Added myers comparison table.

Author: Lethja

xtra/DIFF.LUA

@@ -2,22 +2,34 @@
 
 local PF,CT,M="I2I4I8",{},0xFFFFFFFF
 local function diff_u(fn1,fn2)
-	local function open(fn)
-		local f,e=io.open(fn, "rb")
-		if not f then print(e)os.exit(1)end
-		local o,p=0,""
+	local function open(fn)local f,e=io.open(fn, "rb")if not f then print(e)os.exit(1)end
 		local function crc32(s)local c=M for i=1,#s do local byte=s:byte(i)c=(c >> 8)~CT[(c~byte)&0xFF]end return(~c)&M end
-		while true do local ls,l=o,{}
-			while true do local c=f:read(1)if not c then break end
+		local o,p=0,""while 1 do local ls,l=o,{}
+			while 1 do local c=f:read(1)if not c then break end
 				local function eol()if c=='\r'then local d=f:read(1)f:seek("cur",-1)return d~='\n'end return c=='\n'end
 				o=o+1 table.insert(l,c)if eol()then break end end
 			if #l==0 then break end l=table.concat(l)local ln,c=#l,crc32(l)p=p..string.pack(PF,ln,c,ls)end f:close()return p end
-	--TODO: Replace this code with myers algorithm
 	local f1,f2,size=open(fn1),open(fn2),string.packsize(PF)
-	local function printFile(f)local len=#f//size
-		for i=1,len do local length,crc,offset=string.unpack(PF,f,(i-1)*size+1)
-			print(("Offset: %06d | Length: %03d | CRC32: %08X"):format(offset,length,crc))end end
-	printFile(f1)printFile(f2)end
+	local function cmp(x,y)
+		local l1,c1,o1=string.unpack(PF,f1,(x-1)*size+1)
+		local l2,c2,o2=string.unpack(PF,f2,(y-1)*size+1)
+		if l1~=l2 or c1~=c2 then return false end
+		local function bin()
+			local function line(fn,o,l)
+				local f,e=io.open(fn,"rb")if not f then return nil,e end
+				f:seek("set",o)local get=f:read(l)f:close()return get end
+			local b1,e,b2=line(fn1,o1,l1)if not b1 then error(e)end
+			b2,e=line(fn2,o2,l2)if not b2 then error(e)end
+			return b1==b2 end return bin()end
+	local function print_table()
+		--TODO: store and reverse lookup this table to find the least amount of changes
+		local il,jl=#f1//size,#f2//size
+		for i=1,il do
+			local row = {}
+			for j=1,jl do table.insert(row,cmp(i,j) and "1" or "0")end
+			print(table.concat(row, " "))end end
+	print_table()
+end
 if#arg<2 or#arg%2~=0 then print(arg[-1].." "..arg[0]..[[ old new...
 
 Compare differences between files, print them as unified context.