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<h5 class="subsubsection">23.2.2.29 Manipulating line tables using Python</h5>

<p><a name="index-line-tables-in-python-2377"></a><a name="index-gdb_002eLineTable-2378"></a>
Python code can request and inspect line table information from a
symbol table that is loaded in <span class="sc">gdb</span>.  A line table is a
mapping of source lines to their executable locations in memory.  To
acquire the line table information for a particular symbol table, use
the <code>linetable</code> function (see <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python">Symbol Tables In Python</a>).

   <p>A <code>gdb.LineTable</code> is iterable.  The iterator returns
<code>LineTableEntry</code> objects that correspond to the source line and
address for each line table entry.  <code>LineTableEntry</code> objects have
the following attributes:

<div class="defun">
&mdash; Variable: <b>LineTableEntry.line</b><var><a name="index-LineTableEntry_002eline-2379"></a></var><br>
<blockquote><p>The source line number for this line table entry.  This number
corresponds to the actual line of source.  This attribute is not
writable. 
</p></blockquote></div>

<div class="defun">
&mdash; Variable: <b>LineTableEntry.pc</b><var><a name="index-LineTableEntry_002epc-2380"></a></var><br>
<blockquote><p>The address that is associated with the line table entry where the
executable code for that source line resides in memory.  This
attribute is not writable. 
</p></blockquote></div>

   <p>As there can be multiple addresses for a single source line, you may
receive multiple <code>LineTableEntry</code> objects with matching
<code>line</code> attributes, but with different <code>pc</code> attributes.  The
iterator is sorted in ascending <code>pc</code> order.  Here is a small
example illustrating iterating over a line table.

<pre class="smallexample">     symtab = gdb.selected_frame().find_sal().symtab
     linetable = symtab.linetable()
     for line in linetable:
        print "Line: "+str(line.line)+" Address: "+hex(line.pc)
</pre>
   <p>This will have the following output:

<pre class="smallexample">     Line: 33 Address: 0x4005c8L
     Line: 37 Address: 0x4005caL
     Line: 39 Address: 0x4005d2L
     Line: 40 Address: 0x4005f8L
     Line: 42 Address: 0x4005ffL
     Line: 44 Address: 0x400608L
     Line: 42 Address: 0x40060cL
     Line: 45 Address: 0x400615L
</pre>
   <p>In addition to being able to iterate over a <code>LineTable</code>, it also
has the following direct access methods:

<div class="defun">
&mdash; Function: <b>LineTable.line</b> (<var>line</var>)<var><a name="index-LineTable_002eline-2381"></a></var><br>
<blockquote><p>Return a Python <code>Tuple</code> of <code>LineTableEntry</code> objects for any
entries in the line table for the given <var>line</var>, which specifies
the source code line.  If there are no entries for that source code
<var>line</var>, the Python <code>None</code> is returned. 
</p></blockquote></div>

<div class="defun">
&mdash; Function: <b>LineTable.has_line</b> (<var>line</var>)<var><a name="index-LineTable_002ehas_005fline-2382"></a></var><br>
<blockquote><p>Return a Python <code>Boolean</code> indicating whether there is an entry in
the line table for this source line.  Return <code>True</code> if an entry
is found, or <code>False</code> if not. 
</p></blockquote></div>

<div class="defun">
&mdash; Function: <b>LineTable.source_lines</b> ()<var><a name="index-LineTable_002esource_005flines-2383"></a></var><br>
<blockquote><p>Return a Python <code>List</code> of the source line numbers in the symbol
table.  Only lines with executable code locations are returned.  The
contents of the <code>List</code> will just be the source line entries
represented as Python <code>Long</code> values. 
</p></blockquote></div>

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