song: use boost::hash

src/song.cpp

@@ -21,6 +21,7 @@
 #include <cassert>
 #include <cstring>
 #include <boost/format.hpp>
+#include <boost/functional/hash.hpp>
 #include <boost/lexical_cast.hpp>
 #include <iostream>
 #include <memory>
@@ -32,12 +33,11 @@
 
 namespace {
 
-size_t calc_hash(const char* s, unsigned seed = 0)
+size_t calc_hash(const char *s, size_t seed = 0)
 {
-	size_t hash = seed;
-	while (*s)
-		hash = hash * 101 + *s++;
-	return hash;
+	for (; *s != '\0'; ++s)
+		boost::hash_combine(seed, *s);
+	return seed;
 }
 
 }

src/song.h

@@ -46,7 +46,8 @@ struct Song
 
 	Song(const Song &rhs) : m_song(rhs.m_song), m_hash(rhs.m_hash) { }
 	Song(Song &&rhs) : m_song(std::move(rhs.m_song)), m_hash(rhs.m_hash) { }
-	Song &operator=(Song rhs) {
+	Song &operator=(Song rhs)
+	{
 		m_song = std::move(rhs.m_song);
 		m_hash = rhs.m_hash;
 		return *this;
@@ -85,15 +86,15 @@ struct Song
 	
 	virtual bool empty() const;
 	
-	bool operator==(const Song &rhs) const {
+	bool operator==(const Song &rhs) const
+	{
 		if (m_hash != rhs.m_hash)
 			return false;
 		return strcmp(c_uri(), rhs.c_uri()) == 0;
 	}
-	bool operator!=(const Song &rhs) const {
-		if (m_hash != rhs.m_hash)
-			return true;
-		return strcmp(c_uri(), rhs.c_uri()) != 0;
+	bool operator!=(const Song &rhs) const
+	{
+		return !(operator==(rhs));
 	}
 	
 	const char *c_uri() const { return m_song ? mpd_song_get_uri(m_song.get()) : ""; }