//permutations 全排列
namespace table;
	
class permutations{
	ctor(arr, r){
		if(type.isString(arr)){
			arr = ..string.split(arr);
		}
			
    	var n = #arr;
    	r = r || n;
    	if (r > n) return function() {}; 
    	
    	var indices = [];
    	for(i=1;n) indices[i] = i;
    	
    	var cycles = {};
		for(i=n;n-r+1;-1) cycles[#cycles+1] = i;  
    	
    	var first = 1;
    	return function() {
        	if (first) {
            	first = 0;
            	var o = [];
            	for(i=1;r) o[i] = arr[indices[i]];
            	return o;
        	}
        	
        	for(i=r;1;-1) {
            	cycles[i] = cycles[i] - 1;
            	
            	if (cycles[i] == 0) {
                	var temp = indices[i];
                	for(j=i;n) indices[j] = indices[j+1];
                	
                	indices[n] = temp;
                	cycles[i] = n - i + 1;
            	} else {
                	var j = n - cycles[i] + 1; 
                	indices[i], indices[j] = indices[j], indices[i];
                	
                	var o = [];
                	for(k=1;r) o[k] = arr[indices[k]];
                	return o;
            	}
        	}
    	}	
	}; 
} 

/*****intellisense()
table.permutations = 用于生成全排列迭代器，需要导入才能使用。\n 返回生成全排列数组（纯数组）的迭代器，用于 for in 循环语句。
table.permutations(stringOrArray,r) = @for arr in table.permutations(__/*参数 @1 指定输入数组或字符串。可选用参数 @2 指定输出数组长度。\n输入数组为空或输出数组长度大入输入数组长度时返回空迭代器。*/){
	
}
end intellisense*****/