From f0f4bfb37f36fce6d6e216a90162b81691f61e83 Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Sat, 12 May 2018 17:56:27 +0200
Subject: Add serd_world_get_blank()

---
 include/serd/serd.h       | 10 ++++++++++
 src/world.c               | 26 ++++++++++++++++++++++++--
 src/world.h               |  3 +++
 test/test_reader_writer.c | 18 ++++++++++++++++++
 4 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/include/serd/serd.h b/include/serd/serd.h
index d57f1470..3d08eb07 100644
--- a/include/serd/serd.h
+++ b/include/serd/serd.h
@@ -870,6 +870,16 @@ 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.
 
diff --git a/src/world.c b/src/world.c
index 73bc9927..9503c578 100644
--- a/src/world.c
+++ b/src/world.c
@@ -18,6 +18,7 @@
 
 #include "world.h"
 
+#include "node.h"
 #include "serd_config.h"
 
 #if defined(USE_POSIX_FADVISE)
@@ -30,6 +31,8 @@
 #include <stdlib.h>
 #include <string.h>
 
+#define BLANK_CHARS 12
+
 FILE*
 serd_world_fopen(SerdWorld* world, const char* path, const char* mode)
 {
@@ -78,13 +81,32 @@ 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_new_blank(SERD_STATIC_STRING("b00000000000"));
+
+  return world;
 }
 
 void
 serd_world_free(SerdWorld* world)
 {
-  free(world);
+  if (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 =
+    (size_t)snprintf(buf, BLANK_CHARS + 1, "b%u", ++world->next_blank_id);
+
+  return world->blank_node;
 }
 
 void
diff --git a/src/world.h b/src/world.h
index ab7aad80..99f0c92d 100644
--- a/src/world.h
+++ b/src/world.h
@@ -19,11 +19,14 @@
 
 #include "serd/serd.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/test_reader_writer.c b/test/test_reader_writer.c
index 48f20247..43b820db 100644
--- a/test/test_reader_writer.c
+++ b/test/test_reader_writer.c
@@ -140,6 +140,23 @@ test_read_chunks(void)
   serd_world_free(world);
 }
 
+static int
+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);
+  return 0;
+}
+
 static void
 test_read_string(void)
 {
@@ -358,6 +375,7 @@ main(void)
 {
   test_read_chunks();
   test_read_string();
+  test_get_blank();
 
   const char* const path = "serd_test.ttl";
   test_writer(path);
-- 
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