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//
// EXTKeyPathCoding.h
// extobjc
//
// Created by Justin Spahr-Summers on 19.06.12.
// Copyright (C) 2012 Justin Spahr-Summers.
// Released under the MIT license.
//
#import <Foundation/Foundation.h>
#import "metamacros.h"
/**
* \@keypath allows compile-time verification of key paths. Given a real object
* receiver and key path:
*
* @code
NSString *UTF8StringPath = @keypath(str.lowercaseString.UTF8String);
// => @"lowercaseString.UTF8String"
NSString *versionPath = @keypath(NSObject, version);
// => @"version"
NSString *lowercaseStringPath = @keypath(NSString.new, lowercaseString);
// => @"lowercaseString"
* @endcode
*
* ... the macro returns an \c NSString containing all but the first path
* component or argument (e.g., @"lowercaseString.UTF8String", @"version").
*
* In addition to simply creating a key path, this macro ensures that the key
* path is valid at compile-time (causing a syntax error if not), and supports
* refactoring, such that changing the name of the property will also update any
* uses of \@keypath.
*/
#define keypath(...) \
_Pragma("clang diagnostic push") \
_Pragma("clang diagnostic ignored \"-Warc-repeated-use-of-weak\"") \
metamacro_if_eq(1, metamacro_argcount(__VA_ARGS__))(keypath1(__VA_ARGS__))(keypath2(__VA_ARGS__)) \
_Pragma("clang diagnostic pop") \
#define keypath1(PATH) \
(((void)(NO && ((void)PATH, NO)), \
({ char *__extobjckeypath__ = strchr(# PATH, '.'); NSCAssert(__extobjckeypath__, @"Provided key path is invalid."); __extobjckeypath__ + 1; })))
#define keypath2(OBJ, PATH) \
(((void)(NO && ((void)OBJ.PATH, NO)), # PATH))
/**
* \@collectionKeypath allows compile-time verification of key paths across collections NSArray/NSSet etc. Given a real object
* receiver, collection object receiver and related keypaths:
*
* @code
NSString *employeesFirstNamePath = @collectionKeypath(department.employees, Employee.new, firstName)
// => @"employees.firstName"
NSString *employeesFirstNamePath = @collectionKeypath(Department.new, employees, Employee.new, firstName)
// => @"employees.firstName"
* @endcode
*
*/
#define collectionKeypath(...) \
metamacro_if_eq(3, metamacro_argcount(__VA_ARGS__))(collectionKeypath3(__VA_ARGS__))(collectionKeypath4(__VA_ARGS__))
#define collectionKeypath3(PATH, COLLECTION_OBJECT, COLLECTION_PATH) ([[NSString stringWithFormat:@"%s.%s",keypath(PATH), keypath(COLLECTION_OBJECT, COLLECTION_PATH)] UTF8String])
#define collectionKeypath4(OBJ, PATH, COLLECTION_OBJECT, COLLECTION_PATH) ([[NSString stringWithFormat:@"%s.%s",keypath(OBJ, PATH), keypath(COLLECTION_OBJECT, COLLECTION_PATH)] UTF8String])