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<H2><A NAME="SECTION0020130000000000000000"></A><A NAME="Querying_ASTs"></A>
<BR>
18.1.3 Queries on AST Objects
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<P>
Two functions are provided which allow an application to determine if
an AST was created as an expression or a suite.  Neither of these
functions can be used to determine if an AST was created from source
code via <tt class="function">expr()</tt> or <tt class="function">suite()</tt> or from a parse tree
via <tt class="function">sequence2ast()</tt>.

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4946' xml:id='l2h-4946' class="function">isexpr</tt></b>(</nobr></td>
  <td><var>ast</var>)</td></tr></table></dt>
<dd>
When <var>ast</var> represents an <code>'eval'</code> form, this function
returns true, otherwise it returns false.  This is useful, since code
objects normally cannot be queried for this information using existing
built-in functions.  Note that the code objects created by
<tt class="function">compileast()</tt> cannot be queried like this either, and are
identical to those created by the built-in
<tt class="function">compile()</tt><a id='l2h-4947' xml:id='l2h-4947'></a> function.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-4948' xml:id='l2h-4948' class="function">issuite</tt></b>(</nobr></td>
  <td><var>ast</var>)</td></tr></table></dt>
<dd>
This function mirrors <tt class="function">isexpr()</tt> in that it reports whether an
AST object represents an <code>'exec'</code> form, commonly known as a
``suite.''  It is not safe to assume that this function is equivalent
to "<tt class="samp">not isexpr(<var>ast</var>)</tt>", as additional syntactic fragments may
be supported in the future.
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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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