Add serd_world_get_blank()

4 files changed, 52 insertions, 1 deletions

diff --git a/serd/serd.h b/serd/serd.h
index 6be31a2b..79cd53dc 100644
--- a/serd/serd.h
+++ b/serd/serd.h
@@ -749,6 +749,16 @@ void
 serd_world_free(SerdWorld* world);
 
 /**
+   Return a unique blank node.
+
+   The returned node is valid only until the next time serd_world_get_blank()
+   is called or the world is destroyed.
+*/
+SERD_API
+const SerdNode*
+serd_world_get_blank(SerdWorld* world);
+
+/**
    Set a function to be called when errors occur.
 
    The `error_sink` will be called with `handle` as its first argument.  If
diff --git a/src/world.c b/src/world.c
index f95accf4..9908e4d4 100644
--- a/src/world.c
+++ b/src/world.c
@@ -18,6 +18,7 @@
 
 #include "world.h"
 
+#include "node.h"
 #include "serd_config.h"
 
 #include <errno.h>
@@ -29,6 +30,8 @@
 #   include <fcntl.h>
 #endif
 
+#define BLANK_CHARS 11
+
 FILE*
 serd_world_fopen(SerdWorld* world, const char* path, const char* mode)
 {
@@ -71,15 +74,30 @@ serd_world_errorf(const SerdWorld* world, SerdStatus st, const char* fmt, ...)
 SerdWorld*
 serd_world_new(void)
 {
-	return (SerdWorld*)calloc(1, sizeof(SerdWorld));
+	SerdWorld* world = (SerdWorld*)calloc(1, sizeof(SerdWorld));
+
+	world->blank_node = serd_node_new_blank("b0000000000");
+
+	return world;
 }
 
 void
 serd_world_free(SerdWorld* world)
 {
+	serd_node_free(world->blank_node);
 	free(world);
 }
 
+const SerdNode*
+serd_world_get_blank(SerdWorld* world)
+{
+	char* buf = serd_node_buffer(world->blank_node);
+	memset(buf, 0, BLANK_CHARS + 1);
+	world->blank_node->n_bytes = snprintf(
+		buf, BLANK_CHARS, "b%u", ++world->next_blank_id);
+	return world->blank_node;
+}
+
 void
 serd_world_set_error_sink(SerdWorld*    world,
                           SerdErrorSink error_sink,
diff --git a/src/world.h b/src/world.h
index 85b676ee..99ef27b8 100644
--- a/src/world.h
+++ b/src/world.h
@@ -24,6 +24,8 @@
 struct SerdWorldImpl {
 	SerdErrorSink error_sink;
 	void*         error_handle;
+	uint32_t      next_blank_id;
+	SerdNode*     blank_node;
 };
 
 FILE* serd_world_fopen(SerdWorld* world, const char* path, const char* mode);
diff --git a/tests/serd_test.c b/tests/serd_test.c
index e8d535a3..dbadb5bf 100644
--- a/tests/serd_test.c
+++ b/tests/serd_test.c
@@ -123,6 +123,23 @@ check_rel_uri(const char*     uri,
 	return ret;
 }
 
+static int
+test_get_blank(void)
+{
+	SerdWorld* world = serd_world_new();
+	char       expected[8];
+
+	for (unsigned i = 0; i < 32; ++i) {
+		const SerdNode* blank = serd_world_get_blank(world);
+
+		snprintf(expected, sizeof(expected), "b%u", i + 1);
+		assert(!strcmp(serd_node_get_string(blank), expected));
+	}
+
+	serd_world_free(world);
+	return 0;
+}
+
 int
 main(void)
 {
@@ -379,6 +396,10 @@ main(void)
 
 	SerdWorld* world = serd_world_new();
 
+	if (test_get_blank()) {
+		return 1;
+	}
+
 	SerdNode* u   = serd_node_new_uri("http://example.org/foo");
 	SerdNode* b   = serd_node_new_curie("invalid");
 	SerdNode* c   = serd_node_new_curie("eg.2:b");