... | ... |
@@ -1010,28 +1010,30 @@ |
1010 | 1010 |
node = digraph.target(it); |
1011 | 1011 |
++it; |
1012 | 1012 |
} |
1013 | 1013 |
return true; |
1014 | 1014 |
} |
1015 | 1015 |
|
1016 | 1016 |
/// \brief The source of a path |
1017 | 1017 |
/// |
1018 |
/// This function returns the source of the given path. |
|
1018 |
/// This function returns the source node of the given path. |
|
1019 |
/// If the path is empty, then it returns \c INVALID. |
|
1019 | 1020 |
template <typename Digraph, typename Path> |
1020 | 1021 |
typename Digraph::Node pathSource(const Digraph& digraph, const Path& path) { |
1021 |
return digraph.source(path.front()); |
|
1022 |
return path.empty() ? INVALID : digraph.source(path.front()); |
|
1022 | 1023 |
} |
1023 | 1024 |
|
1024 | 1025 |
/// \brief The target of a path |
1025 | 1026 |
/// |
1026 |
/// This function returns the target of the given path. |
|
1027 |
/// This function returns the target node of the given path. |
|
1028 |
/// If the path is empty, then it returns \c INVALID. |
|
1027 | 1029 |
template <typename Digraph, typename Path> |
1028 | 1030 |
typename Digraph::Node pathTarget(const Digraph& digraph, const Path& path) { |
1029 |
return digraph.target(path.back()); |
|
1031 |
return path.empty() ? INVALID : digraph.target(path.back()); |
|
1030 | 1032 |
} |
1031 | 1033 |
|
1032 | 1034 |
/// \brief Class which helps to iterate through the nodes of a path |
1033 | 1035 |
/// |
1034 | 1036 |
/// In a sense, the path can be treated as a list of arcs. The |
1035 | 1037 |
/// lemon path type stores only this list. As a consequence, it |
1036 | 1038 |
/// cannot enumerate the nodes in the path and the zero length paths |
1037 | 1039 |
/// cannot have a source node. |
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