gopls/internal/golang/comment.go - tools - Git at Google

 // Copyright 2022 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 golang

 import (
 	"context"
 	"errors"
 	"fmt"
 	"go/ast"
 	"go/doc/comment"
 	"go/token"
 	"go/types"
 	"iter"
 	pathpkg "path"
 	"strings"

 	"golang.org/x/tools/gopls/internal/cache"
 	"golang.org/x/tools/gopls/internal/cache/parsego"
 	"golang.org/x/tools/gopls/internal/protocol"
 	"golang.org/x/tools/gopls/internal/settings"
 	"golang.org/x/tools/internal/astutil"
 )

 var errNoCommentReference = errors.New("no comment reference found")

 // DocCommentToMarkdown converts the text of a [doc comment] to Markdown.
 //
 // TODO(adonovan): provide a package (or file imports) as context for
 // proper rendering of doc links; see [newDocCommentParser] and golang/go#61677.
 //
 // [doc comment]: https://go.dev/doc/comment
 func DocCommentToMarkdown(text string, options *settings.Options) string {
 	var parser comment.Parser
 	doc := parser.Parse(text)

 	var printer comment.Printer
 	// The default produces {#Hdr-...} tags for headings.
 	// vscode displays thems, which is undesirable.
 	// The godoc for comment.Printer says the tags
 	// avoid a security problem.
 	printer.HeadingID = func(*comment.Heading) string { return "" }
 	printer.DocLinkURL = func(link *comment.DocLink) string {
 		msg := fmt.Sprintf("https://%s/%s", options.LinkTarget, link.ImportPath)
 		if link.Name != "" {
 			msg += "#"
 			if link.Recv != "" {
 				msg += link.Recv + "."
 			}
 			msg += link.Name
 		}
 		return msg
 	}

 	return string(printer.Markdown(doc))
 }

 // docLinkDefinition finds the definition of the doc link in comments at pos.
 // If there is no reference at pos, returns errNoCommentReference.
 //
 // TODO(hxjiang): simplify the error handling.
 func docLinkDefinition(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, pgf *parsego.File, pos token.Pos) ([]protocol.Location, error) {
 	obj, _, err := resolveDocLink(pkg, pgf, astutil.RangeOf(pos, pos))
 	if err != nil {
 		return nil, err
 	}
 	loc, err := ObjectLocation(ctx, pkg.FileSet(), snapshot, obj)
 	if err != nil {
 		return nil, err
 	}
 	return []protocol.Location{loc}, nil
 }

 // resolveDocLink parses a doc link in a comment such as [fmt.Println]
 // and returns the symbol at pos, along with the link's range.
 func resolveDocLink(pkg *cache.Package, pgf *parsego.File, rng astutil.Range) (types.Object, protocol.Range, error) {
 	var comment *ast.CommentGroup
 	for _, c := range pgf.File.Comments {
 		if astutil.NodeContains(c, rng) {
 			comment = c
 			break
 		}
 	}

 	if comment == nil {
 		return nil, protocol.Range{}, errNoCommentReference
 	}

 	for docLink := range commentDocLinks(comment) {
 		if astutil.NodeContains(docLink.partRange, rng) {
 			if obj := lookupDocLinkSymbol(pkg, pgf, docLink.nameText); obj != nil {
 				rng, err := pgf.NodeRange(docLink.partRange)
 				if err != nil {
 					return nil, protocol.Range{}, err
 				}
 				return obj, rng, nil
 			}
 			break
 		}
 	}

 	return nil, protocol.Range{}, errNoCommentReference
 }

 // A docLink holds the parsed information for a single resolution step of a
 // documentation link. For a link like "[fmt.Scanner.Scan]", the parser will
 // yield three docLink values, one for each progressively resolved part:
 // "fmt", "fmt.Scanner", and "fmt.Scanner.Scan".
 type docLink struct {
 	// The text of the right-most component of the name for this step.
 	// For the name "fmt.Scanner", this is "Scanner".
 	partText  string
 	partRange astutil.Range

 	// The text of the fully-qualified symbol path resolved in this step.
 	// For example, "fmt.Scanner". Used for symbol lookups.
 	nameText string

 	// The text of the entire, original doc link expression, including brackets.
 	// For example, "[fmt.Scanner.Scan]".
 	bracketText string
 }

 // commentDocLinks returns the sequence of Go doc links in the comment group.
 // TODO(hxjiang): move to [parsego] package.
 func commentDocLinks(cg *ast.CommentGroup) iter.Seq[docLink] {
 	return func(yield func(docLink) bool) {
 		for _, comment := range cg.List {
 			// The canonical parsing algorithm is defined by go/doc/comment, but
 			// unfortunately its API provides no way to reliably reconstruct the
 			// position of each doc link from the parsed result.

 			for _, idx := range docLinkRegex.FindAllStringSubmatchIndex(comment.Text, -1) {
 				mstart, mend := idx[2], idx[3]

 				// [bracketPos.Start, bracketPos.End) identifies the start and end
 				// of the brackets. e.g. "[fmt.Scanner.Scan]".
 				bracketText := comment.Text[mstart-1 : mend+1]

 				// [mstart, mend) identifies the first submatch, which is the
 				// reference name in the doc link (sans '*').
 				// e.g. The "[fmt.Println]" reference name is "fmt.Println".
 				match := comment.Text[mstart:mend]

 				if strings.Contains(match, "\n") {
 					continue
 				}

 				// [namePos.Start, namePos.End) identifies the start and end
 				// position of a name. e.g. "fmt", "fmt.Scanner", "fmt.Scanner.Scan".
 				var name string

 				namePos := astutil.RangeOf(comment.Pos()+token.Pos(mstart), comment.Pos()+token.Pos(mstart-1))
 				// [partPos.Start, partPos.End) identifies the start and end
 				// position of a part. e.g. "fmt", "Scanner", "Scan".
 				partPos := namePos
 				for part := range strings.SplitSeq(match, ".") {
 					if name != "" {
 						name += "."
 					}
 					name += part

 					partPos.Start = partPos.EndPos + token.Pos(len("."))  // Move start to the first char of next part
 					partPos.EndPos = partPos.Start + token.Pos(len(part)) // Move end to next char of current part

 					namePos.EndPos = partPos.EndPos

 					if !yield(docLink{
 						partRange:   partPos,
 						partText:    part,
 						nameText:    name,
 						bracketText: bracketText,
 					}) {
 						return
 					}
 				}
 			}
 		}
 	}
 }

 // lookupDocLinkSymbol returns the symbol denoted by a doc link such
 // as "fmt.Println" or "bytes.Buffer.Write" in the specified file.
 func lookupDocLinkSymbol(pkg *cache.Package, pgf *parsego.File, name string) types.Object {
 	scope := pkg.Types().Scope()

 	prefix, suffix, _ := strings.Cut(name, ".")

 	// Try treating the prefix as a package name,
 	// allowing for non-renaming and renaming imports.
 	fileScope := pkg.TypesInfo().Scopes[pgf.File]
 	if fileScope == nil {
 		// As we learned in golang/go#69616, any file may not be Scopes!
 		//  - A non-compiled Go file (such as unsafe.go) won't be in Scopes.
 		//  - A (technically) compiled go file with the wrong package name won't be
 		//    in Scopes, as it will be skipped by go/types.
 		return nil
 	}
 	pkgname, ok := fileScope.Lookup(prefix).(*types.PkgName) // ok => prefix is imported name
 	if !ok {
 		// Handle renaming import, e.g.
 		// [path.Join] after import pathpkg "path".
 		// (Should we look at all files of the package?)
 		for _, imp := range pgf.File.Imports {
 			pkgname2 := pkg.TypesInfo().PkgNameOf(imp)
 			if pkgname2 != nil && pkgname2.Imported().Name() == prefix {
 				pkgname = pkgname2
 				break
 			}
 		}
 	}
 	if pkgname != nil {
 		scope = pkgname.Imported().Scope()
 		if suffix == "" {
 			return pkgname // not really a valid doc link
 		}
 		name = suffix
 	}

 	// TODO(adonovan): try searching the forward closure for packages
 	// that define the symbol but are not directly imported;
 	// see https://github.com/golang/go/issues/61677

 	// Field or sel?
 	recv, sel, ok := strings.Cut(name, ".")
 	if ok {
 		obj := scope.Lookup(recv) // package scope
 		if obj == nil {
 			obj = types.Universe.Lookup(recv)
 		}
 		obj, ok := obj.(*types.TypeName)
 		if !ok {
 			return nil
 		}
 		m, _, _ := types.LookupFieldOrMethod(obj.Type(), true, obj.Pkg(), sel)
 		return m
 	}

 	if obj := scope.Lookup(name); obj != nil {
 		return obj // package-level symbol
 	}
 	return types.Universe.Lookup(name) // built-in symbol
 }

 // newDocCommentParser returns a function that parses [doc comments],
 // with context for Doc Links supplied by the specified package.
 //
 // Imported symbols are rendered using the import mapping for the file
 // that encloses fileNode.
 //
 // The resulting function is not concurrency safe.
 //
 // See issue #61677 for how this might be generalized to support
 // correct contextual parsing of doc comments in Hover too.
 //
 // [doc comment]: https://go.dev/doc/comment
 func newDocCommentParser(pkg *cache.Package) func(fileNode ast.Node, text string) *comment.Doc {
 	var currentFilePos token.Pos // pos whose enclosing file's import mapping should be used
 	parser := &comment.Parser{
 		LookupPackage: func(name string) (importPath string, ok bool) {
 			for _, f := range pkg.Syntax() {
 				// Different files in the same package have
 				// different import mappings. Use the provided
 				// syntax node to find the correct file.
 				if astutil.NodeContainsPos(f, currentFilePos) {
 					// First try each actual imported package name.
 					for _, imp := range f.Imports {
 						pkgName := pkg.TypesInfo().PkgNameOf(imp)
 						if pkgName != nil && pkgName.Name() == name {
 							return pkgName.Imported().Path(), true
 						}
 					}

 					// Then try each imported package's declared name,
 					// as some packages are typically imported under a
 					// non-default name (e.g. pathpkg "path") but
 					// may be referred to in doc links using their
 					// canonical name.
 					for _, imp := range f.Imports {
 						pkgName := pkg.TypesInfo().PkgNameOf(imp)
 						if pkgName != nil && pkgName.Imported().Name() == name {
 							return pkgName.Imported().Path(), true
 						}
 					}

 					// Finally try matching the last segment of each import
 					// path imported by any file in the package, as the
 					// doc comment may appear in a different file from the
 					// import.
 					//
 					// Ideally we would look up the DepsByPkgPath value
 					// (a PackageID) in the metadata graph and use the
 					// package's declared name instead of this heuristic,
 					// but we don't have access to the graph here.
 					for path := range pkg.Metadata().DepsByPkgPath {
 						if pathpkg.Base(trimVersionSuffix(string(path))) == name {
 							return string(path), true
 						}
 					}

 					break
 				}
 			}
 			return "", false
 		},
 		LookupSym: func(recv, name string) (ok bool) {
 			// package-level decl?
 			if recv == "" {
 				return pkg.Types().Scope().Lookup(name) != nil
 			}

 			// method?
 			tname, ok := pkg.Types().Scope().Lookup(recv).(*types.TypeName)
 			if !ok {
 				return false
 			}
 			m, _, _ := types.LookupFieldOrMethod(tname.Type(), true, pkg.Types(), name)
 			return is[*types.Func](m)
 		},
 	}
 	return func(fileNode ast.Node, text string) *comment.Doc {
 		currentFilePos = fileNode.Pos()
 		return parser.Parse(text)
 	}
 }
	// Copyright 2022 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 golang

	import (
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/doc/comment"
	"go/token"
	"go/types"
	"iter"
	pathpkg "path"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/astutil"
	)

	var errNoCommentReference = errors.New("no comment reference found")

	// DocCommentToMarkdown converts the text of a [doc comment] to Markdown.
	//
	// TODO(adonovan): provide a package (or file imports) as context for
	// proper rendering of doc links; see [newDocCommentParser] and golang/go#61677.
	//
	// [doc comment]: https://go.dev/doc/comment
	func DocCommentToMarkdown(text string, options *settings.Options) string {
	var parser comment.Parser
	doc := parser.Parse(text)

	var printer comment.Printer
	// The default produces {#Hdr-...} tags for headings.
	// vscode displays thems, which is undesirable.
	// The godoc for comment.Printer says the tags
	// avoid a security problem.
	printer.HeadingID = func(*comment.Heading) string { return "" }
	printer.DocLinkURL = func(link *comment.DocLink) string {
	msg := fmt.Sprintf("https://%s/%s", options.LinkTarget, link.ImportPath)
	if link.Name != "" {
	msg += "#"
	if link.Recv != "" {
	msg += link.Recv + "."
	}
	msg += link.Name
	}
	return msg
	}

	return string(printer.Markdown(doc))
	}

	// docLinkDefinition finds the definition of the doc link in comments at pos.
	// If there is no reference at pos, returns errNoCommentReference.
	//
	// TODO(hxjiang): simplify the error handling.
	func docLinkDefinition(ctx context.Context, snapshot cache.Snapshot, pkg cache.Package, pgf *parsego.File, pos token.Pos) ([]protocol.Location, error) {
	obj, _, err := resolveDocLink(pkg, pgf, astutil.RangeOf(pos, pos))
	if err != nil {
	return nil, err
	}
	loc, err := ObjectLocation(ctx, pkg.FileSet(), snapshot, obj)
	if err != nil {
	return nil, err
	}
	return []protocol.Location{loc}, nil
	}

	// resolveDocLink parses a doc link in a comment such as [fmt.Println]
	// and returns the symbol at pos, along with the link's range.
	func resolveDocLink(pkg cache.Package, pgf parsego.File, rng astutil.Range) (types.Object, protocol.Range, error) {
	var comment *ast.CommentGroup
	for _, c := range pgf.File.Comments {
	if astutil.NodeContains(c, rng) {
	comment = c
	break
	}
	}

	if comment == nil {
	return nil, protocol.Range{}, errNoCommentReference
	}

	for docLink := range commentDocLinks(comment) {
	if astutil.NodeContains(docLink.partRange, rng) {
	if obj := lookupDocLinkSymbol(pkg, pgf, docLink.nameText); obj != nil {
	rng, err := pgf.NodeRange(docLink.partRange)
	if err != nil {
	return nil, protocol.Range{}, err
	}
	return obj, rng, nil
	}
	break
	}
	}

	return nil, protocol.Range{}, errNoCommentReference
	}

	// A docLink holds the parsed information for a single resolution step of a
	// documentation link. For a link like "[fmt.Scanner.Scan]", the parser will
	// yield three docLink values, one for each progressively resolved part:
	// "fmt", "fmt.Scanner", and "fmt.Scanner.Scan".
	type docLink struct {
	// The text of the right-most component of the name for this step.
	// For the name "fmt.Scanner", this is "Scanner".
	partText string
	partRange astutil.Range

	// The text of the fully-qualified symbol path resolved in this step.
	// For example, "fmt.Scanner". Used for symbol lookups.
	nameText string

	// The text of the entire, original doc link expression, including brackets.
	// For example, "[fmt.Scanner.Scan]".
	bracketText string
	}

	// commentDocLinks returns the sequence of Go doc links in the comment group.
	// TODO(hxjiang): move to [parsego] package.
	func commentDocLinks(cg *ast.CommentGroup) iter.Seq[docLink] {
	return func(yield func(docLink) bool) {
	for _, comment := range cg.List {
	// The canonical parsing algorithm is defined by go/doc/comment, but
	// unfortunately its API provides no way to reliably reconstruct the
	// position of each doc link from the parsed result.

	for _, idx := range docLinkRegex.FindAllStringSubmatchIndex(comment.Text, -1) {
	mstart, mend := idx[2], idx[3]

	// [bracketPos.Start, bracketPos.End) identifies the start and end
	// of the brackets. e.g. "[fmt.Scanner.Scan]".
	bracketText := comment.Text[mstart-1 : mend+1]

	// [mstart, mend) identifies the first submatch, which is the
	// reference name in the doc link (sans '*').
	// e.g. The "[fmt.Println]" reference name is "fmt.Println".
	match := comment.Text[mstart:mend]

	if strings.Contains(match, "\n") {
	continue
	}

	// [namePos.Start, namePos.End) identifies the start and end
	// position of a name. e.g. "fmt", "fmt.Scanner", "fmt.Scanner.Scan".
	var name string

	namePos := astutil.RangeOf(comment.Pos()+token.Pos(mstart), comment.Pos()+token.Pos(mstart-1))
	// [partPos.Start, partPos.End) identifies the start and end
	// position of a part. e.g. "fmt", "Scanner", "Scan".
	partPos := namePos
	for part := range strings.SplitSeq(match, ".") {
	if name != "" {
	name += "."
	}
	name += part

	partPos.Start = partPos.EndPos + token.Pos(len(".")) // Move start to the first char of next part
	partPos.EndPos = partPos.Start + token.Pos(len(part)) // Move end to next char of current part

	namePos.EndPos = partPos.EndPos

	if !yield(docLink{
	partRange: partPos,
	partText: part,
	nameText: name,
	bracketText: bracketText,
	}) {
	return
	}
	}
	}
	}
	}
	}

	// lookupDocLinkSymbol returns the symbol denoted by a doc link such
	// as "fmt.Println" or "bytes.Buffer.Write" in the specified file.
	func lookupDocLinkSymbol(pkg cache.Package, pgf parsego.File, name string) types.Object {
	scope := pkg.Types().Scope()

	prefix, suffix, _ := strings.Cut(name, ".")

	// Try treating the prefix as a package name,
	// allowing for non-renaming and renaming imports.
	fileScope := pkg.TypesInfo().Scopes[pgf.File]
	if fileScope == nil {
	// As we learned in golang/go#69616, any file may not be Scopes!
	// - A non-compiled Go file (such as unsafe.go) won't be in Scopes.
	// - A (technically) compiled go file with the wrong package name won't be
	// in Scopes, as it will be skipped by go/types.
	return nil
	}
	pkgname, ok := fileScope.Lookup(prefix).(*types.PkgName) // ok => prefix is imported name
	if !ok {
	// Handle renaming import, e.g.
	// [path.Join] after import pathpkg "path".
	// (Should we look at all files of the package?)
	for _, imp := range pgf.File.Imports {
	pkgname2 := pkg.TypesInfo().PkgNameOf(imp)
	if pkgname2 != nil && pkgname2.Imported().Name() == prefix {
	pkgname = pkgname2
	break
	}
	}
	}
	if pkgname != nil {
	scope = pkgname.Imported().Scope()
	if suffix == "" {
	return pkgname // not really a valid doc link
	}
	name = suffix
	}

	// TODO(adonovan): try searching the forward closure for packages
	// that define the symbol but are not directly imported;
	// see https://github.com/golang/go/issues/61677

	// Field or sel?
	recv, sel, ok := strings.Cut(name, ".")
	if ok {
	obj := scope.Lookup(recv) // package scope
	if obj == nil {
	obj = types.Universe.Lookup(recv)
	}
	obj, ok := obj.(*types.TypeName)
	if !ok {
	return nil
	}
	m, _, _ := types.LookupFieldOrMethod(obj.Type(), true, obj.Pkg(), sel)
	return m
	}

	if obj := scope.Lookup(name); obj != nil {
	return obj // package-level symbol
	}
	return types.Universe.Lookup(name) // built-in symbol
	}

	// newDocCommentParser returns a function that parses [doc comments],
	// with context for Doc Links supplied by the specified package.
	//
	// Imported symbols are rendered using the import mapping for the file
	// that encloses fileNode.
	//
	// The resulting function is not concurrency safe.
	//
	// See issue #61677 for how this might be generalized to support
	// correct contextual parsing of doc comments in Hover too.
	//
	// [doc comment]: https://go.dev/doc/comment
	func newDocCommentParser(pkg cache.Package) func(fileNode ast.Node, text string) comment.Doc {
	var currentFilePos token.Pos // pos whose enclosing file's import mapping should be used
	parser := &comment.Parser{
	LookupPackage: func(name string) (importPath string, ok bool) {
	for _, f := range pkg.Syntax() {
	// Different files in the same package have
	// different import mappings. Use the provided
	// syntax node to find the correct file.
	if astutil.NodeContainsPos(f, currentFilePos) {
	// First try each actual imported package name.
	for _, imp := range f.Imports {
	pkgName := pkg.TypesInfo().PkgNameOf(imp)
	if pkgName != nil && pkgName.Name() == name {
	return pkgName.Imported().Path(), true
	}
	}

	// Then try each imported package's declared name,
	// as some packages are typically imported under a
	// non-default name (e.g. pathpkg "path") but
	// may be referred to in doc links using their
	// canonical name.
	for _, imp := range f.Imports {
	pkgName := pkg.TypesInfo().PkgNameOf(imp)
	if pkgName != nil && pkgName.Imported().Name() == name {
	return pkgName.Imported().Path(), true
	}
	}

	// Finally try matching the last segment of each import
	// path imported by any file in the package, as the
	// doc comment may appear in a different file from the
	// import.
	//
	// Ideally we would look up the DepsByPkgPath value
	// (a PackageID) in the metadata graph and use the
	// package's declared name instead of this heuristic,
	// but we don't have access to the graph here.
	for path := range pkg.Metadata().DepsByPkgPath {
	if pathpkg.Base(trimVersionSuffix(string(path))) == name {
	return string(path), true
	}
	}

	break
	}
	}
	return "", false
	},
	LookupSym: func(recv, name string) (ok bool) {
	// package-level decl?
	if recv == "" {
	return pkg.Types().Scope().Lookup(name) != nil
	}

	// method?
	tname, ok := pkg.Types().Scope().Lookup(recv).(*types.TypeName)
	if !ok {
	return false
	}
	m, _, _ := types.LookupFieldOrMethod(tname.Type(), true, pkg.Types(), name)
	return is[*types.Func](m)
	},
	}
	return func(fileNode ast.Node, text string) *comment.Doc {
	currentFilePos = fileNode.Pos()
	return parser.Parse(text)
	}
	}