From a2e54a235adc4b443b977b8f648864cc858bcf69 Mon Sep 17 00:00:00 2001
From: Tiago Gomes <tgomes@fc.up.pt>
Date: Thu, 21 Mar 2013 21:49:12 +0000
Subject: [PATCH] Factor: improve factor multiplication

Pass the argument as reference-to-const and also allow chaining of multiplications.
---
 packages/CLPBN/horus/Factor.cpp        | 8 +++++---
 packages/CLPBN/horus/Factor.h          | 2 +-
 packages/CLPBN/horus/GenericFactor.cpp | 7 ++++---
 packages/CLPBN/horus/GenericFactor.h   | 2 +-
 4 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/packages/CLPBN/horus/Factor.cpp b/packages/CLPBN/horus/Factor.cpp
index 45d586d7d..f3fbc704b 100644
--- a/packages/CLPBN/horus/Factor.cpp
+++ b/packages/CLPBN/horus/Factor.cpp
@@ -91,14 +91,16 @@ Factor::sumOutAllExceptIndex (size_t idx)
 }
 
 
-void
-Factor::multiply (Factor& g)
+
+Factor&
+Factor::multiply (const Factor& g)
 {
   if (args_.empty()) {
-    *this = g;
+    operator= (g);
   } else {
     GenericFactor<VarId>::multiply (g);
   }
+  return *this;
 }
 
 
diff --git a/packages/CLPBN/horus/Factor.h b/packages/CLPBN/horus/Factor.h
index a1feaf989..1e1cb0ad1 100644
--- a/packages/CLPBN/horus/Factor.h
+++ b/packages/CLPBN/horus/Factor.h
@@ -30,7 +30,7 @@ class Factor : public GenericFactor<VarId> {
 
     void sumOutAllExceptIndex (size_t idx);
 
-    void multiply (Factor&);
+    Factor& multiply (const Factor&);
 
     std::string getLabel() const;
 
diff --git a/packages/CLPBN/horus/GenericFactor.cpp b/packages/CLPBN/horus/GenericFactor.cpp
index 8ae9927be..3d10180c2 100644
--- a/packages/CLPBN/horus/GenericFactor.cpp
+++ b/packages/CLPBN/horus/GenericFactor.cpp
@@ -82,15 +82,15 @@ GenericFactor<T>::operator[] (size_t idx)
 
 
 
-template <typename T> void
-GenericFactor<T>::multiply (GenericFactor<T>& g)
+template <typename T> GenericFactor<T>&
+GenericFactor<T>::multiply (const GenericFactor<T>& g)
 {
   if (args_ == g.arguments()) {
     // optimization
     Globals::logDomain
       ? params_ += g.params()
       : params_ *= g.params();
-    return;
+    return *this;
   }
   unsigned range_prod = 1;
   bool share_arguments = false;
@@ -124,6 +124,7 @@ GenericFactor<T>::multiply (GenericFactor<T>& g)
       }
     }
   }
+  return *this;
 }
 
 
diff --git a/packages/CLPBN/horus/GenericFactor.h b/packages/CLPBN/horus/GenericFactor.h
index 5f538d7fd..e771fa7b0 100644
--- a/packages/CLPBN/horus/GenericFactor.h
+++ b/packages/CLPBN/horus/GenericFactor.h
@@ -49,7 +49,7 @@ class GenericFactor {
 
     double& operator[] (size_t idx);
 
-    void multiply (GenericFactor<T>& g);
+    GenericFactor<T>& multiply (const GenericFactor<T>& g);
 
     void sumOutIndex (size_t idx);