[Boost-commit] svn:boost r72499 - sandbox/bloom_filter/trunk/libs/bloom_filter/doc/html

Subject: [Boost-commit] svn:boost r72499 - sandbox/bloom_filter/trunk/libs/bloom_filter/doc/html
From: cpp.cabrera_at_[hidden]
Date: 2011-06-08 21:38:03

Author: alejandro
Date: 2011-06-08 21:38:02 EDT (Wed, 08 Jun 2011)
New Revision: 72499
URL: http://svn.boost.org/trac/boost/changeset/72499

Log:
Added extended example detailing advanced usage of Bloom Filter class.
Text files modified: 
   sandbox/bloom_filter/trunk/libs/bloom_filter/doc/html/tutorial.html |    57 ++++++++++++++++++++++++++++++++++++--- 
   1 files changed, 52 insertions(+), 5 deletions(-)

Modified: sandbox/bloom_filter/trunk/libs/bloom_filter/doc/html/tutorial.html
==============================================================================
--- sandbox/bloom_filter/trunk/libs/bloom_filter/doc/html/tutorial.html	(original)
+++ sandbox/bloom_filter/trunk/libs/bloom_filter/doc/html/tutorial.html	2011-06-08 21:38:02 EDT (Wed, 08 Jun 2011)
@@ -85,7 +85,7 @@
       <li>Advanced template parameters:
       <ul>
         <li><code>HashFunctions</code>:
-	an mpl::vector or std::tuple (a compile-time sequence) of Hasher objects.</li>
+	a boost::mpl::vector of Hasher objects.</li>
       </ul>
       </li>
       <li>Advanced state monitoring functions:
@@ -99,12 +99,59 @@
 
     <p>
       A Hasher is a function object that overloads operator() such that the following interface is satisfied:
-      <div class="listing">
-      <code class="c_keyword">template</code> &lt;<code class="c_keyword">typename</code> <code class="c_id">T</code>&gt;
+    </p>
+
+    <div class="listing">
+      <code class="c_keyword">template</code> &lt;<code class="c_keyword">typename</code> <code class="c_id">T, Seed</code>&gt;
       <code class="c_keyword">struct</code> <code class="c_id">ExampleHasher</code> {
-	<code class="c_type">size_t</code> <code class="c_func">operator</code>()(<code class="c_keyword">const</code> <code class="c_type">T</code>&) <code class="c_keyword">const</code>;
+        <code class="c_type">size_t</code> <code class="c_func">operator</code>()(<code class="c_keyword">const</code> <code class="c_type">T</code>&) <code class="c_keyword">const</code>;
       };
-      </div>
+    </div>
+    <p>
+      Note that the template parameter Seed isn't strictly required, as 
+      long as some form of seeding is present in the Hasher object. Now 
+      we can use a richer Bloom filter:
+    </p>
+
+    <div class="listing">
+      <code class="c_comment">// advanced Boost.BloomFilter program</code>
+      <code class="c_keyword">#include</code> <code class="c_include">&lt;boost/bloom_filter/bloom.hpp&gt;</code>
+      <code class="c_keyword">#include</code> <code class="c_include">&lt;iostream&gt;</code>
+      <code class="c_keyword">using namespace</code> <code class="c_namespace">boost::bloom_filter</code>;
+      <code class="c_keyword">using namespace</code> <code class="c_namespace">std</code>;
+	
+      <code class="c_type">int</code> <code class="c_func">main</code>() {
+        <code class="c_keyword">typedef</code> <code class="c_namespace">boost::mpl::vector</code>&lt;<code class="c_type">Hasher</code>&lt;<code class="c_id">int, 1</code>&gt;, 
+	                           <code class="c_type">Hasher</code>&lt;<code class="c_id">int, 2</code>&gt;, 
+				   <code class="c_type">Hasher</code>&lt;<code class="c_id">int, 3</code>&gt; &gt; <code class="c_type">HashFns</code>;
+      <code class="c_type">  bloom_filter</code>&lt;int, 1024, HashFns&gt; <code class="c_id">bloom</code>;
+
+	cout << "false positive rate: " 
+	     << bloom.false_positive_rate()
+	     << endl;
+
+	<code class="c_keyword">for</code> (<code class="c_type">int</code><code class="c_id"> i</code> = 0; i &lt; 5000; ++i) {
+	  bloom.insert(i);
+	}
+
+	<code class="c_keyword">for</code> (<code class="c_type">int</code><code class="c_id"> i</code> = 5000; i &lt; 10000; ++i) {
+	    <code class="c_keyword">if</code> (bloom.contains(i)) cout &lt;&lt; "collision" &lt;&lt; endl;
+	}
+
+	cout << "false positive rate: " 
+	     << bloom.false_positive_rate()
+	     << endl;
+
+	<code class="c_keyword">return</code> 0;
+      }
+    </div>
+
+    <p>
+      All the details of insertion and querying the Bloom filter are handled
+      transparently by the insert() and contains() functions, regardless
+      of the type, bit size, and hash functions used. This makes it very
+      convenient to experiment with different Bloom filter parameters in
+      projects you commit to.
     </p>
 
     <hr/>