1 files changed, 80 insertions, 0 deletions
diff --git a/dot_config/nvim/lua/transformer.lua b/dot_config/nvim/lua/transformer.lua
new file mode 100644
index 0000000..a479826
--- /dev/null
+++ b/dot_config/nvim/lua/transformer.lua
@@ -0,0 +1,80 @@
+--[[
+	Transformer.lua
+	A transforming meta-flow originally built for packer.
+
+	TL;DR you have a function to which you want to eventually pass a table.
+	With this, you can construct the table piece by piece.
+	It will finally call out once you pass () or a string.
+	The string will *prepend* itself to the object.
+
+	Merging rules are a bit complicated:
+	For tables, we merge the ipairs in order (left to right).
+		The final '' is an exception.
+	Then we merge the map-like keys recursively.
+	If the target is a table but the merged key isn't, we append it.
+	Otherwise we always overwrite.
+]]--
+
+---@diagnostic disable-next-line: unused-vararg
+local function tables(...)
+	for i=1,select('#') do
+		if type(select(i)) ~= 'table' then return false end
+	end
+	return true
+end
+
+local function imerge(t1, t2) -- mutates t1
+	for _, v in ipairs(t2) do table.insert(t1, v) end
+end
+
+local bigmerge -- forward declaration
+
+local function kmerge(t1, t2) -- mutates t2
+	for k, v in pairs(t2) do
+		if type(k) == 'number' and k >= 1 and k <= #t1 then
+			-- skip, we did this in imerge
+		else
+			if t1[k] and type(t1[k]) == 'table' then
+				if type(v) == 'table' then
+					t1[k] = bigmerge(t1[k], v)
+				else
+					table.insert(t1[k], v)
+				end
+			else
+				t1[k] = v
+			end
+		end
+	end
+end
+
+bigmerge = function(t1, t2)
+	assert(tables(t1, t2))
+	local out = {}
+	imerge(out, t1)
+	imerge(out, t2)
+	kmerge(out, t1)
+	kmerge(out, t2)
+	return out
+end
+
+local function tgen(use) return function (self, obj)
+	if obj == nil then return use(self) end
+
+	if type(obj) == 'string' then
+		local out = { obj }
+		imerge(out, self)
+		kmerge(out, self)
+		return setmetatable(out, getmetatable(self))()
+	elseif type(obj) == 'table' then
+		local out = bigmerge(self, obj)
+		return setmetatable(out, getmetatable(self))
+
+	else
+		error 'Invalid argument.'
+	end
+
+end end
+
+return function(use)
+	return setmetatable({}, { __call = tgen(use) })
+end