/// <summary>
/// 把集合中的所有元素放入一个字符串。
/// </summary>
/// <typeparam name="T">数据类型。</typeparam>
/// <param name="items">原集合。</param>
/// <param name="callback">回调方法。</param>
/// <param name="separator">分隔符。</param>
/// <param name="start">起始文本。如果集合为空，不包含此数据。</param>
/// <param name="end">结尾文本。如果集合为空，不包含此数据。</param>
/// <param name="ignoreEmptyItem">指示是否忽略集合中为 null 或 <see cref="string.Empty"/> 值的项。</param>
/// <returns>拼接后的字符串。</returns>
public static string Join <T>(this IEnumerable <T> items, Func <T, string> callback, string separator = ",", string start = null, string end = null, bool ignoreEmptyItem = true)
{
var builder = new Text.StringBuilder();
var isStringType = typeof(T) == DefineTypes.String;
foreach (var item in items)
{
if (ignoreEmptyItem && (item == null || (isStringType && item.ToString().Length == 0)))
{
continue;
}
if (builder.Length > 0)
{
builder.Append(separator);
}
builder.Append(callback(item));
}
if (builder.Length == 0)
{
return(string.Empty);
}
if (start != null)
{
builder.Insert(0, start);
}
if (end != null)
{
builder.Append(end);
}
return(builder.ToString());
}
/// <summary>
/// 把集合中的所有元素放入一个字符串。
/// </summary>
/// <typeparam name="T">数据类型。</typeparam>
/// <param name="items">原集合。</param>
/// <param name="callback">回调方法。</param>
/// <param name="separator">分隔符。</param>
/// <param name="start">起始文本。如果集合为空，不包含此数据。</param>
/// <param name="end">结尾文本。如果集合为空，不包含此数据。</param>
/// <returns>拼接后的字符串。</returns>
public static string Join <T>(this IEnumerable <T> items, Func <T, string> callback, string separator = ",", string start = null, string end = null)
{
Text.StringBuilder builder = new Text.StringBuilder();
foreach (var item in items)
{
if (builder.Length > 0)
{
builder.Append(separator);
}
builder.Append(callback(item));
}
if (builder.Length == 0)
{
return(string.Empty);
}
if (start != null)
{
builder.Insert(0, start);
}
if (end != null)
{
builder.Append(end);
}
return(builder.ToString());
}