NSDecimalNumber+CalculatingByString

NSNumber+CGFloat
NSNumber+RomanNumerals

Categories/Foundation/NSNumber/NSDecimalNumber+CalculatingByString.h

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+//
+//  NSDecimalNumber+CalculatingByString.h
+//  NSDecimalNumber+StringCalculation
+//
+//  Created by Adi Li on 11/5/14.
+//  Copyright (c) 2014 Adi Li. All rights reserved.
+//
+
+//https://github.com/adi-li/NSDecimalNumber-StringCalculation
+#import <Foundation/Foundation.h>
+
+@interface NSDecimalNumber (CalculatingByString)
+
++ (NSDecimalNumber *)decimalNumberWithEquation:(NSString *)equation decimalNumbers:(NSDictionary *)numbers;
+@end

Categories/Foundation/NSNumber/NSDecimalNumber+CalculatingByString.m

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+//
+//  NSDecimalNumber+CalculatingByString.m
+//  NSDecimalNumber+StringCalculation
+//
+//  Created by Adi Li on 11/5/14.
+//  Copyright (c) 2014 Adi Li. All rights reserved.
+//
+
+#import "NSDecimalNumber+CalculatingByString.h"
+
+typedef enum {
+    tokenTypeFirstLoop = -1,
+    tokenTypeEndOfEquation,
+    tokenTypeNumber,
+    tokenTypeText,
+    tokenTypeOperator,
+    tokenTypeUnknown = 99,
+} tokenType;
+
+tokenType typeForCharacter (const unichar character);
+NSInteger precedenceForOperator (NSString *operator);
+NSInteger precedenceForOperatorChar (const unichar operator);
+NSArray* tokenizeEquation (NSString *equation, NSDictionary *numbers);
+NSArray* RPNFromTokens (NSArray *tokens);
+
+static NSArray *operators;
+void initOperators();
+
+@implementation NSDecimalNumber (CalculatingByString)
+
++ (NSDecimalNumber *)decimalNumberWithEquation:(NSString *)equation decimalNumbers:(NSDictionary *)numbers
+{
+    NSDecimalNumber *left, *right;
+
+    NSMutableArray *equationStack = [RPNFromTokens(tokenizeEquation(equation, numbers)) mutableCopy];
+    NSMutableArray *resultArray = [@[] mutableCopy];
+
+    NSString *token;
+
+    initOperators();
+
+    do {
+        token = [equationStack firstObject];
+        if ([operators indexOfObject:token] != NSNotFound) {
+            right = [NSDecimalNumber decimalNumberWithString:[resultArray lastObject]];
+            [resultArray removeLastObject];
+            left = [NSDecimalNumber decimalNumberWithString:[resultArray lastObject]];
+            [resultArray removeLastObject];
+
+            assert(![left isEqual:[NSDecimalNumber notANumber]]);
+            assert(![right isEqual:[NSDecimalNumber notANumber]]);
+
+            if ([@"+" isEqualToString:token]) {
+                token = [[left decimalNumberByAdding:right] stringValue];
+
+            } else if ([@"-" isEqualToString:token]) {
+                token = [[left decimalNumberBySubtracting:right] stringValue];
+
+            } else if ([@"*" isEqualToString:token]) {
+                token = [[left decimalNumberByMultiplyingBy:right] stringValue];
+
+            } else if ([@"/" isEqualToString:token]) {
+                token = [[left decimalNumberByDividingBy:right] stringValue];
+
+            } else if ([@"^" isEqualToString:token]) {
+                token = [[left decimalNumberByRaisingToPower:right.integerValue] stringValue];
+
+            }
+        }
+
+        [resultArray addObject:token];
+        [equationStack removeObjectAtIndex:0];
+
+    } while (equationStack.count > 0);
+
+
+
+    return [NSDecimalNumber decimalNumberWithString:[resultArray objectAtIndex:0]];
+}
+
+@end
+
+
+#pragma mark - helper functions
+
+// find the token type for a character
+tokenType typeForCharacter (const unichar character)
+{
+    if ((character >= '0' && character <= '9') || character == '.') {
+        return tokenTypeNumber;
+
+    } else if ((character >= 'A' && character <= 'z') || character == '_') {
+        return tokenTypeText;
+
+    } else if (character == '+' || character == '-' || character == '*' || character == '/' ||
+               character == '(' || character == ')' || character == '^')
+    {
+        return tokenTypeOperator;
+
+    } else if (character == 0) {
+        return tokenTypeEndOfEquation;
+    }
+
+#ifdef DEBUG
+    NSLog(@"Invalid Operator: %@ is not a valid character." ,[NSString stringWithCharacters:&character length:1]);
+    exit(EXIT_FAILURE);
+#endif
+
+    return tokenTypeUnknown;
+}
+
+// find the precedence for a operator
+NSInteger precedenceForOperator (NSString *operator)
+{
+    unichar operatorChar = operator.UTF8String[0];
+
+    return precedenceForOperatorChar(operatorChar);
+}
+
+// find the precedence for a operator
+NSInteger precedenceForOperatorChar (const unichar operator)
+{
+    switch (operator) {
+        case '+':
+        case '-':
+            return 2;
+
+        case '*':
+        case '/':
+            return 3;
+
+        case '^':
+            return 4;
+
+        default:
+            return 0;
+    }
+}
+
+// split the equation into token (e.g. @[@"1", @"+", @"2", @"*", @"3"])
+NSArray* tokenizeEquation (NSString *equation, NSDictionary *numbers)
+{
+    unichar equationChars[equation.length + 1], tempChars[equation.length + 1];
+
+    tokenType lastTokenType = tokenTypeFirstLoop, currentTokenType = tokenTypeFirstLoop;
+
+    NSUInteger tempCharsLength = 0;
+
+    NSMutableArray *equationStack = [@[] mutableCopy];
+
+    equation = [equation stringByReplacingOccurrencesOfString:@" " withString:@""];
+    [equation getCharacters:equationChars];
+
+    for (long i=0; i <= equation.length; i++) {
+        unichar character = equationChars[i];
+        currentTokenType = typeForCharacter(character);
+
+        // compare to last token type to re-define the token type
+        if (character == '-' && lastTokenType != tokenTypeNumber && lastTokenType != tokenTypeText) {
+            // e.g. -1 or -variable
+            currentTokenType = tokenTypeNumber;
+
+        } else if (currentTokenType == tokenTypeNumber && lastTokenType == tokenTypeText) {
+            // e.g. a1 should be a variable
+            currentTokenType = tokenTypeText;
+
+        }
+
+        // if first loop, last == current token type
+        if (lastTokenType == tokenTypeFirstLoop) {
+            lastTokenType = currentTokenType;
+        }
+
+        // token type changed, push the token into stack
+        if (currentTokenType != lastTokenType || lastTokenType == tokenTypeOperator) {
+
+            NSString *string = [NSString stringWithCharacters:tempChars length:tempCharsLength];
+
+            // variable token
+            if (lastTokenType == tokenTypeText) {
+                id object = [numbers objectForKey:string];
+
+                if ([object isKindOfClass:[NSString class]]) {
+                    string = object;
+
+                } else if ([object respondsToSelector:@selector(stringValue)]) {
+                    string = [object stringValue];
+                    assert(![[NSDecimalNumber notANumber] isEqual:[NSDecimalNumber decimalNumberWithString:string]]);
+
+                } else {
+#ifdef DEBUG
+                    NSLog(@"Invalid Variable: object %@ has no string value.", object);
+                    exit(EXIT_FAILURE);
+#endif
+                }
+
+                [equationStack addObject:string];
+                tempCharsLength = 0;
+
+            } else if (lastTokenType == tokenTypeNumber && [@"-" isEqualToString:string]) {
+                // '-': unary minus
+                [equationStack addObject:@"-1"];
+                [equationStack addObject:@"*"];
+
+                tempCharsLength = 0;
+
+            } else {
+                [equationStack addObject:string];
+                tempCharsLength = 0;
+            }
+        }
+
+        // read next character
+        tempChars[tempCharsLength++] = character;
+        lastTokenType = currentTokenType;
+    }
+
+    return equationStack;
+}
+
+// change the tokens array into RPN (Reverse Polish notation) array
+// e.g. @[@"1", @"2", @"3", @"*", @"+"]
+NSArray* RPNFromTokens (NSArray *tokens)
+{
+    NSMutableArray *output = [@[] mutableCopy];
+    NSMutableArray *operatorStack = [@[] mutableCopy];
+    NSString *operator;
+
+    initOperators();
+
+    for (NSString *token in tokens) {
+
+        if ([@"(" isEqualToString:token]) {
+            [operatorStack addObject:token];
+            continue;
+        }
+
+        operator = nil;
+
+        if ([@")" isEqualToString:token]) {
+
+            do {
+                operator = [operatorStack lastObject];
+                [operatorStack removeLastObject];
+
+                if (![@"(" isEqualToString:operator]) {
+                    [output addObject:operator];
+                }
+
+            } while (![@"(" isEqualToString:operator]);
+
+            continue;
+        }
+
+
+        if ([operators indexOfObject:token] != NSNotFound) {
+            operator = [operatorStack lastObject];
+
+            NSInteger precedence = precedenceForOperator(token);
+            NSInteger lastPrecedence = -1;
+
+            if (operator) {
+                lastPrecedence = precedenceForOperator(operator);
+            }
+
+            if (precedence > lastPrecedence) {
+                [operatorStack addObject:token];
+                continue;
+            }
+
+            do {
+                operator = [operatorStack lastObject];
+                if (operator && ![@"(" isEqualToString:operator]) {
+                    [output addObject:operator];
+
+                    [operatorStack removeLastObject];
+                }
+
+            } while (operator && precedence <= lastPrecedence && ![@"(" isEqualToString:operator]);
+
+            [operatorStack addObject:token];
+            continue;
+        }
+
+        [output addObject:token];
+    }
+
+    [output addObjectsFromArray:[[operatorStack reverseObjectEnumerator] allObjects]];
+
+    return output;
+}
+
+
+#pragma mark - Operators static array
+
+void initOperators()
+{
+    if (operators == nil) {
+        operators = @[@"+", @"-", @"*", @"/", @"^"];
+    }
+}

Categories/Foundation/NSNumber/NSNumber+CGFloat.h

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+
+//
+//  NSNumber+CGFloat.h
+//
+//  Created by Alexey Aleshkov on 16.02.14.
+//  Copyright (c) 2014 Alexey Aleshkov. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+#import <UIKit/UIKit.h>
+@interface NSNumber (CGFloat)
+
+- (CGFloat)CGFloatValue;
+
+- (id)initWithCGFloat:(CGFloat)value;
+
++ (NSNumber *)numberWithCGFloat:(CGFloat)value;
+
+@end

Categories/Foundation/NSNumber/NSNumber+CGFloat.m

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+//
+//  NSNumber+CGFloat.m
+//
+//  Created by Alexey Aleshkov on 16.02.14.
+//  Copyright (c) 2014 Alexey Aleshkov. All rights reserved.
+//
+
+#import "NSNumber+CGFloat.h"
+
+@implementation NSNumber (CGFloat)
+
+- (CGFloat)CGFloatValue
+{
+#if (CGFLOAT_IS_DOUBLE == 1)
+    CGFloat result = [self doubleValue];
+#else
+    CGFloat result = [self floatValue];
+#endif
+    return result;
+}
+
+- (id)initWithCGFloat:(CGFloat)value
+{
+#if (CGFLOAT_IS_DOUBLE == 1)
+    self = [self initWithDouble:value];
+#else
+    self = [self initWithFloat:value];
+#endif
+    return self;
+}
+
++ (NSNumber *)numberWithCGFloat:(CGFloat)value
+{
+    NSNumber *result = [[self alloc] initWithCGFloat:value];
+    return result;
+}
+
+@end

Categories/Foundation/NSNumber/NSNumber+RomanNumerals.h

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+//
+//  NSNumber+RomanNumerals.h
+//  SalesBagStandalone
+//
+//  Created by Patrick Zearfoss on 10/19/11.
+//
+
+//https://github.com/pzearfoss/NSNumber-RomanNumerals
+#import <Foundation/Foundation.h>
+
+@interface NSNumber (RomanNumerals)
+
+- (NSString *)romanNumeral;
+
+@end