From 6c0916beb4cf4e0ca38a660b1202608e1db2669c Mon Sep 17 00:00:00 2001
From: JoelKatz <DavidJoelSchwartz@GMail.com>
Date: Wed, 24 Oct 2012 20:03:48 -0700
Subject: [PATCH] An helper function we need.

---
 src/RangeSet.cpp | 14 ++++++++++++++
 src/RangeSet.h   |  3 +++
 2 files changed, 17 insertions(+)

diff --git a/src/RangeSet.cpp b/src/RangeSet.cpp
index be0942a7c3..fb2fbbe43b 100644
--- a/src/RangeSet.cpp
+++ b/src/RangeSet.cpp
@@ -52,6 +52,20 @@ int RangeSet::getPrev(int v) const
 	return RangeSetAbsent;
 }
 
+int RangeSet::prevMissing(int v) const
+{ // largest number not in the set that is less than the given number
+	for (const_reverse_iterator it = rbegin(); it != rend(); ++it)
+	{
+		if (lower(it) <= v)
+		{
+			if (upper(it) < v)
+				return upper(it) + 1;
+			return lower(it) - 1;
+		}
+	}
+	return RangeSetAbsent;
+}
+
 void RangeSet::setValue(int v)
 {
 	setRange(v, v);
diff --git a/src/RangeSet.h b/src/RangeSet.h
index c70acf43b6..b74617d129 100644
--- a/src/RangeSet.h
+++ b/src/RangeSet.h
@@ -33,11 +33,14 @@ public:
 	int getLast() const;
 	int getPrev(int) const;
 
+	int prevMissing(int) const;		// largest number not in the set that is less than the given number
+
 	void setValue(int);
 	void setRange(int, int);
 	void clearValue(int);
 	void clearRange(int, int);
 
+
 	void clear()							{ mRanges.clear(); }
 
 	// iterator stuff