WIP: Add serd_validate

2 files changed, 1017 insertions, 12 deletions

diff --git a/src/serd_validate.c b/src/serd_validate.c
new file mode 100644
index 00000000..b852a3fa
--- /dev/null
+++ b/src/serd_validate.c
@@ -0,0 +1,986 @@
+/*
+  Copyright 2012-2018 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.
+*/
+
+#define _BSD_SOURCE 1     // for realpath
+#define _DEFAULT_SOURCE 1 // for realpath
+
+#include "serd_config.h"
+
+#include "serd/serd.h"
+
+#include <assert.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+#ifdef HAVE_PCRE
+#include <pcre.h>
+#endif
+
+#define NS_foaf "http://xmlns.com/foaf/0.1/"
+#define NS_owl "http://www.w3.org/2002/07/owl#"
+#define NS_rdf "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+#define NS_rdfs "http://www.w3.org/2000/01/rdf-schema#"
+#define NS_xsd "http://www.w3.org/2001/XMLSchema#"
+
+#define CERRORF(fmt, ...) fprintf(stderr, "serd_validate: " fmt, __VA_ARGS__);
+
+#define VERRORF(statement, fmt, ...)                                           \
+	report(statement, "error", fmt, __VA_ARGS__);
+
+#define VERROR(statement, fmt) report(statement, "error", fmt);
+
+#define VNOTEF(statement, fmt, ...) report(statement, "note", fmt, __VA_ARGS__);
+
+#define VNOTE(statement, fmt) report(statement, "note", fmt);
+
+#define SERD_FOREACH(name, range)                                              \
+	for (const SerdStatement* name = NULL;                                     \
+	     !serd_range_empty(range) && (name = serd_range_front(range));         \
+	     serd_range_next(range))
+
+typedef struct
+{
+	SerdNode* foaf_Document;
+	SerdNode* owl_Class;
+	SerdNode* owl_DatatypeProperty;
+	SerdNode* owl_FunctionalProperty;
+	SerdNode* owl_InverseFunctionalProperty;
+	SerdNode* owl_ObjectProperty;
+	SerdNode* owl_Restriction;
+	SerdNode* owl_Thing;
+	SerdNode* owl_allValuesFrom;
+	SerdNode* owl_cardinality;
+	SerdNode* owl_equivalentClass;
+	SerdNode* owl_maxCardinality;
+	SerdNode* owl_minCardinality;
+	SerdNode* owl_onDatatype;
+	SerdNode* owl_onProperty;
+	SerdNode* owl_someValuesFrom;
+	SerdNode* owl_withRestrictions;
+	SerdNode* rdf_PlainLiteral;
+	SerdNode* rdf_Property;
+	SerdNode* rdf_first;
+	SerdNode* rdf_rest;
+	SerdNode* rdf_type;
+	SerdNode* rdfs_Class;
+	SerdNode* rdfs_Datatype;
+	SerdNode* rdfs_Literal;
+	SerdNode* rdfs_Resource;
+	SerdNode* rdfs_domain;
+	SerdNode* rdfs_label;
+	SerdNode* rdfs_range;
+	SerdNode* rdfs_subClassOf;
+	SerdNode* xsd_anyURI;
+	SerdNode* xsd_float;
+	SerdNode* xsd_decimal;
+	SerdNode* xsd_double;
+	SerdNode* xsd_maxExclusive;
+	SerdNode* xsd_maxInclusive;
+	SerdNode* xsd_minExclusive;
+	SerdNode* xsd_minInclusive;
+	SerdNode* xsd_pattern;
+	SerdNode* xsd_string;
+} URIs;
+
+static int n_errors       = 0;
+static int n_restrictions = 0;
+
+static int
+check_class_restriction(SerdModel*           model,
+                        const URIs*          uris,
+                        const SerdNode*      restriction,
+                        const SerdStatement* statement,
+                        const SerdNode*      instance);
+
+static int
+print_version(void)
+{
+	printf("serd_validate " SERD_VERSION
+	       " <http://drobilla.net/software/serd>\n");
+	printf("Copyright 2012-2018 David Robillard <http://drobilla.net>.\n"
+	       "License: <http://www.opensource.org/licenses/isc>\n"
+	       "This is free software; you are free to change and redistribute it."
+	       "\nThere is NO WARRANTY, to the extent permitted by law.\n");
+	return 0;
+}
+
+static int
+print_usage(const char* name, bool error)
+{
+	FILE* const os = error ? stderr : stdout;
+	fprintf(os, "Usage: %s [OPTION]... INPUT...\n", name);
+	fprintf(os, "Validate RDF data\n\n");
+	fprintf(os, "  -h  Display this help and exit\n");
+	fprintf(os, "  -l  Print errors on a single line.\n");
+	fprintf(os, "  -v  Display version information and exit\n");
+	fprintf(os,
+	        "Validate RDF data.  This is a simple validator which checks\n"
+	        "that all used properties are actually defined.  It does not do\n"
+	        "any fancy file retrieval, the files passed on the command line\n"
+	        "are the only data that is read.  In other words, you must pass\n"
+	        "the definition of all vocabularies used on the command line.\n");
+	return error ? 1 : 0;
+}
+
+static char*
+absolute_path(const char* path)
+{
+#ifdef _WIN32
+	char* out = (char*)malloc(MAX_PATH);
+	GetFullPathName(path, MAX_PATH, out, NULL);
+	return out;
+#else
+	return realpath(path, NULL);
+#endif
+}
+
+static int
+report(const SerdStatement* statement, const char* type, const char* fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+
+	fprintf(stderr, "%s: ", type);
+
+	const SerdCursor* cursor = serd_statement_get_cursor(statement);
+	if (cursor) {
+		fprintf(stderr,
+		        "%s:%u:%u: ",
+		        serd_node_get_string(serd_cursor_get_name(cursor)),
+		        serd_cursor_get_line(cursor),
+		        serd_cursor_get_column(cursor));
+	}
+
+	vfprintf(stderr, fmt, args);
+	va_end(args);
+
+	++n_errors;
+	return 1;
+}
+
+static bool
+check(const bool value)
+{
+	++n_restrictions;
+	return value;
+}
+
+/** Return true iff `child` is a descendant of `parent` by `pred` arcs.
+ *
+ * This is, returns true if there is a path from `child` to `parent` by
+ * following `pred` arcs starting from child.
+ */
+static bool
+is_descendant(SerdModel*      model,
+              const URIs*     uris,
+              const SerdNode* child,
+              const SerdNode* parent,
+              const SerdNode* pred)
+{
+	if (serd_node_equals(child, parent) ||
+	    serd_model_ask(model, child, uris->owl_equivalentClass, parent, NULL)) {
+		return true;
+	}
+
+	SerdRange* i = serd_model_range(model, child, pred, NULL, NULL);
+	SERD_FOREACH (s, i) {
+		const SerdNode* o = serd_statement_get_object(s);
+		if (serd_node_equals(child, o)) {
+			continue; // Weird class is explicitly a descendent of itself
+		}
+		if (is_descendant(model, uris, o, parent, pred)) {
+			serd_range_free(i);
+			return true;
+		}
+	}
+	serd_range_free(i);
+
+	return false;
+}
+
+/** Return true iff `child` is a subclass of `parent`. */
+static bool
+is_subclass(SerdModel*      model,
+            const URIs*     uris,
+            const SerdNode* child,
+            const SerdNode* parent)
+{
+	return is_descendant(model, uris, child, parent, uris->rdfs_subClassOf);
+}
+
+/** Return true iff `child` is a sub-datatype of `parent`. */
+static bool
+is_subdatatype(SerdModel*      model,
+               const URIs*     uris,
+               const SerdNode* child,
+               const SerdNode* parent)
+{
+	return is_descendant(model, uris, child, parent, uris->owl_onDatatype);
+}
+
+static bool
+regexp_match(const SerdStatement* pat_statement, const char* pat, const char* str)
+{
+#ifdef HAVE_PCRE
+	// Append a $ to the pattern so we only match if the entire string matches
+	const size_t len  = strlen(pat);
+	char* const  regx = (char*)malloc(len + 2);
+	memcpy(regx, pat, len);
+	regx[len]     = '$';
+	regx[len + 1] = '\0';
+
+	const char* err;
+	int         erroffset;
+	pcre*       re = pcre_compile(regx, PCRE_ANCHORED, &err, &erroffset, NULL);
+	free(regx);
+	if (!re) {
+		VERRORF(pat_statement,
+		        "Error in pattern \"%s\" at offset %d (%s)\n",
+		        pat,
+		        erroffset,
+		        err);
+		return false;
+	}
+
+	const bool ret = pcre_exec(re, NULL, str, strlen(str), 0, 0, NULL, 0) >= 0;
+	pcre_free(re);
+	return ret;
+#endif // HAVE_PCRE
+	return true;
+}
+
+static int
+bound_cmp(SerdModel*      model,
+          const URIs*     uris,
+          const SerdNode* literal,
+          const SerdNode* type,
+          const SerdNode* bound)
+{
+	const char* str       = serd_node_get_string(literal);
+	const char* bound_str = serd_node_get_string(bound);
+	const bool  is_numeric =
+	        is_subdatatype(model, uris, type, uris->xsd_decimal) ||
+	        is_subdatatype(model, uris, type, uris->xsd_double);
+
+	if (is_numeric) {
+		const double fbound   = serd_strtod(bound_str, NULL);
+		const double fliteral = serd_strtod(str, NULL);
+		return ((fliteral < fbound) ? -1 : (fliteral > fbound) ? 1 : 0);
+	} else {
+		return strcmp(str, bound_str);
+	}
+}
+
+static bool
+check_literal_restriction(SerdModel*           model,
+                          const URIs*          uris,
+                          const SerdStatement* statement,
+                          const SerdNode*      literal,
+                          const SerdNode*      type,
+                          const SerdNode*      restriction)
+{
+	const char* str = serd_node_get_string(literal);
+
+	// Check xsd:pattern
+	const SerdStatement* pat_statement = serd_model_get_statement(
+	        model, restriction, uris->xsd_pattern, 0, 0);
+	if (pat_statement) {
+		const SerdNode* pat_node = serd_statement_get_object(pat_statement);
+		const char*     pat      = serd_node_get_string(pat_node);
+		if (check(!regexp_match(pat_statement, pat, str))) {
+			VERRORF(statement,
+			        "Value \"%s\" does not match pattern \"%s\"\n",
+			        serd_node_get_string(literal),
+			        pat);
+			return false;
+		}
+	}
+
+	// Check xsd:minInclusive
+	const SerdNode* lower =
+	        serd_model_get(model, restriction, uris->xsd_minInclusive, 0, 0);
+	if (lower) {
+		if (check(bound_cmp(model, uris, literal, type, lower) < 0)) {
+			VERRORF(statement,
+			        "Value \"%s\" < minimum \"%s\"\n",
+			        serd_node_get_string(literal),
+			        serd_node_get_string(lower));
+			return false;
+		}
+	}
+
+	// Check xsd:maxInclusive
+	const SerdNode* upper =
+	        serd_model_get(model, restriction, uris->xsd_maxInclusive, 0, 0);
+	if (upper) {
+		if (check(bound_cmp(model, uris, literal, type, upper) > 0)) {
+			VERRORF(statement,
+			        "Value \"%s\" > than maximum \"%s\"\n",
+			        serd_node_get_string(literal),
+			        serd_node_get_string(upper));
+			return false;
+		}
+	}
+
+	// Check xsd:minExclusive
+	const SerdNode* elower =
+	        serd_model_get(model, restriction, uris->xsd_minExclusive, 0, 0);
+	if (elower) {
+		if (check(bound_cmp(model, uris, literal, type, elower) <= 0)) {
+			VERRORF(statement,
+			        "Value \"%s\" <= exclusive minimum \"%s\"\n",
+			        serd_node_get_string(literal),
+			        serd_node_get_string(elower));
+			return false;
+		}
+	}
+
+	// Check xsd:maxExclusive
+	const SerdNode* eupper =
+	        serd_model_get(model, restriction, uris->xsd_maxExclusive, 0, 0);
+	if (eupper) {
+		if (check(bound_cmp(model, uris, literal, type, eupper) >= 0)) {
+			VERRORF(statement,
+			        "Value \"%s\" >= exclusive maximum \"%s\"\n",
+			        serd_node_get_string(literal),
+			        serd_node_get_string(eupper));
+			return false;
+		}
+		++n_restrictions;
+	}
+
+	return true; // Unknown restriction, be quietly tolerant
+}
+
+static bool
+is_datatype(SerdModel* model, const URIs* uris, const SerdNode* dtype)
+{
+	SerdRange* t = serd_model_range(model, dtype, uris->rdf_type, NULL, NULL);
+	SERD_FOREACH (s, t) {
+		const SerdNode* type = serd_statement_get_object(s);
+		if (is_subdatatype(model, uris, type, uris->rdfs_Datatype)) {
+			return true; // Subdatatype of rdfs:Datatype
+		}
+	}
+
+	return false;
+}
+
+static bool
+literal_is_valid(SerdModel*           model,
+                 const URIs*          uris,
+                 const SerdStatement* statement,
+                 const SerdNode*      literal,
+                 const SerdNode*      type)
+{
+	if (!type) {
+		return true;
+	}
+
+	// Check that datatype is defined
+	const SerdNode* datatype = serd_node_get_datatype(literal);
+	if (datatype && !is_datatype(model, uris, datatype)) {
+		VERRORF(statement,
+		        "Datatype <%s> is not defined\n",
+		        serd_node_get_string(datatype));
+		return false;
+	}
+
+	// Find restrictions list
+	const SerdNode* head =
+	        serd_model_get(model, type, uris->owl_withRestrictions, 0, 0);
+
+	// Walk list, checking each restriction
+	while (head) {
+		SerdIter* f = serd_model_find(model, head, uris->rdf_first, 0, 0);
+		if (!f) {
+			break;
+		}
+
+		const SerdNode* first = serd_statement_get_object(serd_iter_get(f));
+
+		// Check this restriction
+		if (!check_literal_restriction(
+		            model, uris, statement, literal, type, first)) {
+			VNOTEF(serd_iter_get(f),
+			       "Restriction on <%s>\n",
+			       serd_node_get_string(type));
+			return false;
+		}
+
+		// Seek to next list node
+		head = serd_model_get(model, head, uris->rdf_rest, 0, 0);
+	}
+
+	// Recurse up datatype hierarchy
+	const SerdNode* super =
+	        serd_model_get(model, type, uris->owl_onDatatype, 0, 0);
+	return super ? literal_is_valid(model, uris, statement, literal, super)
+	             : true;
+}
+
+static bool
+has_explicit_type(SerdModel*      model,
+                  const URIs*     uris,
+                  const SerdNode* node,
+                  const SerdNode* klass)
+{
+	if (serd_model_ask(model, node, uris->rdf_type, klass, NULL)) {
+		return true; // Directly stated to be an instance
+	}
+
+	SerdRange* t = serd_model_range(model, node, uris->rdf_type, NULL, NULL);
+	SERD_FOREACH (s, t) {
+		if (is_subclass(model, uris, serd_statement_get_object(s), klass)) {
+			return true; // Explicit instance of a subclass
+		}
+	}
+
+	return false;
+}
+
+static bool
+is_instance_of(SerdModel*           model,
+               const URIs*          uris,
+               const SerdStatement* statement,
+               const SerdNode*      node,
+               const SerdNode*      klass)
+{
+	if (!serd_model_ask(model, node, NULL, NULL, NULL)) {
+		/* Nothing about this node known in the model at all, assume it is some
+		   external resource we can't validate. */
+		return true;
+	} else if (serd_node_get_type(node) == SERD_BLANK) {
+		/* Be permissive for blank nodes and don't require explicit type
+		   annotation, to avoid countless errors with things like lists. */
+		return true;
+	}
+
+	return (has_explicit_type(model, uris, node, klass) ||
+	        serd_node_equals(klass, uris->rdfs_Resource) ||
+	        serd_node_equals(klass, uris->owl_Thing));
+}
+
+static bool
+check_instance_type(SerdModel*           model,
+                    const URIs*          uris,
+                    const SerdStatement* statement,
+                    const SerdNode*      node,
+                    const SerdNode*      klass)
+{
+	if (is_subclass(model, uris, klass, uris->rdfs_Literal) ||
+	    serd_model_ask(model, klass, uris->rdf_type, uris->rdfs_Datatype, 0)) {
+		VERROR(statement, "Class instance found where literal expected\n");
+		return false;
+	}
+
+	if (serd_model_ask(
+	            model, klass, uris->rdf_type, uris->owl_Restriction, NULL)) {
+		if (check_class_restriction(model, uris, klass, statement, node)) {
+			return false;
+		}
+	}
+
+	SerdRange* r =
+	        serd_model_range(model, klass, uris->rdfs_subClassOf, NULL, NULL);
+	SERD_FOREACH (s, r) {
+		const SerdNode* super = serd_statement_get_object(s);
+		if (!serd_node_equals(super, klass)) {
+			if (!check_instance_type(model, uris, statement, node, super)) {
+				return false;
+			}
+		}
+	}
+
+	if (!is_instance_of(model, uris, statement, node, klass)) {
+		VERRORF(statement,
+		        "Node %s is not an instance of %s\n",
+		        serd_node_get_string(node),
+		        serd_node_get_string(klass));
+		return false;
+	}
+
+	return true; // FIXME?
+}
+
+static bool
+check_type(SerdModel*           model,
+           const URIs*          uris,
+           const SerdStatement* statement,
+           const SerdNode*      node,
+           const SerdNode*      type)
+{
+	if (serd_node_equals(type, uris->rdfs_Resource) ||
+	    serd_node_equals(type, uris->owl_Thing)) {
+		return true; // Trivially true for everything (more or less)
+	}
+
+	if (serd_node_get_type(node) == SERD_LITERAL) {
+		if (serd_node_equals(type, uris->rdfs_Literal)) {
+			return true; // Trivially true for a literal
+		} else if (serd_node_equals(type, uris->rdf_PlainLiteral)) {
+			if (serd_node_get_datatype(node)) {
+				VERRORF(statement,
+				        "Literal \"%s\" should be plain, but has datatype "
+				        "<%s>\n",
+				        serd_node_get_string(node),
+				        serd_node_get_string(serd_node_get_datatype(node)));
+				return false;
+			}
+			return true;
+		} else if (!serd_model_ask(model,
+		                           type,
+		                           uris->rdf_type,
+		                           uris->rdfs_Datatype,
+		                           NULL)) {
+			VERRORF(statement,
+			        "Literal \"%s\" where instance of <%s> expected\n",
+			        serd_node_get_string(node),
+			        serd_node_get_string(type));
+			return false;
+		} else {
+			return literal_is_valid(model, uris, statement, node, type);
+		}
+	} else if (serd_node_get_type(node) == SERD_URI) {
+		if (is_subdatatype(model, uris, type, uris->xsd_anyURI)) {
+			/* Type is any URI and this is a URI, so pass.  Restrictions on
+			   anyURI subtypes are not currently checked (very uncommon). */
+			return true;
+		} else {
+			return check_instance_type(model, uris, statement, node, type);
+		}
+	} else {
+		return check_instance_type(model, uris, statement, node, type);
+	}
+
+	VERRORF(statement,
+	        "Unhandled case checking if %s is of type %s\n",
+	        serd_node_get_string(node),
+	        serd_node_get_string(type));
+
+	return false;
+}
+
+static uint64_t
+count_non_blanks(SerdRange* i, SerdField field)
+{
+	uint64_t n = 0;
+	SERD_FOREACH (s, i) {
+		const SerdNode* node = serd_statement_get_node(s, field);
+		if (serd_node_get_type(node) != SERD_BLANK) {
+			++n;
+		}
+	}
+	return n;
+}
+
+static int
+check_statement(SerdModel*           model,
+                const URIs*          uris,
+                const SerdStatement* statement)
+{
+	int st = 0;
+
+	const SerdNode* subj = serd_statement_get_subject(statement);
+	const SerdNode* pred = serd_statement_get_predicate(statement);
+	const SerdNode* obj  = serd_statement_get_object(statement);
+
+	// Check that predicate is defined as some kind of propety
+	bool       is_property = false;
+	SerdRange* t = serd_model_range(model, pred, uris->rdf_type, NULL, NULL);
+	SERD_FOREACH (s, t) {
+		const SerdNode* type = serd_statement_get_object(s);
+		if (is_subclass(model, uris, type, uris->rdf_Property)) {
+			is_property = true;
+			break;
+		}
+	}
+	serd_range_free(t);
+
+	if (!is_property) {
+		st = VERROR(statement, "Use of undefined property\n");
+	}
+
+	if (serd_node_equals(pred, uris->rdf_type)) {
+		// Type statement, check that object is a valid instance of type
+		check_type(model, uris, statement, subj, obj);
+	}
+
+	const bool is_ObjectProperty = serd_model_ask(
+	        model, pred, uris->rdf_type, uris->owl_ObjectProperty, 0);
+	const bool is_FunctionalProperty = serd_model_ask(
+	        model, pred, uris->rdf_type, uris->owl_FunctionalProperty, 0);
+	const bool is_InverseFunctionalProperty =
+	        serd_model_ask(model,
+	                       pred,
+	                       uris->rdf_type,
+	                       uris->owl_InverseFunctionalProperty,
+	                       0);
+	const bool is_DatatypeProperty = serd_model_ask(
+	        model, pred, uris->rdf_type, uris->owl_DatatypeProperty, 0);
+
+	if (!serd_model_ask(model, pred, uris->rdfs_label, NULL, NULL)) {
+		st = VERRORF(statement,
+		             "Property <%s> has no label\n",
+		             serd_node_get_string(pred));
+	}
+
+	if (is_DatatypeProperty && serd_node_get_type(obj) != SERD_LITERAL) {
+		st = VERROR(statement, "Datatype property with non-literal value\n");
+	}
+
+	if (is_ObjectProperty && serd_node_get_type(obj) == SERD_LITERAL) {
+		st = VERROR(statement, "Object property with literal value\n");
+	}
+
+	if (is_FunctionalProperty) {
+		SerdRange*     o = serd_model_range(model, subj, pred, NULL, NULL);
+		const uint64_t n = count_non_blanks(o, SERD_OBJECT);
+		if (n > 1) {
+			st = VERRORF(statement, "Functional property with %u objects\n", n);
+		}
+		serd_range_free(o);
+	}
+
+	if (is_InverseFunctionalProperty) {
+		SerdRange*     s = serd_model_range(model, NULL, pred, obj, NULL);
+		const unsigned n = count_non_blanks(s, SERD_SUBJECT);
+		if (n > 1) {
+			st = VERRORF(statement,
+			             "Inverse functional property with %u subjects\n",
+			             n);
+		}
+		serd_range_free(s);
+	}
+
+	if (serd_node_get_type(obj) == SERD_LITERAL &&
+	    !literal_is_valid(
+	            model, uris, statement, obj, serd_node_get_datatype(obj))) {
+		/* st = VERRORF(statement, "Literal does not match datatype\n"); */
+	}
+
+	// Check range
+	SerdRange* r = serd_model_range(model, pred, uris->rdfs_range, NULL, NULL);
+	SERD_FOREACH (s, r) {
+		const SerdNode* range = serd_statement_get_object(s);
+		if (has_explicit_type(model, uris, obj, range)) {
+			continue; // Explicit type will be checked, avoid duplicate reports
+		}
+
+		if (!check_type(model, uris, statement, obj, range)) {
+			VNOTEF(serd_range_front(r),
+			       "Range of <%s> defined here\n",
+			       serd_node_get_string(pred));
+		}
+	}
+	serd_range_free(r);
+
+	// Check domain
+	SerdRange* d = serd_model_range(model, pred, uris->rdfs_domain, NULL, NULL);
+	SERD_FOREACH (s, d) {
+		const SerdNode* domain = serd_statement_get_object(s);
+		if (has_explicit_type(model, uris, subj, domain)) {
+			continue; // Explicit type will be checked, avoid duplicate reports
+		}
+
+		if (!check_type(model, uris, statement, subj, domain)) {
+			VNOTEF(serd_range_front(d),
+			       "Domain of <%s> defined here\n",
+			       serd_node_get_string(pred));
+		}
+	}
+	serd_range_free(d);
+
+	return st;
+}
+
+static int
+check_properties(SerdModel* model, URIs* uris)
+{
+	int        st = 0;
+	SerdRange* i  = serd_model_range(model, NULL, NULL, NULL, NULL);
+	SERD_FOREACH (statement, i) {
+		st = check_statement(model, uris, statement) || st;
+	}
+	serd_range_free(i);
+
+	return st;
+}
+
+static int
+cardinality_error(const SerdStatement* statement,
+                  const SerdStatement* restriction_statement,
+                  const SerdNode*      property,
+                  const SerdNode*      instance,
+                  const unsigned       actual_values,
+                  const char*          comparison,
+                  const unsigned       expected_values)
+{
+	const int st = VERRORF(statement,
+	                       "Property <%s> has %u %s %u values\n",
+	                       serd_node_get_string(property),
+	                       actual_values,
+	                       comparison,
+	                       expected_values);
+	VNOTE(restriction_statement, "Restriction here\n");
+	return st;
+}
+
+static int
+check_class_restriction(SerdModel*           model,
+                        const URIs*          uris,
+                        const SerdNode*      restriction,
+                        const SerdStatement* statement,
+                        const SerdNode*      instance)
+{
+	int             st   = 0;
+	const SerdNode* prop = serd_model_get(
+	        model, restriction, uris->owl_onProperty, NULL, NULL);
+	if (!prop) {
+		return 0;
+	}
+
+	const unsigned values = serd_model_count(model, instance, prop, NULL, NULL);
+
+	// Check exact cardinality
+	const SerdStatement* c = serd_model_get_statement(
+	        model, restriction, uris->owl_cardinality, NULL, NULL);
+	if (c) {
+		const SerdNode* card  = serd_statement_get_object(c);
+		const unsigned  count = atoi(serd_node_get_string(card));
+		if (check(values != count)) {
+			st = cardinality_error(
+			        statement, c, prop, instance, values, "!=", count);
+		}
+	}
+
+	// Check minimum cardinality
+	const SerdStatement* l = serd_model_get_statement(
+	        model, restriction, uris->owl_minCardinality, NULL, NULL);
+	if (l) {
+		const SerdNode* card  = serd_statement_get_object(l);
+		const unsigned  count = atoi(serd_node_get_string(card));
+		if (check(values < count)) {
+			st = cardinality_error(
+			        statement, l, prop, instance, values, "<", count);
+		}
+	}
+
+	// Check maximum cardinality
+	const SerdStatement* u = serd_model_get_statement(
+	        model, restriction, uris->owl_maxCardinality, NULL, NULL);
+	if (u) {
+		const SerdNode* card  = serd_statement_get_object(u);
+		const unsigned  count = atoi(serd_node_get_string(card));
+		if (check(values > count)) {
+			st = cardinality_error(
+			        statement, u, prop, instance, values, ">", count);
+		}
+	}
+
+	// Check someValuesFrom
+	const SerdStatement* s = serd_model_get_statement(
+		model, restriction, uris->owl_someValuesFrom, 0, 0);
+	if (s) {
+		const SerdNode* some = serd_statement_get_object(s);
+
+		SerdRange* v     = serd_model_range(model, instance, prop, NULL, NULL);
+		bool       found = false;
+		SERD_FOREACH (i, v) {
+			const SerdNode* value = serd_statement_get_object(i);
+			if (check_type(model, uris, statement, value, some)) {
+				found = true;
+				break;
+			}
+		}
+		if (check(!found)) {
+			st = VERRORF(statement,
+			             "%s has no <%s> values of type <%s>\n",
+			             serd_node_get_string(instance),
+			             serd_node_get_string(prop),
+			             serd_node_get_string(some));
+			VNOTE(s, "Restriction here\n");
+		}
+		serd_range_free(v);
+	}
+
+	// Check allValuesFrom
+	const SerdStatement* a = serd_model_get_statement(
+		model, restriction, uris->owl_allValuesFrom, 0, 0);
+	if (a) {
+		++n_restrictions;
+		const SerdNode* all = serd_statement_get_object(a);
+
+		SerdRange* v = serd_model_range(model, instance, prop, NULL, NULL);
+		SERD_FOREACH (i, v) {
+			const SerdNode* value = serd_statement_get_object(i);
+			if (!check_type(model, uris, statement, value, all)) {
+				st = VERRORF(i,
+				             "<%s> value not of type <%s>\n",
+				             serd_node_get_string(prop),
+				             serd_node_get_string(all));
+				VNOTE(a, "Restriction here\n");
+				break;
+			}
+		}
+		serd_range_free(v);
+	}
+
+	return st;
+}
+
+static int
+missing_arg(const char* name, char opt)
+{
+	CERRORF("option requires an argument -- '%c'\n", opt);
+	return print_usage(name, true);
+}
+
+static void
+init_uris(URIs* uris)
+{
+#define URI(prefix, suffix)                                                    \
+	uris->prefix##_##suffix = serd_new_uri(NS_##prefix #suffix)
+
+	URI(foaf, Document);
+	URI(owl, Class);
+	URI(owl, DatatypeProperty);
+	URI(owl, FunctionalProperty);
+	URI(owl, InverseFunctionalProperty);
+	URI(owl, ObjectProperty);
+	URI(owl, Restriction);
+	URI(owl, Thing);
+	URI(owl, allValuesFrom);
+	URI(owl, cardinality);
+	URI(owl, equivalentClass);
+	URI(owl, maxCardinality);
+	URI(owl, minCardinality);
+	URI(owl, onDatatype);
+	URI(owl, onProperty);
+	URI(owl, someValuesFrom);
+	URI(owl, withRestrictions);
+	URI(rdf, PlainLiteral);
+	URI(rdf, Property);
+	URI(rdf, first);
+	URI(rdf, rest);
+	URI(rdf, type);
+	URI(rdfs, Class);
+	URI(rdfs, Datatype);
+	URI(rdfs, Literal);
+	URI(rdfs, Resource);
+	URI(rdfs, domain);
+	URI(rdfs, label);
+	URI(rdfs, range);
+	URI(rdfs, subClassOf);
+	URI(xsd, anyURI);
+	URI(xsd, float);
+	URI(xsd, decimal);
+	URI(xsd, double);
+	URI(xsd, maxExclusive);
+	URI(xsd, maxInclusive);
+	URI(xsd, minExclusive);
+	URI(xsd, minInclusive);
+	URI(xsd, pattern);
+	URI(xsd, string);
+}
+
+int
+main(int argc, char** argv)
+{
+	if (argc < 2) {
+		return print_usage(argv[0], true);
+	}
+
+	int  a          = 1;
+	long stack_size = 4194304;
+	for (; a < argc && argv[a][0] == '-'; ++a) {
+		if (argv[a][1] == 'h') {
+			return print_usage(argv[0], false);
+		} else if (argv[a][1] == 'k') {
+			if (++a == argc) {
+				return missing_arg(argv[0], 'k');
+			}
+			stack_size = strtol(argv[a], NULL, 10);
+			if (stack_size <= 0 || stack_size == LONG_MAX) {
+				CERRORF("stack size `%ld' out of range\n", stack_size);
+				return 1;
+			}
+		} else if (argv[a][1] == 'v') {
+			return print_version();
+		} else {
+			CERRORF("invalid option -- '%s'\n", argv[a] + 1);
+			return print_usage(argv[0], true);
+		}
+	}
+
+	SerdWorld*    world    = serd_world_new();
+	SerdModel*    model    = serd_model_new(world, SERD_SPO | SERD_OPS, false);
+	SerdEnv*      env      = serd_env_new(NULL);
+	SerdInserter* inserter = serd_inserter_new(model, env, NULL);
+	SerdReader*   reader   = serd_reader_new(
+            world, SERD_TURTLE, serd_inserter_get_sink(inserter), stack_size);
+
+	for (; a < argc; ++a) {
+		const char* input   = argv[a];
+		char*       in_path = absolute_path(input);
+
+		if (!in_path) {
+			CERRORF("unable to open file %s\n", input);
+			continue;
+		}
+
+		SerdNode* base_uri_node = serd_new_file_uri(in_path, NULL);
+
+		serd_env_set_base_uri(env, base_uri_node);
+		SerdStatus st = serd_reader_start_file(reader, input, true);
+		st            = serd_reader_read_document(reader);
+		st            = serd_reader_finish(reader);
+
+		if (st) {
+			CERRORF("error reading %s: %s\n", in_path, serd_strerror(st));
+			return 1;
+		}
+
+		serd_node_free(base_uri_node);
+		free(in_path);
+	}
+	serd_reader_free(reader);
+	serd_env_free(env);
+
+	URIs uris;
+	init_uris(&uris);
+
+#ifndef HAVE_PCRE
+	fprintf(stderr, "warning: Built without PCRE, datatypes not checked.\n");
+#endif
+
+	const int st = check_properties(model, &uris);
+
+	printf("Found %d errors among %d files (checked %d restrictions)\n",
+	       n_errors,
+	       argc - 1,
+	       n_restrictions);
+
+	serd_model_free(model);
+	serd_world_free(world);
+
+	return !st && n_errors == 0 ? 0 : 2;
+}
diff --git a/wscript b/wscript
index 14706fd7..7ceec45b 100644
--- a/wscript
+++ b/wscript
@@ -67,6 +67,19 @@ def configure(conf):
                                    defines     = ['_POSIX_C_SOURCE=200809L'],
                                    mandatory   = False)
 
+    autowaf.check_pkg(conf, 'libpcre', uselib_store='PCRE', mandatory=False)
+    if conf.env.HAVE_PCRE:
+        if conf.check(cflags=['-pthread'], mandatory=False):
+            conf.env.PTHREAD_CFLAGS = ['-pthread']
+            if conf.env.CC_NAME != 'clang':
+                conf.env.PTHREAD_LINKFLAGS = ['-pthread']
+        elif conf.check(linkflags=['-lpthread'], mandatory=False):
+            conf.env.PTHREAD_CFLAGS    = []
+            conf.env.PTHREAD_LINKFLAGS = ['-lpthread']
+        else:
+            conf.env.PTHREAD_CFLAGS    = []
+            conf.env.PTHREAD_LINKFLAGS = []
+
     dump = Options.options.dump.split(',')
     if 'all' in dump or 'iter' in dump:
         conf.define('SERD_DEBUG_ITER', 1)
@@ -180,18 +193,24 @@ def build(bld):
 
     # Utilities
     if bld.env.BUILD_UTILS:
-        obj = bld(features     = 'c cprogram',
-                  source       = 'src/serdi.c',
-                  target       = 'serdi',
-                  includes     = ['.', './src'],
-                  use          = 'libserd',
-                  lib          = lib_args['lib'],
-                  install_path = '${BINDIR}')
-        if not bld.env.BUILD_SHARED or bld.env.STATIC_PROGS:
-            obj.use = 'libserd_static'
-        if bld.env.STATIC_PROGS:
-            obj.env.SHLIB_MARKER = obj.env.STLIB_MARKER
-            obj.linkflags        = ['-static']
+        for i in ['serdi', 'serd_validate']:
+            obj = bld(features     = 'c cprogram',
+                      source       = 'src/%s.c' % i,
+                      target       = i,
+                      includes     = ['.', './src'],
+                      use          = 'libserd',
+                      lib          = lib_args['lib'],
+                      linkflags    = [],
+                      install_path = '${BINDIR}')
+            if not bld.env.BUILD_SHARED or bld.env.STATIC_PROGS:
+                obj.use = 'libserd_static'
+            if bld.env.STATIC_PROGS:
+                obj.env.SHLIB_MARKER  = obj.env.STLIB_MARKER
+                obj.linkflags        += ['-static']
+            if i == 'serd_validate':
+                autowaf.use_lib(bld, obj, 'PCRE')
+                obj.cflags     = bld.env.PTHREAD_CFLAGS
+                obj.linkflags += bld.env.PTHREAD_LINKFLAGS
 
     # Documentation
     autowaf.build_dox(bld, 'SERD', SERD_VERSION, top, out)