DbMigrate/ColumnCollection.cs

using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DbMigrate {
    public class ColumnCollection {
        public Dictionary<string, string> Items { get; private set; } = new Dictionary<string, string>();

        public ColumnCollection() {
            Items = new Dictionary<string, string>();
        }

        public string this[string columnName] {
            get {
                if (Items.ContainsKey(columnName)) {
                    return Items[columnName];
                }
                return null;
            }
            set {
                if (Items.ContainsKey(columnName)) {
                    Items[columnName] = value;
                } else {
                    Items.Add(columnName, value);
                }
            }
        }

        public void Add(string columnName, string columnDefinition) {
            if (!Items.ContainsKey(columnName)) {
                Items.Add(columnName, columnDefinition);
            }
        }

        public bool Contains(string columnName) {
            return Items.ContainsKey(columnName);
        }

        public string[] GetColumnNames() {
            return Items.Keys.ToArray();
        }

        public int Count() {
            return Items.Count;
        }

        public void Clear() {
            Items.Clear();
        }

        public override string ToString() {
            StringBuilder sb = new StringBuilder();
            foreach (var kvp in Items) {
                sb.AppendLine($"{kvp.Key}: {kvp.Value}");
            }
            return sb.ToString();
        }
    }
}