Initial work on DIFF.LUA.

Author: Lethja

demo/xtra/DIFF.LUA

@@ -0,0 +1,53 @@
+local function open(filename)
+	local f,e=io.open(filename)
+	if not f then print(e) os.exit(1) end
+	return f
+end
+
+local function blocks(f1, f2)
+	local bs, b = 4096, {}
+	repeat
+		local l, r, lines, data = f1:read(bs), f2:read(bs), {}, nil
+		if l then _, lines.l = string.gsub(l,"\n", "\n") end
+		if r then _, lines.r = string.gsub(r,"\n", "\n") end
+		if l ~= r then data = { l = l, r = r } end
+		if lines.l or lines.r then
+		  table.insert(b, { data = data, lines = lines })
+		end
+	until not l and not r
+	return b
+end
+
+local function lines(str, prev)
+	local l, last = {}
+
+	for line, newline in str:gmatch("([^\n]*)(\n?)") do
+		if newline ~= "\n" then last = line else table.insert(l, line) end
+	end
+
+	if prev and #l > 0 then l[1] = prev .. l[1] end
+	return l, last
+end
+
+local function diff_u(fn1,fn2)
+	local f1, f2 = open(fn1), open(fn2)
+	local diff_b, dl, dr, tl, tr = blocks(f1, f2)
+	f1:close() f2:close()
+
+	if diff_b then
+		for _, v in ipairs(diff_b) do
+			dl, tl = lines(v.data.l)
+			dr, tr = lines(v.data.r)
+			local max = #dl > #dr and #dl or #dr
+
+			for k = 1, max do
+				if dl[k] ~= dr[k] then
+					print("-"..dl[k].."\n+"..dr[k].."\n")
+				end
+			end
+		end
+	end
+end
+
+if #arg < 2 then return end
+diff_u(arg[1], arg[2])