Golang Func.Pos方法代码示例

// boundMethodWrapper returns a synthetic wrapper function that
// delegates to a concrete or interface method.
// The wrapper has one free variable, the method's receiver.
// Use MakeClosure with such a wrapper to construct a bound-method
// closure.  e.g.:
//
//   type T int          or:  type T interface { meth() }
//   func (t T) meth()
//   var t T
//   f := t.meth
//   f() // calls t.meth()
//
// f is a closure of a synthetic wrapper defined as if by:
//
//   f := func() { return t.meth() }
//
// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu)
//
func boundMethodWrapper(prog *Program, obj *types.Func) *Function {
	prog.methodsMu.Lock()
	defer prog.methodsMu.Unlock()
	fn, ok := prog.boundMethodWrappers[obj]
	if !ok {
		description := fmt.Sprintf("bound method wrapper for %s", obj)
		if prog.mode&LogSource != 0 {
			defer logStack("%s", description)()
		}
		fn = &Function{
			name:      "bound$" + obj.FullName(),
			Signature: changeRecv(obj.Type().(*types.Signature), nil), // drop receiver
			Synthetic: description,
			Prog:      prog,
			Pkg:       prog.packages[obj.Pkg()],
			pos:       obj.Pos(),
		}

		cap := &Capture{name: "recv", typ: recvType(obj), parent: fn}
		fn.FreeVars = []*Capture{cap}
		fn.startBody()
		createParams(fn)
		var c Call

		if _, ok := recvType(obj).Underlying().(*types.Interface); !ok { // concrete
			c.Call.Value = prog.declaredFunc(obj)
			c.Call.Args = []Value{cap}
		} else {
			c.Call.Value = cap
			c.Call.Method = obj
		}
		for _, arg := range fn.Params {
			c.Call.Args = append(c.Call.Args, arg)
		}
		emitTailCall(fn, &c)
		fn.finishBody()

		prog.boundMethodWrappers[obj] = fn
	}
	return fn
}

// makeBound returns a bound method wrapper (or "bound"), a synthetic
// function that delegates to a concrete or interface method denoted
// by obj.  The resulting function has no receiver, but has one free
// variable which will be used as the method's receiver in the
// tail-call.
//
// Use MakeClosure with such a wrapper to construct a bound method
// closure.  e.g.:
//
//   type T int          or:  type T interface { meth() }
//   func (t T) meth()
//   var t T
//   f := t.meth
//   f() // calls t.meth()
//
// f is a closure of a synthetic wrapper defined as if by:
//
//   f := func() { return t.meth() }
//
// Unlike makeWrapper, makeBound need perform no indirection or field
// selections because that can be done before the closure is
// constructed.
//
// EXCLUSIVE_LOCKS_ACQUIRED(meth.Prog.methodsMu)
//
func makeBound(prog *Program, obj *types.Func) *Function {
	prog.methodsMu.Lock()
	defer prog.methodsMu.Unlock()
	fn, ok := prog.bounds[obj]
	if !ok {
		description := fmt.Sprintf("bound method wrapper for %s", obj)
		if prog.mode&LogSource != 0 {
			defer logStack("%s", description)()
		}
		fn = &Function{
			name:      obj.Name() + "$bound",
			object:    obj,
			Signature: changeRecv(obj.Type().(*types.Signature), nil), // drop receiver
			Synthetic: description,
			Prog:      prog,
			pos:       obj.Pos(),
		}

		fv := &FreeVar{name: "recv", typ: recvType(obj), parent: fn}
		fn.FreeVars = []*FreeVar{fv}
		fn.startBody()
		createParams(fn, 0)
		var c Call

		if !isInterface(recvType(obj)) { // concrete
			c.Call.Value = prog.declaredFunc(obj)
			c.Call.Args = []Value{fv}
		} else {
			c.Call.Value = fv
			c.Call.Method = obj
		}
		for _, arg := range fn.Params {
			c.Call.Args = append(c.Call.Args, arg)
		}
		emitTailCall(fn, &c)
		fn.finishBody()

		prog.bounds[obj] = fn
	}
	return fn
}

// interfaceMethodWrapper returns a synthetic wrapper function
// permitting an abstract method obj to be called like a standalone
// function, e.g.:
//
//   type I interface { f(x int) R }
//   m := I.f  // wrapper
//   var i I
//   m(i, 0)
//
// The wrapper is defined as if by:
//
//   func (i I) f(x int, ...) R {
//     return i.f(x, ...)
//   }
//
// typ is the type of the receiver (I here).  It isn't necessarily
// equal to the recvType(obj) because one interface may embed another.
// TODO(adonovan): more tests.
//
// TODO(adonovan): opt: currently the stub is created even when used
// in call position: I.f(i, 0).  Clearly this is suboptimal.
//
// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
//
func interfaceMethodWrapper(prog *Program, typ types.Type, obj *types.Func) *Function {
	// If one interface embeds another they'll share the same
	// wrappers for common methods.  This is safe, but it might
	// confuse some tools because of the implicit interface
	// conversion applied to the first argument.  If this becomes
	// a problem, we should include 'typ' in the memoization key.
	fn, ok := prog.ifaceMethodWrappers[obj]
	if !ok {
		description := "interface method wrapper"
		if prog.mode&LogSource != 0 {
			defer logStack("(%s).%s, %s", typ, obj.Name(), description)()
		}
		fn = &Function{
			name:      obj.Name(),
			object:    obj,
			Signature: obj.Type().(*types.Signature),
			Synthetic: description,
			pos:       obj.Pos(),
			Prog:      prog,
			Pkg:       prog.packages[obj.Pkg()],
		}
		fn.startBody()
		fn.addParam("recv", typ, token.NoPos)
		createParams(fn)
		var c Call

		c.Call.Method = obj
		c.Call.Value = fn.Params[0]
		for _, arg := range fn.Params[1:] {
			c.Call.Args = append(c.Call.Args, arg)
		}
		emitTailCall(fn, &c)
		fn.finishBody()

		prog.ifaceMethodWrappers[obj] = fn
	}
	return fn
}

// checkMethod performs safety checks for renaming a method.
// There are three hazards:
// - declaration conflicts
// - selection ambiguity/changes
// - entailed renamings of assignable concrete/interface types (for now, just reject)
func (r *renamer) checkMethod(from *types.Func) {
	// e.g. error.Error
	if from.Pkg() == nil {
		r.errorf(from.Pos(), "you cannot rename built-in method %s", from)
		return
	}

	// As always, having to support concrete methods with pointer
	// and non-pointer receivers, and named vs unnamed types with
	// methods, makes tooling fun.

	// ASSIGNABILITY
	//
	// For now, if any method renaming breaks a required
	// assignability to another type, we reject it.
	//
	// TODO(adonovan): probably we should compute the entailed
	// renamings so that an interface method renaming causes
	// concrete methods to change too.  But which ones?
	//
	// There is no correct answer, only heuristics, because Go's
	// "duck typing" doesn't distinguish intentional from contingent
	// assignability.  There are two obvious approaches:
	//
	// (1) Update the minimum set of types to preserve the
	//     assignability of types all syntactic assignments
	//     (incl. implicit ones in calls, returns, sends, etc).
	//     The satisfy.Finder enumerates these.
	//     This is likely to be an underapproximation.
	//
	// (2) Update all types that are assignable to/from the changed
	//     type.  This requires computing the "implements" relation
	//     for all pairs of types (as godoc and oracle do).
	//     This is likely to be an overapproximation.
	//
	// If a concrete type is renamed, we probably do not want to
	// rename corresponding interfaces; interface renamings should
	// probably be initiated at the interface.  (But what if a
	// concrete type implements multiple interfaces with the same
	// method?  Then the user is stuck.)
	//
	// We need some experience before we decide how to implement this.

	// Check for conflict at point of declaration.
	// Check to ensure preservation of assignability requirements.
	recv := from.Type().(*types.Signature).Recv().Type()
	if isInterface(recv) {
		// Abstract method

		// declaration
		prev, _, _ := types.LookupFieldOrMethod(recv, false, from.Pkg(), r.to)
		if prev != nil {
			r.errorf(from.Pos(), "renaming this interface method %q to %q",
				from.Name(), r.to)
			r.errorf(prev.Pos(), "\twould conflict with this method")
			return
		}

		// Check all interfaces that embed this one for
		// declaration conflicts too.
		for _, info := range r.packages {
			// Start with named interface types (better errors)
			for _, obj := range info.Defs {
				if obj, ok := obj.(*types.TypeName); ok && isInterface(obj.Type()) {
					f, _, _ := types.LookupFieldOrMethod(
						obj.Type(), false, from.Pkg(), from.Name())
					if f == nil {
						continue
					}
					t, _, _ := types.LookupFieldOrMethod(
						obj.Type(), false, from.Pkg(), r.to)
					if t == nil {
						continue
					}
					r.errorf(from.Pos(), "renaming this interface method %q to %q",
						from.Name(), r.to)
					r.errorf(t.Pos(), "\twould conflict with this method")
					r.errorf(obj.Pos(), "\tin named interface type %q", obj.Name())
				}
			}

			// Now look at all literal interface types (includes named ones again).
			for e, tv := range info.Types {
				if e, ok := e.(*ast.InterfaceType); ok {
					_ = e
					_ = tv.Type.(*types.Interface)
					// TODO(adonovan): implement same check as above.
				}
			}
		}

		// assignability
		for T := range r.findAssignments(recv) {
			if obj, _, _ := types.LookupFieldOrMethod(T, false, from.Pkg(), from.Name()); obj == nil {
				continue
//.........这里部分代码省略.........