Merge 0.9->trunk

[prosody.git] / util / iterators.lua

diff --git a/util/iterators.lua b/util/iterators.lua
index 318c1a96b8fad3b45f1d7111ef130d98ab34e8f0..4b429163bfbdbcf963cf0d267c1d3da7b1015ac7 100644 (file)
--- a/util/iterators.lua
+++ b/util/iterators.lua
@@ -8,8 +8,14 @@
 
 --[[ 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 reverse(f, s, var)
+function it.reverse(f, s, var)
        local results = {};
 
        -- First call the normal iterator
@@ -17,7 +23,7 @@ function reverse(f, s, var)
                local ret = { f(s, var) };
                var = ret[1];
                if var == nil then break; end
-               table.insert(results, 1, ret);
+               t_insert(results, 1, ret);
        end
        
        -- Then return our reverse one
@@ -34,12 +40,12 @@ end
 local function _keys_it(t, key)
        return (next(t, key));
 end
-function keys(t)
+function it.keys(t)
        return _keys_it, t;
 end
 
 -- Iterate only over values in a table
-function values(t)
+function it.values(t)
        local key, val;
        return function (t)
                key, val = next(t, key);
@@ -48,38 +54,37 @@ function values(t)
 end
 
 -- Given an iterator, iterate only over unique items
-function unique(f, s, var)
+function it.unique(f, s, var)
        local set = {};
        
        return function ()
                while true do
-                       local ret = { f(s, var) };
+                       local ret = pack(f(s, var));
                        var = ret[1];
                        if var == nil then break; end
                        if not set[var] then
                                set[var] = true;
-                               return var;
+                               return unpack(ret, 1, ret.n);
                        end
                end
        end;
 end
 
 --[[ Return the number of items an iterator returns ]]--
-function count(f, s, var)
+function it.count(f, s, var)
        local x = 0;
        
        while true do
-               local ret = { f(s, var) };
-               var = ret[1];
+               var = f(s, var);
                if var == nil then break; end
                x = x + 1;
-       end     
+       end
        
        return x;
 end
 
 -- Return the first n items an iterator returns
-function head(n, f, s, var)
+function it.head(n, f, s, var)
        local c = 0;
        return function (s, var)
                if c >= n then
@@ -90,10 +95,19 @@ function head(n, f, s, var)
        end, s;
 end
 
-function tail(n, f, s, var)
+-- 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 = { f(s, var) };
+               local ret = pack(f(s, var));
                var = ret[1];
                if var == nil then break; end
                results[(count%n)+1] = ret;
@@ -106,26 +120,52 @@ function tail(n, f, s, var)
        return function ()
                pos = pos + 1;
                if pos > n then return nil; end
-               return unpack(results[((count-1+pos)%n)+1]);
+               local ret = results[((count-1+pos)%n)+1];
+               return unpack(ret, 1, ret.n);
        end
-       --return reverse(head(n, reverse(f, s, var)));
+       --return reverse(head(n, reverse(f, s, var))); -- !
+end
+
+function it.filter(filter, f, s, var)
+       if type(filter) ~= "function" then
+               local filter_value = filter;
+               function filter(x) return x ~= filter_value; end
+       end
+       return function (s, var)
+               local ret;
+               repeat ret = pack(f(s, var));
+                       var = ret[1];
+               until var == nil or filter(unpack(ret, 1, ret.n));
+               return unpack(ret, 1, ret.n);
+       end, 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 it2array(f, s, var)
+function it.to_array(f, s, var)
        local t, var = {};
        while true do
                var = f(s, var);
                if var == nil then break; end
-               table.insert(t, var);
+               t_insert(t, var);
        end
        return t;
 end
 
--- Treat the return of an iterator as key,value pairs, 
+-- Treat the return of an iterator as key,value pairs,
 -- and build a table
-function it2table(f, s, var)
-       local t, var = {};
+function it.to_table(f, s, var)
+       local t, var2 = {};
        while true do
                var, var2 = f(s, var);
                if var == nil then break; end
@@ -133,3 +173,5 @@ function it2table(f, s, var)
        end
        return t;
 end
+
+return it;