Add sord_node_get() for easily getting single property values.

git-svn-id: http://svn.drobilla.net/sord/trunk@280 3d64ff67-21c5-427c-a301-fe4f08042e5a

5 files changed, 72 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index a442b33..fe6c359 100644
--- a/NEWS
+++ b/NEWS
@@ -1,11 +1,12 @@
 sord (0.10.5) unstable;
 
   * Update to waf 1.7.8 and autowaf r90 (install docs to versioned directory)
+  * Add sord_node_get() for easily getting single property values
   * sordmm.hpp: Add convenient constructors for decimal and integer literals
   * sordmm.hpp: Add Node::to_serd_node()
   * sordmm.hpp: Don't automatically add RDF namespace prefix to world
 
- -- David Robillard <d@drobilla.net>  Mon, 14 Jan 2013 01:24:56 -0500
+ -- David Robillard <d@drobilla.net>  Mon, 14 Jan 2013 01:52:25 -0500
 
 sord (0.10.4) stable;
 
diff --git a/sord/sord.h b/sord/sord.h
index 8f1ef38..ee49764 100644
--- a/sord/sord.h
+++ b/sord/sord.h
@@ -397,6 +397,19 @@ sord_search(SordModel*      model,
             const SordNode* p,
             const SordNode* o,
             const SordNode* g);
+/**
+   Search for a single node that matches a pattern.
+   Exactly one of @p s, @p p, @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.
+*/
+SORD_API
+const SordNode*
+sord_get(SordModel*      model,
+         const SordNode* s,
+         const SordNode* p,
+         const SordNode* o,
+         const SordNode* g);
 
 /**
    Return true iff a statement exists.
diff --git a/sord/sordmm.hpp b/sord/sordmm.hpp
index 4ab25e2..da1e49c 100644
--- a/sord/sordmm.hpp
+++ b/sord/sordmm.hpp
@@ -466,6 +466,10 @@ public:
 	                 const Node& predicate,
 	                 const Node& object);
 
+	inline Node get(const Node& subject,
+	                const Node& predicate,
+	                const Node& object);
+
 	inline World& world() const { return _world; }
 
 private:
@@ -631,6 +635,18 @@ Model::find(const Node& subject,
 	return Iter(_world, sord_find(_c_obj, quad));
 }
 
+inline Node
+Model::get(const Node& subject,
+           const Node& predicate,
+           const Node& object)
+{
+	return Node(_world, sord_get(_c_obj,
+	                             subject.c_obj(),
+	                             predicate.c_obj(),
+	                             object.c_obj(),
+	                             NULL));
+}
+
 }  // namespace Sord
 
 #endif  // SORD_SORDMM_HPP
diff --git a/src/sord.c b/src/sord.c
index 9510d50..cad3c4d 100644
--- a/src/sord.c
+++ b/src/sord.c
@@ -844,6 +844,31 @@ sord_search(SordModel*      model,
 	return sord_find(model, pat);
 }
 
+const SordNode*
+sord_get(SordModel*      model,
+         const SordNode* s,
+         const SordNode* p,
+         const SordNode* o,
+         const SordNode* g)
+{
+	if ((bool)s + (bool)p + (bool)o != 2) {
+		return NULL;
+	}
+
+	SordIter*       i   = sord_search(model, s, p, o, g);
+	const SordNode* ret = NULL;
+	if (!s) {
+		ret = sord_iter_get_node(i, SORD_SUBJECT);
+	} else if (!p) {
+		ret = sord_iter_get_node(i, SORD_PREDICATE);
+	} else if (!o) {
+		ret = sord_iter_get_node(i, SORD_OBJECT);
+	}
+
+	sord_iter_free(i);
+	return ret;
+}
+
 bool
 sord_ask(SordModel*      model,
          const SordNode* s,
diff --git a/src/sord_test.c b/src/sord_test.c
index a7a74e5..36fc408 100644
--- a/src/sord_test.c
+++ b/src/sord_test.c
@@ -238,6 +238,22 @@ test_read(SordWorld* world, SordModel* sord, SordNode* g,
 		                 TUP_FMT_ARGS(nomatch));
 	}
 
+	if (sord_get(sord, NULL, NULL, uri(world, 3), g)) {
+		return test_fail("Fail: Get *,*,3 succeeded\n");
+	} else if (!sord_node_equals(
+		           sord_get(sord, uri(world, 1), uri(world, 2), NULL, g),
+		           uri(world, 3))) {
+		return test_fail("Fail: Get 1,2,* != 3\n");
+	} else if (!sord_node_equals(
+		           sord_get(sord, uri(world, 1), NULL, uri(world, 3), g),
+		           uri(world, 2))) {
+		return test_fail("Fail: Get 1,*,3 != 2\n");
+	} else if (!sord_node_equals(
+		           sord_get(sord, NULL, uri(world, 2), uri(world, 3), g),
+		           uri(world, 1))) {
+		return test_fail("Fail: Get *,2,3 != 1\n");
+	}
+
 	for (unsigned i = 0; i < NUM_PATTERNS; ++i) {
 		QueryTest test = patterns[i];
 		SordQuad  pat = { test.query[0], test.query[1], test.query[2], g };