Started to Implement the Parser

MathPad/MPArrayCache.m

@@ -0,0 +1,59 @@
+//
+//  MPArrayCache.m
+//  MathPad
+//
+//  Created by Kim Wittenburg on 31.08.14.
+//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
+//
+
+#import "MPArrayCache.h"
+
+@implementation MPArrayCache {
+    NSUInteger lastIndex;
+}
+
+- (instancetype)init
+{
+    self = [super init];
+    if (self) {
+        lastIndex = 0;
+        _cache = [[NSCache alloc] init];
+    }
+    return self;
+}
+
+- (void)cacheObject:(id)object
+           forIndex:(NSUInteger)index
+{
+    [_cache setObject:object
+               forKey:@(index)];
+    if (index > lastIndex) {
+        lastIndex = index;
+    }
+}
+
+- (id)cachedObjectForIndex:(NSUInteger)index
+{
+    return [_cache objectForKey:@(index)];
+}
+
+- (void)clearCacheAtIndex:(NSUInteger)index replacementLength:(NSUInteger)replacementLength
+{
+    [_cache removeObjectForKey:@(index)];
+    for (NSUInteger i = index+1; i < lastIndex; i++) {
+        id object = [_cache objectForKey:@(i)];
+        if (object) {
+            [_cache removeObjectForKey:@(i)];
+        }
+    }
+    lastIndex += replacementLength - 1;
+}
+
+- (void)clearCacheInRange:(NSRange)range replacementLength:(NSUInteger)replacementLength;
+
+- (void)replaceCachedObjectAtIndex:(NSUInteger)index
+                       withObjects:(NSArray *)objects;
+- (void)replaceCachedObjectsInRange:(NSRange)range
+                        withObjects:(NSArray *)objects;
+
+@end