1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: 2022 The Ebitengine Authors
3
4// Package objc is a low-level pure Go objective-c runtime. This package is easy to use incorrectly, so it is best
5// to use a wrapper that provides the functionality you need in a safer way.
6package objc
7
8import (
9 "errors"
10 "fmt"
11 "math"
12 "reflect"
13 "regexp"
14 "runtime"
15 "unicode"
16 "unsafe"
17
18 "github.com/ebitengine/purego"
19 "github.com/ebitengine/purego/internal/strings"
20)
21
22// TODO: support try/catch?
23// https://stackoverflow.com/questions/7062599/example-of-how-objective-cs-try-catch-implementation-is-executed-at-runtime
24var (
25 objc_msgSend_fn uintptr
26 objc_msgSend_stret_fn uintptr
27 objc_msgSend func(obj ID, cmd SEL, args ...any) ID
28 objc_msgSendSuper2_fn uintptr
29 objc_msgSendSuper2_stret_fn uintptr
30 objc_msgSendSuper2 func(super *objc_super, cmd SEL, args ...any) ID
31 objc_getClass func(name string) Class
32 objc_getProtocol func(name string) *Protocol
33 objc_allocateProtocol func(name string) *Protocol
34 objc_registerProtocol func(protocol *Protocol)
35 objc_allocateClassPair func(super Class, name string, extraBytes uintptr) Class
36 objc_registerClassPair func(class Class)
37 sel_registerName func(name string) SEL
38 class_getSuperclass func(class Class) Class
39 class_getInstanceVariable func(class Class, name string) Ivar
40 class_getInstanceSize func(class Class) uintptr
41 class_addMethod func(class Class, name SEL, imp IMP, types string) bool
42 class_addIvar func(class Class, name string, size uintptr, alignment uint8, types string) bool
43 class_addProtocol func(class Class, protocol *Protocol) bool
44 ivar_getOffset func(ivar Ivar) uintptr
45 ivar_getName func(ivar Ivar) string
46 object_getClass func(obj ID) Class
47 object_getIvar func(obj ID, ivar Ivar) ID
48 object_setIvar func(obj ID, ivar Ivar, value ID)
49 protocol_getName func(protocol *Protocol) string
50 protocol_isEqual func(p *Protocol, p2 *Protocol) bool
51 protocol_addMethodDescription func(p *Protocol, name SEL, types string, isRequiredMethod bool, isInstanceMethod bool)
52 protocol_copyMethodDescriptionList func(p *Protocol, isRequiredMethod bool, isInstanceMethod bool, outCount *uint32) *MethodDescription
53 protocol_copyProtocolList func(p *Protocol, outCount *uint32) **Protocol
54 protocol_copyPropertyList2 func(p *Protocol, outCount *uint32, isRequiredProperty, isInstanceProperty bool) *Property
55 protocol_addProtocol func(p *Protocol, p2 *Protocol)
56 protocol_addProperty func(p *Protocol, name string, attributes []PropertyAttribute, attributeCount uint32, isRequiredProperty bool, isInstanceProperty bool)
57 property_getName func(p Property) string
58 property_getAttributes func(p Property) string
59
60 free func(ptr unsafe.Pointer)
61)
62
63func init() {
64 objc, err := purego.Dlopen("/usr/lib/libobjc.A.dylib", purego.RTLD_GLOBAL|purego.RTLD_NOW)
65 if err != nil {
66 panic(fmt.Errorf("objc: %w", err))
67 }
68 objc_msgSend_fn, err = purego.Dlsym(objc, "objc_msgSend")
69 if err != nil {
70 panic(fmt.Errorf("objc: %w", err))
71 }
72 if runtime.GOARCH == "amd64" {
73 objc_msgSend_stret_fn, err = purego.Dlsym(objc, "objc_msgSend_stret")
74 if err != nil {
75 panic(fmt.Errorf("objc: %w", err))
76 }
77 objc_msgSendSuper2_stret_fn, err = purego.Dlsym(objc, "objc_msgSendSuper2_stret")
78 if err != nil {
79 panic(fmt.Errorf("objc: %w", err))
80 }
81 }
82 purego.RegisterFunc(&objc_msgSend, objc_msgSend_fn)
83 objc_msgSendSuper2_fn, err = purego.Dlsym(objc, "objc_msgSendSuper2")
84 if err != nil {
85 panic(fmt.Errorf("objc: %w", err))
86 }
87 purego.RegisterFunc(&objc_msgSendSuper2, objc_msgSendSuper2_fn)
88 purego.RegisterLibFunc(&object_getClass, objc, "object_getClass")
89 purego.RegisterLibFunc(&objc_getClass, objc, "objc_getClass")
90 purego.RegisterLibFunc(&objc_getProtocol, objc, "objc_getProtocol")
91 purego.RegisterLibFunc(&objc_allocateProtocol, objc, "objc_allocateProtocol")
92 purego.RegisterLibFunc(&objc_registerProtocol, objc, "objc_registerProtocol")
93 purego.RegisterLibFunc(&objc_allocateClassPair, objc, "objc_allocateClassPair")
94 purego.RegisterLibFunc(&objc_registerClassPair, objc, "objc_registerClassPair")
95 purego.RegisterLibFunc(&sel_registerName, objc, "sel_registerName")
96 purego.RegisterLibFunc(&class_getSuperclass, objc, "class_getSuperclass")
97 purego.RegisterLibFunc(&class_getInstanceVariable, objc, "class_getInstanceVariable")
98 purego.RegisterLibFunc(&class_addMethod, objc, "class_addMethod")
99 purego.RegisterLibFunc(&class_addIvar, objc, "class_addIvar")
100 purego.RegisterLibFunc(&class_addProtocol, objc, "class_addProtocol")
101 purego.RegisterLibFunc(&class_getInstanceSize, objc, "class_getInstanceSize")
102 purego.RegisterLibFunc(&ivar_getOffset, objc, "ivar_getOffset")
103 purego.RegisterLibFunc(&ivar_getName, objc, "ivar_getName")
104 purego.RegisterLibFunc(&protocol_getName, objc, "protocol_getName")
105 purego.RegisterLibFunc(&protocol_isEqual, objc, "protocol_isEqual")
106 purego.RegisterLibFunc(&protocol_addMethodDescription, objc, "protocol_addMethodDescription")
107 purego.RegisterLibFunc(&protocol_copyMethodDescriptionList, objc, "protocol_copyMethodDescriptionList")
108 purego.RegisterLibFunc(&protocol_copyProtocolList, objc, "protocol_copyProtocolList")
109 purego.RegisterLibFunc(&protocol_addProtocol, objc, "protocol_addProtocol")
110 purego.RegisterLibFunc(&protocol_addProperty, objc, "protocol_addProperty")
111 purego.RegisterLibFunc(&protocol_copyPropertyList2, objc, "protocol_copyPropertyList2")
112 purego.RegisterLibFunc(&property_getName, objc, "property_getName")
113 purego.RegisterLibFunc(&property_getAttributes, objc, "property_getAttributes")
114 purego.RegisterLibFunc(&object_getIvar, objc, "object_getIvar")
115 purego.RegisterLibFunc(&object_setIvar, objc, "object_setIvar")
116 purego.RegisterLibFunc(&free, purego.RTLD_DEFAULT, "free")
117}
118
119// ID is an opaque pointer to some Objective-C object
120type ID uintptr
121
122// Class returns the class of the object.
123func (id ID) Class() Class {
124 return object_getClass(id)
125}
126
127// Send is a convenience method for sending messages to objects. This function takes a SEL
128// instead of a string since RegisterName grabs the global Objective-C lock. It is best to cache the result
129// of RegisterName.
130func (id ID) Send(sel SEL, args ...any) ID {
131 return objc_msgSend(id, sel, args...)
132}
133
134// GetIvar reads the value of an instance variable in an object.
135func (id ID) GetIvar(ivar Ivar) ID {
136 return object_getIvar(id, ivar)
137}
138
139// SetIvar sets the value of an instance variable in an object.
140func (id ID) SetIvar(ivar Ivar, value ID) {
141 object_setIvar(id, ivar, value)
142}
143
144// keep in sync with func.go
145const maxRegAllocStructSize = 16
146
147// Send is a convenience method for sending messages to objects that can return any type.
148// This function takes a SEL instead of a string since RegisterName grabs the global Objective-C lock.
149// It is best to cache the result of RegisterName.
150func Send[T any](id ID, sel SEL, args ...any) T {
151 var fn func(id ID, sel SEL, args ...any) T
152 var zero T
153 if runtime.GOARCH == "amd64" &&
154 reflect.ValueOf(zero).Kind() == reflect.Struct &&
155 reflect.ValueOf(zero).Type().Size() > maxRegAllocStructSize {
156 purego.RegisterFunc(&fn, objc_msgSend_stret_fn)
157 } else {
158 purego.RegisterFunc(&fn, objc_msgSend_fn)
159 }
160 return fn(id, sel, args...)
161}
162
163// objc_super data structure is generated by the Objective-C compiler when it encounters the super keyword
164// as the receiver of a message. It specifies the class definition of the particular superclass that should
165// be messaged.
166type objc_super struct {
167 receiver ID
168 superClass Class
169}
170
171// SendSuper is a convenience method for sending message to object's super. This function takes a SEL
172// instead of a string since RegisterName grabs the global Objective-C lock. It is best to cache the result
173// of RegisterName.
174func (id ID) SendSuper(sel SEL, args ...any) ID {
175 super := &objc_super{
176 receiver: id,
177 superClass: id.Class(),
178 }
179 return objc_msgSendSuper2(super, sel, args...)
180}
181
182// SendSuper is a convenience method for sending message to object's super that can return any type.
183// This function takes a SEL instead of a string since RegisterName grabs the global Objective-C lock.
184// It is best to cache the result of RegisterName.
185func SendSuper[T any](id ID, sel SEL, args ...any) T {
186 super := &objc_super{
187 receiver: id,
188 superClass: id.Class(),
189 }
190 var fn func(objcSuper *objc_super, sel SEL, args ...any) T
191 var zero T
192 if runtime.GOARCH == "amd64" &&
193 reflect.ValueOf(zero).Kind() == reflect.Struct &&
194 reflect.ValueOf(zero).Type().Size() > maxRegAllocStructSize {
195 purego.RegisterFunc(&fn, objc_msgSendSuper2_stret_fn)
196 } else {
197 purego.RegisterFunc(&fn, objc_msgSendSuper2_fn)
198 }
199 return fn(super, sel, args...)
200}
201
202// SEL is an opaque type that represents a method selector
203type SEL uintptr
204
205// RegisterName registers a method with the Objective-C runtime system, maps the method name to a selector,
206// and returns the selector value. This function grabs the global Objective-c lock. It is best the cache the
207// result of this function.
208func RegisterName(name string) SEL {
209 return sel_registerName(name)
210}
211
212// Class is an opaque type that represents an Objective-C class.
213type Class uintptr
214
215// GetClass returns the Class object for the named class, or nil if the class is not registered with the Objective-C runtime.
216func GetClass(name string) Class {
217 return objc_getClass(name)
218}
219
220// MethodDef represents the Go function and the selector that ObjC uses to access that function.
221type MethodDef struct {
222 Cmd SEL
223 Fn any
224}
225
226// IvarAttrib is the attribute that an ivar has. It affects if and which methods are automatically
227// generated when creating a class with RegisterClass. See [Apple Docs] for an understanding of these attributes.
228// The fields are still accessible using objc.GetIvar and objc.SetIvar regardless of the value of IvarAttrib.
229//
230// Take for example this Objective-C code:
231//
232// @property (readwrite) float value;
233//
234// In Go, the functions can be accessed as followed:
235//
236// var value = purego.Send[float32](id, purego.RegisterName("value"))
237// id.Send(purego.RegisterName("setValue:"), 3.46)
238//
239// [Apple Docs]: https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/ObjectiveC/Chapters/ocProperties.html
240type IvarAttrib int
241
242const (
243 ReadOnly IvarAttrib = 1 << iota
244 ReadWrite
245)
246
247// FieldDef is a definition of a field to add to an Objective-C class.
248// The name of the field is what will be used to access it through the Ivar. If the type is bool
249// the name cannot start with `is` since a getter will be generated with the name `isBoolName`.
250// The name also cannot contain any spaces.
251// The type is the Go equivalent type of the Ivar.
252// Attribute determines if a getter and or setter method is generated for this field.
253type FieldDef struct {
254 Name string
255 Type reflect.Type
256 Attribute IvarAttrib
257}
258
259// ivarRegex checks to make sure the Ivar is correctly formatted
260var ivarRegex = regexp.MustCompile("[a-z_][a-zA-Z0-9_]*")
261
262// RegisterClass takes the name of the class to create, the superclass, a list of protocols this class
263// implements, a list of fields this class has and a list of methods. It returns the created class or an error
264// describing what went wrong.
265func RegisterClass(name string, superClass Class, protocols []*Protocol, ivars []FieldDef, methods []MethodDef) (Class, error) {
266 class := objc_allocateClassPair(superClass, name, 0)
267 if class == 0 {
268 return 0, fmt.Errorf("objc: failed to create class with name '%s'", name)
269 }
270 // Add Protocols
271 for _, p := range protocols {
272 if !class.AddProtocol(p) {
273 return 0, fmt.Errorf("objc: couldn't add Protocol %s", protocol_getName(p))
274 }
275 }
276 // Add exported methods based on the selectors returned from ClassDef(string) SEL
277 for idx, def := range methods {
278 imp, err := func() (imp IMP, err error) {
279 defer func() {
280 if r := recover(); r != nil {
281 err = fmt.Errorf("objc: failed to create IMP: %s", r)
282 }
283 }()
284 return NewIMP(def.Fn), nil
285 }()
286 if err != nil {
287 return 0, fmt.Errorf("objc: couldn't add Method at index %d: %w", idx, err)
288 }
289 encoding, err := encodeFunc(def.Fn)
290 if err != nil {
291 return 0, fmt.Errorf("objc: couldn't add Method at index %d: %w", idx, err)
292 }
293 if !class.AddMethod(def.Cmd, imp, encoding) {
294 return 0, fmt.Errorf("objc: couldn't add Method at index %d", idx)
295 }
296 }
297 // Add Ivars
298 for _, instVar := range ivars {
299 ivar := instVar
300 if !ivarRegex.MatchString(ivar.Name) {
301 return 0, fmt.Errorf("objc: Ivar must start with a lowercase letter and only contain ASCII letters and numbers: '%s'", ivar.Name)
302 }
303 size := ivar.Type.Size()
304 alignment := uint8(math.Log2(float64(ivar.Type.Align())))
305 enc, err := encodeType(ivar.Type, false)
306 if err != nil {
307 return 0, fmt.Errorf("objc: couldn't add Ivar %s: %w", ivar.Name, err)
308 }
309 if !class_addIvar(class, ivar.Name, size, alignment, enc) {
310 return 0, fmt.Errorf("objc: couldn't add Ivar %s", ivar.Name)
311 }
312 offset := class.InstanceVariable(ivar.Name).Offset()
313 switch ivar.Attribute {
314 case ReadWrite:
315 ty := reflect.FuncOf(
316 []reflect.Type{
317 reflect.TypeOf(ID(0)), reflect.TypeOf(SEL(0)), ivar.Type,
318 },
319 nil, false,
320 )
321 var encoding string
322 if encoding, err = encodeFunc(reflect.New(ty).Elem().Interface()); err != nil {
323 return 0, fmt.Errorf("objc: failed to create read method for '%s': %w", ivar.Name, err)
324 }
325 val := reflect.MakeFunc(ty, func(args []reflect.Value) (results []reflect.Value) {
326 // on entry the first and second arguments are ID and SEL followed by the value
327 if len(args) != 3 {
328 panic(fmt.Sprintf("objc: incorrect number of args. expected 3 got %d", len(args)))
329 }
330 // The following reflect code does the equivalent of this:
331 //
332 // ((*struct {
333 // Padding [offset]byte
334 // Value int
335 // })(unsafe.Pointer(args[0].Interface().(ID)))).v = 123
336 //
337 // However, since the type of the variable is unknown reflection is used to actually assign the value
338 id := args[0].Interface().(ID)
339 ptr := *(*unsafe.Pointer)(unsafe.Pointer(&id)) // circumvent go vet
340 reflect.NewAt(ivar.Type, unsafe.Add(ptr, offset)).Elem().Set(args[2])
341 return nil
342 }).Interface()
343 // this code only works for ascii but that shouldn't be a problem
344 selector := "set" + string(unicode.ToUpper(rune(ivar.Name[0]))) + ivar.Name[1:] + ":\x00"
345 class.AddMethod(RegisterName(selector), NewIMP(val), encoding)
346 fallthrough // also implement the read method
347 case ReadOnly:
348 ty := reflect.FuncOf(
349 []reflect.Type{
350 reflect.TypeOf(ID(0)), reflect.TypeOf(SEL(0)),
351 },
352 []reflect.Type{ivar.Type}, false,
353 )
354 var encoding string
355 if encoding, err = encodeFunc(reflect.New(ty).Elem().Interface()); err != nil {
356 return 0, fmt.Errorf("objc: failed to create read method for '%s': %w", ivar.Name, err)
357 }
358 val := reflect.MakeFunc(ty, func(args []reflect.Value) (results []reflect.Value) {
359 // on entry the first and second arguments are ID and SEL
360 if len(args) != 2 {
361 panic(fmt.Sprintf("objc: incorrect number of args. expected 2 got %d", len(args)))
362 }
363 id := args[0].Interface().(ID)
364 ptr := *(*unsafe.Pointer)(unsafe.Pointer(&id)) // circumvent go vet
365 // the variable is located at an offset from the id
366 return []reflect.Value{reflect.NewAt(ivar.Type, unsafe.Add(ptr, offset)).Elem()}
367 }).Interface()
368 if ivar.Type.Kind() == reflect.Bool {
369 // this code only works for ascii but that shouldn't be a problem
370 ivar.Name = "is" + string(unicode.ToUpper(rune(ivar.Name[0]))) + ivar.Name[1:]
371 }
372 class.AddMethod(RegisterName(ivar.Name), NewIMP(val), encoding)
373 default:
374 return 0, fmt.Errorf("objc: unknown Ivar Attribute (%d)", ivar.Attribute)
375 }
376 }
377 objc_registerClassPair(class)
378 return class, nil
379}
380
381const (
382 encId = "@"
383 encClass = "#"
384 encSelector = ":"
385 encChar = "c"
386 encUChar = "C"
387 encShort = "s"
388 encUShort = "S"
389 encInt = "i"
390 encUInt = "I"
391 encLong = "l"
392 encULong = "L"
393 encFloat = "f"
394 encDouble = "d"
395 encBool = "B"
396 encVoid = "v"
397 encPtr = "^"
398 encCharPtr = "*"
399 encStructBegin = "{"
400 encStructEnd = "}"
401 encUnsafePtr = "^v"
402)
403
404// encodeType returns a string representing a type as if it was given to @encode(typ)
405// Source: https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtTypeEncodings.html#//apple_ref/doc/uid/TP40008048-CH100
406func encodeType(typ reflect.Type, insidePtr bool) (string, error) {
407 switch typ {
408 case reflect.TypeOf(Class(0)):
409 return encClass, nil
410 case reflect.TypeOf(ID(0)):
411 return encId, nil
412 case reflect.TypeOf(SEL(0)):
413 return encSelector, nil
414 }
415
416 kind := typ.Kind()
417 switch kind {
418 case reflect.Bool:
419 return encBool, nil
420 case reflect.Int:
421 return encLong, nil
422 case reflect.Int8:
423 return encChar, nil
424 case reflect.Int16:
425 return encShort, nil
426 case reflect.Int32:
427 return encInt, nil
428 case reflect.Int64:
429 return encULong, nil
430 case reflect.Uint:
431 return encULong, nil
432 case reflect.Uint8:
433 return encUChar, nil
434 case reflect.Uint16:
435 return encUShort, nil
436 case reflect.Uint32:
437 return encUInt, nil
438 case reflect.Uint64:
439 return encULong, nil
440 case reflect.Uintptr:
441 return encPtr, nil
442 case reflect.Float32:
443 return encFloat, nil
444 case reflect.Float64:
445 return encDouble, nil
446 case reflect.Ptr:
447 enc, err := encodeType(typ.Elem(), true)
448 return encPtr + enc, err
449 case reflect.Struct:
450 if insidePtr {
451 return encStructBegin + typ.Name() + encStructEnd, nil
452 }
453 encoding := encStructBegin
454 encoding += typ.Name()
455 encoding += "="
456 for i := 0; i < typ.NumField(); i++ {
457 f := typ.Field(i)
458 tmp, err := encodeType(f.Type, false)
459 if err != nil {
460 return "", err
461 }
462 encoding += tmp
463 }
464 encoding = encStructEnd
465 return encoding, nil
466 case reflect.UnsafePointer:
467 return encUnsafePtr, nil
468 case reflect.String:
469 return encCharPtr, nil
470 }
471
472 return "", errors.New(fmt.Sprintf("unhandled/invalid kind %v typed %v", kind, typ))
473}
474
475// encodeFunc returns a functions type as if it was given to @encode(fn)
476func encodeFunc(fn any) (string, error) {
477 typ := reflect.TypeOf(fn)
478 if typ.Kind() != reflect.Func {
479 return "", errors.New("not a func")
480 }
481
482 encoding := ""
483 switch typ.NumOut() {
484 case 0:
485 encoding += encVoid
486 case 1:
487 tmp, err := encodeType(typ.Out(0), false)
488 if err != nil {
489 return "", err
490 }
491 encoding += tmp
492 default:
493 return "", errors.New("too many output parameters")
494 }
495
496 if typ.NumIn() < 2 {
497 return "", errors.New("func doesn't take ID and SEL as its first two parameters")
498 }
499
500 encoding += encId
501
502 for i := 1; i < typ.NumIn(); i++ {
503 tmp, err := encodeType(typ.In(i), false)
504 if err != nil {
505 return "", err
506 }
507 encoding += tmp
508 }
509 return encoding, nil
510}
511
512// SuperClass returns the superclass of a class.
513// You should usually use NSObject‘s superclass method instead of this function.
514func (c Class) SuperClass() Class {
515 return class_getSuperclass(c)
516}
517
518// AddMethod adds a new method to a class with a given name and implementation.
519// The types argument is a string containing the mapping of parameters and return type.
520// Since the function must take at least two arguments—self and _cmd, the second and third
521// characters must be “@:” (the first character is the return type).
522func (c Class) AddMethod(name SEL, imp IMP, types string) bool {
523 return class_addMethod(c, name, imp, types)
524}
525
526// AddProtocol adds a protocol to a class.
527// Returns true if the protocol was added successfully, otherwise false (for example,
528// the class already conforms to that protocol).
529func (c Class) AddProtocol(protocol *Protocol) bool {
530 return class_addProtocol(c, protocol)
531}
532
533// InstanceSize returns the size in bytes of instances of the class or 0 if cls is nil
534func (c Class) InstanceSize() uintptr {
535 return class_getInstanceSize(c)
536}
537
538// InstanceVariable returns an Ivar data structure containing information about the instance variable specified by name.
539func (c Class) InstanceVariable(name string) Ivar {
540 return class_getInstanceVariable(c, name)
541}
542
543// Ivar an opaque type that represents an instance variable.
544type Ivar uintptr
545
546// Offset returns the offset of an instance variable that can be used to assign and read the Ivar's value.
547//
548// For instance variables of type ID or other object types, call Ivar and SetIvar instead
549// of using this offset to access the instance variable data directly.
550func (i Ivar) Offset() uintptr {
551 return ivar_getOffset(i)
552}
553
554func (i Ivar) Name() string {
555 return ivar_getName(i)
556}
557
558// MethodDescription holds the name and type definition of a method.
559type MethodDescription struct {
560 name, types uintptr
561}
562
563// Name returns the name of this method.
564func (m MethodDescription) Name() string {
565 return strings.GoString(m.name)
566}
567
568// Types returns the OBJC runtime encoded type description.
569func (m MethodDescription) Types() string {
570 return strings.GoString(m.types)
571}
572
573// PropertyAttribute contains the null-terminated Name and Value pair of a Properties internal description.
574type PropertyAttribute struct {
575 Name, Value *byte
576}
577
578// Property is an opaque type for Objective-C property metadata.
579type Property uintptr
580
581// Name returns the name of this property.
582func (p Property) Name() string {
583 return property_getName(p)
584}
585
586// Attributes returns a comma separated list of PropertyAttribute
587func (p Property) Attributes() string {
588 return property_getAttributes(p)
589}
590
591// Protocol is a type that declares methods that can be implemented by any class.
592type Protocol [0]func()
593
594// GetProtocol returns the protocol for the given name or nil if there is no protocol by that name.
595func GetProtocol(name string) *Protocol {
596 return objc_getProtocol(name)
597}
598
599// AllocateProtocol creates a new protocol in the OBJC runtime or nil if the protocol already exists.
600func AllocateProtocol(name string) *Protocol {
601 return objc_allocateProtocol(name)
602}
603
604// Register registers the protocol created using AllocateProtocol with the runtime. This must be done
605// before it is used anywhere and can only be called once.
606func (p *Protocol) Register() {
607 objc_registerProtocol(p)
608}
609
610// CopyMethodDescriptionList returns a list of methods that this protocol has given it isRequiredMethod and isInstanceMethod.
611func (p *Protocol) CopyMethodDescriptionList(isRequiredMethod, isInstanceMethod bool) []MethodDescription {
612 count := uint32(0)
613 desc := protocol_copyMethodDescriptionList(p, isRequiredMethod, isInstanceMethod, &count)
614 methods := clone(unsafe.Slice(desc, count))
615 free(unsafe.Pointer(desc))
616 return methods
617}
618
619// CopyProtocolList returns a list of the protocols that this protocol inherits from.
620func (p *Protocol) CopyProtocolList() []*Protocol {
621 count := uint32(0)
622 desc := protocol_copyProtocolList(p, &count)
623 protocols := clone(unsafe.Slice(desc, count))
624 free(unsafe.Pointer(desc))
625 return protocols
626}
627
628// CopyPropertyList returns a list of properties that this protocol has given it isRequiredProperty and isInstanceProperty.
629func (p *Protocol) CopyPropertyList(isRequiredProperty, isInstanceProperty bool) []Property {
630 count := uint32(0)
631 desc := protocol_copyPropertyList2(p, &count, isRequiredProperty, isInstanceProperty)
632 protocols := clone(unsafe.Slice(desc, count))
633 free(unsafe.Pointer(desc))
634 return protocols
635}
636
637// Name returns the name of this protocol.
638func (p *Protocol) Name() string {
639 return protocol_getName(p)
640}
641
642// Equals return true if the two protocols are the same.
643func (p *Protocol) Equals(p2 *Protocol) bool {
644 return protocol_isEqual(p, p2)
645}
646
647// AddMethodDescription adds a method to a protocol. This can only be called between AllocateProtocol and Protocol.Register.
648func (p *Protocol) AddMethodDescription(name SEL, types string, isRequiredMethod, isInstanceMethod bool) {
649 protocol_addMethodDescription(p, name, types, isRequiredMethod, isInstanceMethod)
650}
651
652// AddProtocol marks the protocol as inheriting from another. This can only be called between AllocateProtocol and Protocol.Register.
653func (p *Protocol) AddProtocol(protocol *Protocol) {
654 protocol_addProtocol(p, protocol)
655}
656
657// AddProperty adds a property to the protocol. This can only be called between AllocateProtocol and Protocol.Register.
658func (p *Protocol) AddProperty(name string, attributes []PropertyAttribute, isRequiredProperty, isInstanceProperty bool) {
659 protocol_addProperty(p, name, attributes, uint32(len(attributes)), isRequiredProperty, isInstanceProperty)
660}
661
662// IMP is a function pointer that can be called by Objective-C code.
663type IMP uintptr
664
665// NewIMP takes a Go function that takes (ID, SEL) as its first two arguments.
666// It returns an IMP function pointer that can be called by Objective-C code.
667// The function panics if an error occurs.
668// The function pointer is never deallocated.
669func NewIMP(fn any) IMP {
670 ty := reflect.TypeOf(fn)
671 if ty.Kind() != reflect.Func {
672 panic("objc: not a function")
673 }
674 // IMP is stricter than a normal callback
675 // id (*IMP)(id, SEL, ...)
676 switch {
677 case ty.NumIn() < 2:
678 fallthrough
679 case ty.In(0) != reflect.TypeOf(ID(0)):
680 fallthrough
681 case ty.In(1) != reflect.TypeOf(SEL(0)):
682 panic("objc: NewIMP must take a (id, SEL) as its first two arguments; got " + ty.String())
683 }
684 return IMP(purego.NewCallback(fn))
685}
686
687// TODO: remove and use slices.Clone when minimum version for purego is 1.21
688func clone[S ~[]E, E any](s S) S {
689 // Preserve nilness in case it matters.
690 if s == nil {
691 return nil
692 }
693 // Avoid s[:0:0] as it leads to unwanted liveness when cloning a
694 // zero-length slice of a large array; see https://go.dev/issue/68488.
695 return append(S{}, s...)
696}