db/upnp/Directory: eliminate the "attributes" std::map

Look up attributes in the "atts" array.  Reduce bloat.

src/Expat.cxx

@@ -69,6 +69,17 @@ ExpatParser::Parse(InputStream &is, Error &error)
 	return Parse("", 0, true, error);
 }
 
+const char *
+ExpatParser::GetAttribute(const XML_Char **atts,
+			  const char *name)
+{
+	for (unsigned i = 0; atts[i] != nullptr; i += 2)
+		if (strcmp(atts[i], name) == 0)
+			return atts[i + 1];
+
+	return nullptr;
+}
+
 const char *
 ExpatParser::GetAttributeCase(const XML_Char **atts,
 			      const char *name)

src/Expat.hxx

@@ -55,6 +55,10 @@ public:
 
 	bool Parse(InputStream &is, Error &error);
 
+	gcc_pure
+	static const char *GetAttribute(const XML_Char **atts,
+					const char *name);
+
 	gcc_pure
 	static const char *GetAttributeCase(const XML_Char **atts,
 					    const char *name);
@@ -85,6 +89,12 @@ public:
 		return parser.Parse(is, error);
 	}
 
+	gcc_pure
+	static const char *GetAttribute(const XML_Char **atts,
+					const char *name) {
+		return ExpatParser::GetAttribute(atts, name);
+	}
+
 	gcc_pure
 	static const char *GetAttributeCase(const XML_Char **atts,
 					    const char *name) {

src/db/upnp/Directory.cxx

@@ -24,7 +24,6 @@
 
 #include <string>
 #include <vector>
-#include <map>
 
 #include <string.h>
 
@@ -78,17 +77,19 @@ protected:
 	{
 		m_path.push_back(name);
 
-		std::map<std::string,std::string> attributes;
-		for (int i = 0; attrs[i] != 0; i += 2)
-			attributes[attrs[i]] = attrs[i+1];
-
 		switch (name[0]) {
 		case 'c':
 			if (!strcmp(name, "container")) {
 				m_tobj.clear();
 				m_tobj.type = UPnPDirObject::Type::CONTAINER;
-				m_tobj.m_id = attributes["id"];
+
-				m_tobj.m_pid = attributes["parentID"];
+				const char *id = GetAttribute(attrs, "id");
+				if (id != nullptr)
+					m_tobj.m_id = id;
+
+				const char *pid = GetAttribute(attrs, "parentID");
+				if (pid != nullptr)
+					m_tobj.m_pid = pid;
 			}
 			break;
 
@@ -96,8 +97,14 @@ protected:
 			if (!strcmp(name, "item")) {
 				m_tobj.clear();
 				m_tobj.type = UPnPDirObject::Type::ITEM;
-				m_tobj.m_id = attributes["id"];
+
-				m_tobj.m_pid = attributes["parentID"];
+				const char *id = GetAttribute(attrs, "id");
+				if (id != nullptr)
+					m_tobj.m_id = id;
+
+				const char *pid = GetAttribute(attrs, "parentID");
+				if (pid != nullptr)
+					m_tobj.m_pid = pid;
 			}
 			break;
 
@@ -108,8 +115,9 @@ protected:
 				// nrAudioChannels="2">
 
 				for (auto i = res_attributes; *i != nullptr; ++i) {
-					const std::string s(*i);
+					const char *value = GetAttribute(attrs, *i);
-					m_tobj.m_props[s] = attributes[s];
+					if (value != nullptr)
+						m_tobj.m_props.emplace(*i, value);
 				}
 			}