types.Func:
info = &HoverInformation{source: obj, comment: node.Doc}
case *types.Builtin:
info = &HoverInformation{source: node.Type, comment: node.Doc}
}
}
if info == nil {
info = &HoverInformation{source: obj}
}
if info.comment != nil {
info.FullDocumentation = info.comment.Text()
info.Synopsis = doc.Synopsis(info.FullDocumentation)
}
return info, nil
}
func formatGenDecl(node *ast.GenDecl, obj types.Object, typ types.Type) (*HoverInformation, error) {
if _, ok := typ.(*types.Named); ok {
switch typ.Underlying().(type) {
case *types.Interface, *types.Struct:
return formatGenDecl(node, obj, typ.Underlying())
}
}
var spec ast.Spec
for _, s := range node.Specs {
if s.Pos() <= obj.Pos() && obj.Pos() <= s.End() {
spec = s
break
}
}
if spec == nil {
return nil, errors.Errorf("no spec for node %v at position %v", node, obj.Pos())
}
// If we have a field or method.
switch obj.(type) {
case *types.Var, *types.Const, *types.Func:
return formatVar(spec, obj, node), nil
}
// Handle types.
switch spec := spec.(type) {
case *ast.TypeSpec:
if len(node.Specs) > 1 {
// If multiple types are declared in the same block.
return &HoverInformation{source: spec.Type, comment: spec.Doc}, nil
} else {
return &HoverInformation{source: spec, comment: node.Doc}, nil
}
case *ast.ValueSpec:
return &HoverInformation{source: spec, comment: spec.Doc}, nil
case *ast.ImportSpec:
return &HoverInformation{source: spec, comment: spec.Doc}, nil
}
return nil, errors.Errorf("unable to format spec %v (%T)", spec, spec)
}
func formatVar(node ast.Spec, obj types.Object, decl *ast.GenDecl) *HoverInformation {
var fieldList *ast.FieldList
switch spec := node.(type) {
case *ast.TypeSpec:
switch t := spec.Type.(type) {
case *ast.StructType:
fieldList = t.Fields
case *ast.InterfaceType:
fieldList = t.Methods
}
case *ast.ValueSpec:
comment := spec.Doc
if comment == nil {
comment = decl.Doc
}
if comment == nil {
comment = spec.Comment
}
return &HoverInformation{source: obj, comment: comment}
}
// If we have a struct or interface declaration,
// we need to match the object to the corresponding field or method.
if fieldList != nil {
for i := 0; i < len(fieldList.List); i++ {
field := fieldList.List[i]
if field.Pos() <= obj.Pos() && obj.Pos() <= field.End() {
if field.Doc.Text() != "" {
return &HoverInformation{source: obj, comment: field.Doc}
}
return &HoverInformation{source: obj, comment: field.Comment}
}
}
}
return &HoverInformation{source: obj, comment: decl.Doc}
}
func FormatHover(h *HoverInformation, options *Options) (string, error) {
signature := h.Signature
if signature != "" && options.PreferredContentFormat == protocol.Markdown {
signature = fmt.Sprintf("```go\n%s\n```", signature)
}
switch options.HoverKind {
case SingleLine:
return h.SingleLine, nil
case NoDocumentation:
return signature, nil
case Structured:
b, err := json.Marshal(h)
if err != nil {
return "", err
}
return string(b), nil
}
link := formatLink(h, options)
switch options.HoverKind {
case SynopsisDocumentation:
doc := formatDoc(h.Synopsis, options)
return formatHover(options, signature, link, doc), nil
case FullDocumentation:
doc := formatDoc(h.FullDocumentation, options)
return formatHover(options, signature, link, doc), nil
}
return "", errors.Errorf("no hover for %v", h.source)
}
func formatLink(h *HoverInformation, options *Options) string {
if !options.LinksInHover || options.LinkTarget == "" || h.Link == "" {
return ""
}
plainLink := fmt.Sprintf("https://%s/%s", options.LinkTarget, h.Link)
switch options.PreferredContentFormat {
case protocol.Markdown:
return fmt.Sprintf("[`%s` on %s](%s)", h.SymbolName, options.LinkTarget, plainLink)
case protocol.PlainText:
return ""
default:
return plainLink
}
}
func formatDoc(doc string, options *Options) string {
if options.PreferredContentFormat == protocol.Markdown {
return CommentToMarkdown(doc)
}
return doc
}
func formatHover(options *Options, x ...string) string {
var b strings.Builder
for i, el := range x {
if el != "" {
b.WriteString(el)
// Don't write out final newline.
if i == len(x) {
continue
}
// If any elements of the remainder of the list are non-empty,
// write a newline.
if anyNonEmpty(x[i+1:]) {
if options.PreferredContentFormat == protocol.Markdown {
b.WriteString("\n\n")
} else {
b.WriteRune('\n')
}
}
}
}
return b.String()
}
func anyNonEmpty(x []string) bool {
for _, el := range x {
if el != "" {
return true
}
}
return false
}