From ef6f0d372d8f57220025e273e2905271b5cd8093 Mon Sep 17 00:00:00 2001
From: peter <petrel.harp@gmail.com>
Date: Wed, 7 Dec 2022 11:03:24 -0800
Subject: [PATCH] messing around

---
 c/tskit/tables.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/c/tskit/tables.c b/c/tskit/tables.c
index d23bd41dd1..c5c414c6c2 100644
--- a/c/tskit/tables.c
+++ b/c/tskit/tables.c
@@ -12341,7 +12341,57 @@ tsk_table_collection_add_and_remap_node(tsk_table_collection_t *self,
 int
 forward_extend(tsk_table_collection_t *self)
 {
-    // TODO: use `tsk_diff_iter_X` to iterate over edges?
+    int ret = 0;
+    double *new_left, *new_right;
+    tsk_id_t tj, tk;
+    const tsk_id_t *I, *O;
+    const tsk_id_t M = (tsk_id_t) edges.num_rows;
+    tsk_id_t *parent = NULL;
+
+    new_left = tsk_malloc(self->edges.num_rows * sizeof(*new_left));
+    new_right = tsk_malloc(self->edges.num_rows * sizeof(*new_right));
+    if (new_left == NULL || new_right == NULL) {
+        ret = TSK_ERR_NO_MEMORY;
+        goto out;
+    }
+    memcpy(new_left, self->edges.left, self->edges.num_rows * sizeof(*new_left));
+    memcpy(new_right, self->edges.right, self->edges.num_rows * sizeof(*new_right));
+
+    parent = tsk_malloc(nodes.num_rows * sizeof(*parent));
+    if (parent == NULL) {
+        ret = TSK_ERR_NO_MEMORY;
+        goto out;
+    }
+    tsk_memset(parent, 0xff, nodes.num_rows * sizeof(*parent));
+
+    I = self->indexes.edge_insertion_order;
+    O = self->indexes.edge_removal_order;
+    tj = 0;
+    tk = 0;
+    left = 0;
+    while (tj < M || left < self->sequence_length) {
+        while (tk < M && edges.right[O[tk]] == left) {
+            parent[edges.child[O[tk]]] = TSK_NULL;
+            tk++;
+        }
+        while (tj < M && edges.left[I[tj]] == left) {
+            parent[edges.child[I[tj]]] = edges.parent[I[tj]];
+            tj++;
+        }
+        right = self->sequence_length;
+        if (tj < M) {
+            right = TSK_MIN(right, edges.left[I[tj]]);
+        }
+        if (tk < M) {
+            right = TSK_MIN(right, edges.right[O[tk]]);
+        }
+
+
+    }
+
+
+out:
+    return ret;
 }
 
 int TSK_WARN_UNUSED