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 "slices"
16 stdstrings "strings"
17 "structs"
18 "unicode"
19 "unsafe"
20
21 "github.com/ebitengine/purego"
22 "github.com/ebitengine/purego/internal/strings"
23)
24
25var hostLayoutType = reflect.TypeFor[structs.HostLayout]()
26
27// TODO: support try/catch?
28// https://stackoverflow.com/questions/7062599/example-of-how-objective-cs-try-catch-implementation-is-executed-at-runtime
29var (
30 objc_msgSend_fn uintptr
31 objc_msgSend_stret_fn uintptr
32 objc_msgSend func(obj ID, cmd SEL, args ...any) ID
33 objc_msgSendSuper2_fn uintptr
34 objc_msgSendSuper2_stret_fn uintptr
35 objc_msgSendSuper2 func(super *objc_super, cmd SEL, args ...any) ID
36 objc_getClass func(name string) Class
37 objc_getProtocol func(name string) *Protocol
38 objc_allocateProtocol func(name string) *Protocol
39 objc_registerProtocol func(protocol *Protocol)
40 objc_allocateClassPair func(super Class, name string, extraBytes uintptr) Class
41 objc_registerClassPair func(class Class)
42 sel_registerName func(name string) SEL
43 class_getSuperclass func(class Class) Class
44 class_getInstanceVariable func(class Class, name string) Ivar
45 class_getInstanceSize func(class Class) uintptr
46 class_addMethod func(class Class, name SEL, imp IMP, types string) bool
47 class_addIvar func(class Class, name string, size uintptr, alignment uint8, types string) bool
48 class_addProtocol func(class Class, protocol *Protocol) bool
49 ivar_getOffset func(ivar Ivar) uintptr
50 ivar_getName func(ivar Ivar) string
51 object_getClass func(obj ID) Class
52 object_getIvar func(obj ID, ivar Ivar) ID
53 object_setIvar func(obj ID, ivar Ivar, value ID)
54 protocol_getName func(protocol *Protocol) string
55 protocol_isEqual func(p *Protocol, p2 *Protocol) bool
56 protocol_addMethodDescription func(p *Protocol, name SEL, types string, isRequiredMethod bool, isInstanceMethod bool)
57 protocol_copyMethodDescriptionList func(p *Protocol, isRequiredMethod bool, isInstanceMethod bool, outCount *uint32) *MethodDescription
58 protocol_copyProtocolList func(p *Protocol, outCount *uint32) **Protocol
59 protocol_copyPropertyList2 func(p *Protocol, outCount *uint32, isRequiredProperty, isInstanceProperty bool) *Property
60 protocol_addProtocol func(p *Protocol, p2 *Protocol)
61 protocol_addProperty func(p *Protocol, name string, attributes []PropertyAttribute, attributeCount uint32, isRequiredProperty bool, isInstanceProperty bool)
62 property_getName func(p Property) string
63 property_getAttributes func(p Property) string
64
65 free func(ptr unsafe.Pointer)
66 _Block_copy func(Block) Block
67 _Block_release func(Block)
68)
69
70func init() {
71 objc, err := purego.Dlopen("/usr/lib/libobjc.A.dylib", purego.RTLD_GLOBAL|purego.RTLD_NOW)
72 if err != nil {
73 panic(fmt.Errorf("objc: %w", err))
74 }
75 objc_msgSend_fn, err = purego.Dlsym(objc, "objc_msgSend")
76 if err != nil {
77 panic(fmt.Errorf("objc: %w", err))
78 }
79 if runtime.GOARCH == "amd64" {
80 objc_msgSend_stret_fn, err = purego.Dlsym(objc, "objc_msgSend_stret")
81 if err != nil {
82 panic(fmt.Errorf("objc: %w", err))
83 }
84 objc_msgSendSuper2_stret_fn, err = purego.Dlsym(objc, "objc_msgSendSuper2_stret")
85 if err != nil {
86 panic(fmt.Errorf("objc: %w", err))
87 }
88 }
89 purego.RegisterFunc(&objc_msgSend, objc_msgSend_fn)
90 objc_msgSendSuper2_fn, err = purego.Dlsym(objc, "objc_msgSendSuper2")
91 if err != nil {
92 panic(fmt.Errorf("objc: %w", err))
93 }
94 purego.RegisterFunc(&objc_msgSendSuper2, objc_msgSendSuper2_fn)
95 purego.RegisterLibFunc(&object_getClass, objc, "object_getClass")
96 purego.RegisterLibFunc(&objc_getClass, objc, "objc_getClass")
97 purego.RegisterLibFunc(&objc_getProtocol, objc, "objc_getProtocol")
98 purego.RegisterLibFunc(&objc_allocateProtocol, objc, "objc_allocateProtocol")
99 purego.RegisterLibFunc(&objc_registerProtocol, objc, "objc_registerProtocol")
100 purego.RegisterLibFunc(&objc_allocateClassPair, objc, "objc_allocateClassPair")
101 purego.RegisterLibFunc(&objc_registerClassPair, objc, "objc_registerClassPair")
102 purego.RegisterLibFunc(&sel_registerName, objc, "sel_registerName")
103 purego.RegisterLibFunc(&class_getSuperclass, objc, "class_getSuperclass")
104 purego.RegisterLibFunc(&class_getInstanceVariable, objc, "class_getInstanceVariable")
105 purego.RegisterLibFunc(&class_addMethod, objc, "class_addMethod")
106 purego.RegisterLibFunc(&class_addIvar, objc, "class_addIvar")
107 purego.RegisterLibFunc(&class_addProtocol, objc, "class_addProtocol")
108 purego.RegisterLibFunc(&class_getInstanceSize, objc, "class_getInstanceSize")
109 purego.RegisterLibFunc(&ivar_getOffset, objc, "ivar_getOffset")
110 purego.RegisterLibFunc(&ivar_getName, objc, "ivar_getName")
111 purego.RegisterLibFunc(&protocol_getName, objc, "protocol_getName")
112 purego.RegisterLibFunc(&protocol_isEqual, objc, "protocol_isEqual")
113 purego.RegisterLibFunc(&protocol_addMethodDescription, objc, "protocol_addMethodDescription")
114 purego.RegisterLibFunc(&protocol_copyMethodDescriptionList, objc, "protocol_copyMethodDescriptionList")
115 purego.RegisterLibFunc(&protocol_copyProtocolList, objc, "protocol_copyProtocolList")
116 purego.RegisterLibFunc(&protocol_addProtocol, objc, "protocol_addProtocol")
117 purego.RegisterLibFunc(&protocol_addProperty, objc, "protocol_addProperty")
118 purego.RegisterLibFunc(&protocol_copyPropertyList2, objc, "protocol_copyPropertyList2")
119 purego.RegisterLibFunc(&property_getName, objc, "property_getName")
120 purego.RegisterLibFunc(&property_getAttributes, objc, "property_getAttributes")
121 purego.RegisterLibFunc(&object_getIvar, objc, "object_getIvar")
122 purego.RegisterLibFunc(&object_setIvar, objc, "object_setIvar")
123 purego.RegisterLibFunc(&free, purego.RTLD_DEFAULT, "free")
124
125 purego.RegisterLibFunc(&_Block_copy, objc, "_Block_copy")
126 purego.RegisterLibFunc(&_Block_release, objc, "_Block_release")
127 theBlocksCache = newBlockCache()
128}
129
130// ID is an opaque pointer to some Objective-C object
131type ID uintptr
132
133// Class returns the class of the object.
134func (id ID) Class() Class {
135 return object_getClass(id)
136}
137
138// Send is a convenience method for sending messages to objects. This function takes a SEL
139// instead of a string since RegisterName grabs the global Objective-C lock. It is best to cache the result
140// of RegisterName.
141func (id ID) Send(sel SEL, args ...any) ID {
142 return objc_msgSend(id, sel, args...)
143}
144
145// GetIvar reads the value of an instance variable in an object.
146func (id ID) GetIvar(ivar Ivar) ID {
147 return object_getIvar(id, ivar)
148}
149
150// SetIvar sets the value of an instance variable in an object.
151func (id ID) SetIvar(ivar Ivar, value ID) {
152 object_setIvar(id, ivar, value)
153}
154
155// keep in sync with func.go
156const maxRegAllocStructSize = 16
157
158// Send is a convenience method for sending messages to objects that can return any type.
159// This function takes a SEL instead of a string since RegisterName grabs the global Objective-C lock.
160// It is best to cache the result of RegisterName.
161func Send[T any](id ID, sel SEL, args ...any) T {
162 var fn func(id ID, sel SEL, args ...any) T
163 var zero T
164 if runtime.GOARCH == "amd64" &&
165 reflect.ValueOf(zero).Kind() == reflect.Struct &&
166 reflect.ValueOf(zero).Type().Size() > maxRegAllocStructSize {
167 purego.RegisterFunc(&fn, objc_msgSend_stret_fn)
168 } else {
169 purego.RegisterFunc(&fn, objc_msgSend_fn)
170 }
171 return fn(id, sel, args...)
172}
173
174// objc_super data structure is generated by the Objective-C compiler when it encounters the super keyword
175// as the receiver of a message. It specifies the class definition of the particular superclass that should
176// be messaged.
177type objc_super struct {
178 _ structs.HostLayout
179 receiver ID
180 superClass Class
181}
182
183// SendSuper is a convenience method for sending message to object's super. This function takes a SEL
184// instead of a string since RegisterName grabs the global Objective-C lock. It is best to cache the result
185// of RegisterName.
186func (id ID) SendSuper(sel SEL, args ...any) ID {
187 super := &objc_super{
188 receiver: id,
189 superClass: id.Class(),
190 }
191 return objc_msgSendSuper2(super, sel, args...)
192}
193
194// SendSuper is a convenience method for sending message to object's super that can return any type.
195// This function takes a SEL instead of a string since RegisterName grabs the global Objective-C lock.
196// It is best to cache the result of RegisterName.
197func SendSuper[T any](id ID, sel SEL, args ...any) T {
198 super := &objc_super{
199 receiver: id,
200 superClass: id.Class(),
201 }
202 var fn func(objcSuper *objc_super, sel SEL, args ...any) T
203 var zero T
204 if runtime.GOARCH == "amd64" &&
205 reflect.ValueOf(zero).Kind() == reflect.Struct &&
206 reflect.ValueOf(zero).Type().Size() > maxRegAllocStructSize {
207 purego.RegisterFunc(&fn, objc_msgSendSuper2_stret_fn)
208 } else {
209 purego.RegisterFunc(&fn, objc_msgSendSuper2_fn)
210 }
211 return fn(super, sel, args...)
212}
213
214// SEL is an opaque type that represents a method selector
215type SEL uintptr
216
217// RegisterName registers a method with the Objective-C runtime system, maps the method name to a selector,
218// and returns the selector value. This function grabs the global Objective-c lock. It is best to cache the
219// result of this function.
220func RegisterName(name string) SEL {
221 return sel_registerName(name)
222}
223
224// Class is an opaque type that represents an Objective-C class.
225type Class uintptr
226
227// GetClass returns the Class object for the named class, or nil if the class is not registered with the Objective-C runtime.
228func GetClass(name string) Class {
229 return objc_getClass(name)
230}
231
232// MethodDef represents the Go function and the selector that ObjC uses to access that function.
233type MethodDef struct {
234 Cmd SEL
235 Fn any
236}
237
238// IvarAttrib is the attribute that an ivar has. It affects if and which methods are automatically
239// generated when creating a class with RegisterClass. See [Apple Docs] for an understanding of these attributes.
240// The fields are still accessible using objc.GetIvar and objc.SetIvar regardless of the value of IvarAttrib.
241//
242// Take for example this Objective-C code:
243//
244// @property (readwrite) float value;
245//
246// In Go, the functions can be accessed as follows:
247//
248// var value = purego.Send[float32](id, purego.RegisterName("value"))
249// id.Send(purego.RegisterName("setValue:"), 3.46)
250//
251// [Apple Docs]: https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/ObjectiveC/Chapters/ocProperties.html
252type IvarAttrib int
253
254const (
255 ReadOnly IvarAttrib = 1 << iota
256 ReadWrite
257)
258
259// FieldDef is a definition of a field to add to an Objective-C class.
260// The name of the field is what will be used to access it through the Ivar. If the type is bool
261// the name cannot start with `is` since a getter will be generated with the name `isBoolName`.
262// The name also cannot contain any spaces.
263// The type is the Go equivalent type of the Ivar.
264// Attribute determines if a getter and or setter method is generated for this field.
265type FieldDef struct {
266 Name string
267 Type reflect.Type
268 Attribute IvarAttrib
269}
270
271// ivarRegex checks to make sure the Ivar is correctly formatted
272var ivarRegex = regexp.MustCompile("[a-z_][a-zA-Z0-9_]*")
273
274// RegisterClass takes the name of the class to create, the superclass, a list of protocols this class
275// implements, a list of fields this class has and a list of methods. It returns the created class or an error
276// describing what went wrong.
277func RegisterClass(name string, superClass Class, protocols []*Protocol, ivars []FieldDef, methods []MethodDef) (Class, error) {
278 class := objc_allocateClassPair(superClass, name, 0)
279 if class == 0 {
280 return 0, fmt.Errorf("objc: failed to create class with name '%s'", name)
281 }
282 // Add Protocols
283 for _, p := range protocols {
284 if !class.AddProtocol(p) {
285 return 0, fmt.Errorf("objc: couldn't add Protocol %s", protocol_getName(p))
286 }
287 }
288 // Add exported methods based on the selectors returned from ClassDef(string) SEL
289 for idx, def := range methods {
290 imp, err := func() (imp IMP, err error) {
291 defer func() {
292 if r := recover(); r != nil {
293 err = fmt.Errorf("objc: failed to create IMP: %s", r)
294 }
295 }()
296 return NewIMP(def.Fn), nil
297 }()
298 if err != nil {
299 return 0, fmt.Errorf("objc: couldn't add Method at index %d: %w", idx, err)
300 }
301 encoding, err := encodeFunc(def.Fn)
302 if err != nil {
303 return 0, fmt.Errorf("objc: couldn't add Method at index %d: %w", idx, err)
304 }
305 if !class.AddMethod(def.Cmd, imp, encoding) {
306 return 0, fmt.Errorf("objc: couldn't add Method at index %d", idx)
307 }
308 }
309 // Add Ivars
310 for _, instVar := range ivars {
311 ivar := instVar
312 if !ivarRegex.MatchString(ivar.Name) {
313 return 0, fmt.Errorf("objc: Ivar must start with a lowercase letter and only contain ASCII letters and numbers: '%s'", ivar.Name)
314 }
315 size := ivar.Type.Size()
316 alignment := uint8(math.Log2(float64(ivar.Type.Align())))
317 enc, err := encodeType(ivar.Type, false)
318 if err != nil {
319 return 0, fmt.Errorf("objc: couldn't add Ivar %s: %w", ivar.Name, err)
320 }
321 if !class_addIvar(class, ivar.Name, size, alignment, enc) {
322 return 0, fmt.Errorf("objc: couldn't add Ivar %s", ivar.Name)
323 }
324 offset := class.InstanceVariable(ivar.Name).Offset()
325 switch ivar.Attribute {
326 case ReadWrite:
327 ty := reflect.FuncOf(
328 []reflect.Type{
329 reflect.TypeFor[ID](), reflect.TypeFor[SEL](), ivar.Type,
330 },
331 nil, false,
332 )
333 var encoding string
334 if encoding, err = encodeFunc(reflect.New(ty).Elem().Interface()); err != nil {
335 return 0, fmt.Errorf("objc: failed to create read method for '%s': %w", ivar.Name, err)
336 }
337 val := reflect.MakeFunc(ty, func(args []reflect.Value) (results []reflect.Value) {
338 // on entry the first and second arguments are ID and SEL followed by the value
339 if len(args) != 3 {
340 panic(fmt.Sprintf("objc: incorrect number of args. expected 3 got %d", len(args)))
341 }
342 // The following reflect code does the equivalent of this:
343 //
344 // ((*struct {
345 // Padding [offset]byte
346 // Value int
347 // })(unsafe.Pointer(args[0].Interface().(ID)))).v = 123
348 //
349 // However, since the type of the variable is unknown reflection is used to actually assign the value
350 id, ok := reflect.TypeAssert[ID](args[0])
351 if !ok {
352 panic(fmt.Sprintf("objc: id argument is not a ID but %s", args[0].Type().String()))
353 }
354 ptr := *(*unsafe.Pointer)(unsafe.Pointer(&id)) // circumvent go vet
355 reflect.NewAt(ivar.Type, unsafe.Add(ptr, offset)).Elem().Set(args[2])
356 return nil
357 }).Interface()
358 // this code only works for ascii but that shouldn't be a problem
359 selector := "set" + string(unicode.ToUpper(rune(ivar.Name[0]))) + ivar.Name[1:] + ":\x00"
360 class.AddMethod(RegisterName(selector), NewIMP(val), encoding)
361 fallthrough // also implement the read method
362 case ReadOnly:
363 ty := reflect.FuncOf(
364 []reflect.Type{
365 reflect.TypeFor[ID](), reflect.TypeFor[SEL](),
366 },
367 []reflect.Type{ivar.Type}, false,
368 )
369 var encoding string
370 if encoding, err = encodeFunc(reflect.New(ty).Elem().Interface()); err != nil {
371 return 0, fmt.Errorf("objc: failed to create read method for '%s': %w", ivar.Name, err)
372 }
373 val := reflect.MakeFunc(ty, func(args []reflect.Value) (results []reflect.Value) {
374 // on entry the first and second arguments are ID and SEL
375 if len(args) != 2 {
376 panic(fmt.Sprintf("objc: incorrect number of args. expected 2 got %d", len(args)))
377 }
378 id, ok := reflect.TypeAssert[ID](args[0])
379 if !ok {
380 panic(fmt.Sprintf("objc: id argument is not a ID but %s", args[0].Type().String()))
381 }
382 ptr := *(*unsafe.Pointer)(unsafe.Pointer(&id)) // circumvent go vet
383 // the variable is located at an offset from the id
384 return []reflect.Value{reflect.NewAt(ivar.Type, unsafe.Add(ptr, offset)).Elem()}
385 }).Interface()
386 if ivar.Type.Kind() == reflect.Bool {
387 // this code only works for ascii but that shouldn't be a problem
388 ivar.Name = "is" + string(unicode.ToUpper(rune(ivar.Name[0]))) + ivar.Name[1:]
389 }
390 class.AddMethod(RegisterName(ivar.Name), NewIMP(val), encoding)
391 default:
392 return 0, fmt.Errorf("objc: unknown Ivar Attribute (%d)", ivar.Attribute)
393 }
394 }
395 objc_registerClassPair(class)
396 return class, nil
397}
398
399const (
400 encId = "@"
401 encClass = "#"
402 encSelector = ":"
403 encChar = "c"
404 encUChar = "C"
405 encShort = "s"
406 encUShort = "S"
407 encInt = "i"
408 encUInt = "I"
409 encLongLong = "q"
410 encULongLong = "Q"
411 encFloat = "f"
412 encDouble = "d"
413 encBool = "B"
414 encVoid = "v"
415 encPtr = "^"
416 encCharPtr = "*"
417 encStructBegin = "{"
418 encStructEnd = "}"
419 encUnsafePtr = "^v"
420)
421
422// encodeType returns a string representing a type as if it was given to @encode(typ)
423// Source: https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtTypeEncodings.html#//apple_ref/doc/uid/TP40008048-CH100
424func encodeType(typ reflect.Type, insidePtr bool) (string, error) {
425 switch typ {
426 case reflect.TypeFor[Class]():
427 return encClass, nil
428 case reflect.TypeFor[ID](), reflect.TypeFor[Block]():
429 return encId, nil
430 case reflect.TypeFor[SEL]():
431 return encSelector, nil
432 }
433
434 kind := typ.Kind()
435 switch kind {
436 case reflect.Bool:
437 return encBool, nil
438 case reflect.Int:
439 return encLongLong, nil
440 case reflect.Int8:
441 return encChar, nil
442 case reflect.Int16:
443 return encShort, nil
444 case reflect.Int32:
445 return encInt, nil
446 case reflect.Int64:
447 return encLongLong, nil
448 case reflect.Uint:
449 return encULongLong, nil
450 case reflect.Uint8:
451 return encUChar, nil
452 case reflect.Uint16:
453 return encUShort, nil
454 case reflect.Uint32:
455 return encUInt, nil
456 case reflect.Uint64:
457 return encULongLong, nil
458 case reflect.Uintptr:
459 return encPtr, nil
460 case reflect.Float32:
461 return encFloat, nil
462 case reflect.Float64:
463 return encDouble, nil
464 case reflect.Pointer:
465 enc, err := encodeType(typ.Elem(), true)
466 return encPtr + enc, err
467 case reflect.Struct:
468 if insidePtr {
469 return encStructBegin + typ.Name() + encStructEnd, nil
470 }
471 var encoding stdstrings.Builder
472 encoding.WriteString(encStructBegin)
473 encoding.WriteString(typ.Name())
474 encoding.WriteString("=")
475 for i := range typ.NumField() {
476 f := typ.Field(i)
477 if f.Type.ConvertibleTo(hostLayoutType) {
478 // The structs.HostLayout marker is a signal to the Go compiler
479 // with no counterpart in C, so it is not a member as far as
480 // @encode is concerned. Other zero-sized fields are: clang
481 // encodes a zero-length array member as [0c].
482 continue
483 }
484 tmp, err := encodeType(f.Type, false)
485 if err != nil {
486 return "", err
487 }
488 encoding.WriteString(tmp)
489 }
490 encoding.WriteString(encStructEnd)
491 return encoding.String(), nil
492 case reflect.UnsafePointer:
493 return encUnsafePtr, nil
494 case reflect.String:
495 return encCharPtr, nil
496 }
497
498 return "", errors.New(fmt.Sprintf("unhandled/invalid kind %v typed %v", kind, typ))
499}
500
501// encodeFunc returns a functions type as if it was given to @encode(fn)
502func encodeFunc(fn any) (string, error) {
503 typ := reflect.TypeOf(fn)
504 if typ.Kind() != reflect.Func {
505 return "", errors.New("not a func")
506 }
507
508 var encoding stdstrings.Builder
509 switch typ.NumOut() {
510 case 0:
511 encoding.WriteString(encVoid)
512 case 1:
513 tmp, err := encodeType(typ.Out(0), false)
514 if err != nil {
515 return "", err
516 }
517 encoding.WriteString(tmp)
518 default:
519 return "", errors.New("too many output parameters")
520 }
521
522 if typ.NumIn() < 2 {
523 return "", errors.New("func doesn't take ID and SEL as its first two parameters")
524 }
525
526 encoding.WriteString(encId)
527
528 for i := 1; i < typ.NumIn(); i++ {
529 tmp, err := encodeType(typ.In(i), false)
530 if err != nil {
531 return "", err
532 }
533 encoding.WriteString(tmp)
534 }
535 return encoding.String(), nil
536}
537
538// SuperClass returns the superclass of a class.
539// You should usually use NSObject‘s superclass method instead of this function.
540func (c Class) SuperClass() Class {
541 return class_getSuperclass(c)
542}
543
544// AddMethod adds a new method to a class with a given name and implementation.
545// The types argument is a string containing the mapping of parameters and return type.
546// Since the function must take at least two arguments—self and _cmd, the second and third
547// characters must be “@:” (the first character is the return type).
548func (c Class) AddMethod(name SEL, imp IMP, types string) bool {
549 return class_addMethod(c, name, imp, types)
550}
551
552// AddProtocol adds a protocol to a class.
553// Returns true if the protocol was added successfully, otherwise false (for example,
554// the class already conforms to that protocol).
555func (c Class) AddProtocol(protocol *Protocol) bool {
556 return class_addProtocol(c, protocol)
557}
558
559// InstanceSize returns the size in bytes of instances of the class or 0 if cls is nil
560func (c Class) InstanceSize() uintptr {
561 return class_getInstanceSize(c)
562}
563
564// InstanceVariable returns an Ivar data structure containing information about the instance variable specified by name.
565func (c Class) InstanceVariable(name string) Ivar {
566 return class_getInstanceVariable(c, name)
567}
568
569// Ivar an opaque type that represents an instance variable.
570type Ivar uintptr
571
572// Offset returns the offset of an instance variable that can be used to assign and read the Ivar's value.
573//
574// For instance variables of type ID or other object types, call Ivar and SetIvar instead
575// of using this offset to access the instance variable data directly.
576func (i Ivar) Offset() uintptr {
577 return ivar_getOffset(i)
578}
579
580func (i Ivar) Name() string {
581 return ivar_getName(i)
582}
583
584// MethodDescription holds the name and type definition of a method.
585// It matches the Objective-C runtime's struct objc_method_description.
586type MethodDescription struct {
587 _ structs.HostLayout
588 name, types uintptr
589}
590
591// Name returns the name of this method.
592func (m MethodDescription) Name() string {
593 return strings.GoString(m.name)
594}
595
596// Types returns the OBJC runtime encoded type description.
597func (m MethodDescription) Types() string {
598 return strings.GoString(m.types)
599}
600
601// PropertyAttribute contains the null-terminated Name and Value pair of a Properties internal description.
602// It matches the Objective-C runtime's objc_property_attribute_t.
603type PropertyAttribute struct {
604 _ structs.HostLayout
605 Name, Value *byte
606}
607
608// Property is an opaque type for Objective-C property metadata.
609type Property uintptr
610
611// Name returns the name of this property.
612func (p Property) Name() string {
613 return property_getName(p)
614}
615
616// Attributes returns a comma separated list of PropertyAttribute
617func (p Property) Attributes() string {
618 return property_getAttributes(p)
619}
620
621// Protocol is a type that declares methods that can be implemented by any class.
622type Protocol [0]func()
623
624// GetProtocol returns the protocol for the given name or nil if there is no protocol by that name.
625func GetProtocol(name string) *Protocol {
626 return objc_getProtocol(name)
627}
628
629// AllocateProtocol creates a new protocol in the OBJC runtime or nil if the protocol already exists.
630func AllocateProtocol(name string) *Protocol {
631 return objc_allocateProtocol(name)
632}
633
634// Register registers the protocol created using AllocateProtocol with the runtime. This must be done
635// before it is used anywhere and can only be called once.
636func (p *Protocol) Register() {
637 objc_registerProtocol(p)
638}
639
640// CopyMethodDescriptionList returns a list of methods that this protocol has given it isRequiredMethod and isInstanceMethod.
641func (p *Protocol) CopyMethodDescriptionList(isRequiredMethod, isInstanceMethod bool) []MethodDescription {
642 count := uint32(0)
643 desc := protocol_copyMethodDescriptionList(p, isRequiredMethod, isInstanceMethod, &count)
644 methods := slices.Clone(unsafe.Slice(desc, count))
645 free(unsafe.Pointer(desc))
646 return methods
647}
648
649// CopyProtocolList returns a list of the protocols that this protocol inherits from.
650func (p *Protocol) CopyProtocolList() []*Protocol {
651 count := uint32(0)
652 desc := protocol_copyProtocolList(p, &count)
653 protocols := slices.Clone(unsafe.Slice(desc, count))
654 free(unsafe.Pointer(desc))
655 return protocols
656}
657
658// CopyPropertyList returns a list of properties that this protocol has given it isRequiredProperty and isInstanceProperty.
659func (p *Protocol) CopyPropertyList(isRequiredProperty, isInstanceProperty bool) []Property {
660 count := uint32(0)
661 desc := protocol_copyPropertyList2(p, &count, isRequiredProperty, isInstanceProperty)
662 protocols := slices.Clone(unsafe.Slice(desc, count))
663 free(unsafe.Pointer(desc))
664 return protocols
665}
666
667// Name returns the name of this protocol.
668func (p *Protocol) Name() string {
669 return protocol_getName(p)
670}
671
672// Equals return true if the two protocols are the same.
673func (p *Protocol) Equals(p2 *Protocol) bool {
674 return protocol_isEqual(p, p2)
675}
676
677// AddMethodDescription adds a method to a protocol. This can only be called between AllocateProtocol and Protocol.Register.
678func (p *Protocol) AddMethodDescription(name SEL, types string, isRequiredMethod, isInstanceMethod bool) {
679 protocol_addMethodDescription(p, name, types, isRequiredMethod, isInstanceMethod)
680}
681
682// AddProtocol marks the protocol as inheriting from another. This can only be called between AllocateProtocol and Protocol.Register.
683func (p *Protocol) AddProtocol(protocol *Protocol) {
684 protocol_addProtocol(p, protocol)
685}
686
687// AddProperty adds a property to the protocol. This can only be called between AllocateProtocol and Protocol.Register.
688func (p *Protocol) AddProperty(name string, attributes []PropertyAttribute, isRequiredProperty, isInstanceProperty bool) {
689 protocol_addProperty(p, name, attributes, uint32(len(attributes)), isRequiredProperty, isInstanceProperty)
690}
691
692// IMP is a function pointer that can be called by Objective-C code.
693type IMP uintptr
694
695// NewIMP takes a Go function that takes (ID, SEL) as its first two arguments.
696// It returns an IMP function pointer that can be called by Objective-C code.
697// The function panics if an error occurs.
698// The function pointer is never deallocated.
699func NewIMP(fn any) IMP {
700 ty := reflect.TypeOf(fn)
701 if ty.Kind() != reflect.Func {
702 panic("objc: not a function")
703 }
704 // IMP is stricter than a normal callback
705 // id (*IMP)(id, SEL, ...)
706 switch {
707 case ty.NumIn() < 2:
708 fallthrough
709 case ty.In(0) != reflect.TypeFor[ID]():
710 fallthrough
711 case ty.In(1) != reflect.TypeFor[SEL]():
712 panic("objc: NewIMP must take a (id, SEL) as its first two arguments; got " + ty.String())
713 }
714 return IMP(purego.NewCallback(fn))
715}