Added the MPExpressionTree Classes

MathPad/MPSummand.m

@@ -0,0 +1,71 @@
+//
+//  MPSummand.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 09.10.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "MPSummand.h"
+#import "MPMathRules.h"
+
+@implementation MPSummand
+
+- (id)init
+{
+    self = [super init];
+    if (self) {
+    }
+    return self;
+}
+
+- (instancetype)initWithTokenStream:(MPTokenStream *)tokenStream
+{
+    self = [self init];
+    if (self) {
+        [tokenStream beginIgnoringWhitespaceTokens];
+        if (tokenStream.currentToken.tokenType == MPOperatorListToken) {
+            _operatorChain = [[MPOperatorChain alloc] initWithTokenStream:tokenStream];
+        }
+        _product = [[MPProduct alloc] initWithTokenStream:tokenStream];
+        [tokenStream endIgnoringOrAcceptingWhitespaceTokens];
+    }
+    return self;
+}
+
+- (NSRange)range
+{
+    return NSUnionRange(self.operatorChain.range, self.product.range);
+}
+
+- (BOOL)validate:(MPParseError *__autoreleasing *)error
+{
+    if (self.operatorChain.numberOfOperators > [MPMathRules sharedRules].maximumOperatorChainLength) {
+        if (error) {
+            *error = MPParseError(self.operatorChain.range, @"Too many operators.");
+        }
+        return NO;
+    }
+    return [self.product validate:error];
+}
+
+- (NSDecimalNumber *)evaluate
+{
+    NSDecimalNumber *value = [self.product evaluate];
+    if ([value isNotEqualTo:[NSDecimalNumber notANumber]] && self.operatorChain) {
+        value = [value decimalNumberByMultiplyingBy:[self.operatorChain evaluate]];
+    }
+    return value;
+}
+
+-(NSArray *)expressionElements
+{
+    NSMutableArray *elements = [[NSMutableArray alloc] init];
+    if (self.operatorChain) {
+        [elements addObjectsFromArray:self.operatorChain.expressionElements];
+    }
+    [elements addObjectsFromArray:self.product.expressionElements];
+    return @[self.operatorChain.expressionElements,];
+}
+
+@end