//
//  MPFunction.h
//  MathPad
//
//  Created by Kim Wittenburg on 18.04.14.
//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
//

@import Foundation;
#import "MPExpressionElement.h"
#import "MPParseError.h"

#define MPFunctionAccessorImplementation(Accessor, variableName) \
- (void)set##Accessor:(MPExpression *)value \
{ \
    variableName.parent = nil; \
    variableName = value; \
    variableName.parent = self; \
    [self didChangeChildAtIndex:[self indexOfChild:variableName]]; \
}

@class MPFunction, MPExpression, MPRangePath;

@interface MPFunction : NSObject <NSCoding, NSCopying, MPExpressionElement>

#pragma mark Creation Methods

- (instancetype)init;

#pragma mark Properties
// Subclasses should define accessor properties for all sub expressions, which, in the setter, should send didChangeElementAtRangePath:replacementLength: to self with a replacement length of 1.

#pragma mark Working With the Expression Tree
@property (nonatomic, weak) MPExpression *parent; // Documentation: Do not set
- (MPExpression *)rootExpression;
- (NSIndexPath *)indexPath;

- (NSArray *)childrenAccessors; // Override

- (NSUInteger)numberOfChildren;
- (MPExpression *)childAtIndex:(NSUInteger)index;
- (void)setChild:(MPExpression *)child
         atIndex:(NSUInteger)index;

- (NSArray *)children; // Indexes must equal the ones from the other methods
- (NSUInteger)indexOfChild:(MPExpression *)child;

- (id)elementAtIndexPath:(NSIndexPath *)indexPath;

#pragma mark Evaluating Functions

- (BOOL)validate:(MPParseError *__autoreleasing *)error; // Override
- (NSDecimalNumber *)evaluate; // Override

#pragma mark Messages
- (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
                   replacementLength:(NSUInteger)replacementLength;
- (void)didChangeChildAtIndex:(NSUInteger)index;

#pragma mark Working With Functions
// - (BOOL)isEqualToFunction:(MPFunction *)aFunction; // Override

- (NSString *)description; // Should be overridden
- (NSUInteger)hash;

- (id)copyWithZone:(NSZone *)zone;

@end