1 files changed, 89 insertions, 0 deletions
diff --git a/reftable/iter.h b/reftable/iter.h
new file mode 100644
index 0000000000..cc920970a5
--- /dev/null
+++ b/reftable/iter.h
@@ -0,0 +1,89 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file or at
+ * https://developers.google.com/open-source/licenses/bsd
+ */
+
+#ifndef ITER_H
+#define ITER_H
+
+#include "system.h"
+#include "block.h"
+#include "record.h"
+
+#include "reftable-iterator.h"
+
+/*
+ * The virtual function table for implementing generic reftable iterators.
+ */
+struct reftable_iterator_vtable {
+	int (*seek)(void *iter_arg, struct reftable_record *want);
+	int (*next)(void *iter_arg, struct reftable_record *rec);
+	void (*close)(void *iter_arg);
+};
+
+/*
+ * Position the iterator at the wanted record such that a call to
+ * `iterator_next()` would return that record, if it exists.
+ */
+int iterator_seek(struct reftable_iterator *it, struct reftable_record *want);
+
+/*
+ * Yield the next record and advance the iterator. Returns <0 on error, 0 when
+ * a record was yielded, and >0 when the iterator hit an error.
+ */
+int iterator_next(struct reftable_iterator *it, struct reftable_record *rec);
+
+/*
+ * Set up the iterator such that it behaves the same as an iterator with no
+ * entries.
+ */
+void iterator_set_empty(struct reftable_iterator *it);
+
+/* iterator that produces only ref records that point to `oid` */
+struct filtering_ref_iterator {
+	struct reftable_buf oid;
+	struct reftable_iterator it;
+};
+#define FILTERING_REF_ITERATOR_INIT \
+	{                           \
+		.oid = REFTABLE_BUF_INIT  \
+	}
+
+void iterator_from_filtering_ref_iterator(struct reftable_iterator *,
+					  struct filtering_ref_iterator *);
+
+/* iterator that produces only ref records that point to `oid`,
+ * but using the object index.
+ */
+struct indexed_table_ref_iter {
+	struct reftable_table *table;
+	struct reftable_buf oid;
+
+	/* mutable */
+	uint64_t *offsets;
+
+	/* Points to the next offset to read. */
+	int offset_idx;
+	int offset_len;
+	struct reftable_block block;
+	struct block_iter cur;
+	int is_finished;
+};
+
+#define INDEXED_TABLE_REF_ITER_INIT { \
+	.cur = BLOCK_ITER_INIT, \
+	.oid = REFTABLE_BUF_INIT, \
+}
+
+void iterator_from_indexed_table_ref_iter(struct reftable_iterator *it,
+					  struct indexed_table_ref_iter *itr);
+
+/* Takes ownership of `offsets` */
+int indexed_table_ref_iter_new(struct indexed_table_ref_iter **dest,
+			       struct reftable_table *t, uint8_t *oid,
+			       int oid_len, uint64_t *offsets, int offset_len);
+
+#endif