Mercurial > lxmppd-hg-xmllex / file comparison
comparison: util/iterators.lua
util/iterators.lua
- changeset 919
- 75b8afb79143
- child 1522
- 569d58d21612
equal
deleted
inserted
replaced
| 918:967edf874df7 | 919:75b8afb79143 |
|---|---|
| 1 --[[ Iterators ]]-- | |
| 2 | |
| 3 -- Reverse an iterator | |
| 4 function reverse(f, s, var) | |
| 5 local results = {}; | |
| 6 | |
| 7 -- First call the normal iterator | |
| 8 while true do | |
| 9 local ret = { f(s, var) }; | |
| 10 var = ret[1]; | |
| 11 if var == nil then break; end | |
| 12 table.insert(results, 1, ret); | |
| 13 end | |
| 14 | |
| 15 -- Then return our reverse one | |
| 16 local i,max = 0, #results; | |
| 17 return function (results) | |
| 18 if i<max then | |
| 19 i = i + 1; | |
| 20 return unpack(results[i]); | |
| 21 end | |
| 22 end, results; | |
| 23 end | |
| 24 | |
| 25 -- Iterate only over keys in a table | |
| 26 local function _keys_it(t, key) | |
| 27 return (next(t, key)); | |
| 28 end | |
| 29 function keys(t) | |
| 30 return _keys_it, t; | |
| 31 end | |
| 32 | |
| 33 -- Iterate only over values in a table | |
| 34 function values(t) | |
| 35 local key, val; | |
| 36 return function (t) | |
| 37 key, val = next(t, key); | |
| 38 return val; | |
| 39 end, t; | |
| 40 end | |
| 41 | |
| 42 -- Given an iterator, iterate only over unique items | |
| 43 function unique(f, s, var) | |
| 44 local set = {}; | |
| 45 | |
| 46 return function () | |
| 47 while true do | |
| 48 local ret = { f(s, var) }; | |
| 49 var = ret[1]; | |
| 50 if var == nil then break; end | |
| 51 if not set[var] then | |
| 52 set[var] = true; | |
| 53 return var; | |
| 54 end | |
| 55 end | |
| 56 end; | |
| 57 end | |
| 58 | |
| 59 --[[ Return the number of items an iterator returns ]]-- | |
| 60 function count(f, s, var) | |
| 61 local x = 0; | |
| 62 | |
| 63 while true do | |
| 64 local ret = { f(s, var) }; | |
| 65 var = ret[1]; | |
| 66 if var == nil then break; end | |
| 67 x = x + 1; | |
| 68 end | |
| 69 | |
| 70 return x; | |
| 71 end | |
| 72 | |
| 73 -- Convert the values returned by an iterator to an array | |
| 74 function it2array(f, s, var) | |
| 75 local t, var = {}; | |
| 76 while true do | |
| 77 var = f(s, var); | |
| 78 if var == nil then break; end | |
| 79 table.insert(t, var); | |
| 80 end | |
| 81 return t; | |
| 82 end | |
| 83 | |
| 84 -- Treat the return of an iterator as key,value pairs, | |
| 85 -- and build a table | |
| 86 function it2table(f, s, var) | |
| 87 local t, var = {}; | |
| 88 while true do | |
| 89 var, var2 = f(s, var); | |
| 90 if var == nil then break; end | |
| 91 t[var] = var2; | |
| 92 end | |
| 93 return t; | |
| 94 end |
