rename expression works.

DBEngine.cpp

@@ -151,12 +151,23 @@ Relation DBEngine::projection(vector<string> input, Relation r){
 }
 
 //test error matching
-void DBEngine::rename(Relation& r, vector<string> oldnames, vector<string> newnames){
-	if (oldnames.size() != newnames.size()) {
+Relation DBEngine::rename(vector<string> newnames, Relation &r)
+{
+	vector<string> temp;
+	if (r.getSize() != newnames.size()) {
 		cout << "FAILURE TO RENAME: number of attributes do not match.\n";
-		return;
+		exit(1);
 	}
-	
+	else
+	{
+		temp = r.getAttributeNames();
+		for(int i = 0; i < temp.size(); ++i)
+		{
+			r.renameAttribute(temp[i], newnames[i]);
+		}
+		return r;
+	}
+	/*
 	else if (oldnames != r.getAttributeNames()) {
 		cout << "FAILURE TO RENAME: the attributes to be renamed do not exist in the relation.\n";
 		return;
@@ -167,6 +178,8 @@ void DBEngine::rename(Relation& r, vector<string> oldnames, vector<string> newna
 			r.renameAttribute(oldnames[i], newnames[i]);
 		}
 	}
+	*/
+	
 }
 
 Relation DBEngine::setUnion(Relation r1, Relation r2){

DBEngine.h

@@ -28,7 +28,7 @@ public:
 	void save();
 	void save(string n);
 	void storeCommands(string s);
-	void rename(Relation& r, vector<string> oldnames, vector<string> newnames);
+	Relation rename(vector<string> newnames, Relation &r);
 	Relation setUnion(Relation r1, Relation r2);
 	Relation setDiff(Relation r1, Relation r2);
 	Relation crossProduct(Relation r1, Relation r2);

Parser.cpp

@@ -91,7 +91,46 @@ tuple<vector<string>, Relation> expression(vector<string> input, DBEngine &engin
 	
 	else if(input[0] == "rename")
 	{
-		
+		input.erase(input.begin());
+		if(input[0] == "(")
+		{
+			input.erase(input.begin());
+			vector<string> temp;
+			while(input[0] != ")")
+			{
+				if(input[0] == ",")
+				{
+					input.erase(input.begin());
+				}
+				temp.push_back(input[0]);
+				input.erase(input.begin());
+			}
+			input.erase(input.begin());
+			Relation rfinal("TEMP");
+			if(engine.isRelation(input[0]))
+			{
+				rfinal = engine.rename(temp, engine.getTableFromName(input[0]));
+				input.erase(input.begin());
+				get<0>(t) = input;
+				get<1>(t) = rfinal;
+				return t;
+			}
+			else if(input[0] == "(")
+			{
+				input.erase(input.begin());
+				t = expression(input, engine);
+				input.erase(input.begin());
+				rfinal = engine.rename(temp, get<1>(t));
+				get<0>(t) = input;
+				get<1>(t) = rfinal;
+				return t;
+			}
+		}
+		else
+		{
+			cout << "Rename syntax incorrect." << endl;
+			exit(1);
+		}
 	}
 	
 	else if(engine.isRelation(input[0]))