Add test_set() (#6164).

bitset_test.hpp

@@ -960,6 +960,25 @@ struct bitset_test {
     }
   }
 
+  static void test_set_bit(const Bitset& b, std::size_t pos, bool value)
+  {
+    Bitset lhs(b);
+    std::size_t N = lhs.size();
+    if (pos < N) {
+      Bitset prev(lhs);
+      // Stores a new value in the bit at position pos in lhs.
+      BOOST_CHECK(lhs.test_set(pos, value) == prev[pos]);
+      BOOST_CHECK(lhs[pos] == value);
+
+      // All other values of lhs remain unchanged
+      for (std::size_t I = 0; I < N; ++I)
+        if (I != pos)
+          BOOST_CHECK(lhs[I] == prev[I]);
+    } else {
+      // Not in range, doesn't satisfy precondition.
+    }
+  }
+
   static void operator_shift_left(const Bitset& lhs, std::size_t pos)
   {
     Bitset x(lhs);

dyn_bitset_unit_tests3.cpp

@@ -611,6 +611,23 @@ void run_test_cases( BOOST_EXPLICIT_TEMPLATE_TYPE(Block) )
     Tests::test_bit(b, long_string.size()/2);
   }
   //=====================================================================
+  // Test b.test_set(pos)
+  { // case pos >= b.size()
+    boost::dynamic_bitset<Block> b;
+    Tests::test_set_bit(b, 0, true);
+    Tests::test_set_bit(b, 0, false);
+  }
+  { // case pos < b.size()
+    boost::dynamic_bitset<Block> b(std::string("0"));
+    Tests::test_set_bit(b, 0, true);
+    Tests::test_set_bit(b, 0, false);
+  }
+  { // case pos == b.size() / 2
+    boost::dynamic_bitset<Block> b(long_string);
+    Tests::test_set_bit(b, long_string.size() / 2, true);
+    Tests::test_set_bit(b, long_string.size() / 2, false);
+  }
+  //=====================================================================
   // Test b << pos
   { // case pos == 0
     std::size_t pos = 0;

dynamic_bitset.html

@@ -202,6 +202,7 @@ public:
     dynamic_bitset&amp; <a href="#flip2">flip</a>(size_type n);
     dynamic_bitset&amp; <a href="#flip1">flip</a>();
     bool <a href="#test">test</a>(size_type n) const;
+    bool <a href="#test">test_set</a>(size_type n, bool val = true);
     bool <a href="#all">all</a>() const;
     bool <a href="#any">any</a>() const;
     bool <a href="#none">none</a>() const;
@@ -1159,6 +1160,18 @@ bool <a id="test">test</a>(size_type n) const
  <b>Returns:</b> <tt>true</tt> if bit <tt>n</tt> is set and
 <tt>false</tt> is bit <tt>n</tt> is 0.
 
+<hr />
+<pre>
+bool <a id="test">test_set</a>(size_type n, bool val = true)
+</pre>
+
+<b>Precondition:</b> <tt>n &lt; this-&gt;size()</tt>.<br />
+ <b>Effects:</b> Sets bit <tt>n</tt> if <tt>val</tt> is
+<tt>true</tt>, and clears bit <tt>n</tt> if <tt>val</tt> is
+<tt>false</tt>. <br />
+ <b>Returns:</b> <tt>true</tt> if the previous state of bit
+<tt>n</tt> was set and <tt>false</tt> is bit <tt>n</tt> is 0.
+
 <hr />
 <pre>
 reference <a id="bracket">operator[]</a>(size_type n)

include/boost/dynamic_bitset/dynamic_bitset.hpp

@@ -278,6 +278,7 @@ public:
     dynamic_bitset& flip(size_type n);
     dynamic_bitset& flip();
     bool test(size_type n) const;
+    bool test_set(size_type n, bool val = true);
     bool all() const;
     bool any() const;
     bool none() const;
@@ -1002,6 +1003,16 @@ bool dynamic_bitset<Block, Allocator>::test(size_type pos) const
     return m_unchecked_test(pos);
 }
 
+template <typename Block, typename Allocator>
+bool dynamic_bitset<Block, Allocator>::test_set(size_type pos, bool val)
+{
+    bool const b = test(pos);
+    if (b != val) {
+        set(pos, val);
+    }
+    return b;
+}
+
 template <typename Block, typename Allocator>
 bool dynamic_bitset<Block, Allocator>::all() const
 {