database: Each DatabaseEntry should know its id

This will let me set up a Track class that has pointers to the
corresponding artist, album and genre information without needing to
know their IDs directly.  Having this information available means I
won't need to keep a "join struct" when doing lookups - instead I can
return a pointer to a Track class that already knows everything.

Signed-off-by: Anna Schumaker <schumaker.anna@gmail.com>

DESIGN

@@ -193,13 +193,14 @@ On-disk files:
 
 Database Entry:
 	The database entry class is a base class used for storing data inside
-	a database (below).  The valid flag will be managed by the database
+	a database (below).  The valid flag and id counter will be managed by
-	itself, and should be initialized to false.
+	the database itself, and should be initialized to false and 0.
 
 - DatabaseEntry:
 	class DatabaseEntry {
 	public:
 		bool valid;
+		unsigned int id;
 
 		DatabaseEntry();
 		virtual void ~DatabaseEntry() = 0;
@@ -211,7 +212,7 @@ Database Entry:
 
 - API:
 	DatabaseEntry :: DatabaseEntry():
-		Set valid = false.
+		Set valid = false and id = 0.
 
 	const std::string DatabaseEntry :: primary_key();
 		This function should return a unique string representing this
@@ -239,23 +240,28 @@ Database:
 	include/database.hpp, which will be included by database.h.  Any
 	function not relying on a template can be written in lib/database.cpp.
 
-- Automatic saving
+- Automatic saving:
 	Databases can save automatically whenever a new value is inserted or
 	deleted.  This will be more efficient for Databases that do not change
 	often but will be a huge performance hit for Databases that have many
 	changes at once.  All databases will be loaded automatically from disk.
 
-- Primary keys
+- Primary keys:
 	Databases use the primary_key() function of a DatabaseEntry to enforce
 	uniqueness.  This key is used when inserting a new value into the
 	Database, and will not be updated after.
 
-- Valid bit
+- Valid bit:
 	The "valid" bit of a DatabaseEntry is completely managed by the entry's
 	Database container.  It will be set to true when an entry is inserted
 	and false when deleted.  The Database is also in charge of writing the
 	valid bit to file.
 
+- Id:
+	The "id" field of a DatabaseEntry is also managed by the entry's
+	Database container  It will be set to the entry's ID when the entry is
+	inserted into the database.
+
 - Database:
 	template <class T>
 	class Database {
@@ -313,9 +319,10 @@ Database:
 			- Add the new item to the end of the _db.
 			- Add the new item to _keys.
 			- Set item.valid = true.
+			- Set item.id to the index of the new item.
 			_ Increment _size.
 			- If autosave == true: save().
-			- Return the index of the new item.
+			- Return item.id.
 
 	unsigned int Database :: remove();
 		- Remove the item from the _keys map.

include/database.h

@@ -14,6 +14,7 @@
 class DatabaseEntry {
 public:
 	bool valid;
+	unsigned int id;
 
 	DatabaseEntry();
 	virtual const std::string primary_key() = 0;

include/database.hpp

@@ -60,6 +60,7 @@ void Database<T> :: load()
 		_file >> _db[i].valid;
 		if (_db[i].valid == true) {
 			_db[i].read(_file);
+			_db[i].id = i;
 			_keys.insert(std::pair<std::string, unsigned int>(_db[i].primary_key(), i));
 			_size++;
 		}
@@ -84,6 +85,7 @@ unsigned int Database<T> :: insert(T val)
 	_db.push_back(val);
 	_keys[val.primary_key()] = id;
 	_db[id].valid = true;
+	_db[id].id = id;
 	_size++;
 	autosave();
 	return id;

lib/database.cpp

@@ -5,6 +5,6 @@
 
 
 DatabaseEntry :: DatabaseEntry()
-	       : valid(false)
+	       : valid(false), id(0)
 {
 }

tests/db_entry

@@ -10,7 +10,7 @@ function test_entry
 
 function test_print
 {
-	test_entry $1 $2 "Value: $1 Key: $2 Valid: 0"
+	test_entry $1 $2 "Value: $1 Key: $2 Valid: 0 Id: 0"
 }
 
 function test_primary_key
@@ -30,7 +30,7 @@ function test_read
 	rm $DATA_DIR/db_entry.txt 2>/dev/null || true
 	echo 0 > $DATA_DIR/db_entry.txt
 	echo $1 $2 >> $DATA_DIR/db_entry.txt
-	test_entry "-r $1" $2 "Value: $1 Key: $2 Valid: 0"
+	test_entry "-r $1" $2 "Value: $1 Key: $2 Valid: 0 Id: 0"
 }
 
 

tests/src/database.cpp

@@ -137,13 +137,15 @@ int main(int argc, char **argv)
 
 
 	/**
-	 * 7: Test iterating 
+	 * 7: Test iterating and setting ID
 	 */
 	Database<IntEntry>::iterator it;
 	unsigned int index = 1;
 	for (it = db.begin(); it != db.end(); it = db.next(it)) {
 		if ((*it).val != index)
 			test_results(false, __LINE__);
+		if ((*it).id != index)
+			test_results(false, __LINE__);
 		index+=2;
 	};
 	test_results(true, __LINE__);
@@ -212,9 +214,12 @@ int main(int argc, char **argv)
 		if (it->valid == true) {
 			if (it->val != it2->val)
 				test_results(false, __LINE__);
+			if (it->id != it2->id)
+				test_results(false, __LINE__);
 		}
 		it2++;
 	}
 	test_results(true, __LINE__);
+
 	return 0;
 }

tests/src/db_entry.cpp

@@ -48,7 +48,7 @@ void IntEntry :: read(File &f)
 
 void IntEntry :: print()
 {
-	:: print("Value: %u Key: %s Valid: %d\n", val, key.c_str(), valid);
+	:: print("Value: %u Key: %s Valid: %d Id: %u\n", val, key.c_str(), valid, id);
 }