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Regular expressions and rusty knowledge

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Hello.

Yesterday at work, I was presented with strings like the following:

a) foo
b) foo=bar
c) foo=bar;rate=high
d) foo;rate=high
e) foo;rate
f) foo=bar;rate=high;pos
g) foo=bar;rate=high;pos;brick=many
.
.
.

They are basically semicolon-separated pairs of key=value, where values 
may or may not be present. I thought I would try and come up with a 
regular expression to recognize and allow me to extract tokens from 
them. Here's a more detailed list of the restrictions of the language:

   1. values are optional
   2. the number of key/value pairs is not specified
   3. no string can begin or end with ';'
   4. no string can begin or end with '='
   5. if a key is followed by '=', a corresponding value must be present
   6. for simplicity, assume keys and values are only made of [a-z]

This is what I came up with:

[a-z]+(=([a-z]+))?(;[a-z]+(=([a-z]+))?)*

It seems to adhere to the restrictions and recognize valid strings as 
expected. However, I'm unsure whether my idea of using a RE like that to 
extract tokens is actually feasible (e.g. the value 'high' associated 
with the second key on sample string g). For a moment, I even questioned 
myself whether that was a regular language.

In the end, I suspect the years that have passed since I got my CS 
degree have begun to show and that I'm simply missing something the 
basics here. Anyway, I'd be thankful if somebody could shed some light 
on this and help me remove the rust from my understanding of this subject.

Thank you and regards,

-- 
Ney André de Mello Zunino

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Regular expressions and rusty knowledge Ney André de Mello Zunino <zunino@softplan.com.br> - 2012-08-29 14:56 -0300
  Re: Regular expressions and rusty knowledge Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-08-29 11:19 -0700
  Re: Regular expressions and rusty knowledge Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-08-30 00:12 +0100

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