diff --git a/src/edge.c b/src/edge.c
new file mode 100644
index 0000000..bb6b60b
--- /dev/null
+++ b/src/edge.c
@@ -0,0 +1,78 @@
+/*
+ * edge.c
+ * Copyright (C) 2014 c9s <c9s@c9smba.local>
+ *
+ * Distributed under terms of the MIT license.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+// Jemalloc memory management
+#include <jemalloc/jemalloc.h>
+
+// PCRE
+#include <pcre.h>
+
+// Judy array
+#include <Judy.h>
+
+#include "r3_define.h"
+#include "r3_str.h"
+#include "r3.h"
+#include "str_array.h"
+
+
+
+/**
+ * branch the edge pattern at "dl" offset
+ *
+ */
+void r3_edge_branch(edge *e, int dl) {
+    node *c1; // child 1, child 2
+    edge *e1; // edge 1, edge 2
+    char * s1 = e->pattern + dl;
+    int s1_len = 0;
+
+    edge **tmp_edges = e->child->edges;
+    int   tmp_r3_edge_len = e->child->r3_edge_len;
+
+    // the suffix edge of the leaf
+    c1 = r3_tree_create(3);
+    s1_len = e->pattern_len - dl;
+    e1 = r3_edge_create(strndup(s1, s1_len), s1_len, c1);
+    // printf("edge left: %s\n", e1->pattern);
+
+    // Migrate the child edges to the new edge we just created.
+    for ( int i = 0 ; i < tmp_r3_edge_len ; i++ ) {
+        r3_tree_append_edge(c1, tmp_edges[i]);
+        e->child->edges[i] = NULL;
+    }
+    e->child->r3_edge_len = 0;
+    e->child->endpoint--;
+
+    info("branched pattern: %s\n", e1->pattern);
+
+    r3_tree_append_edge(e->child, e1);
+    c1->endpoint++;
+}
+
+
+edge * r3_edge_create(char * pattern, int pattern_len, node * child) {
+    edge * e = (edge*) malloc( sizeof(edge) );
+    e->pattern = pattern;
+    e->pattern_len = pattern_len;
+    e->child = child;
+    return e;
+}
+
+void r3_edge_free(edge * e) {
+    if (e->pattern) {
+        free(e->pattern);
+    }
+    if ( e->child ) {
+        r3_tree_free(e->child);
+    }
+}
+