Re: [Boost-users] Determining whether a key already exists in a labeled graph

Subject: Re: [Boost-users] Determining whether a key already exists in a labeled graph
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2012-10-05 18:40:42

On Fri, 5 Oct 2012, eric wrote:

> Is there a way to tell if a labeled graph already contains a key?  As I'm
> constructing my graph from database data, I would like to check whether a
> node's parent already exists, and if not create it.

One thing to do is to try to insert it using insert_vertex() or 
label_vertex() and check the return value.  It looks like you can also 
call the vertex() method with the label (or vertex_by_label() as a free 
function in trunk version r80879 or above) and see if the return value is 
graph_traits<GraphType>::null_vertex() (which is returned if the label was 
not found).

-- Jeremiah Willcock