From fdb360c094b575b59640206d7eea0772bb9de26d Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Sat, 12 May 2018 13:28:47 +0200
Subject: WIP: Add model

---
 src/iter.h | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 src/iter.h

(limited to 'src/iter.h')

diff --git a/src/iter.h b/src/iter.h
new file mode 100644
index 00000000..13acca64
--- /dev/null
+++ b/src/iter.h
@@ -0,0 +1,89 @@
+/*
+  Copyright 2011-2018 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#ifndef SERD_ITER_H
+#define SERD_ITER_H
+
+#include "statement.h"
+
+#include "serd/serd.h"
+#include "zix/btree.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/** Triple ordering */
+typedef enum {
+	SPO,   ///<         Subject,   Predicate, Object
+	SOP,   ///<         Subject,   Object,    Predicate
+	OPS,   ///<         Object,    Predicate, Subject
+	OSP,   ///<         Object,    Subject,   Predicate
+	PSO,   ///<         Predicate, Subject,   Object
+	POS,   ///<         Predicate, Object,    Subject
+	GSPO,  ///< Graph,  Subject,   Predicate, Object
+	GSOP,  ///< Graph,  Subject,   Object,    Predicate
+	GOPS,  ///< Graph,  Object,    Predicate, Subject
+	GOSP,  ///< Graph,  Object,    Subject,   Predicate
+	GPSO,  ///< Graph,  Predicate, Subject,   Object
+	GPOS   ///< Graph,  Predicate, Object,    Subject
+} SerdOrder;
+
+/** Mode for searching or iteration */
+typedef enum {
+	ALL,           ///< Iterate over entire store
+	RANGE,         ///< Iterate over range with equal prefix
+	FILTER_RANGE,  ///< Iterate over range with equal prefix, filtering
+	FILTER_ALL     ///< Iterate to end of store, filtering
+} SearchMode;
+
+struct SerdIterImpl {
+	const SerdModel* model;     ///< Model being iterated over
+	ZixBTreeIter*    cur;       ///< Current DB cursor
+	SerdQuad         pat;       ///< Pattern (in ordering order)
+	SerdOrder        order;     ///< Store order (which index)
+	SearchMode       mode;      ///< Iteration mode
+	int              n_prefix;  ///< Prefix for RANGE and FILTER_RANGE
+	uint64_t         version;   ///< Model version when iterator was created
+};
+
+#define NUM_ORDERS 12
+#define TUP_LEN 4
+
+/**
+   Quads of indices for each order, from most to least significant
+   (array indexed by SordOrder)
+*/
+static const int orderings[NUM_ORDERS][TUP_LEN] = {
+	{ 0, 1, 2, 3 }, { 0, 2, 1, 3 },  // SPO, SOP
+	{ 2, 1, 0, 3 }, { 2, 0, 1, 3 },  // OPS, OSP
+	{ 1, 0, 2, 3 }, { 1, 2, 0, 3 },  // PSO, POS
+	{ 3, 0, 1, 2 }, { 3, 0, 2, 1 },  // GSPO, GSOP
+	{ 3, 2, 1, 0 }, { 3, 2, 0, 1 },  // GOPS, GOSP
+	{ 3, 1, 0, 2 }, { 3, 1, 2, 0 }   // GPSO, GPOS
+};
+
+SerdIter* serd_iter_new(const SerdModel* model,
+                        ZixBTreeIter*    cur,
+                        const SerdQuad   pat,
+                        SerdOrder        order,
+                        SearchMode       mode,
+                        int              n_prefix);
+
+bool serd_iter_scan_next(SerdIter* iter);
+
+bool serd_quad_match(const SerdQuad x, const SerdQuad y);
+
+#endif  // SERD_ITER_H
-- 
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