1 files changed, 39 insertions, 0 deletions
diff --git a/tree.h b/tree.h
new file mode 100644
index 0000000..86a9521
--- /dev/null
+++ b/tree.h
@@ -0,0 +1,39 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+
+// The data field is a compact representation of a
+// [(string, struct tree_node*)] list. The strings are all non-empty.
+// Representation: for every list element, first a null-terminated sequence of
+// chars (the string), then sizeof(void*) bytes (the pointer, potentially
+// NULL). After the last list element, an additional 0 byte, which could be
+// interpreted as an empty string, but instead means the end of the list.
+struct tree_node {
+  size_t total_files;
+  size_t total_dirs;
+  size_t total_size;  // sum of on-disk sizes (in bytes)
+  uint8_t *data;
+};
+
+// A single element in a child list.
+struct tree_pair {
+  const char *name;  // ownership is retained by the producer of this tree_pair
+  struct tree_node *sub;  // can be NULL
+};
+
+// The names are copied out of 'pairs'.
+struct tree_node* tree_make(const struct tree_pair *pairs, size_t npairs, size_t disk_size);
+
+// Frees recursively.
+void tree_free(struct tree_node *node);
+
+size_t tree_num_children(const struct tree_node *node);
+
+struct tree_pair tree_index(struct tree_node *node, size_t index);
+
+struct tree_iter { struct tree_node *node; size_t off; };
+struct tree_iter tree_iter_start(struct tree_node *node);
+// Returns whether there was another child
+bool tree_iter_next(struct tree_iter *iter, struct tree_pair *dst);