Add a proper build system

FossilOrigin-Name: 8679c61b2c82da9daa316ed5eb90ba1b69e608127afa318cbdbff56b53d65a74

src/exceptions/PGException.m

@@ -0,0 +1,44 @@
+#import "PGException.h"
+
+@implementation PGException
++ (instancetype)exceptionWithConnection: (PGConnection*)connection
+{
+	return [[[self alloc] initWithConnection: connection] autorelease];
+}
+
+- initWithConnection: (PGConnection*)connection
+{
+	self = [super init];
+
+	@try {
+		_connection = [connection retain];
+		_error = [[OFString alloc]
+		    initWithCString: PQerrorMessage([_connection PG_connection])
+			   encoding: [OFString nativeOSEncoding]];
+	} @catch (id e) {
+		[self release];
+		@throw e;
+	}
+
+	return self;
+}
+
+- (void)dealloc
+{
+	[_connection release];
+	[_error release];
+
+	[super dealloc];
+}
+
+- (OFString*)description
+{
+	return [OFString stringWithFormat: @"A PostgreSQL operation failed: %@",
+					   _error];
+}
+
+- (PGConnection*)connection
+{
+	OF_GETTER(_connection, NO)
+}
+@end