2 -- Copyright (C) 2008-2010 Matthew Wild
3 -- Copyright (C) 2008-2010 Waqas Hussain
5 -- This project is MIT/X11 licensed. Please see the
6 -- COPYING file in the source package for more information.
13 local t_insert = table.insert;
14 local select, next = select, next;
15 local unpack = table.unpack or unpack; --luacheck: ignore 113
16 local pack = table.pack or function (...) return { n = select("#", ...), ... }; end
18 -- Reverse an iterator
19 function it.reverse(f, s, var)
22 -- First call the normal iterator
24 local ret = { f(s, var) };
26 if var == nil then break; end
27 t_insert(results, 1, ret);
30 -- Then return our reverse one
31 local i,max = 0, #results;
32 return function (_results)
35 return unpack(_results[i]);
40 -- Iterate only over keys in a table
41 local function _keys_it(t, key)
42 return (next(t, key));
48 -- Iterate only over values in a table
52 key, val = next(_t, key);
57 -- Iterate over the n:th return value
58 function it.select(n, f, s, var)
60 local ret = pack(f(_s, var));
66 -- Given an iterator, iterate only over unique items
67 function it.unique(f, s, var)
72 local ret = pack(f(s, var));
74 if var == nil then break; end
77 return unpack(ret, 1, ret.n);
83 --[[ Return the number of items an iterator returns ]]--
84 function it.count(f, s, var)
89 if var == nil then break; end
96 -- Return the first n items an iterator returns
97 function it.head(n, f, s, var)
99 return function (_s, _var)
108 -- Skip the first n items an iterator returns
109 function it.skip(n, f, s, var)
116 -- Return the last n items an iterator returns
117 function it.tail(n, f, s, var)
118 local results, count = {}, 0;
120 local ret = pack(f(s, var));
122 if var == nil then break; end
123 results[(count%n)+1] = ret;
127 if n > count then n = count; end
132 if pos > n then return nil; end
133 local ret = results[((count-1+pos)%n)+1];
134 return unpack(ret, 1, ret.n);
136 --return reverse(head(n, reverse(f, s, var))); -- !
139 function it.filter(filter, f, s, var)
140 if type(filter) ~= "function" then
141 local filter_value = filter;
142 function filter(x) return x ~= filter_value; end
144 return function (_s, _var)
146 repeat ret = pack(f(_s, _var));
148 until _var == nil or filter(unpack(ret, 1, ret.n));
149 return unpack(ret, 1, ret.n);
153 local function _ripairs_iter(t, key) if key > 1 then return key-1, t[key-1]; end end
154 function it.ripairs(t)
155 return _ripairs_iter, t, #t+1;
158 local function _range_iter(max, curr) if curr < max then return curr + 1; end end
159 function it.range(x, y)
160 if not y then x, y = 1, x; end -- Default to 1..x if y not given
161 return _range_iter, y, x-1;
164 -- Convert the values returned by an iterator to an array
165 function it.to_array(f, s, var)
169 if var == nil then break; end
175 -- Treat the return of an iterator as key,value pairs,
177 function it.to_table(f, s, var)
180 var, var2 = f(s, var);
181 if var == nil then break; end