E>container_source</CODE> is a model of <A HREF="../concepts/source.html">Source</A>; and
<LI>A <CODE>container_source</CODE> can be constructed from a instance of <CODE>Container</CODE>, which is passed and stored by reference, and accessible <I>via</I> the member function <CODE>container()</CODE>.
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<P>The main idea behind the implementation of <CODE>read()</CODE> is simple: First, you calculate the number of characters to be read, which is the minimum of the number of unread characters remaining in 