I&#39;m new to both boost and Xpressive, but I&#39;ve worked with regex before.  I&#39;ve been able figure most of it out from the Xpressive user guide, but I&#39;m having some trouble with a particular expression.<div><br>
</div><div>I&#39;m using Xpressive to &quot;parse&quot; files from a game called Dwarf Fortress, and one of the lines in the file has a couple places where some information is printed in a different format, or entirely excluded.  The lines are describing the history of the game, specifically the rulers.  For example, one line might look like this:</div>
<div><i>[*] Flichlikus (b.??? d. 3, Reign Began: 1), *** Original Line, Married (d. 91)</i></div><div>While another would look like this:</div><div><i>[*] Thufuchrunkin (b.3, Reign Began: 97), Inherited from mother, Married (d. 160)</i></div>
<div><br></div><div>Thus far, I&#39;ve got it finding the ruler&#39;s name, and their birth date (or &quot;???&quot;).  However, since the date of death is sometimes completely absent, I need some way to get the number if it&#39;s there, and skip it otherwise.  From what I understand, I&#39;ll need to use the lookahead or lookbehind constructs, but they&#39;re well beyond what I&#39;ve done with regex before, so I don&#39;t really even know where to begin.  How would I go about retrieving the date of death if it&#39;s there, and otherwise skipping it entirely (or better yet, set it to a default value...)?</div>
<div><br></div><div>Here&#39;s what I&#39;m using to parse up through the date of birth...</div><div><div><i>mark_tag RU_Name(1), RU_Birth(2), RU_Death(3), RU_ReignBegin(4), RU_Line(5), RU_Married(6);</i></div><div><i>sregex Reg_Ruler = &quot;  [*] &quot; &gt;&gt; ( RU_Name = +(+_w|_s) ) &gt;&gt; &quot;(b.&quot; &gt;&gt; (RU_Birth = (+(_d)|&quot;???&quot;));</i></div>
<div><i><br></i></div><div>Any help would be much appreciated, and a link to a decent tutorial to help me with Xpressive in general would be even better.</div><div><br></div><div>Thanks!</div><div><br></div><div>Tim</div>
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