/
referrers.go
522 lines (455 loc) · 14.5 KB
/
referrers.go
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// Copyright 2013 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 main
import (
"bytes"
"fmt"
"go/ast"
"go/build"
"go/token"
"go/types"
"io"
"log"
"sort"
"strings"
"sync"
"golang.org/x/tools/cmd/guru/serial"
"golang.org/x/tools/go/buildutil"
"golang.org/x/tools/go/loader"
"golang.org/x/tools/refactor/importgraph"
)
// Referrers reports all identifiers that resolve to the same object
// as the queried identifier, within any package in the workspace.
func referrers(q *Query) error {
fset := token.NewFileSet()
lconf := loader.Config{Fset: fset, Build: q.Build}
allowErrors(&lconf)
if _, err := importQueryPackage(q.Pos, &lconf); err != nil {
return err
}
// Load/parse/type-check the query package.
lprog, err := lconf.Load()
if err != nil {
return err
}
qpos, err := parseQueryPos(lprog, q.Pos, false)
if err != nil {
return err
}
id, _ := qpos.path[0].(*ast.Ident)
if id == nil {
return fmt.Errorf("no identifier here")
}
obj := qpos.info.ObjectOf(id)
if obj == nil {
// Happens for y in "switch y := x.(type)",
// the package declaration,
// and unresolved identifiers.
if _, ok := qpos.path[1].(*ast.File); ok { // package decl?
return packageReferrers(q, qpos.info.Pkg.Path())
}
return fmt.Errorf("no object for identifier: %T", qpos.path[1])
}
// Imported package name?
if pkgname, ok := obj.(*types.PkgName); ok {
return packageReferrers(q, pkgname.Imported().Path())
}
if obj.Pkg() == nil {
return fmt.Errorf("references to predeclared %q are everywhere!", obj.Name())
}
// For a globally accessible object defined in package P, we
// must load packages that depend on P. Specifically, for a
// package-level object, we need load only direct importers
// of P, but for a field or interface method, we must load
// any package that transitively imports P.
if global, pkglevel := classify(obj); global {
// We'll use the the object's position to identify it in the larger program.
objposn := fset.Position(obj.Pos())
defpkg := obj.Pkg().Path() // defining package
return globalReferrers(q, qpos.info.Pkg.Path(), defpkg, objposn, pkglevel)
}
q.Output(fset, &referrersInitialResult{
qinfo: qpos.info,
obj: obj,
})
outputUses(q, fset, usesOf(obj, qpos.info), obj.Pkg())
return nil // success
}
// classify classifies objects by how far
// we have to look to find references to them.
func classify(obj types.Object) (global, pkglevel bool) {
if obj.Exported() {
if obj.Parent() == nil {
// selectable object (field or method)
return true, false
}
if obj.Parent() == obj.Pkg().Scope() {
// lexical object (package-level var/const/func/type)
return true, true
}
}
// object with unexported named or defined in local scope
return false, false
}
// packageReferrers reports all references to the specified package
// throughout the workspace.
func packageReferrers(q *Query, path string) error {
// Scan the workspace and build the import graph.
// Ignore broken packages.
_, rev, _ := importgraph.Build(q.Build)
// Find the set of packages that directly import the query package.
// Only those packages need typechecking of function bodies.
users := rev[path]
// Load the larger program.
fset := token.NewFileSet()
lconf := loader.Config{
Fset: fset,
Build: q.Build,
TypeCheckFuncBodies: func(p string) bool {
return users[strings.TrimSuffix(p, "_test")]
},
}
allowErrors(&lconf)
// The importgraph doesn't treat external test packages
// as separate nodes, so we must use ImportWithTests.
for path := range users {
lconf.ImportWithTests(path)
}
// Subtle! AfterTypeCheck needs no mutex for qpkg because the
// topological import order gives us the necessary happens-before edges.
// TODO(adonovan): what about import cycles?
var qpkg *types.Package
// For efficiency, we scan each package for references
// just after it has been type-checked. The loader calls
// AfterTypeCheck (concurrently), providing us with a stream of
// packages.
lconf.AfterTypeCheck = func(info *loader.PackageInfo, files []*ast.File) {
// AfterTypeCheck may be called twice for the same package due to augmentation.
if info.Pkg.Path() == path && qpkg == nil {
// Found the package of interest.
qpkg = info.Pkg
fakepkgname := types.NewPkgName(token.NoPos, qpkg, qpkg.Name(), qpkg)
q.Output(fset, &referrersInitialResult{
qinfo: info,
obj: fakepkgname, // bogus
})
}
// Only inspect packages that directly import the
// declaring package (and thus were type-checked).
if lconf.TypeCheckFuncBodies(info.Pkg.Path()) {
// Find PkgNames that refer to qpkg.
// TODO(adonovan): perhaps more useful would be to show imports
// of the package instead of qualified identifiers.
var refs []*ast.Ident
for id, obj := range info.Uses {
if obj, ok := obj.(*types.PkgName); ok && obj.Imported() == qpkg {
refs = append(refs, id)
}
}
outputUses(q, fset, refs, info.Pkg)
}
clearInfoFields(info) // save memory
}
lconf.Load() // ignore error
if qpkg == nil {
log.Fatalf("query package %q not found during reloading", path)
}
return nil
}
func usesOf(queryObj types.Object, info *loader.PackageInfo) []*ast.Ident {
var refs []*ast.Ident
for id, obj := range info.Uses {
if sameObj(queryObj, obj) {
refs = append(refs, id)
}
}
return refs
}
// outputUses outputs a result describing refs, which appear in the package denoted by info.
func outputUses(q *Query, fset *token.FileSet, refs []*ast.Ident, pkg *types.Package) {
if len(refs) > 0 {
sort.Sort(byNamePos{fset, refs})
q.Output(fset, &referrersPackageResult{
pkg: pkg,
build: q.Build,
fset: fset,
refs: refs,
})
}
}
// globalReferrers reports references throughout the entire workspace to the
// object at the specified source position. Its defining package is defpkg,
// and the query package is qpkg. isPkgLevel indicates whether the object
// is defined at package-level.
func globalReferrers(q *Query, qpkg, defpkg string, objposn token.Position, isPkgLevel bool) error {
// Scan the workspace and build the import graph.
// Ignore broken packages.
_, rev, _ := importgraph.Build(q.Build)
// Find the set of packages that depend on defpkg.
// Only function bodies in those packages need type-checking.
var users map[string]bool
if isPkgLevel {
users = rev[defpkg] // direct importers
if users == nil {
users = make(map[string]bool)
}
users[defpkg] = true // plus the defining package itself
} else {
users = rev.Search(defpkg) // transitive importers
}
// Prepare to load the larger program.
fset := token.NewFileSet()
lconf := loader.Config{
Fset: fset,
Build: q.Build,
TypeCheckFuncBodies: func(p string) bool {
return users[strings.TrimSuffix(p, "_test")]
},
}
allowErrors(&lconf)
// The importgraph doesn't treat external test packages
// as separate nodes, so we must use ImportWithTests.
for path := range users {
lconf.ImportWithTests(path)
}
// The remainder of this function is somewhat tricky because it
// operates on the concurrent stream of packages observed by the
// loader's AfterTypeCheck hook. Most of guru's helper
// functions assume the entire program has already been loaded,
// so we can't use them here.
// TODO(adonovan): smooth things out once the other changes have landed.
// Results are reported concurrently from within the
// AfterTypeCheck hook. The program may provide a useful stream
// of information even if the user doesn't let the program run
// to completion.
var (
mu sync.Mutex
qobj types.Object
qinfo *loader.PackageInfo // info for qpkg
)
// For efficiency, we scan each package for references
// just after it has been type-checked. The loader calls
// AfterTypeCheck (concurrently), providing us with a stream of
// packages.
lconf.AfterTypeCheck = func(info *loader.PackageInfo, files []*ast.File) {
// AfterTypeCheck may be called twice for the same package due to augmentation.
// Only inspect packages that depend on the declaring package
// (and thus were type-checked).
if lconf.TypeCheckFuncBodies(info.Pkg.Path()) {
// Record the query object and its package when we see it.
mu.Lock()
if qobj == nil && info.Pkg.Path() == defpkg {
// Find the object by its position (slightly ugly).
qobj = findObject(fset, &info.Info, objposn)
if qobj == nil {
// It really ought to be there;
// we found it once already.
log.Fatalf("object at %s not found in package %s",
objposn, defpkg)
}
// Object found.
qinfo = info
q.Output(fset, &referrersInitialResult{
qinfo: qinfo,
obj: qobj,
})
}
obj := qobj
mu.Unlock()
// Look for references to the query object.
if obj != nil {
outputUses(q, fset, usesOf(obj, info), info.Pkg)
}
}
clearInfoFields(info) // save memory
}
lconf.Load() // ignore error
if qobj == nil {
log.Fatal("query object not found during reloading")
}
return nil // success
}
// findObject returns the object defined at the specified position.
func findObject(fset *token.FileSet, info *types.Info, objposn token.Position) types.Object {
good := func(obj types.Object) bool {
if obj == nil {
return false
}
posn := fset.Position(obj.Pos())
return posn.Filename == objposn.Filename && posn.Offset == objposn.Offset
}
for _, obj := range info.Defs {
if good(obj) {
return obj
}
}
for _, obj := range info.Implicits {
if good(obj) {
return obj
}
}
return nil
}
// same reports whether x and y are identical, or both are PkgNames
// that import the same Package.
//
func sameObj(x, y types.Object) bool {
if x == y {
return true
}
if x, ok := x.(*types.PkgName); ok {
if y, ok := y.(*types.PkgName); ok {
return x.Imported() == y.Imported()
}
}
return false
}
func clearInfoFields(info *loader.PackageInfo) {
// TODO(adonovan): opt: save memory by eliminating unneeded scopes/objects.
// (Requires go/types change for Go 1.7.)
// info.Pkg.Scope().ClearChildren()
// Discard the file ASTs and their accumulated type
// information to save memory.
info.Files = nil
info.Defs = make(map[*ast.Ident]types.Object)
info.Uses = make(map[*ast.Ident]types.Object)
info.Implicits = make(map[ast.Node]types.Object)
// Also, disable future collection of wholly unneeded
// type information for the package in case there is
// more type-checking to do (augmentation).
info.Types = nil
info.Scopes = nil
info.Selections = nil
}
// -------- utils --------
// An deterministic ordering for token.Pos that doesn't
// depend on the order in which packages were loaded.
func lessPos(fset *token.FileSet, x, y token.Pos) bool {
fx := fset.File(x)
fy := fset.File(y)
if fx != fy {
return fx.Name() < fy.Name()
}
return x < y
}
type byNamePos struct {
fset *token.FileSet
ids []*ast.Ident
}
func (p byNamePos) Len() int { return len(p.ids) }
func (p byNamePos) Swap(i, j int) { p.ids[i], p.ids[j] = p.ids[j], p.ids[i] }
func (p byNamePos) Less(i, j int) bool {
return lessPos(p.fset, p.ids[i].NamePos, p.ids[j].NamePos)
}
// referrersInitialResult is the initial result of a "referrers" query.
type referrersInitialResult struct {
qinfo *loader.PackageInfo
obj types.Object // object it denotes
}
func (r *referrersInitialResult) PrintPlain(printf printfFunc) {
printf(r.obj, "references to %s",
types.ObjectString(r.obj, types.RelativeTo(r.qinfo.Pkg)))
}
func (r *referrersInitialResult) JSON(fset *token.FileSet) []byte {
var objpos string
if pos := r.obj.Pos(); pos.IsValid() {
objpos = fset.Position(pos).String()
}
return toJSON(&serial.ReferrersInitial{
Desc: r.obj.String(),
ObjPos: objpos,
})
}
// referrersPackageResult is the streaming result for one package of a "referrers" query.
type referrersPackageResult struct {
pkg *types.Package
build *build.Context
fset *token.FileSet
refs []*ast.Ident // set of all other references to it
}
// forEachRef calls f(id, text) for id in r.refs, in order.
// Text is the text of the line on which id appears.
func (r *referrersPackageResult) foreachRef(f func(id *ast.Ident, text string)) {
// Show referring lines, like grep.
type fileinfo struct {
refs []*ast.Ident
linenums []int // line number of refs[i]
data chan interface{} // file contents or error
}
var fileinfos []*fileinfo
fileinfosByName := make(map[string]*fileinfo)
// First pass: start the file reads concurrently.
sema := make(chan struct{}, 20) // counting semaphore to limit I/O concurrency
for _, ref := range r.refs {
posn := r.fset.Position(ref.Pos())
fi := fileinfosByName[posn.Filename]
if fi == nil {
fi = &fileinfo{data: make(chan interface{})}
fileinfosByName[posn.Filename] = fi
fileinfos = append(fileinfos, fi)
// First request for this file:
// start asynchronous read.
go func() {
sema <- struct{}{} // acquire token
content, err := readFile(r.build, posn.Filename)
<-sema // release token
if err != nil {
fi.data <- err
} else {
fi.data <- content
}
}()
}
fi.refs = append(fi.refs, ref)
fi.linenums = append(fi.linenums, posn.Line)
}
// Second pass: print refs in original order.
// One line may have several refs at different columns.
for _, fi := range fileinfos {
v := <-fi.data // wait for I/O completion
// Print one item for all refs in a file that could not
// be loaded (perhaps due to //line directives).
if err, ok := v.(error); ok {
var suffix string
if more := len(fi.refs) - 1; more > 0 {
suffix = fmt.Sprintf(" (+ %d more refs in this file)", more)
}
f(fi.refs[0], err.Error()+suffix)
continue
}
lines := bytes.Split(v.([]byte), []byte("\n"))
for i, ref := range fi.refs {
f(ref, string(lines[fi.linenums[i]-1]))
}
}
}
// readFile is like ioutil.ReadFile, but
// it goes through the virtualized build.Context.
func readFile(ctxt *build.Context, filename string) ([]byte, error) {
rc, err := buildutil.OpenFile(ctxt, filename)
if err != nil {
return nil, err
}
defer rc.Close()
var buf bytes.Buffer
if _, err := io.Copy(&buf, rc); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
func (r *referrersPackageResult) PrintPlain(printf printfFunc) {
r.foreachRef(func(id *ast.Ident, text string) {
printf(id, "%s", text)
})
}
func (r *referrersPackageResult) JSON(fset *token.FileSet) []byte {
refs := serial.ReferrersPackage{Package: r.pkg.Path()}
r.foreachRef(func(id *ast.Ident, text string) {
refs.Refs = append(refs.Refs, serial.Ref{
Pos: fset.Position(id.NamePos).String(),
Text: text,
})
})
return toJSON(refs)
}