From e0ecb7a2d82286909a43d645035dd8f1d5e773a3 Mon Sep 17 00:00:00 2001
From: Paul Beckingham <paul@beckingham.net>
Date: Sun, 21 Aug 2011 16:54:50 -0400
Subject: [PATCH] E9 - Relational Operators

- Added missing-data handling for the relational operators <, <=, >
  and >=.
---
 src/E9.cpp | 64 +++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 44 insertions(+), 20 deletions(-)

diff --git a/src/E9.cpp b/src/E9.cpp
index 0824ed49c..a7f81f197 100644
--- a/src/E9.cpp
+++ b/src/E9.cpp
@@ -290,12 +290,18 @@ void E9::operator_lt (Arg& result, Arg& left, Arg& right)
   else if (left._type  == Arg::type_date ||
            right._type == Arg::type_date)
   {
-    Date left_date  (left._value,  _dateformat);
-    Date right_date (right._value, _dateformat);
+    if (left._value == "" ||
+        right._value == "")
+      result._value = "false";
+    else
+    {
+      Date left_date  (left._value,  _dateformat);
+      Date right_date (right._value, _dateformat);
 
-    result._value = (left_date < right_date)
-                  ? "true"
-                  : "false";
+      result._value = (left_date < right_date)
+                    ? "true"
+                    : "false";
+    }
   }
   else
   {
@@ -323,12 +329,18 @@ void E9::operator_lte (Arg& result, Arg& left, Arg& right)
   else if (left._type  == Arg::type_date ||
            right._type == Arg::type_date)
   {
-    Date left_date  (left._value,  _dateformat);
-    Date right_date (right._value, _dateformat);
+    if (left._value == "" ||
+        right._value == "")
+      result._value = "false";
+    else
+    {
+      Date left_date  (left._value,  _dateformat);
+      Date right_date (right._value, _dateformat);
 
-    result._value = (left_date <= right_date)
-                  ? "true"
-                  : "false";
+      result._value = (left_date <= right_date)
+                    ? "true"
+                    : "false";
+    }
   }
   else
   {
@@ -356,12 +368,18 @@ void E9::operator_gte (Arg& result, Arg& left, Arg& right)
   else if (left._type  == Arg::type_date ||
            right._type == Arg::type_date)
   {
-    Date left_date  (left._value,  _dateformat);
-    Date right_date (right._value, _dateformat);
+    if (left._value == "" ||
+        right._value == "")
+      result._value = "false";
+    else
+    {
+      Date left_date  (left._value,  _dateformat);
+      Date right_date (right._value, _dateformat);
 
-    result._value = (left_date >= right_date)
-                  ? "true"
-                  : "false";
+      result._value = (left_date >= right_date)
+                    ? "true"
+                    : "false";
+    }
   }
   else
   {
@@ -388,12 +406,18 @@ void E9::operator_gt (Arg& result, Arg& left, Arg& right)
   else if (left._type  == Arg::type_date ||
            right._type == Arg::type_date)
   {
-    Date left_date  (left._value,  _dateformat);
-    Date right_date (right._value, _dateformat);
+    if (left._value == "" ||
+        right._value == "")
+      result._value = "false";
+    else
+    {
+      Date left_date  (left._value,  _dateformat);
+      Date right_date (right._value, _dateformat);
 
-    result._value = result._value = (left_date > right_date)
-                                  ? "true"
-                                  : "false";
+      result._value = result._value = (left_date > right_date)
+                                    ? "true"
+                                    : "false";
+    }
   }
   else
   {