//
//  MPFactorial.m
//  MathPad
//
//  Created by Kim Wittenburg on 11.10.14.
//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
//

#import "MPFactorial.h"

@implementation MPFactorial

- (instancetype)init
{
    self = [super init];
    if (self) {
    }
    return self;
}

- (instancetype)initWithTokenStream:(MPTokenStream *)tokenStream
{
    self = [self init];
    if (self) {
        [tokenStream beginIgnoringWhitespaceTokens];
        if (tokenStream.currentToken.tokenType != MPFactorialToken) {
            [tokenStream endIgnoringOrAcceptingWhitespaceTokens];
            return nil;
        } else {
            [tokenStream currentTokenConsumed];
        }
        [tokenStream endIgnoringOrAcceptingWhitespaceTokens];
    }
    return self;
}

- (BOOL)validate:(NSError *__autoreleasing *)error
{
    return [self.value validate:error];
}

- (NSDecimalNumber *)evaluate
{
    double value = [self.value evaluate].doubleValue;
    return [[NSDecimalNumber alloc] initWithDouble:tgamma(value+1)];
}

@end