没想到这么不起眼的东西杀了我不少脑细胞……

在控制台中测试没发现啥问题，代码风格什么的就先不管它了

public static class PageNumExt
{public delegate void ToDo(long i);public delegate void PadToDo();public static void GeneratePageNum(this object o,long curr, ToDo cfixToDo, PadToDo padToDo, long fixLen = 2, long padding = 1){o.GeneratePageNum(curr, cfixToDo, cfixToDo, padToDo, fixLen, padding);}public static void GeneratePageNum(this object o,long curr, ToDo currTodo, ToDo cfixToDo, PadToDo padToDo, long fixLen = 2, long padding = 1){GeneratePageNum(o,curr, currTodo,1, long.MaxValue,cfixToDo, i => { },fixLen, cfixToDo,padding, padToDo,fixLen, curr,cfixToDo, i => { });}public static void GeneratePageNum(this object o,long curr, ToDo currToDo,long begin, long end,ToDo beginToDo, ToDo endToDo,long cfix, ToDo cfixToDo,long padding, PadToDo padToDo,long sfixBegin, long pfixEnd,ToDo sfbToDo, ToDo pfeToDo){long i = begin;if (begin < curr){beginToDo(begin);i++;var g1 = i + sfixBegin;var g3 = curr - cfix;var g2 = g3 - padding;if (g1 > g3)g1 = g3;for (; i < g1; i++)sfbToDo(i);if (i < g2){padToDo();i = g2 + 1;}elsefor (; i < g3; i++)cfixToDo(i);}for (; i < curr; i++)cfixToDo(i);currToDo(curr);i = curr + 1;var g = i + cfix;if (g > end)g = end;for (; i < g; i++)cfixToDo(i);if (end > curr){var g1 = end - pfixEnd;var g2 = g1 - padding;if (g < g2)padToDo();elsefor (; i < g1; i++)cfixToDo(i);if (i < g1)i = g1;for (; i < end; i++)pfeToDo(i);endToDo(end);}}
}

参数解说：

curr - 当前页码

currToDO - 怎样输出当前页码

begin - 页码从多少开始

end - 页码到多少结束

beginToDo - 怎样显示起始页码

endToDo - 怎样显示结束页码

cfix - 当前页的前后页码输出多少个

cfixToDo - 当前页前后页码怎样输出

padding - 所有没有被涵盖进其它参数的页码，如果出现次数超过这个参数的值，则完全省略掉

padToDo - 被省略掉的页码应该怎样表现

sfixBegin - 从起始页码开始，延伸显示多少个页码

pfixEnd - 到结束页码位置，延伸显示多少个靠近结束位置的页码

sfbToDo - 起始页码附近的页码应该怎么样表现

pfeToDo -结束页码附近的页码应该怎么样表现

测试用的控制台程序代码：

for (var j = 1; j < 20; j++)
{args.GeneratePageNum(j, i =>{Console.Write('[');Console.Write(i);Console.Write(']');Console.Write(' ');},2, 18,i =>{Console.Write('<');Console.Write(i);Console.Write(' ');},i =>{Console.Write(i);Console.Write('>');},2, i =>{Console.Write('#');Console.Write(i);Console.Write(' ');},1, () => Console.Write(".. "),2, 2, i =>{Console.Write('[');Console.Write(i);Console.Write(' ');}, i =>{Console.Write(i);Console.Write(']');Console.Write(' ');});Console.WriteLine();
}for (var j = 1; j < 10; j++)
{args.GeneratePageNum(j, i =>{Console.Write('[');Console.Write(i);Console.Write(']');Console.Write(' ');}, i =>{Console.Write(i);Console.Write(' ');}, () =>{Console.Write(".. ");}, 2, 1);Console.WriteLine();
}