X-Git-Url: https://git.enpas.org/?a=blobdiff_plain;f=util%2Fiterators.lua;h=bd150ff28cd3572ca407274a9bf4df2276e827df;hb=65e4b7b33de42357340f2fe9733807c8b9d57219;hp=08bb729c63f63a2331213c310dfc8026ee5beac6;hpb=82aa9c749335a601ec308148ce95e3c680ad7705;p=prosody.git

diff --git a/util/iterators.lua b/util/iterators.lua
index 08bb729c..bd150ff2 100644
--- a/util/iterators.lua
+++ b/util/iterators.lua
@@ -1,102 +1,187 @@
 -- Prosody IM
--- Copyright (C) 2008-2009 Matthew Wild
--- Copyright (C) 2008-2009 Waqas Hussain
--- 
+-- 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, next = select, next;
+local unpack = table.unpack or unpack; --luacheck: ignore 113
+local pack = table.pack or function (...) 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
 	while true do
 		local ret = { f(s, var) };
 		var = ret[1];
-	        if var == nil then break; end
-		table.insert(results, 1, ret);
+		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;
+	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 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);
+	return function (_t)
+		key, val = next(_t, key);
 		return val;
 	end, t;
 end
 
+-- Iterate over the n:th return value
+function it.select(n, f, s, var)
+	return function (_s)
+		local ret = pack(f(_s, var));
+		var = ret[1];
+		return ret[n];
+	end, s, var;
+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
+			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];
-	        if var == nil then break; end
+		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 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, var;
+end
+
+-- Skip the first n items an iterator returns
+function it.skip(n, f, s, var)
+	for _ = 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
+
+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)
-	local t, var = {};
+function it.to_array(f, s, var)
+	local t = {};
 	while true do
 		var = f(s, var);
-	        if var == nil then break; end
-		table.insert(t, 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, 
+-- 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
+		if var == nil then break; end
 		t[var] = var2;
 	end
 	return t;
 end
+
+return it;