WIP: Add model

20 files changed, 2796 insertions, 10 deletions

diff --git a/doc/serdi.1 b/doc/serdi.1
index 66d845c6..4b3c9c39 100644
--- a/doc/serdi.1
+++ b/doc/serdi.1
@@ -29,6 +29,13 @@ page of input has arrived.  With this option serdi uses one page less memory,
 but will likely be significantly slower.
 
 .TP
+\fB\-f\fR
+Fast serialisation without object inlining.  This affects only model
+(non-streaming) serialisation, and disables searching and statement reordering
+for pretty printing.  Statements will be written in simple sorted order, which
+is faster, but may result in less readable output in Turtle or TriG.
+
+.TP
 \fB\-h\fR
 Print the command line options.
 
diff --git a/serd/serd.h b/serd/serd.h
index 0f883af9..31ea1a22 100644
--- a/serd/serd.h
+++ b/serd/serd.h
@@ -67,6 +67,18 @@ typedef struct SerdCursorImpl SerdCursor;
 /// Lexical environment for relative URIs or CURIEs (base URI and namespaces)
 typedef struct SerdEnvImpl SerdEnv;
 
+/// An indexed set of statements
+typedef struct SerdModelImpl SerdModel;
+
+/// A statement sink that inserts into a model
+typedef struct SerdInserterImpl SerdInserter;
+
+/// Model Iterator
+typedef struct SerdIterImpl SerdIter;
+
+/// Model Range
+typedef struct SerdRangeImpl SerdRange;
+
 /// Streaming parser that reads a text stream and writes to a statement sink
 typedef struct SerdReaderImpl SerdReader;
 
@@ -86,6 +98,7 @@ typedef enum {
 	SERD_ERR_UNKNOWN,     ///< Unknown error
 	SERD_ERR_BAD_SYNTAX,  ///< Invalid syntax
 	SERD_ERR_BAD_ARG,     ///< Invalid argument
+	SERD_ERR_BAD_ITER,    ///< Use of invalidated iterator
 	SERD_ERR_NOT_FOUND,   ///< Not found
 	SERD_ERR_ID_CLASH,    ///< Encountered clashing blank node IDs
 	SERD_ERR_BAD_CURIE,   ///< Invalid CURIE (e.g. prefix does not exist)
@@ -113,6 +126,14 @@ typedef enum {
 /// Bitwise OR of SerdStatementFlag values
 typedef uint32_t SerdStatementFlags;
 
+/// Flags that control style for a model serialisation
+typedef enum {
+	SERD_NO_INLINE_OBJECTS = 1 << 0, /**< Do not inline objects where possible */
+} SerdSerialisationFlag;
+
+/// Bitwise OR of SerdStatementFlag values
+typedef uint32_t SerdSerialisationFlags;
+
 /**
    Type of a syntactic RDF node
 
@@ -184,6 +205,20 @@ typedef enum {
 	SERD_GRAPH     = 3   ///< Graph     ("context")
 } SerdField;
 
+/// Indexing option
+typedef enum {
+	SERD_INDEX_SPO    = 1,       ///< Subject,   Predicate, Object
+	SERD_INDEX_SOP    = 1 << 1,  ///< Subject,   Object,    Predicate
+	SERD_INDEX_OPS    = 1 << 2,  ///< Object,    Predicate, Subject
+	SERD_INDEX_OSP    = 1 << 3,  ///< Object,    Subject,   Predicate
+	SERD_INDEX_PSO    = 1 << 4,  ///< Predicate, Subject,   Object
+	SERD_INDEX_POS    = 1 << 5,  ///< Predicate, Object,    Subject
+	SERD_INDEX_GRAPHS = 1 << 6   ///< Support multiple graphs in model
+} SerdModelFlag;
+
+/// Bitwise OR of SerdModelFlag values
+typedef uint32_t SerdModelFlags;
+
 /// A syntactic RDF node
 typedef struct SerdNodeImpl SerdNode;
 
@@ -1185,6 +1220,224 @@ serd_nodes_deref(SerdNodes* nodes, const SerdNode* node);
 
 /**
    @}
+   @name Model
+   @{
+*/
+
+/**
+   Create a new model
+
+   @param world The world in which to make this model.
+
+   @param flags Model options, including enabled indices, for example `SERD_SPO |
+   SERD_OPS`.  Be sure to enable an index where the most significant node(s)
+   are not variables in your queries.  For example, to make (? P O) queries,
+   enable either SERD_OPS or SERD_POS.
+*/
+SERD_API
+SerdModel*
+serd_model_new(SerdWorld* world, SerdModelFlags flags);
+
+/// Return a deep copy of `model`
+SERD_API
+SerdModel*
+serd_model_copy(const SerdModel* model);
+
+/// Return true iff `a` is equal to `b`, ignoring statement cursor metadata
+SERD_API
+bool
+serd_model_equals(const SerdModel* a, const SerdModel* b);
+
+/// Close and free `model`
+SERD_API
+void
+serd_model_free(SerdModel* model);
+
+/// Get the world associated with `model`
+SERD_API
+SerdWorld*
+serd_model_get_world(SerdModel* model);
+
+/// Return the number of statements stored in `model`
+SERD_API
+size_t
+serd_model_size(const SerdModel* model);
+
+/// Return true iff there are no statements stored in `model`
+SERD_API
+bool
+serd_model_empty(const SerdModel* model);
+
+/// Return an iterator to the start of `model`
+SERD_API
+SerdIter*
+serd_model_begin(const SerdModel* model);
+
+/// Return an iterator to the end of `model`
+SERD_API
+const SerdIter*
+serd_model_end(const SerdModel* model);
+
+/// Return a range of all statements in `model`
+SERD_API
+SerdRange*
+serd_model_all(const SerdModel* model);
+
+/**
+   Search for statements by a quad pattern
+
+   @return An iterator to the first match, or NULL if no matches found.
+*/
+SERD_API
+SerdIter*
+serd_model_find(const SerdModel* model,
+                const SerdNode*  s,
+                const SerdNode*  p,
+                const SerdNode*  o,
+                const SerdNode*  g);
+
+/**
+   Search for statements by a quad pattern
+
+   @return A range containins all matching statements.
+*/
+SERD_API
+SerdRange*
+serd_model_range(const SerdModel* model,
+                 const SerdNode*  s,
+                 const SerdNode*  p,
+                 const SerdNode*  o,
+                 const SerdNode*  g);
+
+/**
+   Search for a single node that matches a pattern
+
+   Exactly one of `s`, `p`, `o` must be NULL.
+   This function is mainly useful for predicates that only have one value.
+   @return The first matching node, or NULL if no matches are found.
+*/
+SERD_API
+const SerdNode*
+serd_model_get(const SerdModel* model,
+               const SerdNode*  s,
+               const SerdNode*  p,
+               const SerdNode*  o,
+               const SerdNode*  g);
+
+/**
+   Search for a single statement that matches a pattern
+
+   This function is mainly useful for predicates that only have one value.
+
+   @return The first matching statement, or NULL if none are found.
+*/
+SERD_API
+const SerdStatement*
+serd_model_get_statement(const SerdModel* model,
+                         const SerdNode*  s,
+                         const SerdNode*  p,
+                         const SerdNode*  o,
+                         const SerdNode*  g);
+
+/// Return true iff a statement exists
+SERD_API
+bool
+serd_model_ask(const SerdModel* model,
+               const SerdNode*  s,
+               const SerdNode*  p,
+               const SerdNode*  o,
+               const SerdNode*  g);
+
+/// Return the number of matching statements
+SERD_API
+size_t
+serd_model_count(const SerdModel* model,
+                 const SerdNode*  s,
+                 const SerdNode*  p,
+                 const SerdNode*  o,
+                 const SerdNode*  g);
+
+/**
+   Add a statement to a model from nodes
+
+   This function fails if there are any active iterators on `model`.
+*/
+SERD_API
+SerdStatus
+serd_model_add(SerdModel*      model,
+               const SerdNode* s,
+               const SerdNode* p,
+               const SerdNode* o,
+               const SerdNode* g);
+
+/**
+   Add a statement to a model
+
+   This function fails if there are any active iterators on `model`.
+*/
+SERD_API
+SerdStatus
+serd_model_insert(SerdModel* model, const SerdStatement* statement);
+
+/**
+   Add a range of statements to a model
+
+   This function fails if there are any active iterators on `model`.
+*/
+SERD_API
+SerdStatus
+serd_model_add_range(SerdModel* model, SerdRange* range);
+
+/**
+   Remove a quad from a model via an iterator
+
+   Calling this function invalidates all iterators on `model` except `iter`.
+
+   @param model The model which `iter` points to.
+   @param iter Iterator to the element to erase, which is incremented to the
+   next value on return.
+*/
+SERD_API
+SerdStatus
+serd_model_erase(SerdModel* model, SerdIter* iter);
+
+/**
+   Remove a range from a model
+
+   Calling this function invalidates all iterators on `model` except `iter`.
+
+   @param model The model which `range` points to.
+   @param range Range to erase, which will be empty on return;
+*/
+SERD_API
+SerdStatus
+serd_model_erase_range(SerdModel* model, SerdRange* range);
+
+/**
+   @}
+   @name Inserter
+   @{
+*/
+
+/// Create an inserter for writing statements to a model
+SERD_API
+SerdInserter*
+serd_inserter_new(SerdModel*      model,
+                  SerdEnv*        env,
+                  const SerdNode* default_graph);
+
+/// Free an inserter
+SERD_API
+void
+serd_inserter_free(SerdInserter* inserter);
+
+/// Return a sink interface that adds statements via `inserter`
+SERD_API
+SerdSink*
+serd_inserter_get_sink(SerdInserter* inserter);
+
+/**
+   @}
    @name Statement
    @{
 */
@@ -1220,6 +1473,131 @@ const SerdCursor*
 serd_statement_get_cursor(const SerdStatement* statement);
 
 /**
+   Return true iff `a` is equal to `b`, ignoring statement cursor metadata
+
+   Only returns true if nodes are equivalent, does not perform wildcard matching.
+*/
+SERD_API
+bool
+serd_statement_equals(const SerdStatement* a, const SerdStatement* b);
+
+/**
+   Return true iff `statement` matches the given pattern
+
+   The matching rules are the same used for querying: nodes match if they are
+   equivalent, and NULL acts as a wildcard that matches any node.
+*/
+SERD_API
+bool
+serd_statement_matches(const SerdStatement* statement,
+                       const SerdNode*      subject,
+                       const SerdNode*      predicate,
+                       const SerdNode*      object,
+                       const SerdNode*      graph);
+
+/**
+   @}
+   @name Iterator
+   @{
+*/
+
+/// Return a new copy of `iter`
+SERD_API
+SerdIter*
+serd_iter_copy(const SerdIter* iter);
+
+/// Return the statement pointed to by `iter`
+SERD_API
+const SerdStatement*
+serd_iter_get(const SerdIter* iter);
+
+/**
+   Increment `iter` to point to the next statement
+
+   @return True iff `iter` has reached the end.
+*/
+SERD_API
+bool
+serd_iter_next(SerdIter* iter);
+
+/// Return true iff `lhs` is equal to `rhs`
+SERD_API
+bool
+serd_iter_equals(const SerdIter* lhs, const SerdIter* rhs);
+
+/// Free `iter`
+SERD_API
+void
+serd_iter_free(SerdIter* iter);
+
+/**
+   @}
+   @name Range
+   @{
+*/
+
+/// Return a new copy of `range`
+SERD_API
+SerdRange*
+serd_range_copy(const SerdRange* range);
+
+/// Free `range`
+SERD_API
+void
+serd_range_free(SerdRange* range);
+
+/// Return the first statement in `range`, or NULL if `range` is empty
+SERD_API
+const SerdStatement*
+serd_range_front(const SerdRange* range);
+
+/// Return true iff `lhs` is equal to `rhs`
+SERD_API
+bool
+serd_range_equals(const SerdRange* lhs, const SerdRange* rhs);
+
+/// Increment the start of `range` to point to the next statement
+SERD_API
+bool
+serd_range_next(SerdRange* range);
+
+/// Return the number of statements in `range`
+SERD_API
+size_t
+serd_range_size(const SerdRange* range);
+
+/// Return true iff there are no statements in `range`
+SERD_API
+bool
+serd_range_empty(const SerdRange* range);
+
+/// Return an iterator to the start of `range`
+SERD_API
+const SerdIter*
+serd_range_begin(const SerdRange* range);
+
+/// Return an iterator to the end of `range`
+SERD_API
+const SerdIter*
+serd_range_end(const SerdRange* range);
+
+/**
+   Write `range` to `sink`
+
+   The serialisation style can be controlled with `flags`.  The default is to
+   write statements in an order suited for pretty-printing with Turtle or TriG
+   with as many objects written inline as possible.  If
+   `SERD_NO_INLINE_OBJECTS` is given, a simple sorted stream is written
+   instead, which is significantly faster since no searching is required, but
+   can result in ugly output for Turtle or Trig.
+*/
+SERD_API
+SerdStatus
+serd_range_serialise(const SerdRange*       range,
+                     SerdSink*              sink,
+                     SerdSerialisationFlags flags);
+
+/**
    @}
    @name Cursor
    @{
diff --git a/src/inserter.c b/src/inserter.c
new file mode 100644
index 00000000..720ce0dd
--- /dev/null
+++ b/src/inserter.c
@@ -0,0 +1,115 @@
+/*
+  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 "sink.h"
+#include "statement.h"
+#include "world.h"
+
+#include "serd/serd.h"
+
+#include <stdlib.h>
+
+struct SerdInserterImpl {
+	SerdModel* model;
+	SerdNode*  default_graph;
+	SerdSink   iface;
+};
+
+static SerdStatus
+serd_inserter_on_base(SerdInserter* inserter, const SerdNode* uri)
+{
+	return serd_env_set_base_uri(inserter->iface.env, uri);
+}
+
+static SerdStatus
+serd_inserter_on_prefix(SerdInserter*   inserter,
+                        const SerdNode* name,
+                        const SerdNode* uri)
+{
+	return serd_env_set_prefix(inserter->iface.env, name, uri);
+}
+
+static const SerdNode*
+manage_or_intern(SerdNodes* nodes, SerdNode* manage, const SerdNode* intern)
+{
+	return manage ? serd_nodes_manage(nodes, manage)
+	              : serd_nodes_intern(nodes, intern);
+}
+
+static SerdStatus
+serd_inserter_on_statement(SerdInserter*            inserter,
+                           const SerdStatementFlags flags,
+                           const SerdStatement*     statement)
+{
+	(void)flags;
+
+	const SerdNode* const subject   = serd_statement_get_subject(statement);
+	const SerdNode* const predicate = serd_statement_get_predicate(statement);
+	const SerdNode* const object    = serd_statement_get_object(statement);
+	const SerdNode* const graph     = serd_statement_get_graph(statement);
+
+	// Attempt to expand all nodes to eliminate CURIEs
+	SerdNode* const s = serd_env_expand(inserter->iface.env, subject);
+	SerdNode* const p = serd_env_expand(inserter->iface.env, predicate);
+	SerdNode* const o = serd_env_expand(inserter->iface.env, object);
+	SerdNode* const g = serd_env_expand(inserter->iface.env, graph);
+
+	SerdNodes* const nodes       = inserter->model->world->nodes;
+	const SerdNode*  model_graph = manage_or_intern(nodes, g, graph);
+	if (!model_graph) {
+		model_graph = serd_nodes_intern(nodes, inserter->default_graph);
+	}
+
+	const SerdStatus st =
+		serd_model_add_internal(inserter->model,
+		                        statement->cursor,
+		                        manage_or_intern(nodes, s, subject),
+		                        manage_or_intern(nodes, p, predicate),
+		                        manage_or_intern(nodes, o, object),
+		                        model_graph);
+
+	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->default_graph   = serd_node_copy(default_graph);
+	inserter->iface.handle    = inserter;
+	inserter->iface.env       = env;
+	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);
+	}
+}
+
+SerdSink*
+serd_inserter_get_sink(SerdInserter* inserter)
+{
+	return &inserter->iface;
+}
diff --git a/src/iter.c b/src/iter.c
new file mode 100644
index 00000000..eaa6de2c
--- /dev/null
+++ b/src/iter.c
@@ -0,0 +1,239 @@
+/*
+  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>
+#include <string.h>
+
+static bool
+serd_iter_pattern_matches(const SerdIter* iter, const SerdQuad pat)
+{
+	const SerdStatement* key = (const SerdStatement*)zix_btree_get(iter->cur);
+	for (int i = 0; i < iter->n_prefix; ++i) {
+		const int idx = orderings[iter->order][i];
+		if (!serd_node_pattern_match(key->nodes[idx], pat[idx])) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+/**
+   Seek forward as necessary until `iter` points at a matching statement.
+
+   @return true iff iterator reached end of valid range.
+*/
+static bool
+serd_iter_seek_match(SerdIter* iter, const SerdQuad pat)
+{
+	for (; !zix_btree_iter_is_end(iter->cur);
+	     zix_btree_iter_increment(iter->cur)) {
+		const SerdStatement* s = (const SerdStatement*)zix_btree_get(iter->cur);
+		if (serd_statement_matches_quad(s, pat)) {
+			return false; // Found match
+		} else if (iter->mode == FILTER_RANGE &&
+		           !serd_iter_pattern_matches(iter, pat)) {
+			zix_btree_iter_free(iter->cur);
+			iter->cur = NULL;
+			return true; // Reached end of range
+		}
+	}
+
+	assert(zix_btree_iter_is_end(iter->cur));
+	return true; // Reached end of index
+}
+
+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*)calloc(1, sizeof(SerdIter));
+	iter->model    = model;
+	iter->cur      = cur;
+	iter->order    = order;
+	iter->mode     = mode;
+	iter->n_prefix = n_prefix;
+	iter->version  = model->version;
+
+	switch (iter->mode) {
+	case ALL:
+	case RANGE:
+		assert(zix_btree_iter_is_end(iter->cur) ||
+		       serd_statement_matches_quad(
+			       ((const SerdStatement*)zix_btree_get(iter->cur)), pat));
+		break;
+	case FILTER_RANGE:
+	case FILTER_ALL:
+		serd_iter_seek_match(iter, pat);
+		break;
+	}
+
+	// Replace (possibly temporary) nodes in pattern with nodes from the model
+	if (!zix_btree_iter_is_end(iter->cur)) {
+		const SerdStatement* s = (const SerdStatement*)zix_btree_get(iter->cur);
+		for (int i = 0; i < TUP_LEN; ++i) {
+			if (pat[i]) {
+				iter->pat[i] = s->nodes[i];
+			}
+		}
+	}
+
+#ifdef SERD_DEBUG_ITER
+	if (!zix_btree_iter_is_end(iter->cur)) {
+		const SerdStatement* statement = serd_iter_get(iter);
+		SERD_ITER_LOG("New %p pat=" TUP_FMT " realpat=" TUP_FMT
+		              " order=%d prefix=%d mode=%d cur=" TUP_FMT "\n",
+		              (void*)iter,
+		              TUP_FMT_ARGS(pat),
+		              TUP_FMT_ARGS(iter->pat),
+		              iter->order,
+		              iter->n_prefix,
+		              iter->mode,
+		              TUP_FMT_ARGS(statement->nodes));
+	} else {
+		SERD_ITER_LOG("New %p pat=" TUP_FMT " mode=%d at end\n",
+		              (void*)iter,
+		              TUP_FMT_ARGS(pat),
+		              iter->mode);
+	}
+#endif
+
+	return iter;
+}
+
+SerdIter*
+serd_iter_copy(const SerdIter* iter)
+{
+	if (!iter) {
+		return NULL;
+	}
+
+	SerdIter* copy = (SerdIter*)malloc(sizeof(SerdIter));
+	memcpy(copy, iter, sizeof(SerdIter));
+	copy->cur = zix_btree_iter_copy(iter->cur);
+	return copy;
+}
+
+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 (zix_btree_iter_is_end(iter->cur)) {
+		return true;
+	}
+
+	switch (iter->mode) {
+	case ALL:
+		// At the end if the cursor is (assigned above)
+		break;
+	case RANGE:
+		SERD_ITER_LOG("%p range next\n", (void*)iter);
+		// At the end if the MSNs no longer match
+		if (!serd_iter_pattern_matches(iter, iter->pat)) {
+			zix_btree_iter_free(iter->cur);
+			iter->cur = NULL;
+			SERD_ITER_LOG("%p reached non-match end\n", (void*)iter);
+		}
+		break;
+	case FILTER_RANGE:
+	case FILTER_ALL:
+		// Seek forward to next match
+		serd_iter_seek_match(iter, iter->pat);
+		break;
+	}
+
+	if (zix_btree_iter_is_end(iter->cur)) {
+		SERD_ITER_LOG("%p reached end\n", (void*)iter);
+		return true;
+	} else {
+#ifdef SERD_DEBUG_ITER
+		SERD_ITER_LOG("%p reached " TUP_FMT "\n",
+		              (void*)iter,
+		              TUP_FMT_ARGS(serd_iter_get(iter)->nodes));
+#endif
+		return false;
+	}
+}
+
+bool
+serd_iter_next(SerdIter* iter)
+{
+	if (zix_btree_iter_is_end(iter->cur) || !check_version(iter)) {
+		return true;
+	}
+
+	zix_btree_iter_increment(iter->cur);
+	return serd_iter_scan_next(iter);
+}
+
+bool
+serd_iter_equals(const SerdIter* lhs, const SerdIter* rhs)
+{
+	if (!lhs && !rhs) {
+		return true;
+	}
+
+	return (lhs && rhs && lhs->model == rhs->model &&
+	        zix_btree_iter_equals(lhs->cur, rhs->cur) &&
+	        serd_node_pattern_match(lhs->pat[0], rhs->pat[0]) &&
+	        serd_node_pattern_match(lhs->pat[1], rhs->pat[1]) &&
+	        serd_node_pattern_match(lhs->pat[2], rhs->pat[2]) &&
+	        serd_node_pattern_match(lhs->pat[3], rhs->pat[3]) &&
+	        lhs->order == rhs->order && lhs->mode == rhs->mode &&
+	        lhs->n_prefix == rhs->n_prefix);
+}
+
+void
+serd_iter_free(SerdIter* 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..ac3e4b16
--- /dev/null
+++ b/src/iter.h
@@ -0,0 +1,88 @@
+/*
+  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
+	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
diff --git a/src/log.h b/src/log.h
new file mode 100644
index 00000000..c60cb326
--- /dev/null
+++ b/src/log.h
@@ -0,0 +1,60 @@
+/*
+  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 STATEMENT_FMT_ARGS(s) \
+	TUP_FMT_ELEM(serd_statement_get_subject(s)), \
+	TUP_FMT_ELEM(serd_statement_get_predicate(s)), \
+	TUP_FMT_ELEM(serd_statement_get_object(s)), \
+	TUP_FMT_ELEM(serd_statement_get_graph(s))
+
+#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..2e0b824e
--- /dev/null
+++ b/src/model.c
@@ -0,0 +1,649 @@
+/*
+  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 "cursor.h"
+#include "iter.h"
+#include "log.h"
+#include "node.h"
+#include "range.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, const void* y, void* user_data)
+{
+	const int* const           ordering = (const int*)user_data;
+	const SerdStatement* const s        = (const SerdStatement*)x;
+	const SerdStatement* const t        = (const SerdStatement*)y;
+
+	for (int i = 0; i < TUP_LEN; ++i) {
+		const int o = ordering[i];
+		if (o != SERD_GRAPH) {
+			const int cmp =
+				serd_node_wildcard_compare(s->nodes[o], t->nodes[o]);
+			if (cmp) {
+				return cmp;
+			}
+		}
+	}
+
+	return 0;
+}
+
+/**
+   Compare quads lexicographically, with exact (non-wildcard) graph matching.
+*/
+static int
+serd_quad_compare(const void* x, const void* y, void* user_data)
+{
+	const SerdStatement* const s = (const SerdStatement*)x;
+	const SerdStatement* const t = (const SerdStatement*)y;
+
+	// Compare graph without wildcard matching
+	const int cmp = serd_node_compare(
+		s->nodes[SERD_GRAPH], t->nodes[SERD_GRAPH]);
+
+	return cmp ? cmp : serd_triple_compare(x, y, user_data);
+}
+
+/**
+   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(const 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 SerdOrder
+serd_model_best_index(const 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     = RANGE;
+		*n_prefix = graph_search ? 4 : 3;
+		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, SerdModelFlags flags)
+{
+	SerdModel* model = (SerdModel*)calloc(1, sizeof(struct SerdModelImpl));
+
+	flags |= SERD_INDEX_SPO; // SPO index is mandatory
+
+	model->world = world;
+	model->flags = flags;
+
+	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 (flags & (1 << i)) {
+			model->indices[i] =
+				zix_btree_new((ZixComparator)serd_triple_compare,
+				              (const void*)ordering,
+				              NULL);
+			if (flags & SERD_INDEX_GRAPHS) {
+				model->indices[i + (NUM_ORDERS / 2)] =
+					zix_btree_new((ZixComparator)serd_quad_compare,
+					              (const void*)g_ordering,
+					              NULL);
+			}
+		}
+	}
+
+	// Create end iterator
+	const SerdOrder order = model->indices[GSPO] ? GSPO : SPO;
+	ZixBTreeIter*   cur   = zix_btree_end(model->indices[order]);
+	const SerdQuad  pat   = { 0, 0, 0, 0 };
+
+	model->end = serd_iter_new(model, cur, pat, order, ALL, 0);
+
+	return model;
+}
+
+SerdModel*
+serd_model_copy(const SerdModel* model)
+{
+	SerdModel* copy = serd_model_new(model->world, model->flags);
+
+	SerdRange* all = serd_model_all(model);
+	serd_model_add_range(copy, all);
+	serd_range_free(all);
+
+	assert(serd_model_size(model) == serd_model_size(copy));
+	return copy;
+}
+
+SERD_API
+bool
+serd_model_equals(const SerdModel* a, const SerdModel* b)
+{
+	if (!a && !b) {
+		return true;
+	} else if (!a || !b || serd_model_size(a) != serd_model_size(b)) {
+		return false;
+	}
+
+	SerdRange* ra = serd_model_all(a);
+	SerdRange* rb = serd_model_all(b);
+
+	bool result = true;
+	while (!serd_range_empty(ra) && !serd_range_empty(rb)) {
+		if (!serd_statement_equals(serd_range_front(ra),
+		                           serd_range_front(rb))) {
+			result = false;
+			break;
+		}
+
+		serd_range_next(ra);
+		serd_range_next(rb);
+	}
+
+	result = result && serd_range_empty(ra) && serd_range_empty(rb);
+
+	serd_range_free(ra);
+	serd_range_free(rb);
+	return result;
+}
+
+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]);
+		}
+	}
+
+	if (statement->cursor && statement->cursor->file) {
+		serd_nodes_deref(model->world->nodes, statement->cursor->file);
+	}
+
+	free(statement->cursor);
+	free(statement);
+}
+
+void
+serd_model_free(SerdModel* model)
+{
+	if (!model) {
+		return;
+	}
+
+	serd_iter_free(model->end);
+
+	ZixBTree* index = model->indices[model->indices[DEFAULT_GRAPH_ORDER]
+	                                 ? DEFAULT_GRAPH_ORDER
+	                                 : DEFAULT_ORDER];
+
+	// Free statements
+	ZixBTreeIter* t = zix_btree_begin(index);
+	for (; !zix_btree_iter_is_end(t); zix_btree_iter_increment(t)) {
+		SerdStatement* s = (SerdStatement*)zix_btree_get(t);
+		free(s->cursor);
+		free(s);
+	}
+	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_size(const SerdModel* model)
+{
+	const SerdOrder order = model->indices[GSPO] ? GSPO : SPO;
+	return zix_btree_size(model->indices[order]);
+}
+
+bool
+serd_model_empty(const SerdModel* model)
+{
+	return serd_model_size(model) == 0;
+}
+
+SerdIter*
+serd_model_begin(const SerdModel* model)
+{
+	if (serd_model_size(model) == 0) {
+		return serd_iter_copy(serd_model_end(model));
+	} else {
+		const SerdOrder order = model->indices[GSPO] ? GSPO : SPO;
+		ZixBTreeIter*   cur   = zix_btree_begin(model->indices[order]);
+		const SerdQuad  pat   = { 0, 0, 0, 0 };
+		return serd_iter_new(model, cur, pat, order, ALL, 0);
+	}
+}
+
+const SerdIter*
+serd_model_end(const SerdModel* model)
+{
+	return model->end;
+}
+
+SerdRange*
+serd_model_all(const SerdModel* model)
+{
+	return serd_range_new(serd_model_begin(model),
+	                      serd_iter_copy(serd_model_end(model)));
+}
+
+SerdIter*
+serd_model_find(const 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);
+
+	ZixBTree* const db  = model->indices[index_order];
+	ZixBTreeIter*   cur = NULL;
+
+	if (mode == FILTER_ALL) {
+		// No prefix shared with an index at all, linear search (worst case)
+		SERD_FIND_LOG("warning: Linear model search\n");
+		cur = zix_btree_begin(db);
+	} else if (mode == FILTER_RANGE) {
+		/* Some prefix, but filtering still required.  Build a search pattern
+		   with only the prefix to find the lower bound in log time. */
+		SERD_FIND_LOG("warning: Linear range search\n");
+		SerdQuad         prefix_pat = { NULL, NULL, NULL, NULL };
+		const int* const ordering   = orderings[index_order];
+		for (int i = 0; i < n_prefix; ++i) {
+			prefix_pat[ordering[i]] = pat[ordering[i]];
+		}
+		zix_btree_lower_bound(db, prefix_pat, &cur);
+	} else {
+		// Ideal case, pattern matches an index with no filtering required
+		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 && !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);
+}
+
+SerdRange*
+serd_model_range(const SerdModel* model,
+                 const SerdNode*  s,
+                 const SerdNode*  p,
+                 const SerdNode*  o,
+                 const SerdNode*  g)
+{
+	if (!s && !p && !o && !g) {
+		return serd_range_new(serd_model_begin(model),
+		                      serd_iter_copy(serd_model_end(model)));
+	}
+
+	SerdIter* begin = serd_model_find(model, s, p, o, g);
+	SerdIter* end   = begin ? serd_iter_new(model,
+	                                        NULL,
+	                                        begin->pat,
+	                                        begin->order,
+	                                        begin->mode,
+	                                        begin->n_prefix)
+		: NULL;
+	return serd_range_new(begin, end);
+}
+
+const SerdNode*
+serd_model_get(const SerdModel* model,
+               const SerdNode*  s,
+               const SerdNode*  p,
+               const SerdNode*  o,
+               const SerdNode*  g)
+{
+	const SerdStatement* statement =
+		serd_model_get_statement(model, s, p, o, g);
+
+	if (statement) {
+		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;
+}
+
+const SerdStatement*
+serd_model_get_statement(const 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 && i->cur) {
+		const SerdStatement* statement = serd_iter_get(i);
+		serd_iter_free(i);
+		return statement;
+	}
+
+	return NULL;
+}
+
+size_t
+serd_model_count(const SerdModel* model,
+                 const SerdNode*  s,
+                 const SerdNode*  p,
+                 const SerdNode*  o,
+                 const SerdNode*  g)
+{
+	SerdRange* const range = serd_model_range(model, s, p, o, g);
+	const size_t     count = serd_range_size(range);
+	serd_range_free(range);
+	return count;
+}
+
+bool
+serd_model_ask(const 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;
+}
+
+static SerdCursor*
+serd_model_intern_cursor(SerdModel* model, const SerdCursor* cursor)
+{
+	if (cursor) {
+		SerdCursor* copy = (SerdCursor*)calloc(1, sizeof(SerdCursor));
+
+		copy->file = serd_nodes_intern(model->world->nodes, cursor->file);
+		copy->line = cursor->line;
+		copy->col  = cursor->col;
+		return copy;
+	}
+
+	return NULL;
+}
+
+SerdStatus
+serd_model_add_internal(SerdModel*        model,
+                        const SerdCursor* cursor,
+                        const SerdNode*   s,
+                        const SerdNode*   p,
+                        const SerdNode*   o,
+                        const SerdNode*   g)
+{
+	SerdStatement* statement = (SerdStatement*)calloc(1, sizeof(SerdStatement));
+
+	statement->nodes[0] = s;
+	statement->nodes[1] = p;
+	statement->nodes[2] = o;
+	statement->nodes[3] = g;
+	statement->cursor   = serd_model_intern_cursor(model, cursor);
+
+	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; // Statement already indexed
+			}
+		}
+	}
+
+	++model->version;
+	if (added) {
+		return SERD_SUCCESS;
+	}
+
+	serd_model_drop_statement(model, statement);
+	return SERD_FAILURE;
+}
+
+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");
+	}
+
+	return serd_model_add_internal(model,
+	                               NULL,
+	                               serd_nodes_intern(model->world->nodes, s),
+	                               serd_nodes_intern(model->world->nodes, p),
+	                               serd_nodes_intern(model->world->nodes, o),
+	                               serd_nodes_intern(model->world->nodes, g));
+}
+
+SerdStatus
+serd_model_insert(SerdModel* model, const SerdStatement* statement)
+{
+	return serd_model_add_internal(model,
+	                               serd_statement_get_cursor(statement),
+	                               serd_statement_get_subject(statement),
+	                               serd_statement_get_predicate(statement),
+	                               serd_statement_get_object(statement),
+	                               serd_statement_get_graph(statement));
+}
+
+SerdStatus
+serd_model_add_range(SerdModel* model, SerdRange* range)
+{
+	SerdStatus st = SERD_SUCCESS;
+	for (; !st && !serd_range_empty(range); serd_range_next(range)) {
+		st = serd_model_insert(model, serd_range_front(range));
+	}
+
+	return st;
+}
+
+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);
+		}
+	}
+	serd_iter_scan_next(iter);
+
+	serd_model_drop_statement(model, removed);
+	iter->version = ++model->version;
+
+	return SERD_SUCCESS;
+}
+
+SerdStatus
+serd_model_erase_range(SerdModel* model, SerdRange* range)
+{
+	while (!serd_range_empty(range)) {
+		serd_model_erase(model, range->begin);
+	}
+
+	return SERD_SUCCESS;
+}
diff --git a/src/model.h b/src/model.h
new file mode 100644
index 00000000..b4fdbfa3
--- /dev/null
+++ b/src/model.h
@@ -0,0 +1,43 @@
+/*
+  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>
+
+struct SerdModelImpl
+{
+	SerdWorld*     world;       ///< World this model is a part of
+	SerdModelFlags flags;       ///< Active indices and features
+	ZixBTree*      indices[12]; ///< Trees of SordQuad
+	SerdIter*      end;         ///< End iterator (always the same)
+	uint64_t       version;     ///< Version incremented on every change
+};
+
+SerdStatus
+serd_model_add_internal(SerdModel*        model,
+                        const SerdCursor* cursor,
+                        const SerdNode*   s,
+                        const SerdNode*   p,
+                        const SerdNode*   o,
+                        const SerdNode*   g);
+
+#endif // SERD_MODEL_H
diff --git a/src/node.c b/src/node.c
index 65bc6fb6..48511ca4 100644
--- a/src/node.c
+++ b/src/node.c
@@ -331,6 +331,13 @@ serd_node_compare(const SerdNode* a, const SerdNode* b)
 	                         serd_node_maybe_get_meta_c(b));
 }
 
+/** Compare nodes, considering NULL a wildcard match. */
+int
+serd_node_wildcard_compare(const SerdNode* a, const SerdNode* b)
+{
+	return (!a || !b) ? 0 : serd_node_compare(a, b);
+}
+
 static size_t
 serd_uri_string_length(const SerdURI* uri)
 {
diff --git a/src/node.h b/src/node.h
index 53936ca3..afe3d93f 100644
--- a/src/node.h
+++ b/src/node.h
@@ -46,5 +46,6 @@ void      serd_node_set(SerdNode** dst, const SerdNode* src);
 size_t    serd_node_total_size(const SerdNode* node);
 void      serd_node_zero_pad(SerdNode* node);
 SerdNode* serd_new_resolved_uri_i(const char* str, const SerdURI* base);
+int       serd_node_wildcard_compare(const SerdNode* a, const SerdNode* b);
 
 #endif  // SERD_NODE_H
diff --git a/src/range.c b/src/range.c
new file mode 100644
index 00000000..973c6a81
--- /dev/null
+++ b/src/range.c
@@ -0,0 +1,250 @@
+/*
+  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 "range.h"
+
+#include "iter.h"
+#include "log.h"
+#include "model.h"
+#include "sink.h"
+#include "world.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+typedef enum { NAMED, ANON_S, ANON_O, LIST_S, LIST_O } NodeStyle;
+
+static SerdStatus
+write_range_statement(SerdSink*            sink,
+                      const SerdModel*     model,
+                      unsigned             depth,
+                      SerdStatementFlags   flags,
+                      const SerdStatement* statement);
+
+SerdRange*
+serd_range_new(SerdIter* const begin, SerdIter* const end)
+{
+	SerdRange* range = (SerdRange*)malloc(sizeof(SerdRange));
+
+	range->begin = begin;
+	range->end   = end;
+
+	return range;
+}
+
+SerdRange*
+serd_range_copy(const SerdRange* range)
+{
+	SerdRange* copy = (SerdRange*)malloc(sizeof(SerdRange));
+
+	memcpy(copy, range, sizeof(SerdRange));
+	copy->begin = serd_iter_copy(range->begin);
+	copy->end   = serd_iter_copy(range->end);
+
+	return copy;
+}
+
+void
+serd_range_free(SerdRange* range)
+{
+	serd_iter_free(range->begin);
+	serd_iter_free(range->end);
+	free(range);
+}
+
+const SerdStatement*
+serd_range_front(const SerdRange* range)
+{
+	return serd_iter_get(range->begin);
+}
+
+bool
+serd_range_equals(const SerdRange* lhs, const SerdRange* rhs)
+{
+	return (!lhs && !rhs) ||
+	       (lhs && rhs && serd_iter_equals(lhs->begin, rhs->begin) &&
+	        serd_iter_equals(lhs->end, rhs->end));
+}
+
+bool
+serd_range_next(SerdRange* range)
+{
+	return serd_iter_next(range->begin);
+}
+
+size_t
+serd_range_size(const SerdRange* range)
+{
+	SerdRange* r = serd_range_copy(range);
+	uint64_t   n = 0;
+	for (; !serd_range_empty(r); serd_range_next(r)) {
+		++n;
+	}
+	serd_range_free(r);
+	return n;
+}
+
+bool
+serd_range_empty(const SerdRange* range)
+{
+	return !range || serd_iter_equals(range->begin, range->end);
+}
+
+const SerdIter*
+serd_range_begin(const SerdRange* range)
+{
+	return range->begin;
+}
+
+const SerdIter*
+serd_range_end(const SerdRange* range)
+{
+	return range->end;
+}
+
+static NodeStyle
+get_node_style(const SerdModel* model, const SerdNode* object)
+{
+	const size_t num_as_object =
+	        serd_model_count(model, NULL, NULL, object, NULL);
+	if (serd_node_get_type(object) != SERD_BLANK || num_as_object > 1) {
+		return NAMED; // Non-blank and/or blank referred to several times
+	}
+
+	if (serd_model_ask(model, object, model->world->rdf_first, NULL, NULL) &&
+	    serd_model_ask(model, object, model->world->rdf_rest, NULL, NULL)) {
+		return num_as_object == 0 ? LIST_S : LIST_O;
+	}
+
+	return num_as_object == 0 ? ANON_S : ANON_O;
+}
+
+static SerdStatus
+write_range_internal(SerdSink*                sink,
+                     const unsigned           depth,
+                     const SerdStatementFlags flags,
+                     SerdRange*               range)
+{
+	(void)flags;
+
+	SerdStatus       st    = SERD_SUCCESS;
+	const SerdModel* model = range && range->begin ? range->begin->model : NULL;
+	for (; !st && !serd_range_empty(range); serd_range_next(range)) {
+		st = write_range_statement(
+		        sink, model, depth, 0, serd_range_front(range));
+	}
+
+	return st;
+}
+
+static SerdStatus
+write_list(SerdSink*        sink,
+           const SerdModel* model,
+           const unsigned   depth,
+           const SerdNode*  object)
+{
+	SerdStatus       st    = SERD_SUCCESS;
+	const SerdWorld* world = model->world;
+	const SerdNode*  first = world->rdf_first;
+	const SerdNode*  rest  = world->rdf_rest;
+	const SerdNode*  nil   = world->rdf_nil;
+
+	SerdIter* f = serd_model_find(model, object, first, NULL, NULL);
+	while (!st && f && !serd_node_equals(object, nil)) {
+		const SerdStatement* fs = serd_iter_get(f);
+		st = write_range_statement(sink, model, depth + 1, 0, fs);
+		serd_iter_free(f);
+
+		SerdIter* const r = serd_model_find(model, object, rest, NULL, NULL);
+		const SerdNode* next =
+		        r ? serd_statement_get_object(serd_iter_get(r)) : NULL;
+
+		f = next ? serd_model_find(model, next, first, NULL, NULL) : NULL;
+		if (r && f) {
+			// This and next node are good, write rdf:next statement
+			st     = serd_sink_write_statement(sink, 0, serd_iter_get(r));
+			object = next;
+		} else {
+			// Terminate malformed list
+			st = serd_sink_write(
+			        sink, 0, object, rest, nil, serd_statement_get_graph(fs));
+			f = NULL;
+		}
+
+		serd_iter_free(r);
+	}
+
+	return st;
+}
+
+static SerdStatus
+write_range_statement(SerdSink*            sink,
+                      const SerdModel*     model,
+                      const unsigned       depth,
+                      SerdStatementFlags   flags,
+                      const SerdStatement* statement)
+{
+	const SerdNode* subject       = serd_statement_get_subject(statement);
+	const NodeStyle subject_style = get_node_style(model, subject);
+
+	if (depth == 0 && (subject_style == ANON_O || subject_style == LIST_O)) {
+		return SERD_SUCCESS; // Skip subject that will be inlined somewhere
+	} else if (subject_style == ANON_S) {
+		flags |= SERD_EMPTY_S; // Write anonymous subjects in "[] p o" style
+	}
+
+	const SerdNode* object       = serd_statement_get_object(statement);
+	const NodeStyle object_style = get_node_style(model, object);
+	SerdStatus      st           = SERD_SUCCESS;
+	if (object_style == ANON_O) {
+		flags |= SERD_ANON_O;
+
+		SerdRange* subrange = serd_model_range(model, object, NULL, NULL, NULL);
+		st = st ? st : serd_sink_write_statement(sink, flags, statement);
+		st = st ? st : write_range_internal(sink, depth + 1, 0, subrange);
+		st = st ? st : serd_sink_end(sink, object);
+		serd_range_free(subrange);
+
+		return st;
+	} else if (object_style == LIST_O) {
+		flags |= SERD_LIST_O;
+		st = st ? st : serd_sink_write_statement(sink, flags, statement);
+		st = st ? st : write_list(sink, model, depth + 1, object);
+		return st;
+	}
+
+	return serd_sink_write_statement(sink, flags, statement);
+}
+
+SerdStatus
+serd_range_serialise(const SerdRange*             range,
+                     SerdSink*                    sink,
+                     const SerdSerialisationFlags flags)
+{
+	SerdStatus       st   = SERD_SUCCESS;
+	SerdRange* const copy = serd_range_copy(range);
+
+	if (flags & SERD_NO_INLINE_OBJECTS) {
+		for (; !st && !serd_range_empty(copy); serd_range_next(copy)) {
+			st = sink->statement(sink->handle, 0, serd_range_front(copy));
+		}
+	} else {
+		st = write_range_internal(sink, 0, 0, copy);
+	}
+
+	serd_range_free(copy);
+	return st;
+}
diff --git a/src/range.h b/src/range.h
new file mode 100644
index 00000000..d07741ef
--- /dev/null
+++ b/src/range.h
@@ -0,0 +1,36 @@
+/*
+  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_RANGE_H
+#define SERD_RANGE_H
+
+#include "iter.h"
+#include "statement.h"
+
+#include "serd/serd.h"
+
+struct SerdRangeImpl {
+	SerdIter* begin; ///< Iterator to first statement in range
+	SerdIter* end;   ///< Iterator to end of range
+};
+
+SerdRange*
+serd_range_new(SerdIter* begin, SerdIter* end);
+
+bool
+serd_range_scan_next(SerdRange* range);
+
+#endif // SERD_RANGE_H
diff --git a/src/serdi.c b/src/serdi.c
index 0b33ae77..46c5f47a 100644
--- a/src/serdi.c
+++ b/src/serdi.c
@@ -51,10 +51,12 @@ print_usage(const char* name, bool error)
 	fprintf(os, "  -b           Fast bulk output for large serialisations.\n");
 	fprintf(os, "  -c PREFIX    Chop PREFIX from matching blank node IDs.\n");
 	fprintf(os, "  -e           Eat input one character at a time.\n");
+	fprintf(os, "  -f           Fast serialisation without object inlining\n");
 	fprintf(os, "  -h           Display this help and exit.\n");
 	fprintf(os, "  -i SYNTAX    Input syntax: turtle/ntriples/trig/nquads.\n");
 	fprintf(os, "  -k BYTES     Parser stack size.\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");
@@ -93,7 +95,9 @@ main(int argc, char** argv)
 	bool           ascii         = false;
 	bool           bulk_read     = true;
 	bool           bulk_write    = false;
+	bool           no_inline     = false;
 	bool           lax           = false;
+	bool           use_model     = false;
 	bool           quiet         = false;
 	size_t         stack_size    = 4194304;
 	const char*    add_prefix    = NULL;
@@ -110,10 +114,14 @@ main(int argc, char** argv)
 			bulk_write = true;
 		} else if (argv[a][1] == 'e') {
 			bulk_read = false;
+		} else if (argv[a][1] == 'f') {
+			no_inline = true;
 		} else if (argv[a][1] == 'h') {
 			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') {
@@ -195,6 +203,9 @@ main(int argc, char** argv)
 
 	const SerdWriterFlags writer_flags = (ascii ? SERD_STYLE_ASCII : 0);
 
+	const SerdSerialisationFlags serialisation_flags =
+		no_inline ? SERD_NO_INLINE_OBJECTS : 0;
+
 	SerdByteSink* byte_sink = serd_byte_sink_new(
 		(SerdWriteFunc)fwrite, out_fd, bulk_write ? 4096 : 1);
 
@@ -205,9 +216,22 @@ main(int argc, char** argv)
 	                                     (SerdWriteFunc)serd_byte_sink_write,
 	                                     byte_sink);
 
-	SerdReader* reader = serd_reader_new(
-		world, input_syntax, serd_writer_get_sink(writer), stack_size);
+	SerdReader*     reader   = NULL;
+	SerdModel*      model    = NULL;
+	SerdInserter*   inserter = NULL;
+	const SerdSink* sink     = NULL;
+	if (use_model) {
+		const SerdModelFlags flags =
+		        SERD_INDEX_SPO | (input_has_graphs ? SERD_INDEX_GRAPHS : 0) |
+		        (no_inline ? 0 : SERD_INDEX_OPS);
+		model    = serd_model_new(world, flags);
+		inserter = serd_inserter_new(model, env, NULL);
+		sink     = serd_inserter_get_sink(inserter);
+	} else {
+		sink = serd_writer_get_sink(writer);
+	}
 
+	reader = serd_reader_new(world, input_syntax, sink, stack_size);
 	serd_reader_set_strict(reader, !lax);
 	if (quiet) {
 		serd_world_set_message_sink(world, quiet_error_sink, NULL);
@@ -243,6 +267,19 @@ main(int argc, char** argv)
 	}
 
 	serd_reader_finish(reader);
+
+	if (status <= SERD_FAILURE && use_model) {
+		SerdSink* wsink = serd_writer_get_sink(writer);
+		serd_env_send_prefixes(env, wsink);
+
+		SerdRange* range = serd_model_all(model);
+		status = serd_range_serialise(range, wsink, serialisation_flags);
+		serd_range_free(range);
+	}
+
+	serd_node_free(input_name);
+	serd_inserter_free(inserter);
+	serd_model_free(model);
 	serd_reader_free(reader);
 	serd_writer_free(writer);
 	serd_byte_sink_free(byte_sink);
diff --git a/src/statement.c b/src/statement.c
index 24440a38..347cfe78 100644
--- a/src/statement.c
+++ b/src/statement.c
@@ -51,3 +51,35 @@ serd_statement_get_cursor(const SerdStatement* statement)
 {
 	return statement->cursor;
 }
+
+bool
+serd_statement_equals(const SerdStatement* a, const SerdStatement* b)
+{
+	return (serd_node_equals(a->nodes[0], b->nodes[0]) &&
+	        serd_node_equals(a->nodes[1], b->nodes[1]) &&
+	        serd_node_equals(a->nodes[2], b->nodes[2]) &&
+	        serd_node_equals(a->nodes[3], b->nodes[3]));
+}
+
+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
index 7c8384e9..4a1056f2 100644
--- a/src/statement.h
+++ b/src/statement.h
@@ -19,6 +19,8 @@
 
 #include "serd/serd.h"
 
+#include <stdbool.h>
+
 /**
    Quad of nodes (a statement), or a quad pattern.
 
@@ -31,4 +33,14 @@ struct SerdStatementImpl {
 	SerdCursor* cursor;
 };
 
+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 d6f98388..10cd537a 100644
--- a/src/string.c
+++ b/src/string.c
@@ -39,6 +39,7 @@ 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/zix/btree.c b/src/zix/btree.c
index 7521086d..a55c4699 100644
--- a/src/zix/btree.c
+++ b/src/zix/btree.c
@@ -55,6 +55,7 @@ typedef struct {
 } ZixBTreeIterFrame;
 
 struct ZixBTreeIterImpl {
+	unsigned          n_levels; ///< Maximum depth of stack
 	unsigned          level;    ///< Current level in stack
 	ZixBTreeIterFrame stack[];  ///< Position stack
 };
@@ -350,7 +351,9 @@ zix_btree_iter_new(const ZixBTree* const t)
 {
 	const size_t s = t->height * sizeof(ZixBTreeIterFrame);
 
-	return (ZixBTreeIter*)calloc(1, sizeof(ZixBTreeIter) + s);
+	ZixBTreeIter* i = (ZixBTreeIter*)calloc(1, sizeof(ZixBTreeIter) + s);
+	i->n_levels = t->height;
+	return i;
 }
 
 ZIX_PRIVATE void
@@ -712,12 +715,47 @@ zix_btree_begin(const ZixBTree* const t)
 	return i;
 }
 
+ZIX_API ZixBTreeIter*
+zix_btree_end(const ZixBTree* const t)
+{
+	return zix_btree_iter_new(t);
+}
+
+ZIX_API ZixBTreeIter*
+zix_btree_iter_copy(const ZixBTreeIter* const i)
+{
+	if (!i) {
+		return NULL;
+	}
+
+	const size_t s = i->n_levels * sizeof(ZixBTreeIterFrame);
+
+	ZixBTreeIter* j = (ZixBTreeIter*)malloc(sizeof(ZixBTreeIter) + s);
+	memcpy(j, i, sizeof(ZixBTreeIter) + s);
+	return j;
+}
+
 ZIX_API bool
 zix_btree_iter_is_end(const ZixBTreeIter* const i)
 {
 	return !i || i->stack[0].node == NULL;
 }
 
+ZIX_API bool
+zix_btree_iter_equals(const ZixBTreeIter* const lhs, const ZixBTreeIter* const rhs)
+{
+	if (zix_btree_iter_is_end(lhs) && zix_btree_iter_is_end(rhs)) {
+		return true;
+	} else if (!lhs || !rhs || lhs->n_levels != rhs->n_levels) {
+		return false;
+	}
+
+	return !memcmp(lhs,
+	               rhs,
+	               sizeof(ZixBTreeIter) +
+	                       lhs->n_levels * sizeof(ZixBTreeIterFrame));
+}
+
 ZIX_API void
 zix_btree_iter_increment(ZixBTreeIter* const i)
 {
diff --git a/src/zix/btree.h b/src/zix/btree.h
index 46daa24a..0f71d1e3 100644
--- a/src/zix/btree.h
+++ b/src/zix/btree.h
@@ -126,6 +126,27 @@ ZIX_API ZixBTreeIter*
 zix_btree_begin(const ZixBTree* t);
 
 /**
+   Return an iterator to the end of `t` (one past the last element).
+
+   The returned iterator must be freed with zix_btree_iter_free().
+*/
+ZIX_API ZixBTreeIter*
+zix_btree_end(const ZixBTree* t);
+
+/**
+   Return a new copy of `i`.
+*/
+ZIX_API ZixBTreeIter*
+zix_btree_iter_copy(const ZixBTreeIter* const i);
+
+/**
+   Return true iff `lhs` is equal to `rhs`.
+*/
+ZIX_API bool
+zix_btree_iter_equals(const ZixBTreeIter* const lhs,
+                      const ZixBTreeIter* const rhs);
+
+/**
    Return true iff `i` is an iterator to the end of its tree.
 */
 ZIX_API bool
diff --git a/tests/model_test.c b/tests/model_test.c
new file mode 100644
index 00000000..273fedbb
--- /dev/null
+++ b/tests/model_test.c
@@ -0,0 +1,742 @@
+/*
+  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.
+*/
+
+#undef NDEBUG
+
+#include <assert.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "serd/serd.h"
+
+#define WILDCARD_NODE NULL
+
+#define NS_RDF    "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+#define RDF_FIRST NS_RDF "first"
+#define RDF_REST  NS_RDF "rest"
+
+#define N_OBJECTS_PER 2U
+
+typedef const SerdNode* Quad[4];
+
+typedef struct
+{
+	Quad query;
+	int  expected_num_results;
+} QueryTest;
+
+static const SerdNode*
+manage(SerdWorld* world, SerdNode* node)
+{
+	return serd_nodes_manage(serd_world_get_nodes(world), node);
+}
+
+static const SerdNode*
+uri(SerdWorld* world, const size_t num)
+{
+	char str[] = "eg:000";
+	snprintf(str + 3, 4, "%03zu", num);
+	return manage(world, serd_new_uri(str));
+}
+
+static int
+generate(SerdWorld*      world,
+         SerdModel*      model,
+         size_t          n_quads,
+         const SerdNode* graph)
+{
+	SerdNodes* nodes = serd_world_get_nodes(world);
+
+	for (size_t i = 0; i < n_quads; ++i) {
+		size_t num = (i * N_OBJECTS_PER) + 1U;
+
+		const SerdNode* ids[2 + N_OBJECTS_PER];
+		for (size_t j = 0; j < 2 + N_OBJECTS_PER; ++j) {
+			ids[j] = uri(world, num++);
+		}
+
+		for (size_t j = 0; j < N_OBJECTS_PER; ++j) {
+			assert(!serd_model_add(model, ids[0], ids[1], ids[2 + j], graph));
+		}
+	}
+
+	// Add some literals
+
+	// (98 4 "hello") and (98 4 "hello"^^<5>)
+	const SerdNode* hello = manage(world, serd_new_string("hello"));
+	const SerdNode* hello_gb =
+	        manage(world, serd_new_plain_literal("hello", "en-gb"));
+	const SerdNode* hello_us =
+	        manage(world, serd_new_plain_literal("hello", "en-us"));
+	const SerdNode* hello_t4 = serd_nodes_manage(
+	        nodes, serd_new_typed_literal("hello", uri(world, 4)));
+	const SerdNode* hello_t5 = serd_nodes_manage(
+	        nodes, serd_new_typed_literal("hello", uri(world, 5)));
+	assert(!serd_model_add(model, uri(world, 98), uri(world, 4), hello, graph));
+	assert(!serd_model_add(
+	        model, uri(world, 98), uri(world, 4), hello_t5, graph));
+
+	// (96 4 "hello"^^<4>) and (96 4 "hello"^^<5>)
+	assert(!serd_model_add(
+	        model, uri(world, 96), uri(world, 4), hello_t4, graph));
+	assert(!serd_model_add(
+	        model, uri(world, 96), uri(world, 4), hello_t5, graph));
+
+	// (94 5 "hello") and (94 5 "hello"@en-gb)
+	assert(!serd_model_add(model, uri(world, 94), uri(world, 5), hello, graph));
+	assert(!serd_model_add(
+	        model, uri(world, 94), uri(world, 5), hello_gb, graph));
+
+	// (92 6 "hello"@en-us) and (92 6 "hello"@en-gb)
+	assert(!serd_model_add(
+	        model, uri(world, 92), uri(world, 6), hello_us, graph));
+	assert(!serd_model_add(
+	        model, uri(world, 92), uri(world, 6), hello_gb, graph));
+
+	// (14 6 "bonjour"@fr) and (14 6 "salut"@fr)
+	const SerdNode* bonjour =
+	        manage(world, serd_new_plain_literal("bonjour", "fr"));
+	const SerdNode* salut =
+	        manage(world, serd_new_plain_literal("salut", "fr"));
+	assert(!serd_model_add(
+	        model, uri(world, 14), uri(world, 6), bonjour, graph));
+	assert(!serd_model_add(model, uri(world, 14), uri(world, 6), salut, graph));
+
+	// Attempt to add duplicates
+	assert(serd_model_add(model, uri(world, 14), uri(world, 6), salut, graph));
+
+	// Add a blank node subject
+	const SerdNode* ablank = manage(world, serd_new_blank("ablank"));
+	assert(!serd_model_add(model, ablank, uri(world, 6), salut, graph));
+
+	// Add statement with URI object
+	assert(!serd_model_add(model, ablank, uri(world, 6), uri(world, 7), graph));
+
+	return EXIT_SUCCESS;
+}
+
+static int
+test_read(SerdWorld*      world,
+          SerdModel*      model,
+          const SerdNode* g,
+          const size_t    n_quads)
+{
+	SerdIter* iter = serd_model_begin(model);
+	for (; !serd_iter_equals(iter, serd_model_end(model));
+	     serd_iter_next(iter)) {
+		const SerdStatement* statement = serd_iter_get(iter);
+		assert(serd_statement_get_subject(statement));
+		assert(serd_statement_get_predicate(statement));
+		assert(serd_statement_get_object(statement));
+	}
+
+	// Attempt to increment past end
+	assert(serd_iter_next(iter));
+	serd_iter_free(iter);
+
+	const char*     s           = "hello";
+	const SerdNode* plain_hello = manage(world, serd_new_string(s));
+	const SerdNode* type4_hello =
+	        manage(world, serd_new_typed_literal(s, uri(world, 4)));
+	const SerdNode* type5_hello =
+	        manage(world, serd_new_typed_literal(s, uri(world, 5)));
+	const SerdNode* gb_hello =
+	        manage(world, serd_new_plain_literal(s, "en-gb"));
+	const SerdNode* us_hello =
+	        manage(world, serd_new_plain_literal(s, "en-us"));
+
+#define NUM_PATTERNS 18
+
+	QueryTest patterns[NUM_PATTERNS] = {
+	        {{NULL, NULL, NULL}, (int)(n_quads * N_OBJECTS_PER) + 12},
+	        {{uri(world, 1), WILDCARD_NODE, WILDCARD_NODE}, 2},
+	        {{uri(world, 9), uri(world, 9), uri(world, 9)}, 0},
+	        {{uri(world, 1), uri(world, 2), uri(world, 4)}, 1},
+	        {{uri(world, 3), uri(world, 4), WILDCARD_NODE}, 2},
+	        {{WILDCARD_NODE, uri(world, 2), uri(world, 4)}, 1},
+	        {{WILDCARD_NODE, WILDCARD_NODE, uri(world, 4)}, 1},
+	        {{uri(world, 1), WILDCARD_NODE, WILDCARD_NODE}, 2},
+	        {{uri(world, 1), WILDCARD_NODE, uri(world, 4)}, 1},
+	        {{WILDCARD_NODE, uri(world, 2), WILDCARD_NODE}, 2},
+	        {{uri(world, 98), uri(world, 4), plain_hello}, 1},
+	        {{uri(world, 98), uri(world, 4), type5_hello}, 1},
+	        {{uri(world, 96), uri(world, 4), type4_hello}, 1},
+	        {{uri(world, 96), uri(world, 4), type5_hello}, 1},
+	        {{uri(world, 94), uri(world, 5), plain_hello}, 1},
+	        {{uri(world, 94), uri(world, 5), gb_hello}, 1},
+	        {{uri(world, 92), uri(world, 6), gb_hello}, 1},
+	        {{uri(world, 92), uri(world, 6), us_hello}, 1}};
+
+	Quad match = {uri(world, 1), uri(world, 2), uri(world, 4), g};
+	assert(serd_model_ask(model, match[0], match[1], match[2], match[3]));
+
+	Quad nomatch = {uri(world, 1), uri(world, 2), uri(world, 9), g};
+	assert(!serd_model_ask(
+	        model, nomatch[0], nomatch[1], nomatch[2], nomatch[3]));
+
+	assert(!serd_model_get(model, NULL, NULL, uri(world, 3), g));
+	assert(!serd_model_get(model, uri(world, 1), uri(world, 99), NULL, g));
+
+	assert(serd_node_equals(
+	        serd_model_get(model, uri(world, 1), uri(world, 2), NULL, g),
+	        uri(world, 3)));
+	assert(serd_node_equals(
+	        serd_model_get(model, uri(world, 1), NULL, uri(world, 3), g),
+	        uri(world, 2)));
+	assert(serd_node_equals(
+	        serd_model_get(model, NULL, uri(world, 2), uri(world, 3), g),
+	        uri(world, 1)));
+
+	for (unsigned i = 0; i < NUM_PATTERNS; ++i) {
+		QueryTest test = patterns[i];
+		Quad      pat  = {test.query[0], test.query[1], test.query[2], g};
+
+		SerdRange* range =
+		        serd_model_range(model, pat[0], pat[1], pat[2], pat[3]);
+		int num_results = 0;
+		for (; !serd_range_empty(range); serd_range_next(range)) {
+			++num_results;
+			assert(serd_statement_matches(
+			        serd_range_front(range), pat[0], pat[1], pat[2], pat[3]));
+		}
+		serd_range_free(range);
+
+		assert(num_results == test.expected_num_results);
+	}
+
+	// Query blank node subject
+	const SerdNode* ablank      = manage(world, serd_new_blank("ablank"));
+	Quad            pat         = {ablank, 0, 0};
+	int             num_results = 0;
+	SerdRange* range = serd_model_range(model, pat[0], pat[1], pat[2], pat[3]);
+	for (; !serd_range_empty(range); serd_range_next(range)) {
+		++num_results;
+		const SerdStatement* statement = serd_range_front(range);
+		assert(serd_statement_matches(
+		        statement, pat[0], pat[1], pat[2], pat[3]));
+	}
+	serd_range_free(range);
+
+	assert(num_results == 2);
+
+	// Test nested queries
+	const SerdNode* last_subject = 0;
+	range = serd_model_range(model, NULL, NULL, NULL, NULL);
+	for (; !serd_range_empty(range); serd_range_next(range)) {
+		const SerdStatement* statement = serd_range_front(range);
+		const SerdNode*      subject   = serd_statement_get_subject(statement);
+		if (subject == last_subject) {
+			continue;
+		}
+
+		Quad       subpat   = {subject, 0, 0};
+		SerdRange* subrange = serd_model_range(
+		        model, subpat[0], subpat[1], subpat[2], subpat[3]);
+		const SerdStatement* substatement    = serd_range_front(subrange);
+		uint64_t             num_sub_results = 0;
+		assert(serd_statement_get_subject(substatement) == subject);
+		for (; !serd_range_empty(subrange); serd_range_next(subrange)) {
+			assert(serd_statement_matches(serd_range_front(subrange),
+			                              subpat[0],
+			                              subpat[1],
+			                              subpat[2],
+			                              subpat[3]));
+			++num_sub_results;
+		}
+		serd_range_free(subrange);
+		assert(num_sub_results == N_OBJECTS_PER);
+
+		uint64_t count = serd_model_count(model, subject, 0, 0, 0);
+		assert(count == num_sub_results);
+
+		last_subject = subject;
+	}
+	serd_range_free(range);
+
+	return 0;
+}
+
+static SerdStatus
+unexpected_error(void* handle, const SerdMessage* msg)
+{
+	(void)handle;
+
+	fprintf(stderr, "error: ");
+	vfprintf(stderr, msg->fmt, *msg->args);
+	return SERD_SUCCESS;
+}
+
+static SerdStatus
+expected_error(void* handle, const SerdMessage* msg)
+{
+	(void)handle;
+
+	fprintf(stderr, "expected: ");
+	vfprintf(stderr, msg->fmt, *msg->args);
+	return SERD_SUCCESS;
+}
+
+static int
+test_free_null(SerdWorld* world, const size_t n_quads)
+{
+	(void)world;
+	(void)n_quads;
+
+	serd_model_free(NULL); // Shouldn't crash
+	return 0;
+}
+
+static int
+test_get_world(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel* model = serd_model_new(world, SERD_INDEX_SPO);
+	assert(serd_model_get_world(model) == world);
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_all_begin(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel* model = serd_model_new(world, SERD_INDEX_SPO);
+	SerdRange* all   = serd_model_all(model);
+	SerdIter*  begin = serd_model_find(model, NULL, NULL, NULL, NULL);
+	assert(serd_iter_equals(serd_range_begin(all), begin));
+
+	serd_range_free(all);
+	serd_iter_free(begin);
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_add_null(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel* model = serd_model_new(world, SERD_INDEX_SPO);
+
+	serd_world_set_message_sink(world, expected_error, NULL);
+
+	assert(serd_model_add(model, 0, 0, 0, 0));
+	assert(serd_model_add(model, uri(world, 1), 0, 0, 0));
+	assert(serd_model_add(model, uri(world, 1), uri(world, 2), 0, 0));
+	assert(serd_model_empty(model));
+
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_add_with_iterator(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel* model = serd_model_new(world, SERD_INDEX_SPO);
+
+	serd_world_set_message_sink(world, expected_error, NULL);
+	assert(!serd_model_add(
+	        model, uri(world, 1), uri(world, 2), uri(world, 3), 0));
+
+	// Add a statement with an active iterator
+	SerdIter* iter = serd_model_begin(model);
+	assert(!serd_model_add(
+	        model, uri(world, 1), uri(world, 2), uri(world, 4), 0));
+
+	// Check that iterator has been invalidated
+	assert(!serd_iter_get(iter));
+	assert(serd_iter_next(iter));
+
+	serd_iter_free(iter);
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_erase_with_iterator(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel* model = serd_model_new(world, SERD_INDEX_SPO);
+
+	serd_world_set_message_sink(world, expected_error, NULL);
+	assert(!serd_model_add(
+	        model, uri(world, 1), uri(world, 2), uri(world, 3), 0));
+	assert(!serd_model_add(
+	        model, uri(world, 4), uri(world, 5), uri(world, 6), 0));
+
+	// Erase a statement with an active iterator
+	SerdIter* iter1 = serd_model_begin(model);
+	SerdIter* iter2 = serd_model_begin(model);
+	assert(!serd_model_erase(model, iter1));
+
+	// Check that erased iterator points to the next statement
+	assert(serd_statement_matches(serd_iter_get(iter1),
+	                              uri(world, 4),
+	                              uri(world, 5),
+	                              uri(world, 6),
+	                              0));
+
+	// Check that other iterator has been invalidated
+	assert(!serd_iter_get(iter2));
+	assert(serd_iter_next(iter2));
+
+	serd_iter_free(iter2);
+	serd_iter_free(iter1);
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_add_erase(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel* model =
+	        serd_model_new(world, SERD_INDEX_SPO | SERD_INDEX_GRAPHS);
+
+	// Add (s p "hello")
+	const SerdNode* s     = uri(world, 1);
+	const SerdNode* p     = uri(world, 2);
+	const SerdNode* hello = manage(world, serd_new_string("hello"));
+	assert(!serd_model_add(model, s, p, hello, 0));
+	assert(serd_model_ask(model, s, p, hello, 0));
+
+	// Add (s p "hi")
+	const SerdNode* hi = manage(world, serd_new_string("hi"));
+	assert(!serd_model_add(model, s, p, hi, NULL));
+	assert(serd_model_ask(model, s, p, hi, 0));
+
+	// Erase (s p "hi")
+	SerdIter* iter = serd_model_find(model, s, p, hi, NULL);
+	assert(!serd_model_erase(model, iter));
+	assert(serd_model_size(model) == 1);
+	serd_iter_free(iter);
+
+	// Check that erased statement can not be found
+	SerdRange* empty = serd_model_range(model, s, p, hi, NULL);
+	assert(serd_range_empty(empty));
+	serd_range_free(empty);
+
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_erase_all(SerdWorld* world, const size_t n_quads)
+{
+	SerdModel* model = serd_model_new(world, SERD_INDEX_SPO);
+	generate(world, model, n_quads, NULL);
+
+	SerdIter* iter = serd_model_begin(model);
+	while (!serd_iter_equals(iter, serd_model_end(model))) {
+		assert(!serd_model_erase(model, iter));
+	}
+
+	serd_iter_free(iter);
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_copy(SerdWorld* world, const size_t n_quads)
+{
+	SerdModel* model = serd_model_new(world, SERD_INDEX_SPO);
+	generate(world, model, n_quads, NULL);
+
+	SerdModel* copy = serd_model_copy(model);
+	assert(serd_model_equals(model, copy));
+
+	serd_model_free(model);
+	serd_model_free(copy);
+	return 0;
+}
+
+static int
+test_equals(SerdWorld* world, const size_t n_quads)
+{
+	SerdModel* model = serd_model_new(world, SERD_INDEX_SPO);
+	generate(world, model, n_quads, NULL);
+	serd_model_add(
+	        model, uri(world, 0), uri(world, 1), uri(world, 2), uri(world, 3));
+
+	assert(serd_model_equals(NULL, NULL));
+	assert(!serd_model_equals(NULL, model));
+	assert(!serd_model_equals(model, NULL));
+
+	SerdModel* empty = serd_model_new(world, SERD_INDEX_SPO);
+	assert(!serd_model_equals(model, empty));
+
+	SerdModel* different = serd_model_new(world, SERD_INDEX_SPO);
+	generate(world, different, n_quads, NULL);
+	serd_model_add(different,
+	               uri(world, 1),
+	               uri(world, 1),
+	               uri(world, 2),
+	               uri(world, 3));
+
+	assert(serd_model_size(model) == serd_model_size(different));
+	assert(!serd_model_equals(model, different));
+
+	serd_model_free(model);
+	serd_model_free(empty);
+	serd_model_free(different);
+	return 0;
+}
+
+static int
+test_find_past_end(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel*      model = serd_model_new(world, SERD_INDEX_SPO);
+	const SerdNode* s     = uri(world, 1);
+	const SerdNode* p     = uri(world, 2);
+	const SerdNode* o     = uri(world, 3);
+	assert(!serd_model_add(model, s, p, o, 0));
+	assert(serd_model_ask(model, s, p, o, 0));
+
+	const SerdNode* huge  = uri(world, 999);
+	SerdRange*      range = serd_model_range(model, huge, huge, huge, 0);
+	assert(serd_range_empty(range));
+
+	serd_range_free(range);
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_iter_comparison(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel* model = serd_model_new(world, SERD_INDEX_SPO);
+
+	serd_world_set_message_sink(world, expected_error, NULL);
+	assert(!serd_model_add(
+	        model, uri(world, 1), uri(world, 2), uri(world, 3), 0));
+
+	// Add a statement with an active iterator
+	SerdIter* iter1 = serd_model_begin(model);
+	SerdIter* iter2 = serd_model_begin(model);
+	assert(serd_iter_equals(iter1, iter2));
+
+	serd_iter_next(iter1);
+	assert(!serd_iter_equals(iter1, iter2));
+
+	const SerdIter* end = serd_model_end(model);
+	assert(serd_iter_equals(iter1, end));
+
+	serd_iter_free(iter2);
+	serd_iter_free(iter1);
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_triple_index_read(SerdWorld* world, const size_t n_quads)
+{
+	for (unsigned i = 0; i < 6; ++i) {
+		SerdModel* model = serd_model_new(world, (1 << i));
+		generate(world, model, n_quads, 0);
+		assert(!test_read(world, model, 0, n_quads));
+		serd_model_free(model);
+	}
+
+	return 0;
+}
+
+static int
+test_quad_index_read(SerdWorld* world, const size_t n_quads)
+{
+	for (unsigned i = 0; i < 6; ++i) {
+		SerdModel* model = serd_model_new(world, (1 << i) | SERD_INDEX_GRAPHS);
+		const SerdNode* graph = uri(world, 42);
+		generate(world, model, n_quads, graph);
+		assert(!test_read(world, model, graph, n_quads));
+		serd_model_free(model);
+	}
+
+	return 0;
+}
+
+static int
+test_remove_graph(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel* model =
+	        serd_model_new(world, SERD_INDEX_SPO | SERD_INDEX_GRAPHS);
+
+	// Generate a couple of graphs
+	const SerdNode* graph42 = uri(world, 42);
+	const SerdNode* graph43 = uri(world, 43);
+	generate(world, model, 1, graph42);
+	generate(world, model, 1, graph43);
+
+	// Remove one graph via range
+	SerdStatus st;
+	SerdRange* range = serd_model_range(model, NULL, NULL, NULL, graph43);
+	assert(!(st = serd_model_erase_range(model, range)));
+	serd_range_free(range);
+
+	// Erase the first tuple (an element in the default graph)
+	SerdIter* iter = serd_model_begin(model);
+	assert(!serd_model_erase(model, iter));
+	serd_iter_free(iter);
+
+	// Ensure only the other graph is left
+	Quad pat = {0, 0, 0, graph42};
+	for (iter = serd_model_begin(model);
+	     !serd_iter_equals(iter, serd_model_end(model));
+	     serd_iter_next(iter)) {
+		assert(serd_statement_matches(
+		        serd_iter_get(iter), pat[0], pat[1], pat[2], pat[3]));
+	}
+	serd_iter_free(iter);
+
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_default_graph(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel* model =
+	        serd_model_new(world, SERD_INDEX_SPO | SERD_INDEX_GRAPHS);
+	const SerdNode* s  = uri(world, 1);
+	const SerdNode* p  = uri(world, 2);
+	const SerdNode* o  = uri(world, 3);
+	const SerdNode* g1 = uri(world, 101);
+	const SerdNode* g2 = uri(world, 102);
+
+	// Insert the same statement into two graphs
+	assert(!serd_model_add(model, s, p, o, g1));
+	assert(!serd_model_add(model, s, p, o, g2));
+
+	// Ensure we only see statement once in the default graph
+	assert(serd_model_count(model, s, p, o, NULL) == 1);
+
+	serd_model_free(model);
+	return 0;
+}
+
+static int
+test_write_bad_list(SerdWorld* world, const size_t n_quads)
+{
+	(void)n_quads;
+
+	SerdModel* model =
+	        serd_model_new(world, SERD_INDEX_SPO | SERD_INDEX_GRAPHS);
+	SerdNodes*      nodes   = serd_nodes_new();
+	const SerdNode* s       = manage(world, serd_new_uri("urn:s"));
+	const SerdNode* p       = manage(world, serd_new_uri("urn:p"));
+	const SerdNode* list1   = manage(world, serd_new_blank("l1"));
+	const SerdNode* list2   = manage(world, serd_new_blank("l2"));
+	const SerdNode* nofirst = manage(world, serd_new_blank("nof"));
+	const SerdNode* norest  = manage(world, serd_new_blank("nor"));
+	const SerdNode* pfirst  = manage(world, serd_new_uri(RDF_FIRST));
+	const SerdNode* prest   = manage(world, serd_new_uri(RDF_REST));
+	const SerdNode* val1    = manage(world, serd_new_string("a"));
+	const SerdNode* val2    = manage(world, serd_new_string("b"));
+
+	// List where second node has no rdf:first
+	serd_model_add(model, s, p, list1, NULL);
+	serd_model_add(model, list1, pfirst, val1, NULL);
+	serd_model_add(model, list1, prest, nofirst, NULL);
+
+	// List where second node has no rdf:rest
+	serd_model_add(model, s, p, list2, NULL);
+	serd_model_add(model, list2, pfirst, val1, NULL);
+	serd_model_add(model, list2, prest, norest, NULL);
+	serd_model_add(model, norest, pfirst, val2, NULL);
+
+	SerdBuffer  buffer = {NULL, 0};
+	SerdEnv*    env    = serd_env_new(NULL);
+	SerdWriter* writer = serd_writer_new(
+	        world, SERD_TURTLE, 0, env, serd_buffer_sink, &buffer);
+
+	SerdRange* all = serd_model_all(model);
+	serd_range_serialise(all, serd_writer_get_sink(writer), 0);
+	serd_range_free(all);
+
+	serd_writer_finish(writer);
+	const char* str      = serd_buffer_sink_finish(&buffer);
+	const char* expected = "<urn:s>\n"
+	                       "	<urn:p> (\n"
+	                       "		\"a\"\n"
+	                       "	) , (\n"
+	                       "		\"a\"\n"
+	                       "		\"b\"\n"
+	                       "	) .\n";
+
+	assert(!strcmp(str, expected));
+
+	free(buffer.buf);
+	serd_writer_free(writer);
+	serd_model_free(model);
+	serd_env_free(env);
+	serd_nodes_free(nodes);
+	return 0;
+}
+
+int
+main(void)
+{
+	static const size_t n_quads = 300;
+
+	serd_model_free(NULL); // Shouldn't crash
+
+	typedef int (*TestFunc)(SerdWorld*, size_t);
+
+	const TestFunc tests[] = {test_free_null,
+	                          test_get_world,
+	                          test_all_begin,
+	                          test_add_null,
+	                          test_add_with_iterator,
+	                          test_erase_with_iterator,
+	                          test_add_erase,
+	                          test_erase_all,
+	                          test_copy,
+	                          test_equals,
+	                          test_find_past_end,
+	                          test_iter_comparison,
+	                          test_triple_index_read,
+	                          test_quad_index_read,
+	                          test_remove_graph,
+	                          test_default_graph,
+	                          test_write_bad_list,
+	                          NULL};
+
+	SerdWorld* world = serd_world_new();
+	for (const TestFunc* t = tests; *t; ++t) {
+		serd_world_set_message_sink(world, unexpected_error, NULL);
+		if ((*t)(world, n_quads)) {
+			return EXIT_FAILURE;
+		}
+	}
+
+	serd_world_free(world);
+	return 0;
+}
diff --git a/wscript b/wscript
index cc2b0ed5..72d9c5e5 100644
--- a/wscript
+++ b/wscript
@@ -33,6 +33,9 @@ def options(ctx):
          'largefile':    'build with large file support on 32-bit systems',
          'no-posix':     'do not use POSIX functions, even if present'})
 
+    opt.add_option('--dump', type='string', default='', dest='dump',
+                   help='dump debugging output (iter, search, write, all)')
+
 def configure(conf):
     autowaf.display_header('Serd Configuration')
     conf.load('compiler_c', cache=True)
@@ -64,6 +67,14 @@ def configure(conf):
                                    defines     = ['_POSIX_C_SOURCE=200809L'],
                                    mandatory   = False)
 
+    dump = Options.options.dump.split(',')
+    if 'all' in dump or 'iter' in dump:
+        conf.define('SERD_DEBUG_ITER', 1)
+    if 'all' in dump or 'search' in dump:
+        conf.define('SERD_DEBUG_SEARCH', 1)
+    if 'all' in dump or 'write' in dump:
+        conf.define('SERD_DEBUG_WRITE', 1)
+
     autowaf.set_lib_env(conf, 'serd', SERD_VERSION)
     conf.write_config_header('serd_config.h', remove=False)
 
@@ -79,9 +90,13 @@ lib_source = ['src/base64.c',
               'src/byte_source.c',
               'src/cursor.c',
               'src/env.c',
+              'src/inserter.c',
+              'src/iter.c',
+              'src/model.c',
               'src/n3.c',
               'src/node.c',
               'src/nodes.c',
+              'src/range.c',
               'src/reader.c',
               'src/sink.c',
               'src/statement.c',
@@ -91,6 +106,7 @@ lib_source = ['src/base64.c',
               'src/uri.c',
               'src/world.c',
               'src/writer.c',
+              'src/zix/btree.c',
               'src/zix/digest.c',
               'src/zix/hash.c']
 
@@ -153,7 +169,8 @@ def build(bld):
                      ('serd_test', 'tests/serd_test.c'),
                      ('read_chunk_test', 'tests/read_chunk_test.c'),
                      ('nodes_test', 'tests/nodes_test.c'),
-                     ('overflow_test', 'tests/overflow_test.c')]:
+                     ('overflow_test', 'tests/overflow_test.c'),
+                     ('model_test', 'tests/model_test.c')]:
             bld(features     = 'c cprogram',
                 source       = prog[1],
                 use          = 'libserd_profiled',
@@ -294,9 +311,17 @@ def show_diff(from_lines, to_lines, from_filename, to_filename):
             tofile=os.path.abspath(to_filename)):
         sys.stderr.write(line)
 
-def check_output(out_filename, check_filename, subst_from='', subst_to=''):
+def check_output(out_filename, check_filename, subst_from='', subst_to='', sort=False):
     if not os.access(out_filename, os.F_OK):
         Logs.pprint('RED', 'FAIL: output %s is missing' % out_filename)
+    elif sort:
+        out_lines   = sorted(set(io.open(out_filename, encoding='utf-8').readlines()))
+        check_lines = sorted(set(io.open(check_filename, encoding='utf-8').readlines()))
+        if out_lines != check_lines:
+            show_diff(check_lines, out_lines, check_filename, out_filename)
+            return False
+        else:
+            return True
     elif not file_equals(check_filename, out_filename, subst_from, subst_to):
         Logs.pprint('RED', 'FAIL: %s != %s' % (os.path.abspath(out_filename),
                                                check_filename))
@@ -414,14 +439,17 @@ def test_suite(ctx, base_uri, testdir, report, isyntax, osyntax, options=''):
                     # Check output against test suite
                     check_uri  = model[test][mf + 'result'][0]
                     check_path = file_uri_to_path(check_uri)
+                    sort       = '-m' in options
                     result     = autowaf.run_test(
                         ctx, APPNAME,
-                        lambda: check_output(action + '.out', check_path),
+                        lambda: check_output(action + '.out', check_path, sort=sort),
                         True, name=str(action) + ' check', quiet=True)
 
                     # Run round-trip tests
-                    test_thru(ctx, uri, action, check_path,
-                              ' '.join(next(thru_options_iter)), isyntax, osyntax, options, quiet=True)
+                    if not sort:
+                        test_thru(ctx, uri, action, check_path,
+                                  ' '.join(next(thru_options_iter)),
+                                  isyntax, osyntax, options, quiet=True)
 
                 # Write test report entry
                 if report is not None:
@@ -491,7 +519,8 @@ def test(ctx):
                       ['serd_test',
                        'read_chunk_test',
                        'nodes_test',
-                       'overflow_test'],
+                       'overflow_test',
+                       'model_test'],
                       name='Unit')
 
     def test_syntax_io(in_name, expected_name, lang):
@@ -555,7 +584,8 @@ def test(ctx):
                              'serdi_static "file://%s/tests/good/manifest.ttl" > /dev/full' % srcdir,
                              1, name='write_error')
 
-    run_test_suites(ctx, '')
+    for opts in ['', '-m']:
+        run_test_suites(ctx, opts)
 
     autowaf.post_test(ctx, APPNAME)