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-rw-r--r--util/iterators.lua46
1 files changed, 46 insertions, 0 deletions
diff --git a/util/iterators.lua b/util/iterators.lua
index a152e7be..5d16d8c1 100644
--- a/util/iterators.lua
+++ b/util/iterators.lua
@@ -14,6 +14,11 @@ local t_insert = table.insert;
local select, next = select, next;
local unpack = table.unpack or unpack; --luacheck: ignore 113 143
local pack = table.pack or function (...) return { n = select("#", ...), ... }; end -- luacheck: ignore 143
+local type = type;
+local table, setmetatable = table, setmetatable;
+
+local _ENV = nil;
+--luacheck: std none
-- Reverse an iterator
function it.reverse(f, s, var)
@@ -184,4 +189,45 @@ function it.to_table(f, s, var)
return t;
end
+local function _join_iter(j_s, j_var)
+ local iterators, current_idx = j_s[1], j_s[2];
+ local f, s, var = unpack(iterators[current_idx], 1, 3);
+ if j_var ~= nil then
+ var = j_var;
+ end
+ local ret = pack(f(s, var));
+ local var1 = ret[1];
+ if var1 == nil then
+ -- End of this iterator, advance to next
+ if current_idx == #iterators then
+ -- No more iterators, return nil
+ return;
+ end
+ j_s[2] = current_idx + 1;
+ return _join_iter(j_s);
+ end
+ return unpack(ret, 1, ret.n);
+end
+local join_methods = {};
+local join_mt = {
+ __index = join_methods;
+ __call = function (t, s, var) --luacheck: ignore 212/t
+ return _join_iter(s, var);
+ end;
+};
+
+function join_methods:append(f, s, var)
+ table.insert(self, { f, s, var });
+ return self, { self, 1 };
+end
+
+function join_methods:prepend(f, s, var)
+ table.insert(self, { f, s, var }, 1);
+ return self, { self, 1 };
+end
+
+function it.join(f, s, var)
+ return setmetatable({ {f, s, var} }, join_mt);
+end
+
return it;