From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 8 Jul 2012 14:04:05 +0000 (+0300)
Subject: Turn the unique function into a template and make it more efficient
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=ee2c6758fd120fe8bca76521acba06d793121d60;p=builder.git

Turn the unique function into a template and make it more efficient
---

diff --git a/source/buildinfo.cpp b/source/buildinfo.cpp
index ec81567..77243ef 100644
--- a/source/buildinfo.cpp
+++ b/source/buildinfo.cpp
@@ -1,4 +1,5 @@
 #include <algorithm>
+#include <set>
 #include "buildinfo.h"
 
 using namespace std;
@@ -7,17 +8,18 @@ using namespace Msp;
 namespace {
 
 /** Removes any duplicate entries from a list, leaving only the first one.  The
-order of other elements is preserved.  O(n²) efficiency. */
-void unique(StringList &l)
+order of other elements is preserved.  O(nlogn) efficiency. */
+template<typename T>
+void unique(list<T> &l)
 {
-	for(StringList::iterator i=l.begin(); i!=l.end(); ++i)
-		for(StringList::iterator j=i; j!=l.end();)
-		{
-			if(j!=i && *j==*i)
-				j = l.erase(j);
-			else
-				++j;
-		}
+	set<T> seen;
+	for(typename list<T>::iterator i=l.begin(); i!=l.end(); )
+	{
+		if(seen.count(*i))
+			l.erase(i++);
+		else
+			seen.insert(*i++);
+	}
 }
 
 }