1 files changed, 88 insertions, 0 deletions
diff --git a/include/serd/nodes.h b/include/serd/nodes.h
new file mode 100644
index 00000000..c23fe024
--- /dev/null
+++ b/include/serd/nodes.h
@@ -0,0 +1,88 @@
+// Copyright 2011-2022 David Robillard <d@drobilla.net>
+// SPDX-License-Identifier: ISC
+
+#ifndef SERD_NODES_H
+#define SERD_NODES_H
+
+#include "serd/attributes.h"
+#include "serd/memory.h"
+#include "serd/node.h"
+#include "zix/attributes.h"
+
+#include <stddef.h>
+
+SERD_BEGIN_DECLS
+
+/**
+   @defgroup serd_nodes Nodes
+   @ingroup serd_storage
+   @{
+*/
+
+/// Hashing node container for interning and simplified memory management
+typedef struct SerdNodesImpl SerdNodes;
+
+/// Create a new node set
+SERD_API SerdNodes* ZIX_ALLOCATED
+serd_nodes_new(SerdAllocator* ZIX_NULLABLE allocator);
+
+/**
+   Free `nodes` and all nodes that are stored in it.
+
+   Note that this invalidates any node pointers previously returned from
+   `nodes`.
+*/
+SERD_API void
+serd_nodes_free(SerdNodes* ZIX_NULLABLE nodes);
+
+/// Return the number of interned nodes
+SERD_PURE_API size_t
+serd_nodes_size(const SerdNodes* ZIX_NONNULL nodes);
+
+/**
+   Return the existing interned copy of a node if it exists.
+
+   This either returns an equivalent to the given node, or null if this node
+   has not been interned.
+*/
+SERD_API const SerdNode* ZIX_NULLABLE
+serd_nodes_existing(const SerdNodes* ZIX_NONNULL nodes,
+                    const SerdNode* ZIX_NULLABLE node);
+
+/**
+   Intern `node`.
+
+   Multiple calls with equivalent nodes will return the same pointer.
+
+   @return A node that is different than, but equivalent to, `node`.
+*/
+SERD_API const SerdNode* ZIX_ALLOCATED
+serd_nodes_intern(SerdNodes* ZIX_NONNULL       nodes,
+                  const SerdNode* ZIX_NULLABLE node);
+
+/**
+   Make a node of any type.
+
+   A new node will be added if an equivalent node is not already in the set.
+*/
+SERD_API const SerdNode* ZIX_ALLOCATED
+serd_nodes_get(SerdNodes* ZIX_NONNULL nodes, SerdNodeArgs args);
+
+/**
+   Dereference `node`.
+
+   Decrements the reference count of `node`, and frees the internally stored
+   equivalent node if this was the last reference.  Does nothing if no node
+   equivalent to `node` is stored in `nodes`.
+*/
+SERD_API void
+serd_nodes_deref(SerdNodes* ZIX_NONNULL       nodes,
+                 const SerdNode* ZIX_NULLABLE node);
+
+/**
+   @}
+*/
+
+SERD_END_DECLS
+
+#endif // SERD_NODES_H