internal/lsp/source/hover.go - tools - Git at Google

 // 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/lsp/protocol"
 	"golang.org/x/tools/internal/telemetry/trace"
 	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"`

 	// 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
 }

 func (i *IdentifierInfo) Hover(ctx context.Context) (*HoverInformation, error) {
 	ctx, done := trace.StartSpan(ctx, "source.Hover")
 	defer done()

 	h, err := i.Declaration.hover(ctx)
 	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, i.Snapshot.View().Session().Cache().FileSet(), x); err != nil {
 			return nil, err
 		}
 		h.Signature = b.String()
 	case types.Object:
 		h.Signature = objectString(x, i.qf)
 	}
 	if obj := i.Declaration.obj; obj != nil {
 		h.SingleLine = objectString(obj, i.qf)
 	}
 	h.Link, h.SymbolName = i.linkAndSymbolName()
 	if h.comment != nil {
 		h.FullDocumentation = h.comment.Text()
 		h.Synopsis = doc.Synopsis(h.FullDocumentation)
 	}
 	return h, nil
 }

 func (i *IdentifierInfo) linkAndSymbolName() (string, string) {
 	obj := i.Declaration.obj
 	if obj == nil {
 		return "", ""
 	}
 	switch obj := obj.(type) {
 	case *types.PkgName:
 		return obj.Imported().Path(), obj.Name()
 	case *types.Builtin:
 		return fmt.Sprintf("builtin#%s", obj.Name()), obj.Name()
 	}
 	// Don't return links for other unexported types.
 	if !obj.Exported() {
 		return "", ""
 	}
 	var rTypeName string
 	switch obj := obj.(type) {
 	case *types.Var:
 		if obj.IsField() {
 			// If the object is a field, and we have an associated selector
 			// composite literal, or struct, we can determine the link.
 			switch typ := i.enclosing.(type) {
 			case *types.Named:
 				rTypeName = typ.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 named, ok := i.enclosing.(*types.Named); ok {
 					rTypeName = named.Obj().Name()
 				} else if !rtyp.Obj().Exported() {
 					return "", ""
 				} else {
 					rTypeName = rtyp.Obj().Name()
 				}
 			}
 		}
 	}
 	if rTypeName != "" {
 		link := fmt.Sprintf("%s#%s.%s", obj.Pkg().Path(), rTypeName, obj.Name())
 		symbol := fmt.Sprintf("(%s.%s).%s", obj.Pkg().Name(), rTypeName, obj.Name())
 		return link, symbol
 	}
 	// For most cases, the link is "package/path#symbol".
 	return fmt.Sprintf("%s#%s", obj.Pkg().Path(), obj.Name()), fmt.Sprintf("%s.%s", obj.Pkg().Name(), obj.Name())
 }

 // 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
 }

 func (d Declaration) hover(ctx context.Context) (*HoverInformation, error) {
 	_, done := trace.StartSpan(ctx, "source.hover")
 	defer done()

 	obj := d.obj
 	switch node := d.node.(type) {
 	case *ast.ImportSpec:
 		return &HoverInformation{source: node}, nil
 	case *ast.GenDecl:
 		switch obj := obj.(type) {
 		case *types.TypeName, *types.Var, *types.Const, *types.Func:
 			return formatGenDecl(node, obj, obj.Type())
 		}
 	case *ast.TypeSpec:
 		if obj.Parent() == types.Universe {
 			if obj.Name() == "error" {
 				return &HoverInformation{source: node}, nil
 			}
 			return &HoverInformation{source: node.Name}, nil // comments not needed for builtins
 		}
 	case *ast.FuncDecl:
 		switch obj.(type) {
 		case *types.Func:
 			return &HoverInformation{source: obj, comment: node.Doc}, nil
 		case *types.Builtin:
 			return &HoverInformation{source: node.Type, comment: node.Doc}, nil
 		}
 	}
 	return &HoverInformation{source: obj}, 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
 	if spec, ok := node.(*ast.TypeSpec); ok {
 		switch t := spec.Type.(type) {
 		case *ast.StructType:
 			fieldList = t.Fields
 		case *ast.InterfaceType:
 			fieldList = t.Methods
 		}
 	}
 	// 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}
 				} else if field.Comment.Text() != "" {
 					return &HoverInformation{source: obj, comment: field.Comment}
 				}
 			}
 		}
 	}
 	// If we have a package level variable that does have a
 	// comment group attached to it but not in the ast.spec.
 	if decl.Doc.Text() != "" {
 		return &HoverInformation{source: obj, comment: decl.Doc}
 	}

 	// If we weren't able to find documentation for the object.
 	return &HoverInformation{source: obj}
 }

 func FormatHover(h *HoverInformation, options Options) (string, error) {
 	signature := formatSignature(h.Signature, options)
 	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, doc, link, signature), 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.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 formatSignature(signature string, options Options) string {
 	if options.PreferredContentFormat == protocol.Markdown {
 		signature = fmt.Sprintf("```go\n%s\n```", signature)
 	}
 	return signature
 }

 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
 }
	// 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/lsp/protocol"
	"golang.org/x/tools/internal/telemetry/trace"
	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"`

	// 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
	}

	func (i IdentifierInfo) Hover(ctx context.Context) (HoverInformation, error) {
	ctx, done := trace.StartSpan(ctx, "source.Hover")
	defer done()

	h, err := i.Declaration.hover(ctx)
	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, i.Snapshot.View().Session().Cache().FileSet(), x); err != nil {
	return nil, err
	}
	h.Signature = b.String()
	case types.Object:
	h.Signature = objectString(x, i.qf)
	}
	if obj := i.Declaration.obj; obj != nil {
	h.SingleLine = objectString(obj, i.qf)
	}
	h.Link, h.SymbolName = i.linkAndSymbolName()
	if h.comment != nil {
	h.FullDocumentation = h.comment.Text()
	h.Synopsis = doc.Synopsis(h.FullDocumentation)
	}
	return h, nil
	}

	func (i *IdentifierInfo) linkAndSymbolName() (string, string) {
	obj := i.Declaration.obj
	if obj == nil {
	return "", ""
	}
	switch obj := obj.(type) {
	case *types.PkgName:
	return obj.Imported().Path(), obj.Name()
	case *types.Builtin:
	return fmt.Sprintf("builtin#%s", obj.Name()), obj.Name()
	}
	// Don't return links for other unexported types.
	if !obj.Exported() {
	return "", ""
	}
	var rTypeName string
	switch obj := obj.(type) {
	case *types.Var:
	if obj.IsField() {
	// If the object is a field, and we have an associated selector
	// composite literal, or struct, we can determine the link.
	switch typ := i.enclosing.(type) {
	case *types.Named:
	rTypeName = typ.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 named, ok := i.enclosing.(*types.Named); ok {
	rTypeName = named.Obj().Name()
	} else if !rtyp.Obj().Exported() {
	return "", ""
	} else {
	rTypeName = rtyp.Obj().Name()
	}
	}
	}
	}
	if rTypeName != "" {
	link := fmt.Sprintf("%s#%s.%s", obj.Pkg().Path(), rTypeName, obj.Name())
	symbol := fmt.Sprintf("(%s.%s).%s", obj.Pkg().Name(), rTypeName, obj.Name())
	return link, symbol
	}
	// For most cases, the link is "package/path#symbol".
	return fmt.Sprintf("%s#%s", obj.Pkg().Path(), obj.Name()), fmt.Sprintf("%s.%s", obj.Pkg().Name(), obj.Name())
	}

	// 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
	}

	func (d Declaration) hover(ctx context.Context) (*HoverInformation, error) {
	_, done := trace.StartSpan(ctx, "source.hover")
	defer done()

	obj := d.obj
	switch node := d.node.(type) {
	case *ast.ImportSpec:
	return &HoverInformation{source: node}, nil
	case *ast.GenDecl:
	switch obj := obj.(type) {
	case types.TypeName, types.Var, types.Const, types.Func:
	return formatGenDecl(node, obj, obj.Type())
	}
	case *ast.TypeSpec:
	if obj.Parent() == types.Universe {
	if obj.Name() == "error" {
	return &HoverInformation{source: node}, nil
	}
	return &HoverInformation{source: node.Name}, nil // comments not needed for builtins
	}
	case *ast.FuncDecl:
	switch obj.(type) {
	case *types.Func:
	return &HoverInformation{source: obj, comment: node.Doc}, nil
	case *types.Builtin:
	return &HoverInformation{source: node.Type, comment: node.Doc}, nil
	}
	}
	return &HoverInformation{source: obj}, 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
	if spec, ok := node.(*ast.TypeSpec); ok {
	switch t := spec.Type.(type) {
	case *ast.StructType:
	fieldList = t.Fields
	case *ast.InterfaceType:
	fieldList = t.Methods
	}
	}
	// 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}
	} else if field.Comment.Text() != "" {
	return &HoverInformation{source: obj, comment: field.Comment}
	}
	}
	}
	}
	// If we have a package level variable that does have a
	// comment group attached to it but not in the ast.spec.
	if decl.Doc.Text() != "" {
	return &HoverInformation{source: obj, comment: decl.Doc}
	}

	// If we weren't able to find documentation for the object.
	return &HoverInformation{source: obj}
	}

	func FormatHover(h *HoverInformation, options Options) (string, error) {
	signature := formatSignature(h.Signature, options)
	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, doc, link, signature), 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.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 formatSignature(signature string, options Options) string {
	if options.PreferredContentFormat == protocol.Markdown {
	signature = fmt.Sprintf("```go\n%s\n```", signature)
	}
	return signature
	}

	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
	}