util.array: Per-array methods now always mutate the array, array.* return a mutated copy, and most methods (e.g. sort) now return the array

util/array.lua

@@ -6,9 +6,14 @@
 -- COPYING file in the source package for more information.
 --
 
-local array = {};
+local t_insert, t_sort, t_remove, t_concat 
+	= table.insert, table.sort, table.remove, table.concat;
+
+local array = {};
+local array_base = {};
+local array_methods = {};
+local array_mt = { __index = array_methods, __tostring = function (array) return array:concat(", "); end };
 
-local array_mt = { __index = array, __tostring = function (array) return array:concat(", "); end };
 local function new_array(_, t)
 	return setmetatable(t or {}, array_mt);
 end
@@ -20,36 +25,36 @@ end
 
 setmetatable(array, { __call = new_array });
 
-function array:map(func, t2)
-	local t2 = t2 or array{};
-	for k,v in ipairs(self) do
-		t2[k] = func(v);
+function array_base.map(outa, ina, func)
+	for k,v in ipairs(ina) do
+		outa[k] = func(v);
 	end
-	return t2;
+	return outa;
 end
 
-function array:filter(func, t2)
-	local t2 = t2 or array{};
-	for k,v in ipairs(self) do
+function array_base.filter(outa, ina, func)
+	for k,v in ipairs(ina) do
 		if func(v) then
-			t2:push(v);
+			outa:push(v);
 		end
 	end
-	return t2;
+	return outa;
 end
 
+function array_base.sort(outa, ina, ...)
+	if ina ~= outa then
+		outa:append(ina);
+	end
+	t_sort(outa, ...);
+	return outa;
+end
 
-array.push = table.insert;
-array.pop = table.remove;
-array.sort = table.sort;
-array.concat = table.concat;
-array.length = function (t) return #t; end
-
-function array:random()
+--- These methods only mutate
+function array_methods:random()
 	return self[math.random(1,#self)];
 end
 
-function array:shuffle()
+function array_methods:shuffle(outa, ina)
 	local len = #self;
 	for i=1,#self do
 		local r = math.random(i,len);
@@ -58,7 +63,7 @@ function array:shuffle()
 	return self;
 end
 
-function array:reverse()
+function array_methods:reverse()
 	local len = #self-1;
 	for i=len,1,-1 do
 		self:push(self[i]);
@@ -67,7 +72,7 @@ function array:reverse()
 	return self;
 end
 
-function array:append(array)
+function array_methods:append(array)
 	local len,len2  = #self, #array;
 	for i=1,len2 do
 		self[len+i] = array[i];
@@ -75,6 +80,12 @@ function array:append(array)
 	return self;
 end
 
+array_methods.push = table.insert;
+array_methods.pop = table.remove;
+array_methods.concat = table.concat;
+array_methods.length = function (t) return #t; end
+
+--- These methods always create a new array
 function array.collect(f, s, var)
 	local t, var = {};
 	while true do
@@ -85,6 +96,23 @@ function array.collect(f, s, var)
 	return setmetatable(t, array_mt);
 end
 
+---
+
+-- Setup methods from array_base
+for method, f in pairs(array_base) do
+	local method = method; -- Yes, this is necessary :)
+	local base_method = f;
+	-- Setup global array method which makes new array
+	array[method] = function (old_a, ...)
+		local a = new_array();
+		return base_method(a, old_a, ...);
+	end
+	-- Setup per-array (mutating) method
+	array_methods[method] = function (self, ...)
+		return base_method(self, self, ...);
+	end
+end
+
 _G.array = array;
 module("array");