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<h3 class="unnumberedsec">How can I expand macros in the input?</h3>

<p>The best way to approach this problem is at a higher level, e.g., in the parser.
</p>
<p>However, you can do this using multiple input buffers.
</p>
<div class="example">
<pre class="verbatim">%%
macro/[a-z]+	{
/* Saw the macro &quot;macro&quot; followed by extra stuff. */
main_buffer = YY_CURRENT_BUFFER;
expansion_buffer = yy_scan_string(expand(yytext));
yy_switch_to_buffer(expansion_buffer);
}

&lt;&lt;EOF&gt;&gt;	{
if ( expansion_buffer )
{
// We were doing an expansion, return to where
// we were.
yy_switch_to_buffer(main_buffer);
yy_delete_buffer(expansion_buffer);
expansion_buffer = 0;
}
else
yyterminate();
}
</pre></div>

<p>You probably will want a stack of expansion buffers to allow nested macros.
From the above though hopefully the idea is clear.
</p>



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flex-doc 2.6.4-6 / usr / share / doc / flex-doc / html / How-can-I-expand-macros-in-the-input_003f.html
