WIP: Add model

17 files changed, 1344 insertions, 6 deletions

diff --git a/src/inserter.c b/src/inserter.c
new file mode 100644
index 00000000..d7059c57
--- /dev/null
+++ b/src/inserter.c
@@ -0,0 +1,93 @@
+/*
+  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.
+*/
+
+#include "inserter.h"
+
+#include <stdlib.h>
+
+static SerdStatus
+serd_inserter_on_base(SerdInserter* inserter, const SerdNode* uri)
+{
+	return serd_env_set_base_uri(inserter->env, uri);
+}
+
+static SerdStatus
+serd_inserter_on_prefix(SerdInserter*   inserter,
+                        const SerdNode* name,
+                        const SerdNode* uri)
+{
+	return serd_env_set_prefix(inserter->env, name, uri);
+}
+
+static SerdStatus
+serd_inserter_on_statement(SerdInserter*      inserter,
+                           SerdStatementFlags flags,
+                           const SerdNode*    graph,
+                           const SerdNode*    subject,
+                           const SerdNode*    predicate,
+                           const SerdNode*    object)
+{
+	if (!inserter || !subject || !predicate || !object) {
+		return SERD_ERR_BAD_ARG;
+	}
+
+	SerdNode* g = graph ? serd_env_expand_node(inserter->env, graph) : NULL;
+	SerdNode* s = serd_env_expand_node(inserter->env, subject);
+	SerdNode* p = serd_env_expand_node(inserter->env, predicate);
+	SerdNode* o = serd_env_expand_node(inserter->env, object);
+
+	const SerdStatus st = serd_model_add(inserter->model,
+	                                     s ? s : subject,
+	                                     p ? p : predicate,
+	                                     o ? o : object,
+	                                     g ? g : inserter->default_graph);
+
+	serd_node_free(g);
+	serd_node_free(s);
+	serd_node_free(p);
+	serd_node_free(o);
+
+	return st > SERD_FAILURE ? st : SERD_SUCCESS;
+}
+
+SerdInserter*
+serd_inserter_new(SerdModel* model, SerdEnv* env, const SerdNode* default_graph)
+{
+	SerdInserter* inserter    = (SerdInserter*)calloc(1, sizeof(SerdInserter));
+	inserter->model           = model;
+	inserter->env             = env;
+	inserter->default_graph   = serd_node_copy(default_graph);
+	inserter->iface.handle    = inserter;
+	inserter->iface.base      = (SerdBaseSink)serd_inserter_on_base;
+	inserter->iface.prefix    = (SerdPrefixSink)serd_inserter_on_prefix;
+	inserter->iface.statement = (SerdStatementSink)serd_inserter_on_statement;
+	return inserter;
+}
+
+void
+serd_inserter_free(SerdInserter* inserter)
+{
+	if (inserter) {
+		serd_node_free(inserter->default_graph);
+		free(inserter);
+	}
+}
+
+const SerdSinkInterface*
+serd_inserter_get_sink_interface(SerdInserter* inserter)
+{
+	return &inserter->iface;
+}
diff --git a/src/inserter.h b/src/inserter.h
new file mode 100644
index 00000000..0553f5a4
--- /dev/null
+++ b/src/inserter.h
@@ -0,0 +1,29 @@
+/*
+  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_INSERTER_H
+#define SERD_INSERTER_H
+
+#include "serd/serd.h"
+
+struct SerdInserterImpl {
+	SerdModel*        model;
+	SerdEnv*          env;
+	SerdNode*         default_graph;
+	SerdSinkInterface iface;
+};
+
+#endif  // SERD_INSERTER_H
diff --git a/src/iter.c b/src/iter.c
new file mode 100644
index 00000000..904f2562
--- /dev/null
+++ b/src/iter.c
@@ -0,0 +1,234 @@
+/*
+  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.
+*/
+
+#include "iter.h"
+
+#include "log.h"
+#include "model.h"
+#include "statement.h"
+#include "world.h"
+
+#include "serd/serd.h"
+#include "zix/btree.h"
+
+#include <assert.h>
+#include <stdlib.h>
+
+static inline bool
+serd_iter_forward(SerdIter* iter)
+{
+	zix_btree_iter_increment(iter->cur);
+	return zix_btree_iter_is_end(iter->cur);
+}
+
+/**
+   Seek forward as necessary until `iter` points at a match.
+   @return true iff iterator reached end of valid range.
+*/
+static inline bool
+serd_iter_seek_match(SerdIter* iter)
+{
+	for (iter->end = true; !zix_btree_iter_is_end(iter->cur);
+	     serd_iter_forward(iter)) {
+		const SerdStatement* s = (const SerdStatement*)zix_btree_get(iter->cur);
+		if (serd_statement_matches_quad(s, iter->pat)) {
+			return (iter->end = false);
+		}
+	}
+	return true;
+}
+
+/**
+   Seek forward as necessary until `iter` points at a match, or the prefix
+   no longer matches iter->pat.
+   @return true iff iterator reached end of valid range.
+*/
+static inline bool
+serd_iter_seek_match_range(SerdIter* iter)
+{
+	assert(!iter->end);
+
+	do {
+		const SerdStatement* key = (const SerdStatement*)zix_btree_get(iter->cur);
+
+		if (serd_statement_matches_quad(key, iter->pat)) {
+			return false;  // Found match
+		}
+
+		for (int i = 0; i < iter->n_prefix; ++i) {
+			const int idx = orderings[iter->order][i];
+			if (!serd_node_pattern_match(key->nodes[idx], iter->pat[idx])) {
+				iter->end = true;  // Reached end of valid range
+				return true;
+			}
+		}
+	} while (!serd_iter_forward(iter));
+
+	return (iter->end = true);  // Reached end
+}
+
+static bool
+check_version(const SerdIter* const iter)
+{
+	if (iter->version != iter->model->version) {
+		serd_world_errorf(iter->model->world,
+		                  SERD_ERR_BAD_ITER,
+		                  "attempt to use invalidated iterator\n");
+		return false;
+	}
+	return true;
+}
+
+SerdIter*
+serd_iter_new(const SerdModel* model,
+              ZixBTreeIter*    cur,
+              const SerdQuad   pat,
+              SerdOrder        order,
+              SearchMode       mode,
+              int              n_prefix)
+{
+	SerdIter* iter    = (SerdIter*)malloc(sizeof(SerdIter));
+	iter->model       = model;
+	iter->cur         = cur;
+	iter->order       = order;
+	iter->mode        = mode;
+	iter->n_prefix    = n_prefix;
+	iter->version     = model->version;
+	iter->end         = false;
+	for (int i = 0; i < TUP_LEN; ++i) {
+		iter->pat[i] = pat[i];
+	}
+
+	switch (iter->mode) {
+	case ALL:
+	case SINGLE:
+	case RANGE:
+		assert(serd_statement_matches_quad(
+			       ((const SerdStatement*)zix_btree_get(iter->cur)),
+			       iter->pat));
+		break;
+	case FILTER_RANGE: serd_iter_seek_match_range(iter); break;
+	case FILTER_ALL: serd_iter_seek_match(iter); break;
+	}
+
+#ifdef SERD_DEBUG_ITER
+	const SerdStatement* statement = serd_iter_get(iter);
+	SERD_ITER_LOG("New %p pat=" TUP_FMT " cur=" TUP_FMT " end=%d\n",
+	              (void*)iter,
+	              TUP_FMT_ARGS(pat),
+	              TUP_FMT_ARGS(statement->nodes),
+	              iter->end);
+#endif
+
+	return iter;
+}
+
+const SerdModel*
+serd_iter_get_model(const SerdIter* iter)
+{
+	return iter->model;
+}
+
+const SerdStatement*
+serd_iter_get(const SerdIter* iter)
+{
+	return check_version(iter) ? (const SerdStatement*)zix_btree_get(iter->cur)
+	                           : NULL;
+}
+
+bool
+serd_iter_scan_next(SerdIter* iter)
+{
+	if (iter->end) {
+		return true;
+	}
+
+	const SerdStatement* key = NULL;
+	if (!iter->end) {
+		switch (iter->mode) {
+		case ALL:
+			// At the end if the cursor is (assigned above)
+			break;
+		case SINGLE:
+			iter->end = true;
+			SERD_ITER_LOG("%p reached single end\n", (void*)iter);
+			break;
+		case RANGE:
+			SERD_ITER_LOG("%p range next\n", (void*)iter);
+			// At the end if the MSNs no longer match
+			key = (const SerdStatement*)zix_btree_get(iter->cur);
+			assert(key);
+			for (int i = 0; i < iter->n_prefix; ++i) {
+				const int idx = orderings[iter->order][i];
+				if (!serd_node_pattern_match(key->nodes[idx], iter->pat[idx])) {
+					iter->end = true;
+					SERD_ITER_LOG("%p reached non-match end\n", (void*)iter);
+					break;
+				}
+			}
+			break;
+		case FILTER_RANGE:
+			// Seek forward to next match, stopping if prefix changes
+			serd_iter_seek_match_range(iter);
+			break;
+		case FILTER_ALL:
+			// Seek forward to next match
+			serd_iter_seek_match(iter);
+			break;
+		}
+	} else {
+		SERD_ITER_LOG("%p reached index end\n", (void*)iter);
+	}
+
+	if (iter->end) {
+		SERD_ITER_LOG("%p Reached end\n", (void*)iter);
+		return true;
+	} else {
+#ifdef SERD_DEBUG_ITER
+		SERD_ITER_LOG("%p Increment to " TUP_FMT "\n",
+		              (void*)iter,
+		              TUP_FMT_ARGS(serd_iter_get(iter)->nodes));
+#endif
+		return false;
+	}
+}
+
+bool
+serd_iter_next(SerdIter* iter)
+{
+	if (iter->end || !check_version(iter)) {
+		return true;
+	}
+
+	iter->end = serd_iter_forward(iter);
+	return serd_iter_scan_next(iter);
+}
+
+bool
+serd_iter_end(const SerdIter* iter)
+{
+	return !iter || iter->end;
+}
+
+void
+serd_iter_free(SerdIter* iter)
+{
+	SERD_ITER_LOG("%p Free\n", (void*)iter);
+	if (iter) {
+		zix_btree_iter_free(iter->cur);
+		free(iter);
+	}
+}
diff --git a/src/iter.h b/src/iter.h
new file mode 100644
index 00000000..82ab2119
--- /dev/null
+++ b/src/iter.h
@@ -0,0 +1,90 @@
+/*
+  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>
+
+/** 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
+	SINGLE,        ///< Iteration over a single element (exact search)
+	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
+	bool             end;       ///< True iff reached end
+};
+
+#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
diff --git a/src/log.h b/src/log.h
new file mode 100644
index 00000000..368f34b5
--- /dev/null
+++ b/src/log.h
@@ -0,0 +1,54 @@
+/*
+  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_LOG_H
+#define SERD_LOG_H
+
+#ifdef SERD_DEBUG_SEARCH
+/** String name of each ordering (array indexed by SordOrder) */
+static const char* const order_names[] = {
+	"spo",  "sop",  "ops",  "osp",  "pso",  "pos",
+	"gspo", "gsop", "gops", "gosp", "gpso", "gpos"
+};
+#endif
+
+#define TUP_FMT         "(%s %s %s %s)"
+#define TUP_FMT_ELEM(e) ((e) ? serd_node_get_string(e) : "*")
+#define TUP_FMT_ARGS(t) \
+	TUP_FMT_ELEM((t)[0]), \
+	TUP_FMT_ELEM((t)[1]), \
+	TUP_FMT_ELEM((t)[2]), \
+	TUP_FMT_ELEM((t)[3])
+
+#define SERD_LOG(prefix, ...) fprintf(stderr, "serd." prefix ": " __VA_ARGS__)
+
+#ifdef SERD_DEBUG_ITER
+#    define SERD_ITER_LOG(...) SERD_LOG("iter", __VA_ARGS__)
+#else
+#    define SERD_ITER_LOG(...)
+#endif
+#ifdef SERD_DEBUG_SEARCH
+#    define SERD_FIND_LOG(...) SERD_LOG("search", __VA_ARGS__)
+#else
+#    define SERD_FIND_LOG(...)
+#endif
+#ifdef SERD_DEBUG_WRITE
+#    define SERD_WRITE_LOG(...) SERD_LOG("write", __VA_ARGS__)
+#else
+#    define SERD_WRITE_LOG(...)
+#endif
+
+#endif  // SERD_LOG_H
diff --git a/src/model.c b/src/model.c
new file mode 100644
index 00000000..43b815dd
--- /dev/null
+++ b/src/model.c
@@ -0,0 +1,474 @@
+/*
+  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.
+*/
+
+#include "model.h"
+
+#include "iter.h"
+#include "log.h"
+#include "node.h"
+#include "nodes.h"
+#include "statement.h"
+#include "world.h"
+
+#include "zix/btree.h"
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+#define DEFAULT_ORDER SPO
+#define DEFAULT_GRAPH_ORDER GSPO
+
+/**
+   Compare quads lexicographically, ignoring graph.
+
+   NULL IDs (equal to 0) are treated as wildcards, always less than every
+   other possible ID, except itself.
+*/
+static int
+serd_triple_compare(const void* x_ptr, const void* y_ptr, void* user_data)
+{
+	const int* const           ordering = (const int*)user_data;
+	const SerdStatement* const x        = (const SerdStatement*)x_ptr;
+	const SerdStatement* const y        = (const SerdStatement*)y_ptr;
+
+	for (int i = 0; i < TUP_LEN - 1; ++i) {
+		const int idx = ordering[i];
+		assert(idx != SERD_GRAPH);
+
+		const int cmp = serd_node_compare(x->nodes[idx], y->nodes[idx], true);
+		if (cmp) {
+			return cmp;
+		}
+	}
+
+	return 0;
+}
+
+/**
+   Compare quads lexicographically, with exact (non-wildcard) graph matching.
+*/
+static int
+serd_quad_compare(const void* x_ptr, const void* y_ptr, void* user_data)
+{
+	const int* const           ordering = (const int*)user_data;
+	const SerdStatement* const x        = (const SerdStatement*)x_ptr;
+	const SerdStatement* const y        = (const SerdStatement*)y_ptr;
+
+	// Compare graph without wildcard matching
+	const int gcmp = serd_node_compare(
+		x->nodes[SERD_GRAPH], y->nodes[SERD_GRAPH], false);
+	if (gcmp) {
+		return gcmp;
+	}
+
+	// Compare triple fields in appropriate order with wildcard matching
+	for (int i = 0; i < TUP_LEN; ++i) {
+		const int idx = ordering[i];
+		if (idx != SERD_GRAPH) {
+			const int cmp =
+				serd_node_compare(x->nodes[idx], y->nodes[idx], true);
+			if (cmp) {
+				return cmp;
+			}
+		}
+	}
+
+	return 0;
+}
+
+/**
+   Return true iff `serd` has an index for `order`.
+   If `graphs` is true, `order` will be modified to be the
+   corresponding order with a G prepended (so G will be the MSN).
+*/
+static inline bool
+serd_model_has_index(SerdModel* model,
+                     SerdOrder* order,
+                     int*       n_prefix,
+                     bool       graphs)
+{
+	if (graphs) {
+		*order = (SerdOrder)(*order + GSPO);
+		*n_prefix += 1;
+	}
+
+	return model->indices[*order];
+}
+
+/**
+   Return the best available index for a pattern.
+   @param pat Pattern in standard (S P O G) order
+   @param mode Set to the (best) iteration mode for iterating over results
+   @param n_prefix Set to the length of the range prefix
+   (for `mode` == RANGE and `mode` == FILTER_RANGE)
+*/
+static inline SerdOrder
+serd_model_best_index(SerdModel*     model,
+                      const SerdQuad pat,
+                      SearchMode*    mode,
+                      int*           n_prefix)
+{
+	const bool graph_search = (pat[SERD_GRAPH] != 0);
+
+	const unsigned sig = ((pat[0] ? 1 : 0) * 0x100 +
+	                      (pat[1] ? 1 : 0) * 0x010 +
+	                      (pat[2] ? 1 : 0) * 0x001);
+
+	SerdOrder good[2] = { (SerdOrder)-1, (SerdOrder)-1 };
+
+#define PAT_CASE(sig, m, g0, g1, np)                                           \
+	case sig:                                                                  \
+		*mode     = m;                                                         \
+		good[0]   = g0;                                                        \
+		good[1]   = g1;                                                        \
+		*n_prefix = np;                                                        \
+		break
+
+	// Good orderings that don't require filtering
+	*mode     = RANGE;
+	*n_prefix = 0;
+	switch (sig) {
+	case 0x000:
+		assert(graph_search);
+		*mode     = RANGE;
+		*n_prefix = 1;
+		return DEFAULT_GRAPH_ORDER;
+	case 0x111:
+		*mode = SINGLE;
+		return graph_search ? DEFAULT_GRAPH_ORDER : DEFAULT_ORDER;
+
+		PAT_CASE(0x001, RANGE, OPS, OSP, 1);
+		PAT_CASE(0x010, RANGE, POS, PSO, 1);
+		PAT_CASE(0x011, RANGE, OPS, POS, 2);
+		PAT_CASE(0x100, RANGE, SPO, SOP, 1);
+		PAT_CASE(0x101, RANGE, SOP, OSP, 2);
+		PAT_CASE(0x110, RANGE, SPO, PSO, 2);
+	}
+
+	if (*mode == RANGE) {
+		if (serd_model_has_index(model, &good[0], n_prefix, graph_search)) {
+			return good[0];
+		} else if (serd_model_has_index(
+			           model, &good[1], n_prefix, graph_search)) {
+			return good[1];
+		}
+	}
+
+	// Not so good orderings that require filtering, but can
+	// still be constrained to a range
+	switch (sig) {
+		PAT_CASE(0x011, FILTER_RANGE, OSP, PSO, 1);
+		PAT_CASE(0x101, FILTER_RANGE, SPO, OPS, 1);
+		// SPO is always present, so 0x110 is never reached here
+	default: break;
+	}
+
+	if (*mode == FILTER_RANGE) {
+		if (serd_model_has_index(model, &good[0], n_prefix, graph_search)) {
+			return good[0];
+		} else if (serd_model_has_index(
+			           model, &good[1], n_prefix, graph_search)) {
+			return good[1];
+		}
+	}
+
+	if (graph_search) {
+		*mode     = FILTER_RANGE;
+		*n_prefix = 1;
+		return DEFAULT_GRAPH_ORDER;
+	} else {
+		*mode = FILTER_ALL;
+		return DEFAULT_ORDER;
+	}
+}
+
+SerdModel*
+serd_model_new(SerdWorld* world, unsigned indices, SerdModelFlags flags)
+{
+	SerdModel* model = (SerdModel*)calloc(1, sizeof(struct SerdModelImpl));
+	model->world     = world;
+
+	indices |= SERD_SPO;
+
+	for (unsigned i = 0; i < (NUM_ORDERS / 2); ++i) {
+		const int* const ordering   = orderings[i];
+		const int* const g_ordering = orderings[i + (NUM_ORDERS / 2)];
+
+		if (indices & (1 << i)) {
+			model->indices[i] =
+				zix_btree_new((ZixComparator)serd_triple_compare,
+				              (const void*)ordering,
+				              NULL);
+			if (flags & SERD_MODEL_GRAPHS) {
+				model->indices[i + (NUM_ORDERS / 2)] =
+					zix_btree_new((ZixComparator)serd_quad_compare,
+					              (const void*)g_ordering,
+					              NULL);
+			}
+		}
+	}
+
+	return model;
+}
+
+static void
+serd_model_drop_statement(SerdModel* model, SerdStatement* statement)
+
+{
+	for (int i = 0; i < TUP_LEN; ++i) {
+		if (statement->nodes[i]) {
+			serd_nodes_deref(model->world->nodes, statement->nodes[i]);
+		}
+	}
+
+	free(statement);
+}
+
+void
+serd_model_free(SerdModel* model)
+{
+	if (!model) {
+		return;
+	}
+
+	// Free quads
+	ZixBTree* index = model->indices[model->indices[DEFAULT_GRAPH_ORDER]
+	                                 ? DEFAULT_GRAPH_ORDER
+	                                 : DEFAULT_ORDER];
+	ZixBTreeIter* t = zix_btree_begin(index);
+	for (; !zix_btree_iter_is_end(t); zix_btree_iter_increment(t)) {
+		free(zix_btree_get(t));
+	}
+	zix_btree_iter_free(t);
+
+	// Free indices
+	for (unsigned o = 0; o < NUM_ORDERS; ++o) {
+		if (model->indices[o]) {
+			zix_btree_free(model->indices[o]);
+		}
+	}
+
+	free(model);
+}
+
+SerdWorld*
+serd_model_get_world(SerdModel* model)
+{
+	return model->world;
+}
+
+size_t
+serd_model_num_quads(const SerdModel* model)
+{
+	const SerdOrder order = model->indices[GSPO] ? GSPO : SPO;
+	return zix_btree_size(model->indices[order]);
+}
+
+SerdIter*
+serd_model_begin(const SerdModel* model)
+{
+	if (serd_model_num_quads(model) == 0) {
+		return NULL;
+	} else {
+		const SerdOrder order = model->indices[GSPO] ? GSPO : SPO;
+		ZixBTreeIter*   cur   = zix_btree_begin(model->indices[order]);
+		SerdQuad        pat   = { 0, 0, 0, 0 };
+		return serd_iter_new(model, cur, pat, order, ALL, 0);
+	}
+}
+
+SerdIter*
+serd_model_find(SerdModel*      model,
+                const SerdNode* s,
+                const SerdNode* p,
+                const SerdNode* o,
+                const SerdNode* g)
+{
+	const SerdQuad pat = { s, p, o, g };
+	if (!pat[0] && !pat[1] && !pat[2] && !pat[3]) {
+		return serd_model_begin(model);
+	}
+
+	SearchMode      mode;
+	int             n_prefix;
+	const SerdOrder index_order =
+		serd_model_best_index(model, pat, &mode, &n_prefix);
+
+	SERD_FIND_LOG("Find " TUP_FMT "  index=%s  mode=%d  n_prefix=%d\n",
+	              TUP_FMT_ARGS(pat),
+	              order_names[index_order],
+	              mode,
+	              n_prefix);
+
+	if (pat[0] && pat[1] && pat[2] && pat[3]) {
+		mode = SINGLE; // No duplicate quads (Serd is a set)
+	}
+
+	ZixBTree* const db  = model->indices[index_order];
+	ZixBTreeIter*   cur = NULL;
+	zix_btree_lower_bound(db, pat, &cur);
+	if (zix_btree_iter_is_end(cur)) {
+		SERD_FIND_LOG("No match found, iterator at end\n");
+		zix_btree_iter_free(cur);
+		return NULL;
+	}
+	const SerdStatement* const key = (const SerdStatement*)zix_btree_get(cur);
+	if (!key || ((mode == RANGE || mode == SINGLE) &&
+	             !serd_statement_matches_quad(key, pat))) {
+		SERD_FIND_LOG("No match found, cursor at " TUP_FMT "\n",
+		              TUP_FMT_ARGS(key->nodes));
+
+		zix_btree_iter_free(cur);
+		return NULL;
+	}
+
+	return serd_iter_new(model, cur, pat, index_order, mode, n_prefix);
+}
+
+const SerdNode*
+serd_model_get(SerdModel*      model,
+               const SerdNode* s,
+               const SerdNode* p,
+               const SerdNode* o,
+               const SerdNode* g)
+{
+	if ((bool)s + (bool)p + (bool)o != 2) {
+		return NULL;
+	}
+
+	SerdIter* const i = serd_model_find(model, s, p, o, g);
+	if (i) {
+		const SerdStatement* statement = serd_iter_get(i);
+		serd_iter_free(i);
+
+		if (!s) {
+			return serd_statement_get_subject(statement);
+		} else if (!p) {
+			return serd_statement_get_predicate(statement);
+		} else if (!o) {
+			return serd_statement_get_object(statement);
+		}
+	}
+
+	return NULL;
+}
+
+uint64_t
+serd_model_count(SerdModel*      model,
+                 const SerdNode* s,
+                 const SerdNode* p,
+                 const SerdNode* o,
+                 const SerdNode* g)
+{
+	SerdIter* i = serd_model_find(model, s, p, o, g);
+	uint64_t  n = 0;
+	for (; !serd_iter_end(i); serd_iter_next(i)) {
+		++n;
+	}
+	serd_iter_free(i);
+	return n;
+}
+
+bool
+serd_model_ask(SerdModel*      model,
+               const SerdNode* s,
+               const SerdNode* p,
+               const SerdNode* o,
+               const SerdNode* g)
+{
+	SerdIter* iter = serd_model_find(model, s, p, o, g);
+	bool      ret  = (iter != NULL);
+	serd_iter_free(iter);
+	return ret;
+}
+
+SerdStatus
+serd_model_add(SerdModel*      model,
+               const SerdNode* s,
+               const SerdNode* p,
+               const SerdNode* o,
+               const SerdNode* g)
+{
+	if (!s || !p || !o) {
+		return serd_world_errorf(model->world,
+		                         SERD_ERR_BAD_ARG,
+		                         "attempt to add statement with NULL field\n");
+	}
+
+	SerdStatement* statement = (SerdStatement*)malloc(sizeof(SerdStatement));
+	statement->nodes[0]      = serd_nodes_intern(model->world->nodes, s);
+	statement->nodes[1]      = serd_nodes_intern(model->world->nodes, p);
+	statement->nodes[2]      = serd_nodes_intern(model->world->nodes, o);
+	statement->nodes[3]      = serd_nodes_intern(model->world->nodes, g);
+	SERD_WRITE_LOG("Add " TUP_FMT "\n", TUP_FMT_ARGS(statement->nodes));
+
+	bool added = false;
+	for (unsigned i = 0; i < NUM_ORDERS; ++i) {
+		if (model->indices[i]) {
+			if (!zix_btree_insert(model->indices[i], statement)) {
+				added = true;
+			} else if (i == GSPO) {
+				break; // Tuple already indexed
+			}
+		}
+	}
+
+	++model->version;
+	if (added) {
+		return SERD_SUCCESS;
+	}
+
+	serd_model_drop_statement(model, statement);
+	return SERD_FAILURE;
+}
+
+SerdStatus
+serd_model_add_statement(SerdModel* model, const SerdStatement* statement)
+{
+	return serd_model_add(model,
+	                      serd_statement_get_subject(statement),
+	                      serd_statement_get_predicate(statement),
+	                      serd_statement_get_object(statement),
+	                      serd_statement_get_graph(statement));
+}
+
+SerdStatus
+serd_model_erase(SerdModel* model, SerdIter* iter)
+{
+	const SerdStatement* statement = serd_iter_get(iter);
+
+	SERD_WRITE_LOG("Remove " TUP_FMT "\n", TUP_FMT_ARGS(statement->nodes));
+
+	SerdStatement* removed = NULL;
+	for (unsigned i = 0; i < NUM_ORDERS; ++i) {
+		if (model->indices[i]) {
+			zix_btree_remove(model->indices[i],
+			                 statement,
+			                 (void**)&removed,
+			                 i == iter->order ? &iter->cur : NULL);
+			}
+		}
+	}
+	iter->end = zix_btree_iter_is_end(iter->cur);
+	serd_iter_scan_next(iter);
+
+	serd_model_drop_statement(model, removed);
+	iter->version = ++model->version;
+
+	return SERD_SUCCESS;
+}
diff --git a/src/model.h b/src/model.h
new file mode 100644
index 00000000..28cac0cf
--- /dev/null
+++ b/src/model.h
@@ -0,0 +1,39 @@
+/*
+  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_MODEL_H
+#define SERD_MODEL_H
+
+#include "serd/serd.h"
+#include "zix/btree.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define SERD_NUM_ORDERS 12
+
+struct SerdModelImpl {
+	SerdWorld* world;
+
+	/** Index for each possible triple ordering (may or may not exist).
+	 * Each index is a tree of SordQuad with the appropriate ordering.
+	 */
+	ZixBTree* indices[SERD_NUM_ORDERS];
+
+	uint64_t version;
+};
+
+#endif  // SERD_MODEL_H
diff --git a/src/node.c b/src/node.c
index 523893df..32852dc1 100644
--- a/src/node.c
+++ b/src/node.c
@@ -247,6 +247,30 @@ serd_node_equals(const SerdNode* a, const SerdNode* b)
 	return false;
 }
 
+/** Compare nodes, considering NULL a match iff `wildcards` is true. */
+int
+serd_node_compare(const SerdNode* a, const SerdNode* b, bool wildcards)
+{
+	if (a == b) {
+		return 0;
+	} else if (!a || !b) {
+		return wildcards ? 0 : (a < b) ? -1 : (a > b) ? 1 : 0;
+	} else if (a->type != b->type) {
+		return a->type - b->type;
+	}
+
+	int cmp = strcmp(serd_node_get_string(a), serd_node_get_string(b));
+	if (cmp) {
+		return cmp;
+	}
+
+	cmp = serd_node_compare(serd_node_maybe_get_meta_c(a),
+	                        serd_node_maybe_get_meta_c(b),
+	                        false);
+
+	return cmp;
+}
+
 static size_t
 serd_uri_string_length(const SerdURI* uri)
 {
diff --git a/src/node.h b/src/node.h
index 91202db1..004d617b 100644
--- a/src/node.h
+++ b/src/node.h
@@ -44,5 +44,6 @@ SerdNode* serd_node_malloc(size_t n_bytes, SerdNodeFlags flags, SerdType type);
 void      serd_node_set(SerdNode** dst, const SerdNode* src);
 size_t    serd_node_total_size(const SerdNode* node);
 SerdNode* serd_node_new_resolved_uri_i(const char* str, const SerdURI* base);
+int       serd_node_compare(const SerdNode* a, const SerdNode* b, bool wildcards);
 
 #endif  // SERD_NODE_H
diff --git a/src/nodes.c b/src/nodes.c
new file mode 100644
index 00000000..169ca4ca
--- /dev/null
+++ b/src/nodes.c
@@ -0,0 +1,109 @@
+/*
+  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.
+*/
+
+#include "nodes.h"
+
+#include "node.h"
+
+#include "zix/common.h"
+#include "zix/digest.h"
+
+#include <assert.h>
+#include <string.h>
+
+typedef struct {
+	size_t    refs;
+	SerdNode* node;
+} NodesEntry;
+
+typedef struct {
+	size_t          refs;
+	const SerdNode* node;
+} NodesSearchKey;
+
+static uint32_t
+nodes_hash(const void* n)
+{
+	const SerdNode* node = ((const NodesEntry*)n)->node;
+	uint32_t        hash = zix_digest_start();
+	hash = zix_digest_add(hash, node, serd_node_total_size(node));
+	return hash;
+}
+
+static bool
+nodes_equal(const void* a, const void* b)
+{
+	const SerdNode* a_node = ((const NodesEntry*)a)->node;
+	const SerdNode* b_node = ((const NodesEntry*)b)->node;
+	const size_t    a_size = serd_node_total_size(a_node);
+	const size_t    b_size = serd_node_total_size(b_node);
+	return ((a_node == b_node) ||
+	        (a_size == b_size && !memcmp(a_node, b_node, a_size)));
+}
+
+static void
+free_entry(void* value, void* user_data)
+{
+	NodesEntry* entry = (NodesEntry*)value;
+	serd_node_free(entry->node);
+}
+
+SerdNodes*
+serd_nodes_new(void)
+{
+	return zix_hash_new(nodes_hash, nodes_equal, sizeof(NodesEntry));
+}
+
+void
+serd_nodes_free(SerdNodes* nodes)
+{
+	zix_hash_foreach(nodes, free_entry, nodes);
+	zix_hash_free(nodes);
+}
+
+SerdNode*
+serd_nodes_intern(SerdNodes* nodes, const SerdNode* node)
+{
+	if (!node) {
+		return NULL;
+	}
+
+	NodesSearchKey key      = { 1, node };
+	NodesEntry*    inserted = NULL;
+	switch (zix_hash_insert(nodes, &key, (const void**)&inserted)) {
+	case ZIX_STATUS_EXISTS:
+		assert(serd_node_equals(inserted->node, node));
+		++inserted->refs;
+		break;
+	case ZIX_STATUS_SUCCESS:
+		inserted->node = serd_node_copy(node);
+	default: break;
+	}
+
+	return inserted ? inserted->node : NULL;
+}
+
+void
+serd_nodes_deref(SerdNodes* nodes, const SerdNode* node)
+{
+	NodesSearchKey key   = { 1, node };
+	NodesEntry*    entry = (NodesEntry*)zix_hash_find(nodes, &key);
+	if (entry && --entry->refs == 0) {
+		SerdNode* const intern_node = entry->node;
+		zix_hash_remove(nodes, entry);
+		serd_node_free(intern_node);
+	}
+}
diff --git a/src/nodes.h b/src/nodes.h
new file mode 100644
index 00000000..43e6df28
--- /dev/null
+++ b/src/nodes.h
@@ -0,0 +1,33 @@
+/*
+  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_NODES_H
+#define SERD_NODES_H
+
+#include "serd/serd.h"
+#include "zix/hash.h"
+
+typedef ZixHash SerdNodes;
+
+SerdNodes* serd_nodes_new(void);
+
+void serd_nodes_free(SerdNodes* nodes);
+
+SerdNode* serd_nodes_intern(SerdNodes* nodes, const SerdNode* node);
+
+void serd_nodes_deref(SerdNodes* nodes, const SerdNode* node);
+
+#endif  // SERD_NODES_H
diff --git a/src/serdi.c b/src/serdi.c
index 6efce26e..1f12812b 100644
--- a/src/serdi.c
+++ b/src/serdi.c
@@ -94,6 +94,7 @@ print_usage(const char* name, bool error)
 	fprintf(os, "  -h           Display this help and exit.\n");
 	fprintf(os, "  -i SYNTAX    Input syntax: turtle/ntriples/trig/nquads.\n");
 	fprintf(os, "  -l           Lax (non-strict) parsing.\n");
+	fprintf(os, "  -m           Build and serialise a model (no streaming).\n");
 	fprintf(os, "  -o SYNTAX    Output syntax: turtle/ntriples/nquads.\n");
 	fprintf(os, "  -p PREFIX    Add PREFIX to blank node IDs.\n");
 	fprintf(os, "  -q           Suppress all output except data.\n");
@@ -132,6 +133,7 @@ main(int argc, char** argv)
 	bool           bulk_write    = false;
 	bool           full_uris     = false;
 	bool           lax           = false;
+	bool           use_model     = false;
 	bool           quiet         = false;
 	const char*    add_prefix    = NULL;
 	const char*    chop_prefix   = NULL;
@@ -153,6 +155,8 @@ main(int argc, char** argv)
 			return print_usage(argv[0], false);
 		} else if (argv[a][1] == 'l') {
 			lax = true;
+		} else if (argv[a][1] == 'm') {
+			use_model = true;
 		} else if (argv[a][1] == 'q') {
 			quiet = true;
 		} else if (argv[a][1] == 'v') {
@@ -205,11 +209,11 @@ main(int argc, char** argv)
 		input_syntax = SERD_TRIG;
 	}
 
+	const bool input_has_graphs =
+		input_syntax == SERD_NQUADS || input_syntax == SERD_TRIG;
+
 	if (!output_syntax) {
-		output_syntax = (
-			(input_syntax == SERD_TURTLE || input_syntax == SERD_NTRIPLES)
-			? SERD_NTRIPLES
-			: SERD_NQUADS);
+		output_syntax = input_has_graphs ? SERD_NQUADS : SERD_NTRIPLES;
 	}
 
 	SerdNode* base = NULL;
@@ -247,9 +251,19 @@ main(int argc, char** argv)
 		world, output_syntax, (SerdStyle)output_style,
 		env, serd_file_sink, out_fd);
 
-	SerdReader* reader = serd_reader_new(
-		world, input_syntax, serd_writer_get_sink_interface(writer));
+	SerdReader*              reader   = NULL;
+	SerdModel*               model    = NULL;
+	SerdInserter*            inserter = NULL;
+	const SerdSinkInterface* sink     = NULL;
+	if (use_model) {
+		model    = serd_model_new(world, SERD_SPO, input_has_graphs);
+		inserter = serd_inserter_new(model, env, NULL);
+		sink     = serd_inserter_get_sink_interface(inserter);
+	} else {
+		sink = serd_writer_get_sink_interface(writer);
+	}
 
+	reader = serd_reader_new(world, input_syntax, sink);
 	serd_reader_set_strict(reader, !lax);
 	if (quiet) {
 		serd_world_set_error_sink(world, quiet_error_sink, NULL);
@@ -285,6 +299,27 @@ main(int argc, char** argv)
 
 	serd_reader_end_stream(reader);
 
+	if (status <= SERD_FAILURE && use_model) {
+		const SerdSinkInterface* wsink = serd_writer_get_sink_interface(writer);
+		serd_env_foreach(env, wsink->prefix, writer);
+
+		SerdIter* iter = serd_model_begin(model);
+		for (; !serd_iter_end(iter); serd_iter_next(iter)) {
+			const SerdStatement* s = serd_iter_get(iter);
+			if ((status = wsink->statement(wsink->handle,
+			                               0,
+			                               serd_statement_get_graph(s),
+			                               serd_statement_get_subject(s),
+			                               serd_statement_get_predicate(s),
+			                               serd_statement_get_object(s)))) {
+				break;
+			}
+		}
+		serd_iter_free(iter);
+	}
+
+	serd_inserter_free(inserter);
+	serd_model_free(model);
 	serd_reader_free(reader);
 	serd_writer_finish(writer);
 	serd_writer_free(writer);
diff --git a/src/statement.c b/src/statement.c
new file mode 100644
index 00000000..d6d1eef8
--- /dev/null
+++ b/src/statement.c
@@ -0,0 +1,70 @@
+/*
+  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.
+*/
+
+#include "statement.h"
+
+const SerdNode*
+serd_statement_get_node(const SerdStatement* statement, SerdField field)
+{
+	return statement->nodes[field];
+}
+
+const SerdNode*
+serd_statement_get_subject(const SerdStatement* statement)
+{
+	return statement->nodes[SERD_SUBJECT];
+}
+
+const SerdNode*
+serd_statement_get_predicate(const SerdStatement* statement)
+{
+	return statement->nodes[SERD_PREDICATE];
+}
+
+const SerdNode*
+serd_statement_get_object(const SerdStatement* statement)
+{
+	return statement->nodes[SERD_OBJECT];
+}
+
+const SerdNode*
+serd_statement_get_graph(const SerdStatement* statement)
+{
+	return statement->nodes[SERD_GRAPH];
+}
+
+bool
+serd_statement_matches(const SerdStatement* statement,
+                       const SerdNode*      subject,
+                       const SerdNode*      predicate,
+                       const SerdNode*      object,
+                       const SerdNode*      graph)
+
+{
+	return (serd_node_pattern_match(statement->nodes[0], subject) &&
+	        serd_node_pattern_match(statement->nodes[1], predicate) &&
+	        serd_node_pattern_match(statement->nodes[2], object) &&
+	        serd_node_pattern_match(statement->nodes[3], graph));
+}
+
+bool
+serd_statement_matches_quad(const SerdStatement* statement, const SerdQuad quad)
+{
+	return serd_node_pattern_match(statement->nodes[0], quad[0]) &&
+	       serd_node_pattern_match(statement->nodes[1], quad[1]) &&
+	       serd_node_pattern_match(statement->nodes[2], quad[2]) &&
+	       serd_node_pattern_match(statement->nodes[3], quad[3]);
+}
diff --git a/src/statement.h b/src/statement.h
new file mode 100644
index 00000000..20b0ad0c
--- /dev/null
+++ b/src/statement.h
@@ -0,0 +1,47 @@
+/*
+  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_STATEMENT_H
+#define SERD_STATEMENT_H
+
+#include "serd/serd.h"
+
+#include <stdbool.h>
+
+#include "serd/serd.h"
+
+/**
+   Quad of nodes (a statement), or a quad pattern.
+
+   Nodes are ordered (S P O G).  The ID of the default graph is 0.
+*/
+typedef const SerdNode* SerdQuad[4];
+
+struct SerdStatementImpl {
+	SerdQuad nodes;
+};
+
+static inline bool
+serd_node_pattern_match(const SerdNode* a, const SerdNode* b)
+{
+	return !a || !b || (a == b) || serd_node_equals(a, b);
+}
+
+bool
+serd_statement_matches_quad(const SerdStatement* statement,
+                            const SerdQuad       quad);
+
+#endif  // SERD_STATEMENT_H
diff --git a/src/string.c b/src/string.c
index 1755d48a..3ca5bd98 100644
--- a/src/string.c
+++ b/src/string.c
@@ -31,6 +31,7 @@ serd_strerror(SerdStatus status)
 	case SERD_ERR_UNKNOWN:    return "Unknown error";
 	case SERD_ERR_BAD_SYNTAX: return "Invalid syntax";
 	case SERD_ERR_BAD_ARG:    return "Invalid argument";
+	case SERD_ERR_BAD_ITER:   return "Invalid iterator";
 	case SERD_ERR_NOT_FOUND:  return "Not found";
 	case SERD_ERR_ID_CLASH:   return "Blank node ID clash";
 	case SERD_ERR_BAD_CURIE:  return "Invalid CURIE";
diff --git a/src/world.c b/src/world.c
index 9d364e04..fbe9da3f 100644
--- a/src/world.c
+++ b/src/world.c
@@ -77,6 +77,7 @@ serd_world_new(void)
 	SerdWorld* world = (SerdWorld*)calloc(1, sizeof(SerdWorld));
 
 	world->blank_node = serd_node_new_blank("b0000000000");
+	world->nodes      = serd_nodes_new();
 
 	return world;
 }
@@ -84,6 +85,7 @@ serd_world_new(void)
 void
 serd_world_free(SerdWorld* world)
 {
+	serd_nodes_free(world->nodes);
 	free(world);
 }
 
diff --git a/src/world.h b/src/world.h
index e3bd3784..a6722a0c 100644
--- a/src/world.h
+++ b/src/world.h
@@ -19,9 +19,12 @@
 
 #include "serd/serd.h"
 
+#include "nodes.h"
+
 #include <stdio.h>
 
 struct SerdWorldImpl {
+	SerdNodes*    nodes;
 	SerdErrorSink error_sink;
 	void*         error_handle;
 	uint32_t      next_blank_id;