dmspine64backup/DBEngine.cpp

#include <fstream>
#include <iostream>
#include <vector>
#include "DBEngine.h"

DBEngine::DBEngine(){
	size = 0;
}

void DBEngine::createTable(string n){
	Relation r(n);
	tables.push_back(r);
	size++;
}

void DBEngine::createTable(string n, vector<Attribute> a){
	Relation r(n, a);
	tables.push_back(r);
	size++;
}
	
void DBEngine::createTable(Relation r){ 
	tables.push_back(r); 
	size++;
}
	
vector<Relation> DBEngine::getRelations(){ 
	return tables; 
}
	
Relation DBEngine::getTableFromName(string n){
	//will return first occurence
	for(int i = 0; i < tables.size(); i++){
		if (tables[i].getTableName() == n){
			return tables[i];
		}
	}
}

void DBEngine::saveToFile(vector<string> cmds){ 
	//writes nothing meaningful
	ofstream file;
	file.open("savefile.db");
	
	for(int i = 0; i < cmds.size(); ++i){
		file << cmds[i] << endl;
	}
	
	file.close();
}

//assumes that all attribute titles are unique
Relation DBEngine::projection(vector<string> input, Relation r){
	
	vector<Attribute> v;
	string new_name = r.getTableName() + " Projection";
	
	for(int i = 0; i < input.size(); ++i) {
		
		for(int j = 0; j < r.getSize(); ++j) {
			if((r.getAttributes())[j].getName() == input[i])
				v.push_back((r.getAttributes())[j]);
		}
	}
	
	Relation temp(new_name, v);
	return temp;
}

//ASAP: TEST ALL OF THIS
void rename(Relation r, vector<string> oldnames, vector<string> newnames){
	if (oldnames.size() != newnames.size()) {
		cout << "Failure to rename: number of attributes do not match.";
		return;
	}
	
	else if (oldnames != r.getAttributeNames()) {
		cout << "Failure to rename: the attributes to be renamed do not exist in the relation.";
		return;
	}
	
	else {
		Attribute temp;
		
		for(int i = 0; i < oldnames.size(); ++i){
			temp = r.getAttributeByName(oldnames[i]);
			temp.setName(newnames[i]);
		}
	}
}