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diff --git a/src/binary_parse/cached_paged_byte_array.cc b/src/binary_parse/cached_paged_byte_array.cc
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+++ b/src/binary_parse/cached_paged_byte_array.cc
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+// Copyright 2015 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////////
+//
+// The cache layer works as follows:
+// The cache is implemented as a vector (of size 'cache_size') of shared
+// pointers to pages recently used. The least recently used page is stored
+// at the begining of the vector, the most recent at the end.
+
+#include "src/binary_parse/cached_paged_byte_array.h"
+
+#include <cstddef>
+
+namespace piex {
+namespace binary_parse {
+
+CachedPagedByteArray::CachedPagedByteArray(
+    const PagedByteArray* paged_byte_array, size_t cache_size)
+    : paged_byte_array_(paged_byte_array), cache_size_(cache_size) {}
+
+void CachedPagedByteArray::getPage(size_t page_index,
+                                   const unsigned char** begin,
+                                   const unsigned char** end,
+                                   PagedByteArray::PagePtr* page) const {
+  std::lock_guard<std::mutex> lock(mutex_);
+  size_t cache_index;
+  if (getFromCache(page_index, &cache_index)) {
+    // Cache hit, retrieve the page from the cache.
+    *begin = cached_pages_[cache_index].begin;
+    *end = cached_pages_[cache_index].end;
+    *page = cached_pages_[cache_index].page;
+
+    // Remove the page to insert it at the end of the cache later.
+    cached_pages_.erase(cached_pages_.begin() +
+                        static_cast<std::ptrdiff_t>(cache_index));
+  } else {
+    // Cache miss, ask PagedByteArray to load the page.
+    paged_byte_array_->getPage(page_index, begin, end, page);
+
+    // If the cache is full, remove the first (least recently used) page.
+    if (cached_pages_.size() >= cache_size_) {
+      cached_pages_.erase(cached_pages_.begin());
+    }
+  }
+
+  // Cache the most recently used page to the end of the vector.
+  CachedPage cache_page;
+  cache_page.index = page_index;
+  cache_page.page = *page;
+  cache_page.begin = *begin;
+  cache_page.end = *end;
+  cached_pages_.push_back(cache_page);
+}
+
+bool CachedPagedByteArray::getFromCache(size_t page_index,
+                                        size_t* cache_index) const {
+  for (size_t i = 0; i < cached_pages_.size(); ++i) {
+    if (cached_pages_[i].index == page_index) {
+      *cache_index = i;
+      return true;
+    }
+  }
+  return false;
+}
+
+}  // namespace binary_parse
+}  // namespace piex