PostgreSQLColumn.swift

/// Represents a PostgreSQL column.
public struct PostgreSQLColumn: Hashable, Equatable {
    /// The table this column belongs to.
    public var tableOID: UInt32
    
    /// The column's name.
    public var name: String
    
    /// Creates a new `PostgreSQLColumn`.
    public init(tableOID: UInt32 = 0, name: String) {
        self.tableOID = tableOID
        self.name = name
    }
}

extension PostgreSQLColumn: CustomStringConvertible {
    /// See `CustomStringConvertible`.
    public var description: String {
        switch tableOID {
        case 0: return name
        default: return tableOID.description + "." + name
        }
    }
}

extension Dictionary where Key == PostgreSQLColumn {
    /// Accesses the _first_ value from this dictionary with a matching field name.
    ///
    /// - Note: This performs a linear search over the dictionary and thus is fairly slow.
    public func firstValue(tableOID: UInt32 = 0, name: String) -> Value? {
        for (column, data) in self {
            if (tableOID == 0 || column.tableOID == 0 || column.tableOID == tableOID) && column.name == name {
                return data
            }
        }
        return nil
    }
}