This may be a really dumb idea, but I've used a similar method before (in BASIC) to save memory space, back when 64Kb was considered huge.

Couldn't you store the key/value pairs back to back in a single string, and then pull them out with a regex?

The format could be something like "key1:value1|key2:value2|key3:value3|" allowing you to search for the key, and if found grab it and everything up to the next | character, then split on the : character to get the corresponding value.

You could use whatever separators you wished, but there would need to be two different ones for this to work and to make it more readable for humans.

Unfortunately, I'm not confident enough with the syntax of regular expressions (yet) to give an example, but from the sounds of it you know enough to work that out for yourself and to tell if I'm spouting complete nonsense.

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"Every program has at least one bug and can be shortened by at least one instruction -- from which, by induction, one can deduce that every program can be reduced to one instruction which doesn't work." -- (Author Unknown)