Adding Angular and dependent packages for testing

third_party/pkg/angular/lib/core/cache.dart

+part of angular.core;
+
+class CacheStats {
+  final int capacity;
+  final int size;
+  final int hits;
+  final int misses;
+  CacheStats(this.capacity, this.size, this.hits, this.misses);
+  String toString() =>
+      "[CacheStats: capacity: $capacity, size: $size, hits: $hits, misses: $misses]";
+}
+
+
+/**
+ * The Cache interface.
+ */
+abstract class Cache<K, V> {
+  /**
+   * Returns the value for `key` from the cache.  If `key` is not in the cache,
+   * returns `null`.
+   */
+  V get(K key);
+  /**
+   * Inserts/Updates the `key` in the cache with `value` and returns the value.
+   */
+  V put(K key, V value);
+  /**
+   * Removes `key` from the cache.  If `key` isn't present in the cache, does
+   * nothing.
+   */
+  V remove(K key);
+  /**
+   * Removes all entries from the cache.
+   */
+  void removeAll();
+  int get capacity;
+  int get size;
+  CacheStats stats();
+}
+
+
+/**
+ * An unbounded cache.
+ */
+class UnboundedCache<K, V> implements Cache<K, V> {
+  Map<K, V> _entries = <K, V>{};
+  int _hits = 0;
+  int _misses = 0;
+
+  V get(K key) {
+    V value = _entries[key];
+    if (value != null || _entries.containsKey(key)) {
+      ++_hits;
+    } else {
+      ++_misses;
+    }
+    return value;
+  }
+  V put(K key, V value) => _entries[key] = value;
+  V remove(K key) => _entries.remove(key);
+  void removeAll() => _entries.clear();
+  int get capacity => 0;
+  int get size => _entries.length;
+  CacheStats stats() => new CacheStats(capacity, size, _hits, _misses);
+  // Debugging helper.
+  String toString() => "[$runtimeType: size=${_entries.length}, items=$_entries]";
+}
+
+
+/**
+ * Simple LRU cache.
+ *
+ * TODO(chirayu):
+ * - add docs
+ * - add tests
+ * - should stringify keys?
+ */
+class LruCache<K, V> extends Cache<K, V> {
+  Map<K, V> _entries = new LinkedHashMap<K, V>();
+  int _capacity;
+  int _hits = 0;
+  int _misses = 0;
+
+  LruCache({int capacity}) {
+    this._capacity = (capacity == null) ? 0 : capacity;
+  }
+
+  V get(K key) {
+    V value = _entries[key];
+    if (value != null || _entries.containsKey(key)) {
+      ++_hits;
+      // refresh
+      _entries.remove(key);
+      _entries[key] = value;
+    } else {
+      ++_misses;
+    }
+    return value;
+  }
+
+  V put(K key, V value) {
+    // idempotent.  needed to refresh an existing key.
+    _entries.remove(key);
+    // _capacity always > 0 but might not be true in some future.
+    if (_capacity > 0 && _capacity == _entries.length) {
+      // drop oldest entry when at capacity
+      // _entries.keys.first is fairly cheap - 2 new calls.
+      _entries.remove(_entries.keys.first);
+    }
+    _entries[key] = value;
+    return value;
+  }
+
+  V remove(K key) => _entries.remove(key);
+  void removeAll() => _entries.clear();
+  int get capacity => _capacity;
+  int get size => _entries.length;
+  CacheStats stats() => new CacheStats(capacity, size, _hits, _misses);
+  // Debugging helper.
+  String toString() => "[$runtimeType: capacity=$capacity, size=$size, items=$_entries]";
+}