1 files changed, 49 insertions, 3 deletions

diff --git a/graph/src/lib.rs b/graph/src/lib.rs
index 058d62c..36fc545 100644
--- a/graph/src/lib.rs
+++ b/graph/src/lib.rs
@@ -22,6 +22,7 @@ pub use adlist::ALGraph;
 
 pub mod labelled;
 
+pub use labelled::simple::{SLGBuilder, SLGraph};
 pub use labelled::DLGraph;
 pub use labelled::PLGraph;
 
@@ -29,6 +30,8 @@ pub mod builder;
 
 pub use builder::Builder;
 
+pub mod dfs;
+
 use error::Error;
 
 /// The expected behaviour of an immutable graph.
@@ -138,6 +141,7 @@ pub trait Graph: Default {
         let mut file = std::fs::File::options()
             .write(true)
             .create(true)
+            .truncate(true)
             .open(filename)?;
 
         use std::io::Write;
@@ -290,8 +294,8 @@ pub trait RedirectGraph: Graph {
 /// This trait defines some convenient methods for accessing the
 /// labels of vertices.
 pub trait VLabelGraph<T: GraphLabel>: Graph {
-    /// A type that iterates through tuples of labels and targets of
-    /// edges.
+    /// A type that iterates through tuples of target labels and
+    /// target indices of edges.
     type TupleIter<'a>: Iterator<Item = (T, usize)> + 'a
     where
         Self: 'a,
@@ -321,13 +325,55 @@ pub trait VLabelGraph<T: GraphLabel>: Graph {
     }
 
     /// Return an iterator of tuples of vertex labels and indices of
-    /// targets edges out of a node.
+    /// targets for edges out of a node.
     ///
     /// The name is a weird new word created to stand as a
     /// simplification of the phrase "vertex label and children of".
     fn verlabren_of(&self, node_id: usize) -> Result<Self::TupleIter<'_>, Error>;
 }
 
+/// A graph whose edges are associated with labels.
+///
+/// This trait defines some convenient methods for accessing the
+/// labels of edges.
+pub trait ELabelGraph<T: GraphLabel>: Graph {
+    /// A type that iterates through tuples of edge labels and target
+    /// indices of edges.
+    type TupleIter<'a>: Iterator<Item = (T, usize)> + 'a
+    where
+        Self: 'a,
+        T: 'a;
+
+    #[inline]
+    /// Return the label of an edge or an error if the node is
+    /// invalid.
+    ///
+    /// The default implementation always returns `None` after
+    /// checking the validity of the edge.
+    fn edge_label(&self, from: usize, to: usize) -> Result<Option<T>, Error> {
+        self.has_edge(from, to).map(|_| None)
+    }
+
+    /// Return an iterator of tuples of edge labels and indices of
+    /// targets for edges out of a node.
+    ///
+    /// The name is a weird new word created to stand as a
+    /// simplification of the phrase "edge label and children of".
+    fn edlabren_of(&self, node_id: usize) -> Result<Self::TupleIter<'_>, Error>;
+}
+
+impl<T: GraphLabel, G: LabelGraph<T>> ELabelGraph<T> for G {
+    type TupleIter<'a> = <G as LabelGraph<T>>::TupleIter<'a>
+    where
+        Self: 'a,
+        T: 'a;
+
+    #[inline]
+    fn edlabren_of(&self, node_id: usize) -> Result<Self::TupleIter<'_>, Error> {
+        LabelGraph::tuples_of(self, node_id)
+    }
+}
+
 /// A labelled graph is just a graph with labels associated to
 /// vertices and / or edges.
 ///