godot/core/extension/gdextension_interface.h

/**************************************************************************/
/*  gdextension_interface.h                                               */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
/*                        https://godotengine.org                         */
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
/*                                                                        */
/* Permission is hereby granted, free of charge, to any person obtaining  */
/* a copy of this software and associated documentation files (the        */
/* "Software"), to deal in the Software without restriction, including    */
/* without limitation the rights to use, copy, modify, merge, publish,    */
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/* permit persons to whom the Software is furnished to do so, subject to  */
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/* The above copyright notice and this permission notice shall be         */
/* included in all copies or substantial portions of the Software.        */
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#ifndef GDEXTENSION_INTERFACE_H
#define GDEXTENSION_INTERFACE_H

/* This is a C class header, you can copy it and use it directly in your own binders.
 * Together with the JSON file, you should be able to generate any binder.
 */

#include <stddef.h>
#include <stdint.h>

#ifndef __cplusplus
typedef uint32_t char32_t;
typedef uint16_t char16_t;
#endif

#ifdef __cplusplus
extern "C" {
#endif

/* VARIANT TYPES */

typedef enum {
	GDEXTENSION_VARIANT_TYPE_NIL,

	/*  atomic types */
	GDEXTENSION_VARIANT_TYPE_BOOL,
	GDEXTENSION_VARIANT_TYPE_INT,
	GDEXTENSION_VARIANT_TYPE_FLOAT,
	GDEXTENSION_VARIANT_TYPE_STRING,

	/* math types */
	GDEXTENSION_VARIANT_TYPE_VECTOR2,
	GDEXTENSION_VARIANT_TYPE_VECTOR2I,
	GDEXTENSION_VARIANT_TYPE_RECT2,
	GDEXTENSION_VARIANT_TYPE_RECT2I,
	GDEXTENSION_VARIANT_TYPE_VECTOR3,
	GDEXTENSION_VARIANT_TYPE_VECTOR3I,
	GDEXTENSION_VARIANT_TYPE_TRANSFORM2D,
	GDEXTENSION_VARIANT_TYPE_VECTOR4,
	GDEXTENSION_VARIANT_TYPE_VECTOR4I,
	GDEXTENSION_VARIANT_TYPE_PLANE,
	GDEXTENSION_VARIANT_TYPE_QUATERNION,
	GDEXTENSION_VARIANT_TYPE_AABB,
	GDEXTENSION_VARIANT_TYPE_BASIS,
	GDEXTENSION_VARIANT_TYPE_TRANSFORM3D,
	GDEXTENSION_VARIANT_TYPE_PROJECTION,

	/* misc types */
	GDEXTENSION_VARIANT_TYPE_COLOR,
	GDEXTENSION_VARIANT_TYPE_STRING_NAME,
	GDEXTENSION_VARIANT_TYPE_NODE_PATH,
	GDEXTENSION_VARIANT_TYPE_RID,
	GDEXTENSION_VARIANT_TYPE_OBJECT,
	GDEXTENSION_VARIANT_TYPE_CALLABLE,
	GDEXTENSION_VARIANT_TYPE_SIGNAL,
	GDEXTENSION_VARIANT_TYPE_DICTIONARY,
	GDEXTENSION_VARIANT_TYPE_ARRAY,

	/* typed arrays */
	GDEXTENSION_VARIANT_TYPE_PACKED_BYTE_ARRAY,
	GDEXTENSION_VARIANT_TYPE_PACKED_INT32_ARRAY,
	GDEXTENSION_VARIANT_TYPE_PACKED_INT64_ARRAY,
	GDEXTENSION_VARIANT_TYPE_PACKED_FLOAT32_ARRAY,
	GDEXTENSION_VARIANT_TYPE_PACKED_FLOAT64_ARRAY,
	GDEXTENSION_VARIANT_TYPE_PACKED_STRING_ARRAY,
	GDEXTENSION_VARIANT_TYPE_PACKED_VECTOR2_ARRAY,
	GDEXTENSION_VARIANT_TYPE_PACKED_VECTOR3_ARRAY,
	GDEXTENSION_VARIANT_TYPE_PACKED_COLOR_ARRAY,

	GDEXTENSION_VARIANT_TYPE_VARIANT_MAX
} GDExtensionVariantType;

typedef enum {
	/* comparison */
	GDEXTENSION_VARIANT_OP_EQUAL,
	GDEXTENSION_VARIANT_OP_NOT_EQUAL,
	GDEXTENSION_VARIANT_OP_LESS,
	GDEXTENSION_VARIANT_OP_LESS_EQUAL,
	GDEXTENSION_VARIANT_OP_GREATER,
	GDEXTENSION_VARIANT_OP_GREATER_EQUAL,

	/* mathematic */
	GDEXTENSION_VARIANT_OP_ADD,
	GDEXTENSION_VARIANT_OP_SUBTRACT,
	GDEXTENSION_VARIANT_OP_MULTIPLY,
	GDEXTENSION_VARIANT_OP_DIVIDE,
	GDEXTENSION_VARIANT_OP_NEGATE,
	GDEXTENSION_VARIANT_OP_POSITIVE,
	GDEXTENSION_VARIANT_OP_MODULE,
	GDEXTENSION_VARIANT_OP_POWER,

	/* bitwise */
	GDEXTENSION_VARIANT_OP_SHIFT_LEFT,
	GDEXTENSION_VARIANT_OP_SHIFT_RIGHT,
	GDEXTENSION_VARIANT_OP_BIT_AND,
	GDEXTENSION_VARIANT_OP_BIT_OR,
	GDEXTENSION_VARIANT_OP_BIT_XOR,
	GDEXTENSION_VARIANT_OP_BIT_NEGATE,

	/* logic */
	GDEXTENSION_VARIANT_OP_AND,
	GDEXTENSION_VARIANT_OP_OR,
	GDEXTENSION_VARIANT_OP_XOR,
	GDEXTENSION_VARIANT_OP_NOT,

	/* containment */
	GDEXTENSION_VARIANT_OP_IN,
	GDEXTENSION_VARIANT_OP_MAX

} GDExtensionVariantOperator;

// In this API there are multiple functions which expect the caller to pass a pointer
// on return value as parameter.
// In order to make it clear if the caller should initialize the return value or not
// we have two flavor of types:
// - `GDExtensionXXXPtr` for pointer on an initialized value
// - `GDExtensionUninitializedXXXPtr` for pointer on uninitialized value
//
// Notes:
// - Not respecting those requirements can seems harmless, but will lead to unexpected
//   segfault or memory leak (for instance with a specific compiler/OS, or when two
//   native extensions start doing ptrcall on each other).
// - Initialization must be done with the function pointer returned by `variant_get_ptr_constructor`,
//   zero-initializing the variable should not be considered a valid initialization method here !
// - Some types have no destructor (see `extension_api.json`'s `has_destructor` field), for
//   them it is always safe to skip the constructor for the return value if you are in a hurry ;-)

typedef void *GDExtensionVariantPtr;
typedef const void *GDExtensionConstVariantPtr;
typedef void *GDExtensionUninitializedVariantPtr;
typedef void *GDExtensionStringNamePtr;
typedef const void *GDExtensionConstStringNamePtr;
typedef void *GDExtensionUninitializedStringNamePtr;
typedef void *GDExtensionStringPtr;
typedef const void *GDExtensionConstStringPtr;
typedef void *GDExtensionUninitializedStringPtr;
typedef void *GDExtensionObjectPtr;
typedef const void *GDExtensionConstObjectPtr;
typedef void *GDExtensionUninitializedObjectPtr;
typedef void *GDExtensionTypePtr;
typedef const void *GDExtensionConstTypePtr;
typedef void *GDExtensionUninitializedTypePtr;
typedef const void *GDExtensionMethodBindPtr;
typedef int64_t GDExtensionInt;
typedef uint8_t GDExtensionBool;
typedef uint64_t GDObjectInstanceID;
typedef void *GDExtensionRefPtr;
typedef const void *GDExtensionConstRefPtr;

/* VARIANT DATA I/O */

typedef enum {
	GDEXTENSION_CALL_OK,
	GDEXTENSION_CALL_ERROR_INVALID_METHOD,
	GDEXTENSION_CALL_ERROR_INVALID_ARGUMENT, // Expected a different variant type.
	GDEXTENSION_CALL_ERROR_TOO_MANY_ARGUMENTS, // Expected lower number of arguments.
	GDEXTENSION_CALL_ERROR_TOO_FEW_ARGUMENTS, // Expected higher number of arguments.
	GDEXTENSION_CALL_ERROR_INSTANCE_IS_NULL,
	GDEXTENSION_CALL_ERROR_METHOD_NOT_CONST, // Used for const call.
} GDExtensionCallErrorType;

typedef struct {
	GDExtensionCallErrorType error;
	int32_t argument;
	int32_t expected;
} GDExtensionCallError;

typedef void (*GDExtensionVariantFromTypeConstructorFunc)(GDExtensionUninitializedVariantPtr, GDExtensionTypePtr);
typedef void (*GDExtensionTypeFromVariantConstructorFunc)(GDExtensionUninitializedTypePtr, GDExtensionVariantPtr);
typedef void (*GDExtensionPtrOperatorEvaluator)(GDExtensionConstTypePtr p_left, GDExtensionConstTypePtr p_right, GDExtensionTypePtr r_result);
typedef void (*GDExtensionPtrBuiltInMethod)(GDExtensionTypePtr p_base, const GDExtensionConstTypePtr *p_args, GDExtensionTypePtr r_return, int p_argument_count);
typedef void (*GDExtensionPtrConstructor)(GDExtensionUninitializedTypePtr p_base, const GDExtensionConstTypePtr *p_args);
typedef void (*GDExtensionPtrDestructor)(GDExtensionTypePtr p_base);
typedef void (*GDExtensionPtrSetter)(GDExtensionTypePtr p_base, GDExtensionConstTypePtr p_value);
typedef void (*GDExtensionPtrGetter)(GDExtensionConstTypePtr p_base, GDExtensionTypePtr r_value);
typedef void (*GDExtensionPtrIndexedSetter)(GDExtensionTypePtr p_base, GDExtensionInt p_index, GDExtensionConstTypePtr p_value);
typedef void (*GDExtensionPtrIndexedGetter)(GDExtensionConstTypePtr p_base, GDExtensionInt p_index, GDExtensionTypePtr r_value);
typedef void (*GDExtensionPtrKeyedSetter)(GDExtensionTypePtr p_base, GDExtensionConstTypePtr p_key, GDExtensionConstTypePtr p_value);
typedef void (*GDExtensionPtrKeyedGetter)(GDExtensionConstTypePtr p_base, GDExtensionConstTypePtr p_key, GDExtensionTypePtr r_value);
typedef uint32_t (*GDExtensionPtrKeyedChecker)(GDExtensionConstVariantPtr p_base, GDExtensionConstVariantPtr p_key);
typedef void (*GDExtensionPtrUtilityFunction)(GDExtensionTypePtr r_return, const GDExtensionConstTypePtr *p_args, int p_argument_count);

typedef GDExtensionObjectPtr (*GDExtensionClassConstructor)();

typedef void *(*GDExtensionInstanceBindingCreateCallback)(void *p_token, void *p_instance);
typedef void (*GDExtensionInstanceBindingFreeCallback)(void *p_token, void *p_instance, void *p_binding);
typedef GDExtensionBool (*GDExtensionInstanceBindingReferenceCallback)(void *p_token, void *p_binding, GDExtensionBool p_reference);

typedef struct {
	GDExtensionInstanceBindingCreateCallback create_callback;
	GDExtensionInstanceBindingFreeCallback free_callback;
	GDExtensionInstanceBindingReferenceCallback reference_callback;
} GDExtensionInstanceBindingCallbacks;

/* EXTENSION CLASSES */

typedef void *GDExtensionClassInstancePtr;

typedef GDExtensionBool (*GDExtensionClassSet)(GDExtensionClassInstancePtr p_instance, GDExtensionConstStringNamePtr p_name, GDExtensionConstVariantPtr p_value);
typedef GDExtensionBool (*GDExtensionClassGet)(GDExtensionClassInstancePtr p_instance, GDExtensionConstStringNamePtr p_name, GDExtensionVariantPtr r_ret);
typedef uint64_t (*GDExtensionClassGetRID)(GDExtensionClassInstancePtr p_instance);

typedef struct {
	GDExtensionVariantType type;
	GDExtensionStringNamePtr name;
	GDExtensionStringNamePtr class_name;
	uint32_t hint; // Bitfield of `PropertyHint` (defined in `extension_api.json`).
	GDExtensionStringPtr hint_string;
	uint32_t usage; // Bitfield of `PropertyUsageFlags` (defined in `extension_api.json`).
} GDExtensionPropertyInfo;

typedef struct {
	GDExtensionStringNamePtr name;
	GDExtensionPropertyInfo return_value;
	uint32_t flags; // Bitfield of `GDExtensionClassMethodFlags`.
	int32_t id;

	/* Arguments: `default_arguments` is an array of size `argument_count`. */
	uint32_t argument_count;
	GDExtensionPropertyInfo *arguments;

	/* Default arguments: `default_arguments` is an array of size `default_argument_count`. */
	uint32_t default_argument_count;
	GDExtensionVariantPtr *default_arguments;
} GDExtensionMethodInfo;

typedef const GDExtensionPropertyInfo *(*GDExtensionClassGetPropertyList)(GDExtensionClassInstancePtr p_instance, uint32_t *r_count);
typedef void (*GDExtensionClassFreePropertyList)(GDExtensionClassInstancePtr p_instance, const GDExtensionPropertyInfo *p_list);
typedef GDExtensionBool (*GDExtensionClassPropertyCanRevert)(GDExtensionClassInstancePtr p_instance, GDExtensionConstStringNamePtr p_name);
typedef GDExtensionBool (*GDExtensionClassPropertyGetRevert)(GDExtensionClassInstancePtr p_instance, GDExtensionConstStringNamePtr p_name, GDExtensionVariantPtr r_ret);
typedef GDExtensionBool (*GDExtensionClassValidateProperty)(GDExtensionClassInstancePtr p_instance, GDExtensionPropertyInfo *p_property);
typedef void (*GDExtensionClassNotification)(GDExtensionClassInstancePtr p_instance, int32_t p_what); // Deprecated. Use GDExtensionClassNotification2 instead.
typedef void (*GDExtensionClassNotification2)(GDExtensionClassInstancePtr p_instance, int32_t p_what, GDExtensionBool p_reversed);
typedef void (*GDExtensionClassToString)(GDExtensionClassInstancePtr p_instance, GDExtensionBool *r_is_valid, GDExtensionStringPtr p_out);
typedef void (*GDExtensionClassReference)(GDExtensionClassInstancePtr p_instance);
typedef void (*GDExtensionClassUnreference)(GDExtensionClassInstancePtr p_instance);
typedef void (*GDExtensionClassCallVirtual)(GDExtensionClassInstancePtr p_instance, const GDExtensionConstTypePtr *p_args, GDExtensionTypePtr r_ret);
typedef GDExtensionObjectPtr (*GDExtensionClassCreateInstance)(void *p_class_userdata);
typedef void (*GDExtensionClassFreeInstance)(void *p_class_userdata, GDExtensionClassInstancePtr p_instance);
typedef GDExtensionClassInstancePtr (*GDExtensionClassRecreateInstance)(void *p_class_userdata, GDExtensionObjectPtr p_object);
typedef GDExtensionClassCallVirtual (*GDExtensionClassGetVirtual)(void *p_class_userdata, GDExtensionConstStringNamePtr p_name);
typedef void *(*GDExtensionClassGetVirtualCallData)(void *p_class_userdata, GDExtensionConstStringNamePtr p_name);
typedef void (*GDExtensionClassCallVirtualWithData)(GDExtensionClassInstancePtr p_instance, GDExtensionConstStringNamePtr p_name, void *p_virtual_call_userdata, const GDExtensionConstTypePtr *p_args, GDExtensionTypePtr r_ret);

typedef struct {
	GDExtensionBool is_virtual;
	GDExtensionBool is_abstract;
	GDExtensionClassSet set_func;
	GDExtensionClassGet get_func;
	GDExtensionClassGetPropertyList get_property_list_func;
	GDExtensionClassFreePropertyList free_property_list_func;
	GDExtensionClassPropertyCanRevert property_can_revert_func;
	GDExtensionClassPropertyGetRevert property_get_revert_func;
	GDExtensionClassNotification notification_func;
	GDExtensionClassToString to_string_func;
	GDExtensionClassReference reference_func;
	GDExtensionClassUnreference unreference_func;
	GDExtensionClassCreateInstance create_instance_func; // (Default) constructor; mandatory. If the class is not instantiable, consider making it virtual or abstract.
	GDExtensionClassFreeInstance free_instance_func; // Destructor; mandatory.
	GDExtensionClassGetVirtual get_virtual_func; // Queries a virtual function by name and returns a callback to invoke the requested virtual function.
	GDExtensionClassGetRID get_rid_func;
	void *class_userdata; // Per-class user data, later accessible in instance bindings.
} GDExtensionClassCreationInfo; // Deprecated. Use GDExtensionClassCreationInfo3 instead.

typedef struct {
	GDExtensionBool is_virtual;
	GDExtensionBool is_abstract;
	GDExtensionBool is_exposed;
	GDExtensionClassSet set_func;
	GDExtensionClassGet get_func;
	GDExtensionClassGetPropertyList get_property_list_func;
	GDExtensionClassFreePropertyList free_property_list_func;
	GDExtensionClassPropertyCanRevert property_can_revert_func;
	GDExtensionClassPropertyGetRevert property_get_revert_func;
	GDExtensionClassValidateProperty validate_property_func;
	GDExtensionClassNotification2 notification_func;
	GDExtensionClassToString to_string_func;
	GDExtensionClassReference reference_func;
	GDExtensionClassUnreference unreference_func;
	GDExtensionClassCreateInstance create_instance_func; // (Default) constructor; mandatory. If the class is not instantiable, consider making it virtual or abstract.
	GDExtensionClassFreeInstance free_instance_func; // Destructor; mandatory.
	GDExtensionClassRecreateInstance recreate_instance_func;
	// Queries a virtual function by name and returns a callback to invoke the requested virtual function.
	GDExtensionClassGetVirtual get_virtual_func;
	// Paired with `call_virtual_with_data_func`, this is an alternative to `get_virtual_func` for extensions that
	// need or benefit from extra data when calling virtual functions.
	// Returns user data that will be passed to `call_virtual_with_data_func`.
	// Returning `NULL` from this function signals to Godot that the virtual function is not overridden.
	// Data returned from this function should be managed by the extension and must be valid until the extension is deinitialized.
	// You should supply either `get_virtual_func`, or `get_virtual_call_data_func` with `call_virtual_with_data_func`.
	GDExtensionClassGetVirtualCallData get_virtual_call_data_func;
	// Used to call virtual functions when `get_virtual_call_data_func` is not null.
	GDExtensionClassCallVirtualWithData call_virtual_with_data_func;
	GDExtensionClassGetRID get_rid_func;
	void *class_userdata; // Per-class user data, later accessible in instance bindings.
} GDExtensionClassCreationInfo2; // Deprecated. Use GDExtensionClassCreationInfo3 instead.

typedef struct {
	GDExtensionBool is_virtual;
	GDExtensionBool is_abstract;
	GDExtensionBool is_exposed;
	GDExtensionBool is_runtime;
	GDExtensionClassSet set_func;
	GDExtensionClassGet get_func;
	GDExtensionClassGetPropertyList get_property_list_func;
	GDExtensionClassFreePropertyList free_property_list_func;
	GDExtensionClassPropertyCanRevert property_can_revert_func;
	GDExtensionClassPropertyGetRevert property_get_revert_func;
	GDExtensionClassValidateProperty validate_property_func;
	GDExtensionClassNotification2 notification_func;
	GDExtensionClassToString to_string_func;
	GDExtensionClassReference reference_func;
	GDExtensionClassUnreference unreference_func;
	GDExtensionClassCreateInstance create_instance_func; // (Default) constructor; mandatory. If the class is not instantiable, consider making it virtual or abstract.
	GDExtensionClassFreeInstance free_instance_func; // Destructor; mandatory.
	GDExtensionClassRecreateInstance recreate_instance_func;
	// Queries a virtual function by name and returns a callback to invoke the requested virtual function.
	GDExtensionClassGetVirtual get_virtual_func;
	// Paired with `call_virtual_with_data_func`, this is an alternative to `get_virtual_func` for extensions that
	// need or benefit from extra data when calling virtual functions.
	// Returns user data that will be passed to `call_virtual_with_data_func`.
	// Returning `NULL` from this function signals to Godot that the virtual function is not overridden.
	// Data returned from this function should be managed by the extension and must be valid until the extension is deinitialized.
	// You should supply either `get_virtual_func`, or `get_virtual_call_data_func` with `call_virtual_with_data_func`.
	GDExtensionClassGetVirtualCallData get_virtual_call_data_func;
	// Used to call virtual functions when `get_virtual_call_data_func` is not null.
	GDExtensionClassCallVirtualWithData call_virtual_with_data_func;
	GDExtensionClassGetRID get_rid_func;
	void *class_userdata; // Per-class user data, later accessible in instance bindings.
} GDExtensionClassCreationInfo3;

typedef void *GDExtensionClassLibraryPtr;

/* Method */

typedef enum {
	GDEXTENSION_METHOD_FLAG_NORMAL = 1,
	GDEXTENSION_METHOD_FLAG_EDITOR = 2,
	GDEXTENSION_METHOD_FLAG_CONST = 4,
	GDEXTENSION_METHOD_FLAG_VIRTUAL = 8,
	GDEXTENSION_METHOD_FLAG_VARARG = 16,
	GDEXTENSION_METHOD_FLAG_STATIC = 32,
	GDEXTENSION_METHOD_FLAGS_DEFAULT = GDEXTENSION_METHOD_FLAG_NORMAL,
} GDExtensionClassMethodFlags;

typedef enum {
	GDEXTENSION_METHOD_ARGUMENT_METADATA_NONE,
	GDEXTENSION_METHOD_ARGUMENT_METADATA_INT_IS_INT8,
	GDEXTENSION_METHOD_ARGUMENT_METADATA_INT_IS_INT16,
	GDEXTENSION_METHOD_ARGUMENT_METADATA_INT_IS_INT32,
	GDEXTENSION_METHOD_ARGUMENT_METADATA_INT_IS_INT64,
	GDEXTENSION_METHOD_ARGUMENT_METADATA_INT_IS_UINT8,
	GDEXTENSION_METHOD_ARGUMENT_METADATA_INT_IS_UINT16,
	GDEXTENSION_METHOD_ARGUMENT_METADATA_INT_IS_UINT32,
	GDEXTENSION_METHOD_ARGUMENT_METADATA_INT_IS_UINT64,
	GDEXTENSION_METHOD_ARGUMENT_METADATA_REAL_IS_FLOAT,
	GDEXTENSION_METHOD_ARGUMENT_METADATA_REAL_IS_DOUBLE
} GDExtensionClassMethodArgumentMetadata;

typedef void (*GDExtensionClassMethodCall)(void *method_userdata, GDExtensionClassInstancePtr p_instance, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionVariantPtr r_return, GDExtensionCallError *r_error);
typedef void (*GDExtensionClassMethodValidatedCall)(void *method_userdata, GDExtensionClassInstancePtr p_instance, const GDExtensionConstVariantPtr *p_args, GDExtensionVariantPtr r_return);
typedef void (*GDExtensionClassMethodPtrCall)(void *method_userdata, GDExtensionClassInstancePtr p_instance, const GDExtensionConstTypePtr *p_args, GDExtensionTypePtr r_ret);

typedef struct {
	GDExtensionStringNamePtr name;
	void *method_userdata;
	GDExtensionClassMethodCall call_func;
	GDExtensionClassMethodPtrCall ptrcall_func;
	uint32_t method_flags; // Bitfield of `GDExtensionClassMethodFlags`.

	/* If `has_return_value` is false, `return_value_info` and `return_value_metadata` are ignored.
	 *
	 * @todo Consider dropping `has_return_value` and making the other two properties match `GDExtensionMethodInfo` and `GDExtensionClassVirtualMethod` for consistency in future version of this struct.
	 */
	GDExtensionBool has_return_value;
	GDExtensionPropertyInfo *return_value_info;
	GDExtensionClassMethodArgumentMetadata return_value_metadata;

	/* Arguments: `arguments_info` and `arguments_metadata` are array of size `argument_count`.
	 * Name and hint information for the argument can be omitted in release builds. Class name should always be present if it applies.
	 *
	 * @todo Consider renaming `arguments_info` to `arguments` for consistency in future version of this struct.
	 */
	uint32_t argument_count;
	GDExtensionPropertyInfo *arguments_info;
	GDExtensionClassMethodArgumentMetadata *arguments_metadata;

	/* Default arguments: `default_arguments` is an array of size `default_argument_count`. */
	uint32_t default_argument_count;
	GDExtensionVariantPtr *default_arguments;
} GDExtensionClassMethodInfo;

typedef struct {
	GDExtensionStringNamePtr name;
	uint32_t method_flags; // Bitfield of `GDExtensionClassMethodFlags`.

	GDExtensionPropertyInfo return_value;
	GDExtensionClassMethodArgumentMetadata return_value_metadata;

	uint32_t argument_count;
	GDExtensionPropertyInfo *arguments;
	GDExtensionClassMethodArgumentMetadata *arguments_metadata;
} GDExtensionClassVirtualMethodInfo;

typedef void (*GDExtensionCallableCustomCall)(void *callable_userdata, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionVariantPtr r_return, GDExtensionCallError *r_error);
typedef GDExtensionBool (*GDExtensionCallableCustomIsValid)(void *callable_userdata);
typedef void (*GDExtensionCallableCustomFree)(void *callable_userdata);

typedef uint32_t (*GDExtensionCallableCustomHash)(void *callable_userdata);
typedef GDExtensionBool (*GDExtensionCallableCustomEqual)(void *callable_userdata_a, void *callable_userdata_b);
typedef GDExtensionBool (*GDExtensionCallableCustomLessThan)(void *callable_userdata_a, void *callable_userdata_b);

typedef void (*GDExtensionCallableCustomToString)(void *callable_userdata, GDExtensionBool *r_is_valid, GDExtensionStringPtr r_out);

typedef struct {
	/* Only `call_func` and `token` are strictly required, however, `object_id` should be passed if its not a static method.
	 *
	 * `token` should point to an address that uniquely identifies the GDExtension (for example, the
	 * `GDExtensionClassLibraryPtr` passed to the entry symbol function.
	 *
	 * `hash_func`, `equal_func`, and `less_than_func` are optional. If not provided both `call_func` and
	 * `callable_userdata` together are used as the identity of the callable for hashing and comparison purposes.
	 *
	 * The hash returned by `hash_func` is cached, `hash_func` will not be called more than once per callable.
	 *
	 * `is_valid_func` is necessary if the validity of the callable can change before destruction.
	 *
	 * `free_func` is necessary if `callable_userdata` needs to be cleaned up when the callable is freed.
	 */
	void *callable_userdata;
	void *token;

	GDObjectInstanceID object_id;

	GDExtensionCallableCustomCall call_func;
	GDExtensionCallableCustomIsValid is_valid_func;
	GDExtensionCallableCustomFree free_func;

	GDExtensionCallableCustomHash hash_func;
	GDExtensionCallableCustomEqual equal_func;
	GDExtensionCallableCustomLessThan less_than_func;

	GDExtensionCallableCustomToString to_string_func;
} GDExtensionCallableCustomInfo;

/* SCRIPT INSTANCE EXTENSION */

typedef void *GDExtensionScriptInstanceDataPtr; // Pointer to custom ScriptInstance native implementation.

typedef GDExtensionBool (*GDExtensionScriptInstanceSet)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionConstStringNamePtr p_name, GDExtensionConstVariantPtr p_value);
typedef GDExtensionBool (*GDExtensionScriptInstanceGet)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionConstStringNamePtr p_name, GDExtensionVariantPtr r_ret);
typedef const GDExtensionPropertyInfo *(*GDExtensionScriptInstanceGetPropertyList)(GDExtensionScriptInstanceDataPtr p_instance, uint32_t *r_count);
typedef void (*GDExtensionScriptInstanceFreePropertyList)(GDExtensionScriptInstanceDataPtr p_instance, const GDExtensionPropertyInfo *p_list);
typedef GDExtensionBool (*GDExtensionScriptInstanceGetClassCategory)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionPropertyInfo *p_class_category);

typedef GDExtensionVariantType (*GDExtensionScriptInstanceGetPropertyType)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionConstStringNamePtr p_name, GDExtensionBool *r_is_valid);
typedef GDExtensionBool (*GDExtensionScriptInstanceValidateProperty)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionPropertyInfo *p_property);

typedef GDExtensionBool (*GDExtensionScriptInstancePropertyCanRevert)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionConstStringNamePtr p_name);
typedef GDExtensionBool (*GDExtensionScriptInstancePropertyGetRevert)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionConstStringNamePtr p_name, GDExtensionVariantPtr r_ret);

typedef GDExtensionObjectPtr (*GDExtensionScriptInstanceGetOwner)(GDExtensionScriptInstanceDataPtr p_instance);
typedef void (*GDExtensionScriptInstancePropertyStateAdd)(GDExtensionConstStringNamePtr p_name, GDExtensionConstVariantPtr p_value, void *p_userdata);
typedef void (*GDExtensionScriptInstanceGetPropertyState)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionScriptInstancePropertyStateAdd p_add_func, void *p_userdata);

typedef const GDExtensionMethodInfo *(*GDExtensionScriptInstanceGetMethodList)(GDExtensionScriptInstanceDataPtr p_instance, uint32_t *r_count);
typedef void (*GDExtensionScriptInstanceFreeMethodList)(GDExtensionScriptInstanceDataPtr p_instance, const GDExtensionMethodInfo *p_list);

typedef GDExtensionBool (*GDExtensionScriptInstanceHasMethod)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionConstStringNamePtr p_name);

typedef void (*GDExtensionScriptInstanceCall)(GDExtensionScriptInstanceDataPtr p_self, GDExtensionConstStringNamePtr p_method, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionVariantPtr r_return, GDExtensionCallError *r_error);
typedef void (*GDExtensionScriptInstanceNotification)(GDExtensionScriptInstanceDataPtr p_instance, int32_t p_what); // Deprecated. Use GDExtensionScriptInstanceNotification2 instead.
typedef void (*GDExtensionScriptInstanceNotification2)(GDExtensionScriptInstanceDataPtr p_instance, int32_t p_what, GDExtensionBool p_reversed);
typedef void (*GDExtensionScriptInstanceToString)(GDExtensionScriptInstanceDataPtr p_instance, GDExtensionBool *r_is_valid, GDExtensionStringPtr r_out);

typedef void (*GDExtensionScriptInstanceRefCountIncremented)(GDExtensionScriptInstanceDataPtr p_instance);
typedef GDExtensionBool (*GDExtensionScriptInstanceRefCountDecremented)(GDExtensionScriptInstanceDataPtr p_instance);

typedef GDExtensionObjectPtr (*GDExtensionScriptInstanceGetScript)(GDExtensionScriptInstanceDataPtr p_instance);
typedef GDExtensionBool (*GDExtensionScriptInstanceIsPlaceholder)(GDExtensionScriptInstanceDataPtr p_instance);

typedef void *GDExtensionScriptLanguagePtr;

typedef GDExtensionScriptLanguagePtr (*GDExtensionScriptInstanceGetLanguage)(GDExtensionScriptInstanceDataPtr p_instance);

typedef void (*GDExtensionScriptInstanceFree)(GDExtensionScriptInstanceDataPtr p_instance);

typedef void *GDExtensionScriptInstancePtr; // Pointer to ScriptInstance.

typedef struct {
	GDExtensionScriptInstanceSet set_func;
	GDExtensionScriptInstanceGet get_func;
	GDExtensionScriptInstanceGetPropertyList get_property_list_func;
	GDExtensionScriptInstanceFreePropertyList free_property_list_func;

	GDExtensionScriptInstancePropertyCanRevert property_can_revert_func;
	GDExtensionScriptInstancePropertyGetRevert property_get_revert_func;

	GDExtensionScriptInstanceGetOwner get_owner_func;
	GDExtensionScriptInstanceGetPropertyState get_property_state_func;

	GDExtensionScriptInstanceGetMethodList get_method_list_func;
	GDExtensionScriptInstanceFreeMethodList free_method_list_func;
	GDExtensionScriptInstanceGetPropertyType get_property_type_func;

	GDExtensionScriptInstanceHasMethod has_method_func;

	GDExtensionScriptInstanceCall call_func;
	GDExtensionScriptInstanceNotification notification_func;

	GDExtensionScriptInstanceToString to_string_func;

	GDExtensionScriptInstanceRefCountIncremented refcount_incremented_func;
	GDExtensionScriptInstanceRefCountDecremented refcount_decremented_func;

	GDExtensionScriptInstanceGetScript get_script_func;

	GDExtensionScriptInstanceIsPlaceholder is_placeholder_func;

	GDExtensionScriptInstanceSet set_fallback_func;
	GDExtensionScriptInstanceGet get_fallback_func;

	GDExtensionScriptInstanceGetLanguage get_language_func;

	GDExtensionScriptInstanceFree free_func;

} GDExtensionScriptInstanceInfo; // Deprecated. Use GDExtensionScriptInstanceInfo2 instead.

typedef struct {
	GDExtensionScriptInstanceSet set_func;
	GDExtensionScriptInstanceGet get_func;
	GDExtensionScriptInstanceGetPropertyList get_property_list_func;
	GDExtensionScriptInstanceFreePropertyList free_property_list_func;
	GDExtensionScriptInstanceGetClassCategory get_class_category_func; // Optional. Set to NULL for the default behavior.

	GDExtensionScriptInstancePropertyCanRevert property_can_revert_func;
	GDExtensionScriptInstancePropertyGetRevert property_get_revert_func;

	GDExtensionScriptInstanceGetOwner get_owner_func;
	GDExtensionScriptInstanceGetPropertyState get_property_state_func;

	GDExtensionScriptInstanceGetMethodList get_method_list_func;
	GDExtensionScriptInstanceFreeMethodList free_method_list_func;
	GDExtensionScriptInstanceGetPropertyType get_property_type_func;
	GDExtensionScriptInstanceValidateProperty validate_property_func;

	GDExtensionScriptInstanceHasMethod has_method_func;

	GDExtensionScriptInstanceCall call_func;
	GDExtensionScriptInstanceNotification2 notification_func;

	GDExtensionScriptInstanceToString to_string_func;

	GDExtensionScriptInstanceRefCountIncremented refcount_incremented_func;
	GDExtensionScriptInstanceRefCountDecremented refcount_decremented_func;

	GDExtensionScriptInstanceGetScript get_script_func;

	GDExtensionScriptInstanceIsPlaceholder is_placeholder_func;

	GDExtensionScriptInstanceSet set_fallback_func;
	GDExtensionScriptInstanceGet get_fallback_func;

	GDExtensionScriptInstanceGetLanguage get_language_func;

	GDExtensionScriptInstanceFree free_func;

} GDExtensionScriptInstanceInfo2;

/* INITIALIZATION */

typedef enum {
	GDEXTENSION_INITIALIZATION_CORE,
	GDEXTENSION_INITIALIZATION_SERVERS,
	GDEXTENSION_INITIALIZATION_SCENE,
	GDEXTENSION_INITIALIZATION_EDITOR,
	GDEXTENSION_MAX_INITIALIZATION_LEVEL,
} GDExtensionInitializationLevel;

typedef struct {
	/* Minimum initialization level required.
	 * If Core or Servers, the extension needs editor or game restart to take effect */
	GDExtensionInitializationLevel minimum_initialization_level;
	/* Up to the user to supply when initializing */
	void *userdata;
	/* This function will be called multiple times for each initialization level. */
	void (*initialize)(void *userdata, GDExtensionInitializationLevel p_level);
	void (*deinitialize)(void *userdata, GDExtensionInitializationLevel p_level);
} GDExtensionInitialization;

typedef void (*GDExtensionInterfaceFunctionPtr)();
typedef GDExtensionInterfaceFunctionPtr (*GDExtensionInterfaceGetProcAddress)(const char *p_function_name);

/*
 * Each GDExtension should define a C function that matches the signature of GDExtensionInitializationFunction,
 * and export it so that it can be loaded via dlopen() or equivalent for the given platform.
 *
 * For example:
 *
 *   GDExtensionBool my_extension_init(GDExtensionInterfaceGetProcAddress p_get_proc_address, GDExtensionClassLibraryPtr p_library, GDExtensionInitialization *r_initialization);
 *
 * This function's name must be specified as the 'entry_symbol' in the .gdextension file.
 *
 * This makes it the entry point of the GDExtension and will be called on initialization.
 *
 * The GDExtension can then modify the r_initialization structure, setting the minimum initialization level,
 * and providing pointers to functions that will be called at various stages of initialization/shutdown.
 *
 * The rest of the GDExtension's interface to Godot consists of function pointers that can be loaded
 * by calling p_get_proc_address("...") with the name of the function.
 *
 * For example:
 *
 *   GDExtensionInterfaceGetGodotVersion get_godot_version = (GDExtensionInterfaceGetGodotVersion)p_get_proc_address("get_godot_version");
 *
 * (Note that snippet may cause "cast between incompatible function types" on some compilers, you can
 * silence this by adding an intermediary `void*` cast.)
 *
 * You can then call it like a normal function:
 *
 *   GDExtensionGodotVersion godot_version;
 *   get_godot_version(&godot_version);
 *   printf("Godot v%d.%d.%d\n", godot_version.major, godot_version.minor, godot_version.patch);
 *
 * All of these interface functions are described below, together with the name that's used to load it,
 * and the function pointer typedef that shows its signature.
 */
typedef GDExtensionBool (*GDExtensionInitializationFunction)(GDExtensionInterfaceGetProcAddress p_get_proc_address, GDExtensionClassLibraryPtr p_library, GDExtensionInitialization *r_initialization);

/* INTERFACE */

typedef struct {
	uint32_t major;
	uint32_t minor;
	uint32_t patch;
	const char *string;
} GDExtensionGodotVersion;

/**
 * @name get_godot_version
 * @since 4.1
 *
 * Gets the Godot version that the GDExtension was loaded into.
 *
 * @param r_godot_version A pointer to the structure to write the version information into.
 */
typedef void (*GDExtensionInterfaceGetGodotVersion)(GDExtensionGodotVersion *r_godot_version);

/* INTERFACE: Memory */

/**
 * @name mem_alloc
 * @since 4.1
 *
 * Allocates memory.
 *
 * @param p_bytes The amount of memory to allocate in bytes.
 *
 * @return A pointer to the allocated memory, or NULL if unsuccessful.
 */
typedef void *(*GDExtensionInterfaceMemAlloc)(size_t p_bytes);

/**
 * @name mem_realloc
 * @since 4.1
 *
 * Reallocates memory.
 *
 * @param p_ptr A pointer to the previously allocated memory.
 * @param p_bytes The number of bytes to resize the memory block to.
 *
 * @return A pointer to the allocated memory, or NULL if unsuccessful.
 */
typedef void *(*GDExtensionInterfaceMemRealloc)(void *p_ptr, size_t p_bytes);

/**
 * @name mem_free
 * @since 4.1
 *
 * Frees memory.
 *
 * @param p_ptr A pointer to the previously allocated memory.
 */
typedef void (*GDExtensionInterfaceMemFree)(void *p_ptr);

/* INTERFACE: Godot Core */

/**
 * @name print_error
 * @since 4.1
 *
 * Logs an error to Godot's built-in debugger and to the OS terminal.
 *
 * @param p_description The code trigging the error.
 * @param p_function The function name where the error occurred.
 * @param p_file The file where the error occurred.
 * @param p_line The line where the error occurred.
 * @param p_editor_notify Whether or not to notify the editor.
 */
typedef void (*GDExtensionInterfacePrintError)(const char *p_description, const char *p_function, const char *p_file, int32_t p_line, GDExtensionBool p_editor_notify);

/**
 * @name print_error_with_message
 * @since 4.1
 *
 * Logs an error with a message to Godot's built-in debugger and to the OS terminal.
 *
 * @param p_description The code trigging the error.
 * @param p_message The message to show along with the error.
 * @param p_function The function name where the error occurred.
 * @param p_file The file where the error occurred.
 * @param p_line The line where the error occurred.
 * @param p_editor_notify Whether or not to notify the editor.
 */
typedef void (*GDExtensionInterfacePrintErrorWithMessage)(const char *p_description, const char *p_message, const char *p_function, const char *p_file, int32_t p_line, GDExtensionBool p_editor_notify);

/**
 * @name print_warning
 * @since 4.1
 *
 * Logs a warning to Godot's built-in debugger and to the OS terminal.
 *
 * @param p_description The code trigging the warning.
 * @param p_function The function name where the warning occurred.
 * @param p_file The file where the warning occurred.
 * @param p_line The line where the warning occurred.
 * @param p_editor_notify Whether or not to notify the editor.
 */
typedef void (*GDExtensionInterfacePrintWarning)(const char *p_description, const char *p_function, const char *p_file, int32_t p_line, GDExtensionBool p_editor_notify);

/**
 * @name print_warning_with_message
 * @since 4.1
 *
 * Logs a warning with a message to Godot's built-in debugger and to the OS terminal.
 *
 * @param p_description The code trigging the warning.
 * @param p_message The message to show along with the warning.
 * @param p_function The function name where the warning occurred.
 * @param p_file The file where the warning occurred.
 * @param p_line The line where the warning occurred.
 * @param p_editor_notify Whether or not to notify the editor.
 */
typedef void (*GDExtensionInterfacePrintWarningWithMessage)(const char *p_description, const char *p_message, const char *p_function, const char *p_file, int32_t p_line, GDExtensionBool p_editor_notify);

/**
 * @name print_script_error
 * @since 4.1
 *
 * Logs a script error to Godot's built-in debugger and to the OS terminal.
 *
 * @param p_description The code trigging the error.
 * @param p_function The function name where the error occurred.
 * @param p_file The file where the error occurred.
 * @param p_line The line where the error occurred.
 * @param p_editor_notify Whether or not to notify the editor.
 */
typedef void (*GDExtensionInterfacePrintScriptError)(const char *p_description, const char *p_function, const char *p_file, int32_t p_line, GDExtensionBool p_editor_notify);

/**
 * @name print_script_error_with_message
 * @since 4.1
 *
 * Logs a script error with a message to Godot's built-in debugger and to the OS terminal.
 *
 * @param p_description The code trigging the error.
 * @param p_message The message to show along with the error.
 * @param p_function The function name where the error occurred.
 * @param p_file The file where the error occurred.
 * @param p_line The line where the error occurred.
 * @param p_editor_notify Whether or not to notify the editor.
 */
typedef void (*GDExtensionInterfacePrintScriptErrorWithMessage)(const char *p_description, const char *p_message, const char *p_function, const char *p_file, int32_t p_line, GDExtensionBool p_editor_notify);

/**
 * @name get_native_struct_size
 * @since 4.1
 *
 * Gets the size of a native struct (ex. ObjectID) in bytes.
 *
 * @param p_name A pointer to a StringName identifying the struct name.
 *
 * @return The size in bytes.
 */
typedef uint64_t (*GDExtensionInterfaceGetNativeStructSize)(GDExtensionConstStringNamePtr p_name);

/* INTERFACE: Variant */

/**
 * @name variant_new_copy
 * @since 4.1
 *
 * Copies one Variant into a another.
 *
 * @param r_dest A pointer to the destination Variant.
 * @param p_src A pointer to the source Variant.
 */
typedef void (*GDExtensionInterfaceVariantNewCopy)(GDExtensionUninitializedVariantPtr r_dest, GDExtensionConstVariantPtr p_src);

/**
 * @name variant_new_nil
 * @since 4.1
 *
 * Creates a new Variant containing nil.
 *
 * @param r_dest A pointer to the destination Variant.
 */
typedef void (*GDExtensionInterfaceVariantNewNil)(GDExtensionUninitializedVariantPtr r_dest);

/**
 * @name variant_destroy
 * @since 4.1
 *
 * Destroys a Variant.
 *
 * @param p_self A pointer to the Variant to destroy.
 */
typedef void (*GDExtensionInterfaceVariantDestroy)(GDExtensionVariantPtr p_self);

/**
 * @name variant_call
 * @since 4.1
 *
 * Calls a method on a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param p_method A pointer to a StringName identifying the method.
 * @param p_args A pointer to a C array of Variant.
 * @param p_argument_count The number of arguments.
 * @param r_return A pointer a Variant which will be assigned the return value.
 * @param r_error A pointer the structure which will hold error information.
 *
 * @see Variant::callp()
 */
typedef void (*GDExtensionInterfaceVariantCall)(GDExtensionVariantPtr p_self, GDExtensionConstStringNamePtr p_method, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionUninitializedVariantPtr r_return, GDExtensionCallError *r_error);

/**
 * @name variant_call_static
 * @since 4.1
 *
 * Calls a static method on a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param p_method A pointer to a StringName identifying the method.
 * @param p_args A pointer to a C array of Variant.
 * @param p_argument_count The number of arguments.
 * @param r_return A pointer a Variant which will be assigned the return value.
 * @param r_error A pointer the structure which will be updated with error information.
 *
 * @see Variant::call_static()
 */
typedef void (*GDExtensionInterfaceVariantCallStatic)(GDExtensionVariantType p_type, GDExtensionConstStringNamePtr p_method, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionUninitializedVariantPtr r_return, GDExtensionCallError *r_error);

/**
 * @name variant_evaluate
 * @since 4.1
 *
 * Evaluate an operator on two Variants.
 *
 * @param p_op The operator to evaluate.
 * @param p_a The first Variant.
 * @param p_b The second Variant.
 * @param r_return A pointer a Variant which will be assigned the return value.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 *
 * @see Variant::evaluate()
 */
typedef void (*GDExtensionInterfaceVariantEvaluate)(GDExtensionVariantOperator p_op, GDExtensionConstVariantPtr p_a, GDExtensionConstVariantPtr p_b, GDExtensionUninitializedVariantPtr r_return, GDExtensionBool *r_valid);

/**
 * @name variant_set
 * @since 4.1
 *
 * Sets a key on a Variant to a value.
 *
 * @param p_self A pointer to the Variant.
 * @param p_key A pointer to a Variant representing the key.
 * @param p_value A pointer to a Variant representing the value.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 *
 * @see Variant::set()
 */
typedef void (*GDExtensionInterfaceVariantSet)(GDExtensionVariantPtr p_self, GDExtensionConstVariantPtr p_key, GDExtensionConstVariantPtr p_value, GDExtensionBool *r_valid);

/**
 * @name variant_set_named
 * @since 4.1
 *
 * Sets a named key on a Variant to a value.
 *
 * @param p_self A pointer to the Variant.
 * @param p_key A pointer to a StringName representing the key.
 * @param p_value A pointer to a Variant representing the value.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 *
 * @see Variant::set_named()
 */
typedef void (*GDExtensionInterfaceVariantSetNamed)(GDExtensionVariantPtr p_self, GDExtensionConstStringNamePtr p_key, GDExtensionConstVariantPtr p_value, GDExtensionBool *r_valid);

/**
 * @name variant_set_keyed
 * @since 4.1
 *
 * Sets a keyed property on a Variant to a value.
 *
 * @param p_self A pointer to the Variant.
 * @param p_key A pointer to a Variant representing the key.
 * @param p_value A pointer to a Variant representing the value.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 *
 * @see Variant::set_keyed()
 */
typedef void (*GDExtensionInterfaceVariantSetKeyed)(GDExtensionVariantPtr p_self, GDExtensionConstVariantPtr p_key, GDExtensionConstVariantPtr p_value, GDExtensionBool *r_valid);

/**
 * @name variant_set_indexed
 * @since 4.1
 *
 * Sets an index on a Variant to a value.
 *
 * @param p_self A pointer to the Variant.
 * @param p_index The index.
 * @param p_value A pointer to a Variant representing the value.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 * @param r_oob A pointer to a boolean which will be set to true if the index is out of bounds.
 */
typedef void (*GDExtensionInterfaceVariantSetIndexed)(GDExtensionVariantPtr p_self, GDExtensionInt p_index, GDExtensionConstVariantPtr p_value, GDExtensionBool *r_valid, GDExtensionBool *r_oob);

/**
 * @name variant_get
 * @since 4.1
 *
 * Gets the value of a key from a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param p_key A pointer to a Variant representing the key.
 * @param r_ret A pointer to a Variant which will be assigned the value.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 */
typedef void (*GDExtensionInterfaceVariantGet)(GDExtensionConstVariantPtr p_self, GDExtensionConstVariantPtr p_key, GDExtensionUninitializedVariantPtr r_ret, GDExtensionBool *r_valid);

/**
 * @name variant_get_named
 * @since 4.1
 *
 * Gets the value of a named key from a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param p_key A pointer to a StringName representing the key.
 * @param r_ret A pointer to a Variant which will be assigned the value.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 */
typedef void (*GDExtensionInterfaceVariantGetNamed)(GDExtensionConstVariantPtr p_self, GDExtensionConstStringNamePtr p_key, GDExtensionUninitializedVariantPtr r_ret, GDExtensionBool *r_valid);

/**
 * @name variant_get_keyed
 * @since 4.1
 *
 * Gets the value of a keyed property from a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param p_key A pointer to a Variant representing the key.
 * @param r_ret A pointer to a Variant which will be assigned the value.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 */
typedef void (*GDExtensionInterfaceVariantGetKeyed)(GDExtensionConstVariantPtr p_self, GDExtensionConstVariantPtr p_key, GDExtensionUninitializedVariantPtr r_ret, GDExtensionBool *r_valid);

/**
 * @name variant_get_indexed
 * @since 4.1
 *
 * Gets the value of an index from a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param p_index The index.
 * @param r_ret A pointer to a Variant which will be assigned the value.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 * @param r_oob A pointer to a boolean which will be set to true if the index is out of bounds.
 */
typedef void (*GDExtensionInterfaceVariantGetIndexed)(GDExtensionConstVariantPtr p_self, GDExtensionInt p_index, GDExtensionUninitializedVariantPtr r_ret, GDExtensionBool *r_valid, GDExtensionBool *r_oob);

/**
 * @name variant_iter_init
 * @since 4.1
 *
 * Initializes an iterator over a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param r_iter A pointer to a Variant which will be assigned the iterator.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 *
 * @return true if the operation is valid; otherwise false.
 *
 * @see Variant::iter_init()
 */
typedef GDExtensionBool (*GDExtensionInterfaceVariantIterInit)(GDExtensionConstVariantPtr p_self, GDExtensionUninitializedVariantPtr r_iter, GDExtensionBool *r_valid);

/**
 * @name variant_iter_next
 * @since 4.1
 *
 * Gets the next value for an iterator over a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param r_iter A pointer to a Variant which will be assigned the iterator.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 *
 * @return true if the operation is valid; otherwise false.
 *
 * @see Variant::iter_next()
 */
typedef GDExtensionBool (*GDExtensionInterfaceVariantIterNext)(GDExtensionConstVariantPtr p_self, GDExtensionVariantPtr r_iter, GDExtensionBool *r_valid);

/**
 * @name variant_iter_get
 * @since 4.1
 *
 * Gets the next value for an iterator over a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param r_iter A pointer to a Variant which will be assigned the iterator.
 * @param r_ret A pointer to a Variant which will be assigned false if the operation is invalid.
 * @param r_valid A pointer to a boolean which will be set to false if the operation is invalid.
 *
 * @see Variant::iter_get()
 */
typedef void (*GDExtensionInterfaceVariantIterGet)(GDExtensionConstVariantPtr p_self, GDExtensionVariantPtr r_iter, GDExtensionUninitializedVariantPtr r_ret, GDExtensionBool *r_valid);

/**
 * @name variant_hash
 * @since 4.1
 *
 * Gets the hash of a Variant.
 *
 * @param p_self A pointer to the Variant.
 *
 * @return The hash value.
 *
 * @see Variant::hash()
 */
typedef GDExtensionInt (*GDExtensionInterfaceVariantHash)(GDExtensionConstVariantPtr p_self);

/**
 * @name variant_recursive_hash
 * @since 4.1
 *
 * Gets the recursive hash of a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param p_recursion_count The number of recursive loops so far.
 *
 * @return The hash value.
 *
 * @see Variant::recursive_hash()
 */
typedef GDExtensionInt (*GDExtensionInterfaceVariantRecursiveHash)(GDExtensionConstVariantPtr p_self, GDExtensionInt p_recursion_count);

/**
 * @name variant_hash_compare
 * @since 4.1
 *
 * Compares two Variants by their hash.
 *
 * @param p_self A pointer to the Variant.
 * @param p_other A pointer to the other Variant to compare it to.
 *
 * @return The hash value.
 *
 * @see Variant::hash_compare()
 */
typedef GDExtensionBool (*GDExtensionInterfaceVariantHashCompare)(GDExtensionConstVariantPtr p_self, GDExtensionConstVariantPtr p_other);

/**
 * @name variant_booleanize
 * @since 4.1
 *
 * Converts a Variant to a boolean.
 *
 * @param p_self A pointer to the Variant.
 *
 * @return The boolean value of the Variant.
 */
typedef GDExtensionBool (*GDExtensionInterfaceVariantBooleanize)(GDExtensionConstVariantPtr p_self);

/**
 * @name variant_duplicate
 * @since 4.1
 *
 * Duplicates a Variant.
 *
 * @param p_self A pointer to the Variant.
 * @param r_ret A pointer to a Variant to store the duplicated value.
 * @param p_deep Whether or not to duplicate deeply (when supported by the Variant type).
 */
typedef void (*GDExtensionInterfaceVariantDuplicate)(GDExtensionConstVariantPtr p_self, GDExtensionVariantPtr r_ret, GDExtensionBool p_deep);

/**
 * @name variant_stringify
 * @since 4.1
 *
 * Converts a Variant to a string.
 *
 * @param p_self A pointer to the Variant.
 * @param r_ret A pointer to a String to store the resulting value.
 */
typedef void (*GDExtensionInterfaceVariantStringify)(GDExtensionConstVariantPtr p_self, GDExtensionStringPtr r_ret);

/**
 * @name variant_get_type
 * @since 4.1
 *
 * Gets the type of a Variant.
 *
 * @param p_self A pointer to the Variant.
 *
 * @return The variant type.
 */
typedef GDExtensionVariantType (*GDExtensionInterfaceVariantGetType)(GDExtensionConstVariantPtr p_self);

/**
 * @name variant_has_method
 * @since 4.1
 *
 * Checks if a Variant has the given method.
 *
 * @param p_self A pointer to the Variant.
 * @param p_method A pointer to a StringName with the method name.
 *
 * @return
 */
typedef GDExtensionBool (*GDExtensionInterfaceVariantHasMethod)(GDExtensionConstVariantPtr p_self, GDExtensionConstStringNamePtr p_method);

/**
 * @name variant_has_member
 * @since 4.1
 *
 * Checks if a type of Variant has the given member.
 *
 * @param p_type The Variant type.
 * @param p_member A pointer to a StringName with the member name.
 *
 * @return
 */
typedef GDExtensionBool (*GDExtensionInterfaceVariantHasMember)(GDExtensionVariantType p_type, GDExtensionConstStringNamePtr p_member);

/**
 * @name variant_has_key
 * @since 4.1
 *
 * Checks if a Variant has a key.
 *
 * @param p_self A pointer to the Variant.
 * @param p_key A pointer to a Variant representing the key.
 * @param r_valid A pointer to a boolean which will be set to false if the key doesn't exist.
 *
 * @return true if the key exists; otherwise false.
 */
typedef GDExtensionBool (*GDExtensionInterfaceVariantHasKey)(GDExtensionConstVariantPtr p_self, GDExtensionConstVariantPtr p_key, GDExtensionBool *r_valid);

/**
 * @name variant_get_type_name
 * @since 4.1
 *
 * Gets the name of a Variant type.
 *
 * @param p_type The Variant type.
 * @param r_name A pointer to a String to store the Variant type name.
 */
typedef void (*GDExtensionInterfaceVariantGetTypeName)(GDExtensionVariantType p_type, GDExtensionUninitializedStringPtr r_name);

/**
 * @name variant_can_convert
 * @since 4.1
 *
 * Checks if Variants can be converted from one type to another.
 *
 * @param p_from The Variant type to convert from.
 * @param p_to The Variant type to convert to.
 *
 * @return true if the conversion is possible; otherwise false.
 */
typedef GDExtensionBool (*GDExtensionInterfaceVariantCanConvert)(GDExtensionVariantType p_from, GDExtensionVariantType p_to);

/**
 * @name variant_can_convert_strict
 * @since 4.1
 *
 * Checks if Variant can be converted from one type to another using stricter rules.
 *
 * @param p_from The Variant type to convert from.
 * @param p_to The Variant type to convert to.
 *
 * @return true if the conversion is possible; otherwise false.
 */
typedef GDExtensionBool (*GDExtensionInterfaceVariantCanConvertStrict)(GDExtensionVariantType p_from, GDExtensionVariantType p_to);

/**
 * @name get_variant_from_type_constructor
 * @since 4.1
 *
 * Gets a pointer to a function that can create a Variant of the given type from a raw value.
 *
 * @param p_type The Variant type.
 *
 * @return A pointer to a function that can create a Variant of the given type from a raw value.
 */
typedef GDExtensionVariantFromTypeConstructorFunc (*GDExtensionInterfaceGetVariantFromTypeConstructor)(GDExtensionVariantType p_type);

/**
 * @name get_variant_to_type_constructor
 * @since 4.1
 *
 * Gets a pointer to a function that can get the raw value from a Variant of the given type.
 *
 * @param p_type The Variant type.
 *
 * @return A pointer to a function that can get the raw value from a Variant of the given type.
 */
typedef GDExtensionTypeFromVariantConstructorFunc (*GDExtensionInterfaceGetVariantToTypeConstructor)(GDExtensionVariantType p_type);

/**
 * @name variant_get_ptr_operator_evaluator
 * @since 4.1
 *
 * Gets a pointer to a function that can evaluate the given Variant operator on the given Variant types.
 *
 * @param p_operator The variant operator.
 * @param p_type_a The type of the first Variant.
 * @param p_type_b The type of the second Variant.
 *
 * @return A pointer to a function that can evaluate the given Variant operator on the given Variant types.
 */
typedef GDExtensionPtrOperatorEvaluator (*GDExtensionInterfaceVariantGetPtrOperatorEvaluator)(GDExtensionVariantOperator p_operator, GDExtensionVariantType p_type_a, GDExtensionVariantType p_type_b);

/**
 * @name variant_get_ptr_builtin_method
 * @since 4.1
 *
 * Gets a pointer to a function that can call a builtin method on a type of Variant.
 *
 * @param p_type The Variant type.
 * @param p_method A pointer to a StringName with the method name.
 * @param p_hash A hash representing the method signature.
 *
 * @return A pointer to a function that can call a builtin method on a type of Variant.
 */
typedef GDExtensionPtrBuiltInMethod (*GDExtensionInterfaceVariantGetPtrBuiltinMethod)(GDExtensionVariantType p_type, GDExtensionConstStringNamePtr p_method, GDExtensionInt p_hash);

/**
 * @name variant_get_ptr_constructor
 * @since 4.1
 *
 * Gets a pointer to a function that can call one of the constructors for a type of Variant.
 *
 * @param p_type The Variant type.
 * @param p_constructor The index of the constructor.
 *
 * @return A pointer to a function that can call one of the constructors for a type of Variant.
 */
typedef GDExtensionPtrConstructor (*GDExtensionInterfaceVariantGetPtrConstructor)(GDExtensionVariantType p_type, int32_t p_constructor);

/**
 * @name variant_get_ptr_destructor
 * @since 4.1
 *
 * Gets a pointer to a function than can call the destructor for a type of Variant.
 *
 * @param p_type The Variant type.
 *
 * @return A pointer to a function than can call the destructor for a type of Variant.
 */
typedef GDExtensionPtrDestructor (*GDExtensionInterfaceVariantGetPtrDestructor)(GDExtensionVariantType p_type);

/**
 * @name variant_construct
 * @since 4.1
 *
 * Constructs a Variant of the given type, using the first constructor that matches the given arguments.
 *
 * @param p_type The Variant type.
 * @param p_base A pointer to a Variant to store the constructed value.
 * @param p_args A pointer to a C array of Variant pointers representing the arguments for the constructor.
 * @param p_argument_count The number of arguments to pass to the constructor.
 * @param r_error A pointer the structure which will be updated with error information.
 */
typedef void (*GDExtensionInterfaceVariantConstruct)(GDExtensionVariantType p_type, GDExtensionUninitializedVariantPtr r_base, const GDExtensionConstVariantPtr *p_args, int32_t p_argument_count, GDExtensionCallError *r_error);

/**
 * @name variant_get_ptr_setter
 * @since 4.1
 *
 * Gets a pointer to a function that can call a member's setter on the given Variant type.
 *
 * @param p_type The Variant type.
 * @param p_member A pointer to a StringName with the member name.
 *
 * @return A pointer to a function that can call a member's setter on the given Variant type.
 */
typedef GDExtensionPtrSetter (*GDExtensionInterfaceVariantGetPtrSetter)(GDExtensionVariantType p_type, GDExtensionConstStringNamePtr p_member);

/**
 * @name variant_get_ptr_getter
 * @since 4.1
 *
 * Gets a pointer to a function that can call a member's getter on the given Variant type.
 *
 * @param p_type The Variant type.
 * @param p_member A pointer to a StringName with the member name.
 *
 * @return A pointer to a function that can call a member's getter on the given Variant type.
 */
typedef GDExtensionPtrGetter (*GDExtensionInterfaceVariantGetPtrGetter)(GDExtensionVariantType p_type, GDExtensionConstStringNamePtr p_member);

/**
 * @name variant_get_ptr_indexed_setter
 * @since 4.1
 *
 * Gets a pointer to a function that can set an index on the given Variant type.
 *
 * @param p_type The Variant type.
 *
 * @return A pointer to a function that can set an index on the given Variant type.
 */
typedef GDExtensionPtrIndexedSetter (*GDExtensionInterfaceVariantGetPtrIndexedSetter)(GDExtensionVariantType p_type);

/**
 * @name variant_get_ptr_indexed_getter
 * @since 4.1
 *
 * Gets a pointer to a function that can get an index on the given Variant type.
 *
 * @param p_type The Variant type.
 *
 * @return A pointer to a function that can get an index on the given Variant type.
 */
typedef GDExtensionPtrIndexedGetter (*GDExtensionInterfaceVariantGetPtrIndexedGetter)(GDExtensionVariantType p_type);

/**
 * @name variant_get_ptr_keyed_setter
 * @since 4.1
 *
 * Gets a pointer to a function that can set a key on the given Variant type.
 *
 * @param p_type The Variant type.
 *
 * @return A pointer to a function that can set a key on the given Variant type.
 */
typedef GDExtensionPtrKeyedSetter (*GDExtensionInterfaceVariantGetPtrKeyedSetter)(GDExtensionVariantType p_type);

/**
 * @name variant_get_ptr_keyed_getter
 * @since 4.1
 *
 * Gets a pointer to a function that can get a key on the given Variant type.
 *
 * @param p_type The Variant type.
 *
 * @return A pointer to a function that can get a key on the given Variant type.
 */
typedef GDExtensionPtrKeyedGetter (*GDExtensionInterfaceVariantGetPtrKeyedGetter)(GDExtensionVariantType p_type);

/**
 * @name variant_get_ptr_keyed_checker
 * @since 4.1
 *
 * Gets a pointer to a function that can check a key on the given Variant type.
 *
 * @param p_type The Variant type.
 *
 * @return A pointer to a function that can check a key on the given Variant type.
 */
typedef GDExtensionPtrKeyedChecker (*GDExtensionInterfaceVariantGetPtrKeyedChecker)(GDExtensionVariantType p_type);

/**
 * @name variant_get_constant_value
 * @since 4.1
 *
 * Gets the value of a constant from the given Variant type.
 *
 * @param p_type The Variant type.
 * @param p_constant A pointer to a StringName with the constant name.
 * @param r_ret A pointer to a Variant to store the value.
 */
typedef void (*GDExtensionInterfaceVariantGetConstantValue)(GDExtensionVariantType p_type, GDExtensionConstStringNamePtr p_constant, GDExtensionUninitializedVariantPtr r_ret);

/**
 * @name variant_get_ptr_utility_function
 * @since 4.1
 *
 * Gets a pointer to a function that can call a Variant utility function.
 *
 * @param p_function A pointer to a StringName with the function name.
 * @param p_hash A hash representing the function signature.
 *
 * @return A pointer to a function that can call a Variant utility function.
 */
typedef GDExtensionPtrUtilityFunction (*GDExtensionInterfaceVariantGetPtrUtilityFunction)(GDExtensionConstStringNamePtr p_function, GDExtensionInt p_hash);

/* INTERFACE: String Utilities */

/**
 * @name string_new_with_latin1_chars
 * @since 4.1
 *
 * Creates a String from a Latin-1 encoded C string.
 *
 * @param r_dest A pointer to a Variant to hold the newly created String.
 * @param p_contents A pointer to a Latin-1 encoded C string (null terminated).
 */
typedef void (*GDExtensionInterfaceStringNewWithLatin1Chars)(GDExtensionUninitializedStringPtr r_dest, const char *p_contents);

/**
 * @name string_new_with_utf8_chars
 * @since 4.1
 *
 * Creates a String from a UTF-8 encoded C string.
 *
 * @param r_dest A pointer to a Variant to hold the newly created String.
 * @param p_contents A pointer to a UTF-8 encoded C string (null terminated).
 */
typedef void (*GDExtensionInterfaceStringNewWithUtf8Chars)(GDExtensionUninitializedStringPtr r_dest, const char *p_contents);

/**
 * @name string_new_with_utf16_chars
 * @since 4.1
 *
 * Creates a String from a UTF-16 encoded C string.
 *
 * @param r_dest A pointer to a Variant to hold the newly created String.
 * @param p_contents A pointer to a UTF-16 encoded C string (null terminated).
 */
typedef void (*GDExtensionInterfaceStringNewWithUtf16Chars)(GDExtensionUninitializedStringPtr r_dest, const char16_t *p_contents);

/**
 * @name string_new_with_utf32_chars
 * @since 4.1
 *
 * Creates a String from a UTF-32 encoded C string.
 *
 * @param r_dest A pointer to a Variant to hold the newly created String.
 * @param p_contents A pointer to a UTF-32 encoded C string (null terminated).
 */
typedef void (*GDExtensionInterfaceStringNewWithUtf32Chars)(GDExtensionUninitializedStringPtr r_dest, const char32_t *p_contents);

/**
 * @name string_new_with_wide_chars
 * @since 4.1
 *
 * Creates a String from a wide C string.
 *
 * @param r_dest A pointer to a Variant to hold the newly created String.
 * @param p_contents A pointer to a wide C string (null terminated).
 */
typedef void (*GDExtensionInterfaceStringNewWithWideChars)(GDExtensionUninitializedStringPtr r_dest, const wchar_t *p_contents);

/**
 * @name string_new_with_latin1_chars_and_len
 * @since 4.1
 *
 * Creates a String from a Latin-1 encoded C string with the given length.
 *
 * @param r_dest A pointer to a Variant to hold the newly created String.
 * @param p_contents A pointer to a Latin-1 encoded C string.
 * @param p_size The number of characters (= number of bytes).
 */
typedef void (*GDExtensionInterfaceStringNewWithLatin1CharsAndLen)(GDExtensionUninitializedStringPtr r_dest, const char *p_contents, GDExtensionInt p_size);

/**
 * @name string_new_with_utf8_chars_and_len
 * @since 4.1
 *
 * Creates a String from a UTF-8 encoded C string with the given length.
 *
 * @param r_dest A pointer to a Variant to hold the newly created String.
 * @param p_contents A pointer to a UTF-8 encoded C string.
 * @param p_size The number of bytes (not code units).
 */
typedef void (*GDExtensionInterfaceStringNewWithUtf8CharsAndLen)(GDExtensionUninitializedStringPtr r_dest, const char *p_contents, GDExtensionInt p_size);

/**
 * @name string_new_with_utf16_chars_and_len
 * @since 4.1
 *
 * Creates a String from a UTF-16 encoded C string with the given length.
 *
 * @param r_dest A pointer to a Variant to hold the newly created String.
 * @param p_contents A pointer to a UTF-16 encoded C string.
 * @param p_size The number of characters (not bytes).
 */
typedef void (*GDExtensionInterfaceStringNewWithUtf16CharsAndLen)(GDExtensionUninitializedStringPtr r_dest, const char16_t *p_contents, GDExtensionInt p_char_count);

/**
 * @name string_new_with_utf32_chars_and_len
 * @since 4.1
 *
 * Creates a String from a UTF-32 encoded C string with the given length.
 *
 * @param r_dest A pointer to a Variant to hold the newly created String.
 * @param p_contents A pointer to a UTF-32 encoded C string.
 * @param p_size The number of characters (not bytes).
 */
typedef void (*GDExtensionInterfaceStringNewWithUtf32CharsAndLen)(GDExtensionUninitializedStringPtr r_dest, const char32_t *p_contents, GDExtensionInt p_char_count);

/**
 * @name string_new_with_wide_chars_and_len
 * @since 4.1
 *
 * Creates a String from a wide C string with the given length.
 *
 * @param r_dest A pointer to a Variant to hold the newly created String.
 * @param p_contents A pointer to a wide C string.
 * @param p_size The number of characters (not bytes).
 */
typedef void (*GDExtensionInterfaceStringNewWithWideCharsAndLen)(GDExtensionUninitializedStringPtr r_dest, const wchar_t *p_contents, GDExtensionInt p_char_count);

/**
 * @name string_to_latin1_chars
 * @since 4.1
 *
 * Converts a String to a Latin-1 encoded C string.
 *
 * It doesn't write a null terminator.
 *
 * @param p_self A pointer to the String.
 * @param r_text A pointer to the buffer to hold the resulting data. If NULL is passed in, only the length will be computed.
 * @param p_max_write_length The maximum number of characters that can be written to r_text. It has no affect on the return value.
 *
 * @return The resulting encoded string length in characters (not bytes), not including a null terminator.
 */
typedef GDExtensionInt (*GDExtensionInterfaceStringToLatin1Chars)(GDExtensionConstStringPtr p_self, char *r_text, GDExtensionInt p_max_write_length);

/**
 * @name string_to_utf8_chars
 * @since 4.1
 *
 * Converts a String to a UTF-8 encoded C string.
 *
 * It doesn't write a null terminator.
 *
 * @param p_self A pointer to the String.
 * @param r_text A pointer to the buffer to hold the resulting data. If NULL is passed in, only the length will be computed.
 * @param p_max_write_length The maximum number of characters that can be written to r_text. It has no affect on the return value.
 *
 * @return The resulting encoded string length in characters (not bytes), not including a null terminator.
 */
typedef GDExtensionInt (*GDExtensionInterfaceStringToUtf8Chars)(GDExtensionConstStringPtr p_self, char *r_text, GDExtensionInt p_max_write_length);

/**
 * @name string_to_utf16_chars
 * @since 4.1
 *
 * Converts a String to a UTF-16 encoded C string.
 *
 * It doesn't write a null terminator.
 *
 * @param p_self A pointer to the String.
 * @param r_text A pointer to the buffer to hold the resulting data. If NULL is passed in, only the length will be computed.
 * @param p_max_write_length The maximum number of characters that can be written to r_text. It has no affect on the return value.
 *
 * @return The resulting encoded string length in characters (not bytes), not including a null terminator.
 */
typedef GDExtensionInt (*GDExtensionInterfaceStringToUtf16Chars)(GDExtensionConstStringPtr p_self, char16_t *r_text, GDExtensionInt p_max_write_length);

/**
 * @name string_to_utf32_chars
 * @since 4.1
 *
 * Converts a String to a UTF-32 encoded C string.
 *
 * It doesn't write a null terminator.
 *
 * @param p_self A pointer to the String.
 * @param r_text A pointer to the buffer to hold the resulting data. If NULL is passed in, only the length will be computed.
 * @param p_max_write_length The maximum number of characters that can be written to r_text. It has no affect on the return value.
 *
 * @return The resulting encoded string length in characters (not bytes), not including a null terminator.
 */
typedef GDExtensionInt (*GDExtensionInterfaceStringToUtf32Chars)(GDExtensionConstStringPtr p_self, char32_t *r_text, GDExtensionInt p_max_write_length);

/**
 * @name string_to_wide_chars
 * @since 4.1
 *
 * Converts a String to a wide C string.
 *
 * It doesn't write a null terminator.
 *
 * @param p_self A pointer to the String.
 * @param r_text A pointer to the buffer to hold the resulting data. If NULL is passed in, only the length will be computed.
 * @param p_max_write_length The maximum number of characters that can be written to r_text. It has no affect on the return value.
 *
 * @return The resulting encoded string length in characters (not bytes), not including a null terminator.
 */
typedef GDExtensionInt (*GDExtensionInterfaceStringToWideChars)(GDExtensionConstStringPtr p_self, wchar_t *r_text, GDExtensionInt p_max_write_length);

/**
 * @name string_operator_index
 * @since 4.1
 *
 * Gets a pointer to the character at the given index from a String.
 *
 * @param p_self A pointer to the String.
 * @param p_index The index.
 *
 * @return A pointer to the requested character.
 */
typedef char32_t *(*GDExtensionInterfaceStringOperatorIndex)(GDExtensionStringPtr p_self, GDExtensionInt p_index);

/**
 * @name string_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to the character at the given index from a String.
 *
 * @param p_self A pointer to the String.
 * @param p_index The index.
 *
 * @return A const pointer to the requested character.
 */
typedef const char32_t *(*GDExtensionInterfaceStringOperatorIndexConst)(GDExtensionConstStringPtr p_self, GDExtensionInt p_index);

/**
 * @name string_operator_plus_eq_string
 * @since 4.1
 *
 * Appends another String to a String.
 *
 * @param p_self A pointer to the String.
 * @param p_b A pointer to the other String to append.
 */
typedef void (*GDExtensionInterfaceStringOperatorPlusEqString)(GDExtensionStringPtr p_self, GDExtensionConstStringPtr p_b);

/**
 * @name string_operator_plus_eq_char
 * @since 4.1
 *
 * Appends a character to a String.
 *
 * @param p_self A pointer to the String.
 * @param p_b A pointer to the character to append.
 */
typedef void (*GDExtensionInterfaceStringOperatorPlusEqChar)(GDExtensionStringPtr p_self, char32_t p_b);

/**
 * @name string_operator_plus_eq_cstr
 * @since 4.1
 *
 * Appends a Latin-1 encoded C string to a String.
 *
 * @param p_self A pointer to the String.
 * @param p_b A pointer to a Latin-1 encoded C string (null terminated).
 */
typedef void (*GDExtensionInterfaceStringOperatorPlusEqCstr)(GDExtensionStringPtr p_self, const char *p_b);

/**
 * @name string_operator_plus_eq_wcstr
 * @since 4.1
 *
 * Appends a wide C string to a String.
 *
 * @param p_self A pointer to the String.
 * @param p_b A pointer to a wide C string (null terminated).
 */
typedef void (*GDExtensionInterfaceStringOperatorPlusEqWcstr)(GDExtensionStringPtr p_self, const wchar_t *p_b);

/**
 * @name string_operator_plus_eq_c32str
 * @since 4.1
 *
 * Appends a UTF-32 encoded C string to a String.
 *
 * @param p_self A pointer to the String.
 * @param p_b A pointer to a UTF-32 encoded C string (null terminated).
 */
typedef void (*GDExtensionInterfaceStringOperatorPlusEqC32str)(GDExtensionStringPtr p_self, const char32_t *p_b);

/**
 * @name string_resize
 * @since 4.2
 *
 * Resizes the underlying string data to the given number of characters.
 *
 * Space needs to be allocated for the null terminating character ('\0') which
 * also must be added manually, in order for all string functions to work correctly.
 *
 * Warning: This is an error-prone operation - only use it if there's no other
 * efficient way to accomplish your goal.
 *
 * @param p_self A pointer to the String.
 * @param p_resize The new length for the String.
 *
 * @return Error code signifying if the operation successful.
 */
typedef GDExtensionInt (*GDExtensionInterfaceStringResize)(GDExtensionStringPtr p_self, GDExtensionInt p_resize);

/* INTERFACE: StringName Utilities */

/**
 * @name string_name_new_with_latin1_chars
 * @since 4.2
 *
 * Creates a StringName from a Latin-1 encoded C string.
 *
 * If `p_is_static` is true, then:
 * - The StringName will reuse the `p_contents` buffer instead of copying it.
 *   You must guarantee that the buffer remains valid for the duration of the application (e.g. string literal).
 * - You must not call a destructor for this StringName. Incrementing the initial reference once should achieve this.
 *
 * `p_is_static` is purely an optimization and can easily introduce undefined behavior if used wrong. In case of doubt, set it to false.
 *
 * @param r_dest A pointer to uninitialized storage, into which the newly created StringName is constructed.
 * @param p_contents A pointer to a C string (null terminated and Latin-1 or ASCII encoded).
 * @param p_is_static Whether the StringName reuses the buffer directly (see above).
 */
typedef void (*GDExtensionInterfaceStringNameNewWithLatin1Chars)(GDExtensionUninitializedStringNamePtr r_dest, const char *p_contents, GDExtensionBool p_is_static);

/**
 * @name string_name_new_with_utf8_chars
 * @since 4.2
 *
 * Creates a StringName from a UTF-8 encoded C string.
 *
 * @param r_dest A pointer to uninitialized storage, into which the newly created StringName is constructed.
 * @param p_contents A pointer to a C string (null terminated and UTF-8 encoded).
 */
typedef void (*GDExtensionInterfaceStringNameNewWithUtf8Chars)(GDExtensionUninitializedStringNamePtr r_dest, const char *p_contents);

/**
 * @name string_name_new_with_utf8_chars_and_len
 * @since 4.2
 *
 * Creates a StringName from a UTF-8 encoded string with a given number of characters.
 *
 * @param r_dest A pointer to uninitialized storage, into which the newly created StringName is constructed.
 * @param p_contents A pointer to a C string (null terminated and UTF-8 encoded).
 * @param p_size The number of bytes (not UTF-8 code points).
 */
typedef void (*GDExtensionInterfaceStringNameNewWithUtf8CharsAndLen)(GDExtensionUninitializedStringNamePtr r_dest, const char *p_contents, GDExtensionInt p_size);

/* INTERFACE: XMLParser Utilities */

/**
 * @name xml_parser_open_buffer
 * @since 4.1
 *
 * Opens a raw XML buffer on an XMLParser instance.
 *
 * @param p_instance A pointer to an XMLParser object.
 * @param p_buffer A pointer to the buffer.
 * @param p_size The size of the buffer.
 *
 * @return A Godot error code (ex. OK, ERR_INVALID_DATA, etc).
 *
 * @see XMLParser::open_buffer()
 */
typedef GDExtensionInt (*GDExtensionInterfaceXmlParserOpenBuffer)(GDExtensionObjectPtr p_instance, const uint8_t *p_buffer, size_t p_size);

/* INTERFACE: FileAccess Utilities */

/**
 * @name file_access_store_buffer
 * @since 4.1
 *
 * Stores the given buffer using an instance of FileAccess.
 *
 * @param p_instance A pointer to a FileAccess object.
 * @param p_src A pointer to the buffer.
 * @param p_length The size of the buffer.
 *
 * @see FileAccess::store_buffer()
 */
typedef void (*GDExtensionInterfaceFileAccessStoreBuffer)(GDExtensionObjectPtr p_instance, const uint8_t *p_src, uint64_t p_length);

/**
 * @name file_access_get_buffer
 * @since 4.1
 *
 * Reads the next p_length bytes into the given buffer using an instance of FileAccess.
 *
 * @param p_instance A pointer to a FileAccess object.
 * @param p_dst A pointer to the buffer to store the data.
 * @param p_length The requested number of bytes to read.
 *
 * @return The actual number of bytes read (may be less than requested).
 */
typedef uint64_t (*GDExtensionInterfaceFileAccessGetBuffer)(GDExtensionConstObjectPtr p_instance, uint8_t *p_dst, uint64_t p_length);

/* INTERFACE: WorkerThreadPool Utilities */

/**
 * @name worker_thread_pool_add_native_group_task
 * @since 4.1
 *
 * Adds a group task to an instance of WorkerThreadPool.
 *
 * @param p_instance A pointer to a WorkerThreadPool object.
 * @param p_func A pointer to a function to run in the thread pool.
 * @param p_userdata A pointer to arbitrary data which will be passed to p_func.
 * @param p_tasks The number of tasks needed in the group.
 * @param p_high_priority Whether or not this is a high priority task.
 * @param p_description A pointer to a String with the task description.
 *
 * @return The task group ID.
 *
 * @see WorkerThreadPool::add_group_task()
 */
typedef int64_t (*GDExtensionInterfaceWorkerThreadPoolAddNativeGroupTask)(GDExtensionObjectPtr p_instance, void (*p_func)(void *, uint32_t), void *p_userdata, int p_elements, int p_tasks, GDExtensionBool p_high_priority, GDExtensionConstStringPtr p_description);

/**
 * @name worker_thread_pool_add_native_task
 * @since 4.1
 *
 * Adds a task to an instance of WorkerThreadPool.
 *
 * @param p_instance A pointer to a WorkerThreadPool object.
 * @param p_func A pointer to a function to run in the thread pool.
 * @param p_userdata A pointer to arbitrary data which will be passed to p_func.
 * @param p_high_priority Whether or not this is a high priority task.
 * @param p_description A pointer to a String with the task description.
 *
 * @return The task ID.
 */
typedef int64_t (*GDExtensionInterfaceWorkerThreadPoolAddNativeTask)(GDExtensionObjectPtr p_instance, void (*p_func)(void *), void *p_userdata, GDExtensionBool p_high_priority, GDExtensionConstStringPtr p_description);

/* INTERFACE: Packed Array */

/**
 * @name packed_byte_array_operator_index
 * @since 4.1
 *
 * Gets a pointer to a byte in a PackedByteArray.
 *
 * @param p_self A pointer to a PackedByteArray object.
 * @param p_index The index of the byte to get.
 *
 * @return A pointer to the requested byte.
 */
typedef uint8_t *(*GDExtensionInterfacePackedByteArrayOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_byte_array_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a byte in a PackedByteArray.
 *
 * @param p_self A const pointer to a PackedByteArray object.
 * @param p_index The index of the byte to get.
 *
 * @return A const pointer to the requested byte.
 */
typedef const uint8_t *(*GDExtensionInterfacePackedByteArrayOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_color_array_operator_index
 * @since 4.1
 *
 * Gets a pointer to a color in a PackedColorArray.
 *
 * @param p_self A pointer to a PackedColorArray object.
 * @param p_index The index of the Color to get.
 *
 * @return A pointer to the requested Color.
 */
typedef GDExtensionTypePtr (*GDExtensionInterfacePackedColorArrayOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_color_array_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a color in a PackedColorArray.
 *
 * @param p_self A const pointer to a const PackedColorArray object.
 * @param p_index The index of the Color to get.
 *
 * @return A const pointer to the requested Color.
 */
typedef GDExtensionTypePtr (*GDExtensionInterfacePackedColorArrayOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_float32_array_operator_index
 * @since 4.1
 *
 * Gets a pointer to a 32-bit float in a PackedFloat32Array.
 *
 * @param p_self A pointer to a PackedFloat32Array object.
 * @param p_index The index of the float to get.
 *
 * @return A pointer to the requested 32-bit float.
 */
typedef float *(*GDExtensionInterfacePackedFloat32ArrayOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_float32_array_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a 32-bit float in a PackedFloat32Array.
 *
 * @param p_self A const pointer to a PackedFloat32Array object.
 * @param p_index The index of the float to get.
 *
 * @return A const pointer to the requested 32-bit float.
 */
typedef const float *(*GDExtensionInterfacePackedFloat32ArrayOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_float64_array_operator_index
 * @since 4.1
 *
 * Gets a pointer to a 64-bit float in a PackedFloat64Array.
 *
 * @param p_self A pointer to a PackedFloat64Array object.
 * @param p_index The index of the float to get.
 *
 * @return A pointer to the requested 64-bit float.
 */
typedef double *(*GDExtensionInterfacePackedFloat64ArrayOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_float64_array_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a 64-bit float in a PackedFloat64Array.
 *
 * @param p_self A const pointer to a PackedFloat64Array object.
 * @param p_index The index of the float to get.
 *
 * @return A const pointer to the requested 64-bit float.
 */
typedef const double *(*GDExtensionInterfacePackedFloat64ArrayOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_int32_array_operator_index
 * @since 4.1
 *
 * Gets a pointer to a 32-bit integer in a PackedInt32Array.
 *
 * @param p_self A pointer to a PackedInt32Array object.
 * @param p_index The index of the integer to get.
 *
 * @return A pointer to the requested 32-bit integer.
 */
typedef int32_t *(*GDExtensionInterfacePackedInt32ArrayOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_int32_array_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a 32-bit integer in a PackedInt32Array.
 *
 * @param p_self A const pointer to a PackedInt32Array object.
 * @param p_index The index of the integer to get.
 *
 * @return A const pointer to the requested 32-bit integer.
 */
typedef const int32_t *(*GDExtensionInterfacePackedInt32ArrayOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_int64_array_operator_index
 * @since 4.1
 *
 * Gets a pointer to a 64-bit integer in a PackedInt64Array.
 *
 * @param p_self A pointer to a PackedInt64Array object.
 * @param p_index The index of the integer to get.
 *
 * @return A pointer to the requested 64-bit integer.
 */
typedef int64_t *(*GDExtensionInterfacePackedInt64ArrayOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_int64_array_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a 64-bit integer in a PackedInt64Array.
 *
 * @param p_self A const pointer to a PackedInt64Array object.
 * @param p_index The index of the integer to get.
 *
 * @return A const pointer to the requested 64-bit integer.
 */
typedef const int64_t *(*GDExtensionInterfacePackedInt64ArrayOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_string_array_operator_index
 * @since 4.1
 *
 * Gets a pointer to a string in a PackedStringArray.
 *
 * @param p_self A pointer to a PackedStringArray object.
 * @param p_index The index of the String to get.
 *
 * @return A pointer to the requested String.
 */
typedef GDExtensionStringPtr (*GDExtensionInterfacePackedStringArrayOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_string_array_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a string in a PackedStringArray.
 *
 * @param p_self A const pointer to a PackedStringArray object.
 * @param p_index The index of the String to get.
 *
 * @return A const pointer to the requested String.
 */
typedef GDExtensionStringPtr (*GDExtensionInterfacePackedStringArrayOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_vector2_array_operator_index
 * @since 4.1
 *
 * Gets a pointer to a Vector2 in a PackedVector2Array.
 *
 * @param p_self A pointer to a PackedVector2Array object.
 * @param p_index The index of the Vector2 to get.
 *
 * @return A pointer to the requested Vector2.
 */
typedef GDExtensionTypePtr (*GDExtensionInterfacePackedVector2ArrayOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_vector2_array_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a Vector2 in a PackedVector2Array.
 *
 * @param p_self A const pointer to a PackedVector2Array object.
 * @param p_index The index of the Vector2 to get.
 *
 * @return A const pointer to the requested Vector2.
 */
typedef GDExtensionTypePtr (*GDExtensionInterfacePackedVector2ArrayOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_vector3_array_operator_index
 * @since 4.1
 *
 * Gets a pointer to a Vector3 in a PackedVector3Array.
 *
 * @param p_self A pointer to a PackedVector3Array object.
 * @param p_index The index of the Vector3 to get.
 *
 * @return A pointer to the requested Vector3.
 */
typedef GDExtensionTypePtr (*GDExtensionInterfacePackedVector3ArrayOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionInt p_index);

/**
 * @name packed_vector3_array_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a Vector3 in a PackedVector3Array.
 *
 * @param p_self A const pointer to a PackedVector3Array object.
 * @param p_index The index of the Vector3 to get.
 *
 * @return A const pointer to the requested Vector3.
 */
typedef GDExtensionTypePtr (*GDExtensionInterfacePackedVector3ArrayOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionInt p_index);

/**
 * @name array_operator_index
 * @since 4.1
 *
 * Gets a pointer to a Variant in an Array.
 *
 * @param p_self A pointer to an Array object.
 * @param p_index The index of the Variant to get.
 *
 * @return A pointer to the requested Variant.
 */
typedef GDExtensionVariantPtr (*GDExtensionInterfaceArrayOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionInt p_index);

/**
 * @name array_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a Variant in an Array.
 *
 * @param p_self A const pointer to an Array object.
 * @param p_index The index of the Variant to get.
 *
 * @return A const pointer to the requested Variant.
 */
typedef GDExtensionVariantPtr (*GDExtensionInterfaceArrayOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionInt p_index);

/**
 * @name array_ref
 * @since 4.1
 *
 * Sets an Array to be a reference to another Array object.
 *
 * @param p_self A pointer to the Array object to update.
 * @param p_from A pointer to the Array object to reference.
 */
typedef void (*GDExtensionInterfaceArrayRef)(GDExtensionTypePtr p_self, GDExtensionConstTypePtr p_from);

/**
 * @name array_set_typed
 * @since 4.1
 *
 * Makes an Array into a typed Array.
 *
 * @param p_self A pointer to the Array.
 * @param p_type The type of Variant the Array will store.
 * @param p_class_name A pointer to a StringName with the name of the object (if p_type is GDEXTENSION_VARIANT_TYPE_OBJECT).
 * @param p_script A pointer to a Script object (if p_type is GDEXTENSION_VARIANT_TYPE_OBJECT and the base class is extended by a script).
 */
typedef void (*GDExtensionInterfaceArraySetTyped)(GDExtensionTypePtr p_self, GDExtensionVariantType p_type, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstVariantPtr p_script);

/* INTERFACE: Dictionary */

/**
 * @name dictionary_operator_index
 * @since 4.1
 *
 * Gets a pointer to a Variant in a Dictionary with the given key.
 *
 * @param p_self A pointer to a Dictionary object.
 * @param p_key A pointer to a Variant representing the key.
 *
 * @return A pointer to a Variant representing the value at the given key.
 */
typedef GDExtensionVariantPtr (*GDExtensionInterfaceDictionaryOperatorIndex)(GDExtensionTypePtr p_self, GDExtensionConstVariantPtr p_key);

/**
 * @name dictionary_operator_index_const
 * @since 4.1
 *
 * Gets a const pointer to a Variant in a Dictionary with the given key.
 *
 * @param p_self A const pointer to a Dictionary object.
 * @param p_key A pointer to a Variant representing the key.
 *
 * @return A const pointer to a Variant representing the value at the given key.
 */
typedef GDExtensionVariantPtr (*GDExtensionInterfaceDictionaryOperatorIndexConst)(GDExtensionConstTypePtr p_self, GDExtensionConstVariantPtr p_key);

/* INTERFACE: Object */

/**
 * @name object_method_bind_call
 * @since 4.1
 *
 * Calls a method on an Object.
 *
 * @param p_method_bind A pointer to the MethodBind representing the method on the Object's class.
 * @param p_instance A pointer to the Object.
 * @param p_args A pointer to a C array of Variants representing the arguments.
 * @param p_arg_count The number of arguments.
 * @param r_ret A pointer to Variant which will receive the return value.
 * @param r_error A pointer to a GDExtensionCallError struct that will receive error information.
 */
typedef void (*GDExtensionInterfaceObjectMethodBindCall)(GDExtensionMethodBindPtr p_method_bind, GDExtensionObjectPtr p_instance, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_arg_count, GDExtensionUninitializedVariantPtr r_ret, GDExtensionCallError *r_error);

/**
 * @name object_method_bind_ptrcall
 * @since 4.1
 *
 * Calls a method on an Object (using a "ptrcall").
 *
 * @param p_method_bind A pointer to the MethodBind representing the method on the Object's class.
 * @param p_instance A pointer to the Object.
 * @param p_args A pointer to a C array representing the arguments.
 * @param r_ret A pointer to the Object that will receive the return value.
 */
typedef void (*GDExtensionInterfaceObjectMethodBindPtrcall)(GDExtensionMethodBindPtr p_method_bind, GDExtensionObjectPtr p_instance, const GDExtensionConstTypePtr *p_args, GDExtensionTypePtr r_ret);

/**
 * @name object_destroy
 * @since 4.1
 *
 * Destroys an Object.
 *
 * @param p_o A pointer to the Object.
 */
typedef void (*GDExtensionInterfaceObjectDestroy)(GDExtensionObjectPtr p_o);

/**
 * @name global_get_singleton
 * @since 4.1
 *
 * Gets a global singleton by name.
 *
 * @param p_name A pointer to a StringName with the singleton name.
 *
 * @return A pointer to the singleton Object.
 */
typedef GDExtensionObjectPtr (*GDExtensionInterfaceGlobalGetSingleton)(GDExtensionConstStringNamePtr p_name);

/**
 * @name object_get_instance_binding
 * @since 4.1
 *
 * Gets a pointer representing an Object's instance binding.
 *
 * @param p_o A pointer to the Object.
 * @param p_library A token the library received by the GDExtension's entry point function.
 * @param p_callbacks A pointer to a GDExtensionInstanceBindingCallbacks struct.
 *
 * @return
 */
typedef void *(*GDExtensionInterfaceObjectGetInstanceBinding)(GDExtensionObjectPtr p_o, void *p_token, const GDExtensionInstanceBindingCallbacks *p_callbacks);

/**
 * @name object_set_instance_binding
 * @since 4.1
 *
 * Sets an Object's instance binding.
 *
 * @param p_o A pointer to the Object.
 * @param p_library A token the library received by the GDExtension's entry point function.
 * @param p_binding A pointer to the instance binding.
 * @param p_callbacks A pointer to a GDExtensionInstanceBindingCallbacks struct.
 */
typedef void (*GDExtensionInterfaceObjectSetInstanceBinding)(GDExtensionObjectPtr p_o, void *p_token, void *p_binding, const GDExtensionInstanceBindingCallbacks *p_callbacks);

/**
 * @name object_free_instance_binding
 * @since 4.2
 *
 * Free an Object's instance binding.
 *
 * @param p_o A pointer to the Object.
 * @param p_library A token the library received by the GDExtension's entry point function.
 */
typedef void (*GDExtensionInterfaceObjectFreeInstanceBinding)(GDExtensionObjectPtr p_o, void *p_token);

/**
 * @name object_set_instance
 * @since 4.1
 *
 * Sets an extension class instance on a Object.
 *
 * @param p_o A pointer to the Object.
 * @param p_classname A pointer to a StringName with the registered extension class's name.
 * @param p_instance A pointer to the extension class instance.
 */
typedef void (*GDExtensionInterfaceObjectSetInstance)(GDExtensionObjectPtr p_o, GDExtensionConstStringNamePtr p_classname, GDExtensionClassInstancePtr p_instance); /* p_classname should be a registered extension class and should extend the p_o object's class. */

/**
 * @name object_get_class_name
 * @since 4.1
 *
 * Gets the class name of an Object.
 *
 * If the GDExtension wraps the Godot object in an abstraction specific to its class, this is the
 * function that should be used to determine which wrapper to use.
 *
 * @param p_object A pointer to the Object.
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param r_class_name A pointer to a String to receive the class name.
 *
 * @return true if successful in getting the class name; otherwise false.
 */
typedef GDExtensionBool (*GDExtensionInterfaceObjectGetClassName)(GDExtensionConstObjectPtr p_object, GDExtensionClassLibraryPtr p_library, GDExtensionUninitializedStringNamePtr r_class_name);

/**
 * @name object_cast_to
 * @since 4.1
 *
 * Casts an Object to a different type.
 *
 * @param p_object A pointer to the Object.
 * @param p_class_tag A pointer uniquely identifying a built-in class in the ClassDB.
 *
 * @return Returns a pointer to the Object, or NULL if it can't be cast to the requested type.
 */
typedef GDExtensionObjectPtr (*GDExtensionInterfaceObjectCastTo)(GDExtensionConstObjectPtr p_object, void *p_class_tag);

/**
 * @name object_get_instance_from_id
 * @since 4.1
 *
 * Gets an Object by its instance ID.
 *
 * @param p_instance_id The instance ID.
 *
 * @return A pointer to the Object.
 */
typedef GDExtensionObjectPtr (*GDExtensionInterfaceObjectGetInstanceFromId)(GDObjectInstanceID p_instance_id);

/**
 * @name object_get_instance_id
 * @since 4.1
 *
 * Gets the instance ID from an Object.
 *
 * @param p_object A pointer to the Object.
 *
 * @return The instance ID.
 */
typedef GDObjectInstanceID (*GDExtensionInterfaceObjectGetInstanceId)(GDExtensionConstObjectPtr p_object);

/**
 * @name object_has_script_method
 * @since 4.3
 *
 * Checks if this object has a script with the given method.
 *
 * @param p_object A pointer to the Object.
 * @param p_method A pointer to a StringName identifying the method.
 *
 * @returns true if the object has a script and that script has a method with the given name. Returns false if the object has no script.
 */
typedef GDExtensionBool (*GDExtensionInterfaceObjectHasScriptMethod)(GDExtensionConstObjectPtr p_object, GDExtensionConstStringNamePtr p_method);

/**
 * @name object_call_script_method
 * @since 4.3
 *
 * Call the given script method on this object.
 *
 * @param p_object A pointer to the Object.
 * @param p_method A pointer to a StringName identifying the method.
 * @param p_args A pointer to a C array of Variant.
 * @param p_argument_count The number of arguments.
 * @param r_return A pointer a Variant which will be assigned the return value.
 * @param r_error A pointer the structure which will hold error information.
 */
typedef void (*GDExtensionInterfaceObjectCallScriptMethod)(GDExtensionObjectPtr p_object, GDExtensionConstStringNamePtr p_method, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionUninitializedVariantPtr r_return, GDExtensionCallError *r_error);

/* INTERFACE: Reference */

/**
 * @name ref_get_object
 * @since 4.1
 *
 * Gets the Object from a reference.
 *
 * @param p_ref A pointer to the reference.
 *
 * @return A pointer to the Object from the reference or NULL.
 */
typedef GDExtensionObjectPtr (*GDExtensionInterfaceRefGetObject)(GDExtensionConstRefPtr p_ref);

/**
 * @name ref_set_object
 * @since 4.1
 *
 * Sets the Object referred to by a reference.
 *
 * @param p_ref A pointer to the reference.
 * @param p_object A pointer to the Object to refer to.
 */
typedef void (*GDExtensionInterfaceRefSetObject)(GDExtensionRefPtr p_ref, GDExtensionObjectPtr p_object);

/* INTERFACE: Script Instance */

/**
 * @name script_instance_create
 * @since 4.1
 * @deprecated in Godot 4.2. Use `script_instance_create2` instead.
 *
 * Creates a script instance that contains the given info and instance data.
 *
 * @param p_info A pointer to a GDExtensionScriptInstanceInfo struct.
 * @param p_instance_data A pointer to a data representing the script instance in the GDExtension. This will be passed to all the function pointers on p_info.
 *
 * @return A pointer to a ScriptInstanceExtension object.
 */
typedef GDExtensionScriptInstancePtr (*GDExtensionInterfaceScriptInstanceCreate)(const GDExtensionScriptInstanceInfo *p_info, GDExtensionScriptInstanceDataPtr p_instance_data);

/**
 * @name script_instance_create2
 * @since 4.2
 *
 * Creates a script instance that contains the given info and instance data.
 *
 * @param p_info A pointer to a GDExtensionScriptInstanceInfo2 struct.
 * @param p_instance_data A pointer to a data representing the script instance in the GDExtension. This will be passed to all the function pointers on p_info.
 *
 * @return A pointer to a ScriptInstanceExtension object.
 */
typedef GDExtensionScriptInstancePtr (*GDExtensionInterfaceScriptInstanceCreate2)(const GDExtensionScriptInstanceInfo2 *p_info, GDExtensionScriptInstanceDataPtr p_instance_data);

/**
 * @name placeholder_script_instance_create
 * @since 4.2
 *
 * Creates a placeholder script instance for a given script and instance.
 *
 * This interface is optional as a custom placeholder could also be created with script_instance_create().
 *
 * @param p_language A pointer to a ScriptLanguage.
 * @param p_script A pointer to a Script.
 * @param p_owner A pointer to an Object.
 *
 * @return A pointer to a PlaceHolderScriptInstance object.
 */
typedef GDExtensionScriptInstancePtr (*GDExtensionInterfacePlaceHolderScriptInstanceCreate)(GDExtensionObjectPtr p_language, GDExtensionObjectPtr p_script, GDExtensionObjectPtr p_owner);

/**
 * @name placeholder_script_instance_update
 * @since 4.2
 *
 * Updates a placeholder script instance with the given properties and values.
 *
 * The passed in placeholder must be an instance of PlaceHolderScriptInstance
 * such as the one returned by placeholder_script_instance_create().
 *
 * @param p_placeholder A pointer to a PlaceHolderScriptInstance.
 * @param p_properties A pointer to an Array of Dictionary representing PropertyInfo.
 * @param p_values A pointer to a Dictionary mapping StringName to Variant values.
 */
typedef void (*GDExtensionInterfacePlaceHolderScriptInstanceUpdate)(GDExtensionScriptInstancePtr p_placeholder, GDExtensionConstTypePtr p_properties, GDExtensionConstTypePtr p_values);

/**
 * @name object_get_script_instance
 * @since 4.2
 *
 * Get the script instance data attached to this object.
 *
 * @param p_object A pointer to the Object.
 * @param p_language A pointer to the language expected for this script instance.
 *
 * @return A GDExtensionScriptInstanceDataPtr that was attached to this object as part of script_instance_create.
 */
typedef GDExtensionScriptInstanceDataPtr (*GDExtensionInterfaceObjectGetScriptInstance)(GDExtensionConstObjectPtr p_object, GDExtensionObjectPtr p_language);

/* INTERFACE: Callable */

/**
 * @name callable_custom_create
 * @since 4.2
 *
 * Creates a custom Callable object from a function pointer.
 *
 * Provided struct can be safely freed once the function returns.
 *
 * @param r_callable A pointer that will receive the new Callable.
 * @param p_callable_custom_info The info required to construct a Callable.
 */
typedef void (*GDExtensionInterfaceCallableCustomCreate)(GDExtensionUninitializedTypePtr r_callable, GDExtensionCallableCustomInfo *p_callable_custom_info);

/**
 * @name callable_custom_get_userdata
 * @since 4.2
 *
 * Retrieves the userdata pointer from a custom Callable.
 *
 * If the Callable is not a custom Callable or the token does not match the one provided to callable_custom_create() via GDExtensionCallableCustomInfo then NULL will be returned.
 *
 * @param p_callable A pointer to a Callable.
 * @param p_token A pointer to an address that uniquely identifies the GDExtension.
 */
typedef void *(*GDExtensionInterfaceCallableCustomGetUserData)(GDExtensionConstTypePtr p_callable, void *p_token);

/* INTERFACE: ClassDB */

/**
 * @name classdb_construct_object
 * @since 4.1
 *
 * Constructs an Object of the requested class.
 *
 * The passed class must be a built-in godot class, or an already-registered extension class. In both cases, object_set_instance() should be called to fully initialize the object.
 *
 * @param p_classname A pointer to a StringName with the class name.
 *
 * @return A pointer to the newly created Object.
 */
typedef GDExtensionObjectPtr (*GDExtensionInterfaceClassdbConstructObject)(GDExtensionConstStringNamePtr p_classname);

/**
 * @name classdb_get_method_bind
 * @since 4.1
 *
 * Gets a pointer to the MethodBind in ClassDB for the given class, method and hash.
 *
 * @param p_classname A pointer to a StringName with the class name.
 * @param p_methodname A pointer to a StringName with the method name.
 * @param p_hash A hash representing the function signature.
 *
 * @return A pointer to the MethodBind from ClassDB.
 */
typedef GDExtensionMethodBindPtr (*GDExtensionInterfaceClassdbGetMethodBind)(GDExtensionConstStringNamePtr p_classname, GDExtensionConstStringNamePtr p_methodname, GDExtensionInt p_hash);

/**
 * @name classdb_get_class_tag
 * @since 4.1
 *
 * Gets a pointer uniquely identifying the given built-in class in the ClassDB.
 *
 * @param p_classname A pointer to a StringName with the class name.
 *
 * @return A pointer uniquely identifying the built-in class in the ClassDB.
 */
typedef void *(*GDExtensionInterfaceClassdbGetClassTag)(GDExtensionConstStringNamePtr p_classname);

/* INTERFACE: ClassDB Extension */

/**
 * @name classdb_register_extension_class
 * @since 4.1
 * @deprecated in Godot 4.2. Use `classdb_register_extension_class3` instead.
 *
 * Registers an extension class in the ClassDB.
 *
 * Provided struct can be safely freed once the function returns.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_parent_class_name A pointer to a StringName with the parent class name.
 * @param p_extension_funcs A pointer to a GDExtensionClassCreationInfo struct.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClass)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_parent_class_name, const GDExtensionClassCreationInfo *p_extension_funcs);

/**
 * @name classdb_register_extension_class2
 * @since 4.2
 * @deprecated in Godot 4.3. Use `classdb_register_extension_class3` instead.
 *
 * Registers an extension class in the ClassDB.
 *
 * Provided struct can be safely freed once the function returns.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_parent_class_name A pointer to a StringName with the parent class name.
 * @param p_extension_funcs A pointer to a GDExtensionClassCreationInfo2 struct.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClass2)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_parent_class_name, const GDExtensionClassCreationInfo2 *p_extension_funcs);

/**
 * @name classdb_register_extension_class3
 * @since 4.3
 *
 * Registers an extension class in the ClassDB.
 *
 * Provided struct can be safely freed once the function returns.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_parent_class_name A pointer to a StringName with the parent class name.
 * @param p_extension_funcs A pointer to a GDExtensionClassCreationInfo2 struct.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClass3)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_parent_class_name, const GDExtensionClassCreationInfo3 *p_extension_funcs);

/**
 * @name classdb_register_extension_class_method
 * @since 4.1
 *
 * Registers a method on an extension class in the ClassDB.
 *
 * Provided struct can be safely freed once the function returns.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_method_info A pointer to a GDExtensionClassMethodInfo struct.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassMethod)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionClassMethodInfo *p_method_info);

/**
 * @name classdb_register_extension_class_virtual_method
 * @since 4.3
 *
 * Registers a virtual method on an extension class in ClassDB, that can be implemented by scripts or other extensions.
 *
 * Provided struct can be safely freed once the function returns.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_method_info A pointer to a GDExtensionClassMethodInfo struct.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassVirtualMethod)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionClassVirtualMethodInfo *p_method_info);

/**
 * @name classdb_register_extension_class_integer_constant
 * @since 4.1
 *
 * Registers an integer constant on an extension class in the ClassDB.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_enum_name A pointer to a StringName with the enum name.
 * @param p_constant_name A pointer to a StringName with the constant name.
 * @param p_constant_value The constant value.
 * @param p_is_bitfield Whether or not this is a bit field.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassIntegerConstant)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_enum_name, GDExtensionConstStringNamePtr p_constant_name, GDExtensionInt p_constant_value, GDExtensionBool p_is_bitfield);

/**
 * @name classdb_register_extension_class_property
 * @since 4.1
 *
 * Registers a property on an extension class in the ClassDB.
 *
 * Provided struct can be safely freed once the function returns.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_info A pointer to a GDExtensionPropertyInfo struct.
 * @param p_setter A pointer to a StringName with the name of the setter method.
 * @param p_getter A pointer to a StringName with the name of the getter method.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassProperty)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionPropertyInfo *p_info, GDExtensionConstStringNamePtr p_setter, GDExtensionConstStringNamePtr p_getter);

/**
 * @name classdb_register_extension_class_property_indexed
 * @since 4.2
 *
 * Registers an indexed property on an extension class in the ClassDB.
 *
 * Provided struct can be safely freed once the function returns.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_info A pointer to a GDExtensionPropertyInfo struct.
 * @param p_setter A pointer to a StringName with the name of the setter method.
 * @param p_getter A pointer to a StringName with the name of the getter method.
 * @param p_index The index to pass as the first argument to the getter and setter methods.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassPropertyIndexed)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionPropertyInfo *p_info, GDExtensionConstStringNamePtr p_setter, GDExtensionConstStringNamePtr p_getter, GDExtensionInt p_index);

/**
 * @name classdb_register_extension_class_property_group
 * @since 4.1
 *
 * Registers a property group on an extension class in the ClassDB.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_group_name A pointer to a String with the group name.
 * @param p_prefix A pointer to a String with the prefix used by properties in this group.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassPropertyGroup)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringPtr p_group_name, GDExtensionConstStringPtr p_prefix);

/**
 * @name classdb_register_extension_class_property_subgroup
 * @since 4.1
 *
 * Registers a property subgroup on an extension class in the ClassDB.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_subgroup_name A pointer to a String with the subgroup name.
 * @param p_prefix A pointer to a String with the prefix used by properties in this subgroup.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassPropertySubgroup)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringPtr p_subgroup_name, GDExtensionConstStringPtr p_prefix);

/**
 * @name classdb_register_extension_class_signal
 * @since 4.1
 *
 * Registers a signal on an extension class in the ClassDB.
 *
 * Provided structs can be safely freed once the function returns.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 * @param p_signal_name A pointer to a StringName with the signal name.
 * @param p_argument_info A pointer to a GDExtensionPropertyInfo struct.
 * @param p_argument_count The number of arguments the signal receives.
 */
typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassSignal)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_signal_name, const GDExtensionPropertyInfo *p_argument_info, GDExtensionInt p_argument_count);

/**
 * @name classdb_unregister_extension_class
 * @since 4.1
 *
 * Unregisters an extension class in the ClassDB.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param p_class_name A pointer to a StringName with the class name.
 */
typedef void (*GDExtensionInterfaceClassdbUnregisterExtensionClass)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name); /* Unregistering a parent class before a class that inherits it will result in failure. Inheritors must be unregistered first. */

/**
 * @name get_library_path
 * @since 4.1
 *
 * Gets the path to the current GDExtension library.
 *
 * @param p_library A pointer the library received by the GDExtension's entry point function.
 * @param r_path A pointer to a String which will receive the path.
 */
typedef void (*GDExtensionInterfaceGetLibraryPath)(GDExtensionClassLibraryPtr p_library, GDExtensionUninitializedStringPtr r_path);

/**
 * @name editor_add_plugin
 * @since 4.1
 *
 * Adds an editor plugin.
 *
 * It's safe to call during initialization.
 *
 * @param p_class_name A pointer to a StringName with the name of a class (descending from EditorPlugin) which is already registered with ClassDB.
 */
typedef void (*GDExtensionInterfaceEditorAddPlugin)(GDExtensionConstStringNamePtr p_class_name);

/**
 * @name editor_remove_plugin
 * @since 4.1
 *
 * Removes an editor plugin.
 *
 * @param p_class_name A pointer to a StringName with the name of a class that was previously added as an editor plugin.
 */
typedef void (*GDExtensionInterfaceEditorRemovePlugin)(GDExtensionConstStringNamePtr p_class_name);

/**
 * @name editor_help_load_xml_from_utf8_chars
 * @since 4.3
 *
 * Loads new XML-formatted documentation data in the editor.
 *
 * The provided pointer can be immediately freed once the function returns.
 *
 * @param p_data A pointer to an UTF-8 encoded C string (null terminated).
 */
typedef void (*GDExtensionsInterfaceEditorHelpLoadXmlFromUtf8Chars)(const char *p_data);

/**
 * @name editor_help_load_xml_from_utf8_chars_and_len
 * @since 4.3
 *
 * Loads new XML-formatted documentation data in the editor.
 *
 * The provided pointer can be immediately freed once the function returns.
 *
 * @param p_data A pointer to an UTF-8 encoded C string.
 * @param p_size The number of bytes (not code units).
 */
typedef void (*GDExtensionsInterfaceEditorHelpLoadXmlFromUtf8CharsAndLen)(const char *p_data, GDExtensionInt p_size);

#ifdef __cplusplus
}
#endif

#endif // GDEXTENSION_INTERFACE_H