Structuring linear input

I need to change a linear input into something more structure; e.g. 
	<A/>	<B/>	<C/>	<D/>	<D/>	<C/>	<B/>	<D/>	<A/>
<B/>

The result should look like this:
	<A>
		<B>
			<block>
				<C/><D/>
			</block>
			<block>
				<D/>
			</block>
			<block>
				<C/>
			</block>
		</B>
		<B>
			<block>
				<D/>
			</block>
		</B>
	<A/>
	<A>
		<B/>
	</A>

The linear input can be described by the following regular expression:
	(A (B (C* D*)*)*)*

Does anyone has any idea how this problem can be solved?


Alain


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