5 files changed, 86 insertions, 2 deletions

diff --git a/include/serd/world.h b/include/serd/world.h
index 22ae57ed..abf2999c 100644
--- a/include/serd/world.h
+++ b/include/serd/world.h
@@ -6,6 +6,7 @@
 
 #include "serd/attributes.h"
 #include "serd/error.h"
+#include "serd/node.h"
 
 SERD_BEGIN_DECLS
 
@@ -32,6 +33,15 @@ SERD_API void
 serd_world_free(SerdWorld* SERD_NULLABLE 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_NONNULL
+serd_world_get_blank(SerdWorld* SERD_NONNULL world);
+
+/**
    Set a function to be called when errors occur.
 
    The `error_func` will be called with `handle` as its first argument.  If
diff --git a/src/world.c b/src/world.c
index c3c3660f..ececd646 100644
--- a/src/world.c
+++ b/src/world.c
@@ -3,9 +3,12 @@
 
 #include "world.h"
 
+#include "node.h"
 #include "serd_config.h"
 #include "system.h"
 
+#include "serd/string_view.h"
+
 #if defined(USE_POSIX_FADVISE)
 #  include <fcntl.h>
 #endif
@@ -14,6 +17,7 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 FILE*
 serd_world_fopen(SerdWorld* world, const char* path, const char* mode)
@@ -83,13 +87,43 @@ serd_world_errorf(const SerdWorld* const world,
 SerdWorld*
 serd_world_new(void)
 {
-  return (SerdWorld*)calloc(1, sizeof(SerdWorld));
+  SerdWorld* world      = (SerdWorld*)calloc(1, sizeof(SerdWorld));
+  SerdNode*  blank_node = serd_new_blank(serd_string("b00000000000"));
+
+  if (!world || !blank_node) {
+    serd_node_free(blank_node);
+    free(world);
+    return NULL;
+  }
+
+  world->blank_node = blank_node;
+
+  return world;
 }
 
 void
 serd_world_free(SerdWorld* const world)
 {
-  free(world);
+  if (world) {
+    serd_node_free(world->blank_node);
+    free(world);
+  }
+}
+
+const SerdNode*
+serd_world_get_blank(SerdWorld* const world)
+{
+#define BLANK_CHARS 12
+
+  char* buf = serd_node_buffer(world->blank_node);
+  memset(buf, 0, BLANK_CHARS + 1);
+
+  world->blank_node->length =
+    (size_t)snprintf(buf, BLANK_CHARS + 1, "b%u", ++world->next_blank_id);
+
+  return world->blank_node;
+
+#undef BLANK_CHARS
 }
 
 void
diff --git a/src/world.h b/src/world.h
index dd3d4043..b330d4e4 100644
--- a/src/world.h
+++ b/src/world.h
@@ -5,14 +5,18 @@
 #define SERD_SRC_WORLD_H
 
 #include "serd/error.h"
+#include "serd/node.h"
 #include "serd/status.h"
 #include "serd/world.h"
 
+#include <stdint.h>
 #include <stdio.h>
 
 struct SerdWorldImpl {
   SerdErrorFunc error_func;
   void*         error_handle;
+  uint32_t      next_blank_id;
+  SerdNode*     blank_node;
 };
 
 /// Open a file configured for fast sequential reading
diff --git a/test/meson.build b/test/meson.build
index 0ee7cd23..efcb00f0 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -128,6 +128,7 @@ unit_tests = [
   'string',
   'syntax',
   'uri',
+  'world',
   'writer',
 ]
 
diff --git a/test/test_world.c b/test/test_world.c
new file mode 100644
index 00000000..3f7f6ea6
--- /dev/null
+++ b/test/test_world.c
@@ -0,0 +1,35 @@
+// Copyright 2011-2020 David Robillard <d@drobilla.net>
+// SPDX-License-Identifier: ISC
+
+#undef NDEBUG
+
+#include "serd/node.h"
+#include "serd/world.h"
+
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+static void
+test_get_blank(void)
+{
+  SerdWorld* world = serd_world_new();
+  char       expected[12];
+
+  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_string(blank), expected));
+  }
+
+  serd_world_free(world);
+}
+
+int
+main(void)
+{
+  test_get_blank();
+
+  return 0;
+}