From 8ff3a1675d9282d4ca3170ba397218cad97999e9 Mon Sep 17 00:00:00 2001
From: Paul Beckingham <paul@beckingham.net>
Date: Mon, 4 Jul 2011 14:22:33 -0400
Subject: [PATCH] Duration

- Implemented operator+=, operator-=.
- Added unit tests.
---
 src/Duration.cpp    | 55 +++++++++++++++++++++++++++++++++++++++++++--
 src/Duration.h      |  7 ++++--
 test/duration.t.cpp | 32 +++++++++++++++++++++++++-
 3 files changed, 89 insertions(+), 5 deletions(-)

diff --git a/src/Duration.cpp b/src/Duration.cpp
index 423558f6e..15e91c749 100644
--- a/src/Duration.cpp
+++ b/src/Duration.cpp
@@ -155,9 +155,60 @@ Duration& Duration::operator= (const Duration& other)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-Duration& Duration::operator- (const Duration& other)
+Duration Duration::operator- (const Duration& other)
 {
-  throw std::string ("Error: Duration::operator- unimplemented");
+  int left  =       mSecs * (      mNegative ? -1 : 1);
+  int right = other.mSecs * (other.mNegative ? -1 : 1);
+
+  left -= right;
+
+  Duration result;
+  result.mSecs = abs (left);
+  result.mNegative = left < 0;
+
+  return result;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+Duration Duration::operator+ (const Duration& other)
+{
+  int left  =       mSecs * (      mNegative ? -1 : 1);
+  int right = other.mSecs * (other.mNegative ? -1 : 1);
+
+  left += right;
+
+  Duration result;
+  result.mSecs = abs (left);
+  result.mNegative = left < 0;
+
+  return result;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+Duration& Duration::operator-= (const Duration& other)
+{
+  int left  =       mSecs * (      mNegative ? -1 : 1);
+  int right = other.mSecs * (other.mNegative ? -1 : 1);
+
+  left -= right;
+
+  mSecs = abs (left);
+  mNegative = left < 0;
+
+  return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+Duration& Duration::operator+= (const Duration& other)
+{
+  int left  =       mSecs * (      mNegative ? -1 : 1);
+  int right = other.mSecs * (other.mNegative ? -1 : 1);
+
+  left += right;
+
+  mSecs = abs (left);
+  mNegative = left < 0;
+
   return *this;
 }
 
diff --git a/src/Duration.h b/src/Duration.h
index ceef31a71..065135bac 100644
--- a/src/Duration.h
+++ b/src/Duration.h
@@ -43,7 +43,10 @@ public:
   bool operator> (const Duration&);
   bool operator>= (const Duration&);
   Duration& operator= (const Duration&);
-  Duration& operator- (const Duration&);
+  Duration operator- (const Duration&);
+  Duration operator+ (const Duration&);
+  Duration& operator-= (const Duration&);
+  Duration& operator+= (const Duration&);
   ~Duration ();                          // Destructor
 
   operator time_t () const;
@@ -56,7 +59,7 @@ public:
   static bool valid (const std::string&);
   void parse (const std::string&);
 
-private:
+protected:
   time_t mSecs;
   bool mNegative;
 };
diff --git a/test/duration.t.cpp b/test/duration.t.cpp
index a9892b153..d76ab4f86 100644
--- a/test/duration.t.cpp
+++ b/test/duration.t.cpp
@@ -48,7 +48,7 @@ int convertDuration (const std::string& input)
 
 int main (int argc, char** argv)
 {
-  UnitTest t (618);
+  UnitTest t (628);
 
   Duration d;
 
@@ -741,6 +741,36 @@ int main (int argc, char** argv)
     left = Duration ("1sec");   right = Duration ("2secs");  t.notok (left >= right, "duration NOT 1sec >= 2secs");
     left = Duration ("2secs");  right = Duration ("2secs");  t.ok (left >= right, "duration 1sec >= 2secs");
     left = Duration ("2secs");  right = Duration ("1secs");  t.ok (left >= right, "duration 1sec >= 2secs");
+
+    // operator+
+    left  = Duration (1);
+    right = Duration (2);
+    Duration result = left + right;
+    t.is ((int)(time_t)left,   1, "1 + 2 = 3, 1 is still 1");
+    t.is ((int)(time_t)right,  2, "1 + 2 = 3, 2 is still 2");
+    t.is ((int)(time_t)result, 3, "1 + 2 = 3");
+
+    // operator+=
+    left  = Duration (1);
+    right = Duration (2);
+    left += right;
+    t.is ((int)(time_t)left,   3, "1 += 2, 1 is now 3");
+    t.is ((int)(time_t)right,  2, "1 += 2, 2 is still 2");
+
+    // operator-
+    left  = Duration (3);
+    right = Duration (2);
+    result = left - right;
+    t.is ((int)(time_t)left,   3, "3 - 2 = 1, 3 is still 3");
+    t.is ((int)(time_t)right,  2, "3 - 2 = 1, 2 is still 2");
+    t.is ((int)(time_t)result, 1, "3 - 2 = 1");
+
+    // operator-=
+    left  = Duration (3);
+    right = Duration (2);
+    left -= right;
+    t.is ((int)(time_t)left,   1, "3 -= 2, 3 is now 1");
+    t.is ((int)(time_t)right,  2, "3 -= 2, 2 is still 2");
   }
 
   catch (const std::string& e) { t.diag (e); }