Golang code-google-com-p-go-tools-go-types.Identical类(方法)实例源码

//ranges through config file and checks all expressions.
// prints result messages to stdout
func (c *checker) CheckAll() ([]CheckResult, error) {
	result := []CheckResult{}
	cnf, err := conf.ReadConfigFile(c.configFile)
	if err != nil {
		return nil, err
	}
	for _, section := range cnf.GetSections() {
		if section == "default" {
			continue
		}
		expr, _ := cnf.GetString(section, "expr")
		_, r, err := types.Eval(expr, c.pkg, c.sc)
		if err != nil {
			fmt.Fprintln(os.Stderr, err)
			continue
		}
		cr := &CheckResult{
			Name: section,
		}
		var m string
		if exact.BoolVal(r) {
			m, err = cnf.GetString(section, "true")
			if err != nil {
				continue
			}
		} else {
			m, err = cnf.GetString(section, "false")
			if err != nil {
				continue
			}
		}
		val, err := cnf.GetString(section, "val")
		if err == nil {
			t, v, err := types.Eval(val, c.pkg, c.sc)
			if err == nil {
				if types.Identical(t, types.Typ[types.UntypedFloat]) || types.Identical(t, types.Typ[types.Float64]) {
					x, _ := exact.Float64Val(v)
					cr.Value = x
				}
			}
		}
		owner, err := cnf.GetString(section, "owner")
		if err == nil {
			cr.Owner = owner
		} else {
			cr.Owner = "unknown"
		}

		_, msg, err := types.Eval(m, c.pkg, c.sc)
		if err != nil {
			cr.Message = m
		} else {
			cr.Message = exact.StringVal(msg)
		}
		result = append(result, *cr)
	}
	return result, nil
}

// typeAssert checks whether dynamic type of itf is instr.AssertedType.
// It returns the extracted value on success, and panics on failure,
// unless instr.CommaOk, in which case it always returns a "value,ok" tuple.
//
func typeAssert(i *interpreter, instr *ssa.TypeAssert, itf iface) value {
	var v value
	err := ""
	if itf.t == nil {
		err = fmt.Sprintf("interface conversion: interface is nil, not %s", instr.AssertedType)

	} else if idst, ok := instr.AssertedType.Underlying().(*types.Interface); ok {
		v = itf
		err = checkInterface(i, idst, itf)

	} else if types.Identical(itf.t, instr.AssertedType) {
		v = copyVal(itf.v) // extract value

	} else {
		err = fmt.Sprintf("interface conversion: interface is %s, not %s", itf.t, instr.AssertedType)
	}

	if err != "" {
		if !instr.CommaOk {
			panic(err)
		}
		return tuple{zero(instr.AssertedType), false}
	}
	if instr.CommaOk {
		return tuple{v, true}
	}
	return v
}

// Set sets the map entry for key to val,
// and returns the previous entry, if any.
func (m *Map) Set(key types.Type, value interface{}) (prev interface{}) {
	if m.table != nil {
		hash := m.hasher.Hash(key)
		bucket := m.table[hash]
		var hole *entry
		for i, e := range bucket {
			if e.key == nil {
				hole = &bucket[i]
			} else if types.Identical(key, e.key) {
				prev = e.value
				bucket[i].value = value
				return
			}
		}

		if hole != nil {
			*hole = entry{key, value} // overwrite deleted entry
		} else {
			m.table[hash] = append(bucket, entry{key, value})
		}
	} else {
		if m.hasher.memo == nil {
			m.hasher = MakeHasher()
		}
		hash := m.hasher.Hash(key)
		m.table = map[uint32][]entry{hash: {entry{key, value}}}
	}

	m.length++
	return
}

// computeTrackBits sets a.track to the necessary 'track' bits for the pointer queries.
func (a *analysis) computeTrackBits() {
	var queryTypes []types.Type
	for v := range a.config.Queries {
		queryTypes = append(queryTypes, v.Type())
	}
	for v := range a.config.IndirectQueries {
		queryTypes = append(queryTypes, mustDeref(v.Type()))
	}
	for _, t := range queryTypes {
		switch t.Underlying().(type) {
		case *types.Chan:
			a.track |= trackChan
		case *types.Map:
			a.track |= trackMap
		case *types.Pointer:
			a.track |= trackPtr
		case *types.Slice:
			a.track |= trackSlice
		case *types.Interface:
			a.track = trackAll
			return
		}
		if rVObj := a.reflectValueObj; rVObj != nil && types.Identical(t, rVObj.Type()) {
			a.track = trackAll
			return
		}
	}
}

// containsAllIdsOf reports whether the method identifiers of T are a
// superset of those in U.  If U belongs to an interface type, the
// result is equal to types.Assignable(T, U), but is cheaper to compute.
//
// TODO(gri): make this a method of *types.MethodSet.
//
func containsAllIdsOf(T, U *types.MethodSet) bool {
	t, tlen := 0, T.Len()
	u, ulen := 0, U.Len()
	for t < tlen && u < ulen {
		tMeth := T.At(t).Obj()
		uMeth := U.At(u).Obj()
		tId := tMeth.Id()
		uId := uMeth.Id()
		if tId > uId {
			// U has a method T lacks: fail.
			return false
		}
		if tId < uId {
			// T has a method U lacks: ignore it.
			t++
			continue
		}
		// U and T both have a method of this Id.  Check types.
		if !types.Identical(tMeth.Type(), uMeth.Type()) {
			return false // type mismatch
		}
		u++
		t++
	}
	return u == ulen
}

// assign records pairs of distinct types that are related by
// assignability, where the left-hand side is an interface and both
// sides have methods.
//
// It should be called for all assignability checks, type assertions,
// explicit conversions and comparisons between two types, unless the
// types are uninteresting (e.g. lhs is a concrete type, or the empty
// interface; rhs has no methods).
//
func (f *Finder) assign(lhs, rhs types.Type) {
	if types.Identical(lhs, rhs) {
		return
	}
	if !isInterface(lhs) {
		return
	}
	if f.msetcache.MethodSet(lhs).Len() == 0 {
		return
	}
	if f.msetcache.MethodSet(rhs).Len() == 0 {
		return
	}
	// canonicalize types
	lhsc, ok := f.canon.At(lhs).(types.Type)
	if !ok {
		lhsc = lhs
		f.canon.Set(lhs, lhsc)
	}
	rhsc, ok := f.canon.At(rhs).(types.Type)
	if !ok {
		rhsc = rhs
		f.canon.Set(rhs, rhsc)
	}
	// record the pair
	f.Result[Constraint{lhsc, rhsc}] = true
}

func (c *funcContext) translateImplicitConversion(expr ast.Expr, desiredType types.Type) *expression {
	if desiredType == nil {
		return c.translateExpr(expr)
	}
	if expr == nil {
		return c.formatExpr("%s", c.zeroValue(desiredType))
	}

	exprType := c.p.info.Types[expr].Type
	if types.Identical(exprType, desiredType) {
		return c.translateExpr(expr)
	}

	basicExprType, isBasicExpr := exprType.Underlying().(*types.Basic)
	if isBasicExpr && basicExprType.Kind() == types.UntypedNil {
		return c.formatExpr("%s", c.zeroValue(desiredType))
	}

	switch desiredType.Underlying().(type) {
	case *types.Slice:
		return c.formatExpr("$subslice(new %1s(%2e.$array), %2e.$offset, %2e.$offset + %2e.$length)", c.typeName(desiredType), expr)

	case *types.Interface:
		if isWrapped(exprType) {
			return c.formatExpr("new %s(%e)", c.typeName(exprType), expr)
		}
		if _, isStruct := exprType.Underlying().(*types.Struct); isStruct {
			return c.formatExpr("new %1e.constructor.Struct(%1e)", expr)
		}
	}

	return c.translateExpr(expr)
}

func checkEqualButNotIdentical(t *testing.T, x, y types.Type, comment string) {
	if !types.Identical(x, y) {
		t.Errorf("%s: not equal: %s, %s", comment, x, y)
	}
	if x == y {
		t.Errorf("%s: identical: %v, %v", comment, x, y)
	}
}

// At returns the map entry for the given key.
// The result is nil if the entry is not present.
//
func (m *Map) At(key types.Type) interface{} {
	if m != nil && m.table != nil {
		for _, e := range m.table[m.hasher.Hash(key)] {
			if e.key != nil && types.Identical(key, e.key) {
				return e.value
			}
		}
	}
	return nil
}

// testMainSlice emits to fn code to construct a slice of type slice
// (one of []testing.Internal{Test,Benchmark,Example}) for all
// functions in expfuncs whose name starts with prefix (one of
// "Test", "Benchmark" or "Example") and whose type is appropriate.
// It returns the slice value.
//
func testMainSlice(fn *Function, expfuncs []*Function, prefix string, slice types.Type) Value {
	tElem := slice.(*types.Slice).Elem()
	tFunc := tElem.Underlying().(*types.Struct).Field(1).Type()

	var testfuncs []*Function
	for _, f := range expfuncs {
		if isTest(f.Name(), prefix) && types.Identical(f.Signature, tFunc) {
			testfuncs = append(testfuncs, f)
		}
	}
	if testfuncs == nil {
		return nilConst(slice)
	}

	tString := types.Typ[types.String]
	tPtrString := types.NewPointer(tString)
	tPtrElem := types.NewPointer(tElem)
	tPtrFunc := types.NewPointer(tFunc)

	// Emit: array = new [n]testing.InternalTest
	tArray := types.NewArray(tElem, int64(len(testfuncs)))
	array := emitNew(fn, tArray, token.NoPos)
	array.Comment = "test main"
	for i, testfunc := range testfuncs {
		// Emit: pitem = &array[i]
		ia := &IndexAddr{X: array, Index: intConst(int64(i))}
		ia.setType(tPtrElem)
		pitem := fn.emit(ia)

		// Emit: pname = &pitem.Name
		fa := &FieldAddr{X: pitem, Field: 0} // .Name
		fa.setType(tPtrString)
		pname := fn.emit(fa)

		// Emit: *pname = "testfunc"
		emitStore(fn, pname, NewConst(exact.MakeString(testfunc.Name()), tString))

		// Emit: pfunc = &pitem.F
		fa = &FieldAddr{X: pitem, Field: 1} // .F
		fa.setType(tPtrFunc)
		pfunc := fn.emit(fa)

		// Emit: *pfunc = testfunc
		emitStore(fn, pfunc, testfunc)
	}

	// Emit: slice array[:]
	sl := &Slice{X: array}
	sl.setType(slice)
	return fn.emit(sl)
}

// findAssignments returns the set of types to or from which type T is
// assigned in the program syntax.
func (r *renamer) findAssignments(T types.Type) map[types.Type]bool {
	if r.satisfyConstraints == nil {
		// Compute on demand: it's expensive.
		var f satisfy.Finder
		for _, info := range r.packages {
			f.Find(&info.Info, info.Files)
		}
		r.satisfyConstraints = f.Result
	}

	result := make(map[types.Type]bool)
	for key := range r.satisfyConstraints {
		// key = (lhs, rhs) where lhs is always an interface.
		if types.Identical(key.RHS, T) {
			result[key.LHS] = true
		}
		if isInterface(T) && types.Identical(key.LHS, T) {
			// must check both sides
			result[key.RHS] = true
		}
	}
	return result
}

// Delete removes the entry with the given key, if any.
// It returns true if the entry was found.
//
func (m *Map) Delete(key types.Type) bool {
	if m != nil && m.table != nil {
		hash := m.hasher.Hash(key)
		bucket := m.table[hash]
		for i, e := range bucket {
			if e.key != nil && types.Identical(key, e.key) {
				// We can't compact the bucket as it
				// would disturb iterators.
				bucket[i] = entry{}
				m.length--
				return true
			}
		}
	}
	return false
}

func checkFuncValue(t *testing.T, prog *ssa.Program, obj *types.Func) {
	fn := prog.FuncValue(obj)
	// fmt.Printf("FuncValue(%s) = %s\n", obj, fn) // debugging
	if fn == nil {
		t.Errorf("FuncValue(%s) == nil", obj)
		return
	}
	if fnobj := fn.Object(); fnobj != obj {
		t.Errorf("FuncValue(%s).Object() == %s; value was %s",
			obj, fnobj, fn.Name())
		return
	}
	if !types.Identical(fn.Type(), obj.Type()) {
		t.Errorf("FuncValue(%s).Type() == %s", obj, fn.Type())
		return
	}
}

// isValuePreserving returns true if a conversion from ut_src to
// ut_dst is value-preserving, i.e. just a change of type.
// Precondition: neither argument is a named type.
//
func isValuePreserving(ut_src, ut_dst types.Type) bool {
	// Identical underlying types?
	if types.Identical(ut_dst, ut_src) {
		return true
	}

	switch ut_dst.(type) {
	case *types.Chan:
		// Conversion between channel types?
		_, ok := ut_src.(*types.Chan)
		return ok

	case *types.Pointer:
		// Conversion between pointers with identical base types?
		_, ok := ut_src.(*types.Pointer)
		return ok
	}
	return false
}

// isErrorMethodCall reports whether the call is of a method with signature
//	func Error() string
// where "string" is the universe's string type. We know the method is called "Error".
func (f *File) isErrorMethodCall(call *ast.CallExpr) bool {
	typ := f.pkg.types[call].Type
	if typ != nil {
		// We know it's called "Error", so just check the function signature.
		return types.Identical(f.pkg.types[call.Fun].Type, stringerMethodType)
	}
	// Without types, we can still check by hand.
	// Is it a selector expression? Otherwise it's a function call, not a method call.
	sel, ok := call.Fun.(*ast.SelectorExpr)
	if !ok {
		return false
	}
	// The package is type-checked, so if there are no arguments, we're done.
	if len(call.Args) > 0 {
		return false
	}
	// Check the type of the method declaration
	typ = f.pkg.types[sel].Type
	if typ == nil {
		return false
	}
	// The type must be a signature, but be sure for safety.
	sig, ok := typ.(*types.Signature)
	if !ok {
		return false
	}
	// There must be a receiver for it to be a method call. Otherwise it is
	// a function, not something that satisfies the error interface.
	if sig.Recv() == nil {
		return false
	}
	// There must be no arguments. Already verified by type checking, but be thorough.
	if sig.Params().Len() > 0 {
		return false
	}
	// Finally the real questions.
	// There must be one result.
	if sig.Results().Len() != 1 {
		return false
	}
	// It must have return type "string" from the universe.
	return sig.Results().At(0).Type() == types.Typ[types.String]
}

func checkConstValue(t *testing.T, prog *ssa.Program, obj *types.Const) {
	c := prog.ConstValue(obj)
	// fmt.Printf("ConstValue(%s) = %s\n", obj, c) // debugging
	if c == nil {
		t.Errorf("ConstValue(%s) == nil", obj)
		return
	}
	if !types.Identical(c.Type(), obj.Type()) {
		t.Errorf("ConstValue(%s).Type() == %s", obj, c.Type())
		return
	}
	if obj.Name() != "nil" {
		if !exact.Compare(c.Value, token.EQL, obj.Val()) {
			t.Errorf("ConstValue(%s).Value (%s) != %s",
				obj, c.Value, obj.Val())
			return
		}
	}
}

// checkShadowing checks whether the identifier shadows an identifier in an outer scope.
func (f *File) checkShadowing(ident *ast.Ident) {
	if ident.Name == "_" {
		// Can't shadow the blank identifier.
		return
	}
	obj := f.pkg.defs[ident]
	if obj == nil {
		return
	}
	// obj.Parent.Parent is the surrounding scope. If we can find another declaration
	// starting from there, we have a shadowed variable.
	shadowed := obj.Parent().Parent().LookupParent(obj.Name())
	if shadowed == nil {
		return
	}
	// Don't complain if it's shadowing a universe-declared variable; that's fine.
	if shadowed.Parent() == types.Universe {
		return
	}
	if *strictShadowing {
		// The shadowed variable must appear before this one to be an instance of shadowing.
		if shadowed.Pos() > ident.Pos() {
			return
		}
	} else {
		// Don't complain if the span of validity of the shadowed variable doesn't include
		// the shadowing variable.
		span, ok := f.pkg.spans[shadowed]
		if !ok {
			f.Badf(ident.Pos(), "internal error: no range for %s", ident.Name)
			return
		}
		if !span.contains(ident.Pos()) {
			return
		}
	}
	// Don't complain if the types differ: that implies the programmer really wants two variables.
	if types.Identical(obj.Type(), shadowed.Type()) {
		f.Badf(ident.Pos(), "declaration of %s shadows declaration at %s", obj.Name(), f.loc(shadowed.Pos()))
	}
}

// emitCompare emits to f code compute the boolean result of
// comparison comparison 'x op y'.
//
func emitCompare(f *Function, op token.Token, x, y Value, pos token.Pos) Value {
	xt := x.Type().Underlying()
	yt := y.Type().Underlying()

	// Special case to optimise a tagless SwitchStmt so that
	// these are equivalent
	//   switch { case e: ...}
	//   switch true { case e: ... }
	//   if e==true { ... }
	// even in the case when e's type is an interface.
	// TODO(adonovan): opt: generalise to x==true, false!=y, etc.
	if x == vTrue && op == token.EQL {
		if yt, ok := yt.(*types.Basic); ok && yt.Info()&types.IsBoolean != 0 {
			return y
		}
	}

	if types.Identical(xt, yt) {
		// no conversion necessary
	} else if _, ok := xt.(*types.Interface); ok {
		y = emitConv(f, y, x.Type())
	} else if _, ok := yt.(*types.Interface); ok {
		x = emitConv(f, x, y.Type())
	} else if _, ok := x.(*Const); ok {
		x = emitConv(f, x, y.Type())
	} else if _, ok := y.(*Const); ok {
		y = emitConv(f, y, x.Type())
	} else {
		// other cases, e.g. channels.  No-op.
	}

	v := &BinOp{
		Op: op,
		X:  x,
		Y:  y,
	}
	v.setPos(pos)
	v.setType(tBool)
	return f.emit(v)
}

func checkVarValue(t *testing.T, prog *ssa.Program, pkg *ssa.Package, ref []ast.Node, obj *types.Var, expKind string, wantAddr bool) {
	// The prefix of all assertions messages.
	prefix := fmt.Sprintf("VarValue(%s @ L%d)",
		obj, prog.Fset.Position(ref[0].Pos()).Line)

	v, gotAddr := prog.VarValue(obj, pkg, ref)

	// Kind is the concrete type of the ssa Value.
	gotKind := "nil"
	if v != nil {
		gotKind = fmt.Sprintf("%T", v)[len("*ssa."):]
	}

	// fmt.Printf("%s = %v (kind %q; expect %q) wantAddr=%t gotAddr=%t\n", prefix, v, gotKind, expKind, wantAddr, gotAddr) // debugging

	// Check the kinds match.
	// "nil" indicates expected failure (e.g. optimized away).
	if expKind != gotKind {
		t.Errorf("%s concrete type == %s, want %s", prefix, gotKind, expKind)
	}

	// Check the types match.
	// If wantAddr, the expected type is the object's address.
	if v != nil {
		expType := obj.Type()
		if wantAddr {
			expType = types.NewPointer(expType)
			if !gotAddr {
				t.Errorf("%s: got value, want address", prefix)
			}
		} else if gotAddr {
			t.Errorf("%s: got address, want value", prefix)
		}
		if !types.Identical(v.Type(), expType) {
			t.Errorf("%s.Type() == %s, want %s", prefix, v.Type(), expType)
		}
	}
}

// emitConv emits to f code to convert Value val to exactly type typ,
// and returns the converted value.  Implicit conversions are required
// by language assignability rules in assignments, parameter passing,
// etc.  Conversions cannot fail dynamically.
//
func emitConv(f *Function, val Value, typ types.Type) Value {
	t_src := val.Type()

	// Identical types?  Conversion is a no-op.
	if types.Identical(t_src, typ) {
		return val
	}

	ut_dst := typ.Underlying()
	ut_src := t_src.Underlying()

	// Just a change of type, but not value or representation?
	if isValuePreserving(ut_src, ut_dst) {
		c := &ChangeType{X: val}
		c.setType(typ)
		return f.emit(c)
	}

	// Conversion to, or construction of a value of, an interface type?
	if _, ok := ut_dst.(*types.Interface); ok {
		// Assignment from one interface type to another?
		if _, ok := ut_src.(*types.Interface); ok {
			c := &ChangeInterface{X: val}
			c.setType(typ)
			return f.emit(c)
		}

		// Untyped nil constant?  Return interface-typed nil constant.
		if ut_src == tUntypedNil {
			return nilConst(typ)
		}

		// Convert (non-nil) "untyped" literals to their default type.
		if t, ok := ut_src.(*types.Basic); ok && t.Info()&types.IsUntyped != 0 {
			val = emitConv(f, val, DefaultType(ut_src))
		}

		f.Pkg.needMethodsOf(val.Type())
		mi := &MakeInterface{X: val}
		mi.setType(typ)
		return f.emit(mi)
	}

	// Conversion of a compile-time constant value?
	if c, ok := val.(*Const); ok {
		if _, ok := ut_dst.(*types.Basic); ok || c.IsNil() {
			// Conversion of a compile-time constant to
			// another constant type results in a new
			// constant of the destination type and
			// (initially) the same abstract value.
			// We don't truncate the value yet.
			return NewConst(c.Value, typ)
		}

		// We're converting from constant to non-constant type,
		// e.g. string -> []byte/[]rune.
	}

	// A representation-changing conversion.
	c := &Convert{X: val}
	c.setType(typ)
	return f.emit(c)
}