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Protocol parser state machine of the reference implementation:
<img src="proto_parse.svg">
Legend:
<ul>
<li> yellow boxes are states
<li> blue arrows are optional features for a more tolerant parser
<li> round nodes are actions that shall be taken
<li> arrow with text: execute action or switch state if condition is true
<li> arrow without text: do this if no other condition is met
</ul>
<h3>Notes on the reference implementation </H3>
The reference implementation builds a <b>tree of nodes</b> for the arguments.
Each node is either a list or a text. A node has a pointer to its parent, its
first child and its next sibling. While parsing list-of-lists, the parser
keeps a <i>current node</i>. A new node is either added as the last sibling of
the <i>current node</i> (new argument on a list) or as the first
child of the <i>current node</i> (first argument of a new list when the list is
open).
<p>
When a list is closed, the parent of the <i>current node</i> becomes the
new <i>current node</i>.
<p>
When parsing a new message, the current node is NULL until the argument list
is open; the new <i>current node</i> also becomes the argument tree root.
If the argument tree root is closed, a newline shall follow, because that's
how a message is terminated.
<p>
The <b>binary string</b> part of the state machine has 2 more internal
states:
<ul>
<li> a boolean indicating whether we are parsing the length or the string (before or after the '=')
<li> an integer string length
</ul>
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