//
//  MPExpression.h
//  MathPad
//
//  Created by Kim Wittenburg on 17.04.14.
//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
//

@class MPExpression, MPFunction;

extern NSString *MPAdditionOperator;
extern NSString *MPSubtractionOperator;
extern NSString *MPMultiplicationOperator;
extern NSString *MPDivisionOperator;

@interface MPExpression : NSObject <NSCopying, NSMutableCopying, NSCoding>

#pragma mark Creation Methods

- (instancetype)initWithSymbols:(NSArray *)symbols;

#pragma mark Working With the Expression Tree

@property (nonatomic, weak) MPFunction *parent; // Documentation: Do not set, may be nil
- (void)functionSymbolChanged:(MPFunction *)symbol
             atLocalIndexPath:(NSIndexPath *)indexPath; // Index path of change in symbol

- (void)fixSymbols;

#pragma mark Primitive Methods

- (NSUInteger)numberOfSymbols;
- (id)symbolAtIndex:(NSUInteger)index; // Either an NSString or a MPFunction (which can be mutated)

- (double)doubleValue; // Evaluates Expression

@end

@interface MPExpression (MPExpressionExtensionMethods)

+ (NSArray *)operators;

#pragma mark Creation Methods

- (id)init;
- (instancetype)initWithString:(NSString *)aString;
- (instancetype)initWithFunction:(MPFunction *)aFunction;


+ (instancetype)expression;
+ (instancetype)expressionWithString:(NSString *)aString;
+ (instancetype)expressionWithFunction:(MPFunction *)aFunction;
+ (instancetype)expressionWithSymbols:(NSArray *)symbols;

#pragma mark Working with Expressions

- (NSUInteger)length;

- (MPExpression *)subexpressionFromIndex:(NSUInteger)from;
- (MPExpression *)subexpressionToIndex:(NSUInteger)to;
- (MPExpression *)subexpressionWithRange:(NSRange)range;

- (BOOL)isEqualToExpression:(MPExpression *)anExpression;

- (MPExpression *)expressionByAppendingString:(NSString *)aString;
- (MPExpression *)expressionByAppendingFunction:(MPFunction *)aFunction;
- (MPExpression *)expressionByAppendingExpression:(MPExpression *)anExpression;
- (MPExpression *)expressionByAppendingSymbols:(NSArray *)symbols;

#pragma mark Evaluating Expressions

- (float)floatValue;
- (int)intValue;
- (NSInteger)integerValue;
- (long long)longLongValue;

#pragma mark Querying an Expression's Contents

- (NSArray *)symbols;

- (NSString *)description;

- (NSUInteger)hash;

@end

@interface MPMutableExpression : MPExpression

- (void)replaceSymbolsInRange:(NSRange)range
                  withSymbols:(NSArray *)symbols;

- (void)beginEditing;
- (void)endEditing;

@end

@interface MPMutableExpression (MPMutableExpressionExtensionMethods)

- (void)insertString:(NSString *)aString
             atIndex:(NSUInteger)loc;
- (void)insertFunction:(MPFunction *)aFunction
               atIndex:(NSUInteger)loc;
- (void)insertExpression:(MPExpression *)anExpression
                 atIndex:(NSUInteger)loc;
- (void)insertSymbols:(NSArray *)symbols
              atIndex:(NSUInteger)loc;

- (void)deleteSymbolsInRange:(NSRange)range;

- (void)appendString:(NSString *)aString;
- (void)appendFunction:(MPFunction *)aFunction;
- (void)appendExpression:(MPExpression *)anExpression;
- (void)appendSymbols:(NSArray *)symbols;

- (void)setString:(NSString *)aString;
- (void)setFunction:(MPFunction *)aFunction;
- (void)setExpression:(MPExpression *)anExpression;
- (void)setSymbols:(NSArray *)symbols;

@end