Help with Strategy Pathern!

Question

Hello,
I need to parse a very complex text file. If I keep all the parsing code in one file, it will be huge. Then I thought probably I can use strategy patthern to decouple it.
"Another technique has a context pass itself as an argument, and the strategy request data from the context explicitly. "
"Alternatively, the strategy can store a reference to its context, eliminating the need to pass anything at all. Either way, the strategy can request exactly what it needs"
I want to use the way it mentioned in the GoF book, pass context or store a reference in the strategy, but.......don't know how to implement it :(
Any help or code sample will be really appreciated!!!
Thanks!

Answer 1

I wrote the parsing program already, but everything is in a big class, more than 1000 lines.....It's not good, right?
The program structure is like:
Class parseFile {
void parse () {
file = readFile();
line = file.readLine();
flag = getFlag();
switch (flag) {
case 0:
if line.startWith(...) then { .....}
if line.startWith(...) then { .....}
if line.startWith(...) then { .....}
case 1:
case 2:
case 7:
The structure is hard to maintain
That's why I'm trying to use Strategy pattern to rewrite it.
Any suggestions?
Thanks!