<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><font class="Apple-style-span" face="Arial">Hello all,</font><div><font class="Apple-style-span" face="Arial"><br></font></div><div><font class="Apple-style-span" face="Arial">I'm developing a bundle for handling biomolecular structure files (PDB files). I'm now working on </font></div><div><font class="Apple-style-span" face="Arial">getting the language description sorted out. In doing this I ran into a regex problem.</font></div><div><font class="Apple-style-span" face="Arial"><br></font></div><div><font class="Apple-style-span" face="Arial">The situation:</font></div><div><font class="Apple-style-span" face="Arial">A PDB file is essentially a table. One line from such a table can be as follows:</font></div><div><font class="Apple-style-span" face="Arial"><br></font></div><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;">ATOM 14 CA GLN A 2 -27.648 -9.581 30.325 1.00 10.00</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;"><br></span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;">In the language description I would like to use a regular expression construct that </span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;">matched 'GLN' only if the line starts with either 'ATOM' or 'HETATM'. This seams like</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;">a conditional regular expression but my attempts to implement it at such have failed</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;">so far.</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;"><br></span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;">Can anyone help?</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;"><br></span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;">Thanks,</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><font class="Apple-style-span" face="Arial" size="3"><span class="Apple-style-span" style="font-size: 12px;">Marc</span></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 10px/normal Monaco; "><br></div></div></body></html>