//
//  MPParsedVariable.m
//  MathPad
//
//  Created by Kim Wittenburg on 13.09.14.
//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
//

#import "MPParsedVariable.h"
#import "MPEvaluationContext.h"

@interface MPParsedVariable ()
@property (nonatomic) NSRange range;
@property (nonatomic, strong) NSString *variableName;
@end

@implementation MPParsedVariable

- (instancetype)initWithRange:(NSRange)range
                     inString:(NSString *)string
{
    self = [super init];
    if (self) {
        _range = range;
        if (range.location != NSNotFound) {
            _variableName = [string substringWithRange:range];
        }
    }
    return self;
}

- (BOOL)exists
{
    return self.range.location != NSNotFound;
}

- (NSDecimalNumber *)evaluateWithError:(MPParseError *__autoreleasing *)error
{
    NSDecimalNumber *value = [[MPEvaluationContext sharedContext] valueForVariableName:self.variableName];
    if (!value) {
        *error = MPParseError(self.range, @"Undefined Variable.");
        return nil;
    }
    return value;
}

@end