Refactoring of the LineSearchMinimizer.

1. New LineSearchDirection interface, factory and instances.
2. Cleanup of LineSearchMinimizer to use the State and Direction objects.
3. LBFGS -> LowRankInverseHessian.
4. Refactoring of the RunCallbacks function and share it across
   LineSearchMinimizer and TrustRegionMinimizer.

Change-Id: I19354afc6f5d6567b28918710c2012dc30ef8f32
diff --git a/internal/ceres/minimizer.cc b/internal/ceres/minimizer.cc
new file mode 100644
index 0000000..912ac99
--- /dev/null
+++ b/internal/ceres/minimizer.cc
@@ -0,0 +1,67 @@
+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
+// http://code.google.com/p/ceres-solver/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+//   this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+// * Neither the name of Google Inc. nor the names of its contributors may be
+//   used to endorse or promote products derived from this software without
+//   specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: sameeragarwal@google.com (Sameer Agarwal)
+
+#include "ceres/minimizer.h"
+#include "ceres/types.h"
+#include "glog/logging.h"
+
+namespace ceres {
+namespace internal {
+
+Minimizer::~Minimizer() {};
+
+bool Minimizer::RunCallbacks(const vector<IterationCallback*> callbacks,
+                             const IterationSummary& iteration_summary,
+                             Solver::Summary* summary) {
+  CallbackReturnType status = SOLVER_CONTINUE;
+  int i = 0;
+  while (status == SOLVER_CONTINUE && i < callbacks.size()) {
+    status = (*callbacks[i])(iteration_summary);
+    ++i;
+  }
+  switch (status) {
+    case SOLVER_CONTINUE:
+      return true;
+    case SOLVER_TERMINATE_SUCCESSFULLY:
+      summary->termination_type = USER_SUCCESS;
+      VLOG(1) << "Terminating: User callback returned USER_SUCCESS.";
+      return false;
+    case SOLVER_ABORT:
+      summary->termination_type = USER_ABORT;
+      VLOG(1) << "Terminating: User callback returned  USER_ABORT.";
+      return false;
+    default:
+      LOG(FATAL) << "Unknown type of user callback status";
+  }
+  return false;
+}
+
+}  // namespace internal
+}  // namespace ceres