1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--
--[[ Iterators ]]--
local it = {};
local t_insert = table.insert;
local select, unpack, next = select, unpack, next;
local function pack(...) return { n = select("#", ...), ... }; end
-- Reverse an iterator
function it.reverse(f, s, var)
local results = {};
-- First call the normal iterator
while true do
local ret = { f(s, var) };
var = ret[1];
if var == nil then break; end
t_insert(results, 1, ret);
end
-- Then return our reverse one
local i,max = 0, #results;
return function (results)
if i<max then
i = i + 1;
return unpack(results[i]);
end
end, results;
end
-- Iterate only over keys in a table
local function _keys_it(t, key)
return (next(t, key));
end
function it.keys(t)
return _keys_it, t;
end
-- Iterate only over values in a table
function it.values(t)
local key, val;
return function (t)
key, val = next(t, key);
return val;
end, t;
end
-- Given an iterator, iterate only over unique items
function it.unique(f, s, var)
local set = {};
return function ()
while true do
local ret = pack(f(s, var));
var = ret[1];
if var == nil then break; end
if not set[var] then
set[var] = true;
return unpack(ret, 1, ret.n);
end
end
end;
end
--[[ Return the number of items an iterator returns ]]--
function it.count(f, s, var)
local x = 0;
while true do
local var = f(s, var);
if var == nil then break; end
x = x + 1;
end
return x;
end
-- Return the first n items an iterator returns
function it.head(n, f, s, var)
local c = 0;
return function (s, var)
if c >= n then
return nil;
end
c = c + 1;
return f(s, var);
end, s;
end
-- Skip the first n items an iterator returns
function it.skip(n, f, s, var)
for i=1,n do
var = f(s, var);
end
return f, s, var;
end
-- Return the last n items an iterator returns
function it.tail(n, f, s, var)
local results, count = {}, 0;
while true do
local ret = pack(f(s, var));
var = ret[1];
if var == nil then break; end
results[(count%n)+1] = ret;
count = count + 1;
end
if n > count then n = count; end
local pos = 0;
return function ()
pos = pos + 1;
if pos > n then return nil; end
local ret = results[((count-1+pos)%n)+1];
return unpack(ret, 1, ret.n);
end
--return reverse(head(n, reverse(f, s, var)));
end
local function _ripairs_iter(t, key) if key > 1 then return key-1, t[key-1]; end end
function it.ripairs(t)
return _ripairs_iter, t, #t+1;
end
local function _range_iter(max, curr) if curr < max then return curr + 1; end end
function it.range(x, y)
if not y then x, y = 1, x; end -- Default to 1..x if y not given
return _range_iter, y, x-1;
end
-- Convert the values returned by an iterator to an array
function it.to_array(f, s, var)
local t, var = {};
while true do
var = f(s, var);
if var == nil then break; end
t_insert(t, var);
end
return t;
end
-- Treat the return of an iterator as key,value pairs,
-- and build a table
function it.to_table(f, s, var)
local t, var2 = {};
while true do
var, var2 = f(s, var);
if var == nil then break; end
t[var] = var2;
end
return t;
end
return it;
|
