blob: dbdba041268ba3d7cb8db6c6e7c23148930c165d [file] [log] [blame]
// 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 (
"fmt"
"go/ast"
"go/token"
"go/types"
"reflect"
"sort"
"strings"
"golang.org/x/tools/cmd/guru/serial"
"golang.org/x/tools/go/loader"
"golang.org/x/tools/go/types/typeutil"
"golang.org/x/tools/refactor/importgraph"
)
// The implements function displays the "implements" relation as it pertains to the
// selected type.
// If the selection is a method, 'implements' displays
// the corresponding methods of the types that would have been reported
// by an implements query on the receiver type.
//
func implements(q *Query) error {
lconf := loader.Config{Build: q.Build}
allowErrors(&lconf)
qpkg, err := importQueryPackage(q.Pos, &lconf)
if err != nil {
return err
}
// Set the packages to search.
if len(q.Scope) > 0 {
// Inspect all packages in the analysis scope, if specified.
if err := setPTAScope(&lconf, q.Scope); err != nil {
return err
}
} else {
// Otherwise inspect the forward and reverse
// transitive closure of the selected package.
// (In theory even this is incomplete.)
_, rev, _ := importgraph.Build(q.Build)
for path := range rev.Search(qpkg) {
lconf.ImportWithTests(path)
}
// TODO(adonovan): for completeness, we should also
// type-check and inspect function bodies in all
// imported packages. This would be expensive, but we
// could optimize by skipping functions that do not
// contain type declarations. This would require
// changing the loader's TypeCheckFuncBodies hook to
// provide the []*ast.File.
}
// Load/parse/type-check the program.
lprog, err := lconf.Load()
if err != nil {
return err
}
qpos, err := parseQueryPos(lprog, q.Pos, false)
if err != nil {
return err
}
// Find the selected type.
path, action := findInterestingNode(qpos.info, qpos.path)
var method *types.Func
var T types.Type // selected type (receiver if method != nil)
switch action {
case actionExpr:
// method?
if id, ok := path[0].(*ast.Ident); ok {
if obj, ok := qpos.info.ObjectOf(id).(*types.Func); ok {
recv := obj.Type().(*types.Signature).Recv()
if recv == nil {
return fmt.Errorf("this function is not a method")
}
method = obj
T = recv.Type()
}
}
// If not a method, use the expression's type.
if T == nil {
T = qpos.info.TypeOf(path[0].(ast.Expr))
}
case actionType:
T = qpos.info.TypeOf(path[0].(ast.Expr))
}
if T == nil {
return fmt.Errorf("not a type, method, or value")
}
// Find all named types, even local types (which can have
// methods due to promotion) and the built-in "error".
// We ignore aliases 'type M = N' to avoid duplicate
// reporting of the Named type N.
var allNamed []*types.Named
for _, info := range lprog.AllPackages {
for _, obj := range info.Defs {
if obj, ok := obj.(*types.TypeName); ok && !isAlias(obj) {
if named, ok := obj.Type().(*types.Named); ok {
allNamed = append(allNamed, named)
}
}
}
}
allNamed = append(allNamed, types.Universe.Lookup("error").Type().(*types.Named))
var msets typeutil.MethodSetCache
// Test each named type.
var to, from, fromPtr []types.Type
for _, U := range allNamed {
if isInterface(T) {
if msets.MethodSet(T).Len() == 0 {
continue // empty interface
}
if isInterface(U) {
if msets.MethodSet(U).Len() == 0 {
continue // empty interface
}
// T interface, U interface
if !types.Identical(T, U) {
if types.AssignableTo(U, T) {
to = append(to, U)
}
if types.AssignableTo(T, U) {
from = append(from, U)
}
}
} else {
// T interface, U concrete
if types.AssignableTo(U, T) {
to = append(to, U)
} else if pU := types.NewPointer(U); types.AssignableTo(pU, T) {
to = append(to, pU)
}
}
} else if isInterface(U) {
if msets.MethodSet(U).Len() == 0 {
continue // empty interface
}
// T concrete, U interface
if types.AssignableTo(T, U) {
from = append(from, U)
} else if pT := types.NewPointer(T); types.AssignableTo(pT, U) {
fromPtr = append(fromPtr, U)
}
}
}
var pos interface{} = qpos
if nt, ok := deref(T).(*types.Named); ok {
pos = nt.Obj()
}
// Sort types (arbitrarily) to ensure test determinism.
sort.Sort(typesByString(to))
sort.Sort(typesByString(from))
sort.Sort(typesByString(fromPtr))
var toMethod, fromMethod, fromPtrMethod []*types.Selection // contain nils
if method != nil {
for _, t := range to {
toMethod = append(toMethod,
types.NewMethodSet(t).Lookup(method.Pkg(), method.Name()))
}
for _, t := range from {
fromMethod = append(fromMethod,
types.NewMethodSet(t).Lookup(method.Pkg(), method.Name()))
}
for _, t := range fromPtr {
fromPtrMethod = append(fromPtrMethod,
types.NewMethodSet(t).Lookup(method.Pkg(), method.Name()))
}
}
q.Output(lprog.Fset, &implementsResult{
qpos, T, pos, to, from, fromPtr, method, toMethod, fromMethod, fromPtrMethod,
})
return nil
}
type implementsResult struct {
qpos *queryPos
t types.Type // queried type (not necessarily named)
pos interface{} // pos of t (*types.Name or *QueryPos)
to []types.Type // named or ptr-to-named types assignable to interface T
from []types.Type // named interfaces assignable from T
fromPtr []types.Type // named interfaces assignable only from *T
// if a method was queried:
method *types.Func // queried method
toMethod []*types.Selection // method of type to[i], if any
fromMethod []*types.Selection // method of type from[i], if any
fromPtrMethod []*types.Selection // method of type fromPtrMethod[i], if any
}
func (r *implementsResult) PrintPlain(printf printfFunc) {
relation := "is implemented by"
meth := func(sel *types.Selection) {
if sel != nil {
printf(sel.Obj(), "\t%s method (%s).%s",
relation, r.qpos.typeString(sel.Recv()), sel.Obj().Name())
}
}
if isInterface(r.t) {
if types.NewMethodSet(r.t).Len() == 0 { // TODO(adonovan): cache mset
printf(r.pos, "empty interface type %s", r.qpos.typeString(r.t))
return
}
if r.method == nil {
printf(r.pos, "interface type %s", r.qpos.typeString(r.t))
} else {
printf(r.method, "abstract method %s", r.qpos.objectString(r.method))
}
// Show concrete types (or methods) first; use two passes.
for i, sub := range r.to {
if !isInterface(sub) {
if r.method == nil {
printf(deref(sub).(*types.Named).Obj(), "\t%s %s type %s",
relation, typeKind(sub), r.qpos.typeString(sub))
} else {
meth(r.toMethod[i])
}
}
}
for i, sub := range r.to {
if isInterface(sub) {
if r.method == nil {
printf(sub.(*types.Named).Obj(), "\t%s %s type %s",
relation, typeKind(sub), r.qpos.typeString(sub))
} else {
meth(r.toMethod[i])
}
}
}
relation = "implements"
for i, super := range r.from {
if r.method == nil {
printf(super.(*types.Named).Obj(), "\t%s %s",
relation, r.qpos.typeString(super))
} else {
meth(r.fromMethod[i])
}
}
} else {
relation = "implements"
if r.from != nil {
if r.method == nil {
printf(r.pos, "%s type %s",
typeKind(r.t), r.qpos.typeString(r.t))
} else {
printf(r.method, "concrete method %s",
r.qpos.objectString(r.method))
}
for i, super := range r.from {
if r.method == nil {
printf(super.(*types.Named).Obj(), "\t%s %s",
relation, r.qpos.typeString(super))
} else {
meth(r.fromMethod[i])
}
}
}
if r.fromPtr != nil {
if r.method == nil {
printf(r.pos, "pointer type *%s", r.qpos.typeString(r.t))
} else {
// TODO(adonovan): de-dup (C).f and (*C).f implementing (I).f.
printf(r.method, "concrete method %s",
r.qpos.objectString(r.method))
}
for i, psuper := range r.fromPtr {
if r.method == nil {
printf(psuper.(*types.Named).Obj(), "\t%s %s",
relation, r.qpos.typeString(psuper))
} else {
meth(r.fromPtrMethod[i])
}
}
} else if r.from == nil {
printf(r.pos, "%s type %s implements only interface{}",
typeKind(r.t), r.qpos.typeString(r.t))
}
}
}
func (r *implementsResult) JSON(fset *token.FileSet) []byte {
var method *serial.DescribeMethod
if r.method != nil {
method = &serial.DescribeMethod{
Name: r.qpos.objectString(r.method),
Pos: fset.Position(r.method.Pos()).String(),
}
}
return toJSON(&serial.Implements{
T: makeImplementsType(r.t, fset),
AssignableTo: makeImplementsTypes(r.to, fset),
AssignableFrom: makeImplementsTypes(r.from, fset),
AssignableFromPtr: makeImplementsTypes(r.fromPtr, fset),
AssignableToMethod: methodsToSerial(r.qpos.info.Pkg, r.toMethod, fset),
AssignableFromMethod: methodsToSerial(r.qpos.info.Pkg, r.fromMethod, fset),
AssignableFromPtrMethod: methodsToSerial(r.qpos.info.Pkg, r.fromPtrMethod, fset),
Method: method,
})
}
func makeImplementsTypes(tt []types.Type, fset *token.FileSet) []serial.ImplementsType {
var r []serial.ImplementsType
for _, t := range tt {
r = append(r, makeImplementsType(t, fset))
}
return r
}
func makeImplementsType(T types.Type, fset *token.FileSet) serial.ImplementsType {
var pos token.Pos
if nt, ok := deref(T).(*types.Named); ok { // implementsResult.t may be non-named
pos = nt.Obj().Pos()
}
return serial.ImplementsType{
Name: T.String(),
Pos: fset.Position(pos).String(),
Kind: typeKind(T),
}
}
// typeKind returns a string describing the underlying kind of type,
// e.g. "slice", "array", "struct".
func typeKind(T types.Type) string {
s := reflect.TypeOf(T.Underlying()).String()
return strings.ToLower(strings.TrimPrefix(s, "*types."))
}
func isInterface(T types.Type) bool { return types.IsInterface(T) }
type typesByString []types.Type
func (p typesByString) Len() int { return len(p) }
func (p typesByString) Less(i, j int) bool { return p[i].String() < p[j].String() }
func (p typesByString) Swap(i, j int) { p[i], p[j] = p[j], p[i] }