From 9a2f489a7f6bc60e3f8ccc3881f3fbf8ebd87eda 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()

---
 serd/serd.h       | 10 ++++++++++
 src/world.c       | 20 +++++++++++++++++++-
 src/world.h       |  2 ++
 tests/serd_test.c | 18 ++++++++++++++++++
 4 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/serd/serd.h b/serd/serd.h
index 5f1c4929..aceb9cdc 100644
--- a/serd/serd.h
+++ b/serd/serd.h
@@ -760,6 +760,16 @@ SERD_API
 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.
 
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 0aaea8fc..201d038f 100644
--- a/src/world.h
+++ b/src/world.h
@@ -25,6 +25,8 @@
 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 f280c22a..81ae33d0 100644
--- a/tests/serd_test.c
+++ b/tests/serd_test.c
@@ -176,6 +176,23 @@ test_read_chunks(void)
 	serd_world_free(world);
 }
 
+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;
+}
+
 static void
 test_string_to_double(void)
 {
@@ -742,6 +759,7 @@ main(void)
 	test_blank();
 	test_env();
 	test_read_chunks();
+	test_get_blank();
 
 	const char* const path = "serd_test.ttl";
 	test_writer(path);
-- 
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