Add function to SerdSink for freeing opaque handle

This can be used to associate dynamically allocated data with a sink and have
it managed along with the sink's lifetime.

8 files changed, 33 insertions, 12 deletions

diff --git a/serd/serd.h b/serd/serd.h
index 7cf55f53..0ace8671 100644
--- a/serd/serd.h
+++ b/serd/serd.h
@@ -1102,6 +1102,9 @@ serd_env_write_prefixes(const SerdEnv* env, const SerdSink* sink);
    @{
 */
 
+/// Function to free an opaque handle
+typedef void (*SerdFreeFunc)(void* ptr);
+
 /**
    Create a new sink
 
@@ -1109,11 +1112,12 @@ serd_env_write_prefixes(const SerdEnv* env, const SerdSink* sink);
    serd_sink_set_*_func functions to set handlers for various events.
 
    @param handle Opaque handle that will be passed to sink functions.
+   @param free_handle Free function to call on handle in serd_sink_free().
    @param env Environment for sink, updated as base uri or prefixes change.
 */
 SERD_API
 SerdSink*
-serd_sink_new(void* handle, SerdEnv* env);
+serd_sink_new(void* handle, SerdFreeFunc free_handle, SerdEnv* env);
 
 /// Free `sink`
 SERD_API
diff --git a/serd/serd.hpp b/serd/serd.hpp
index f0b55fe5..190f5eb1 100644
--- a/serd/serd.hpp
+++ b/serd/serd.hpp
@@ -1050,7 +1050,7 @@ public:
 class Sink : public SinkWrapper<SerdSink>
 {
 public:
-	Sink() : SinkWrapper(serd_sink_new(this, nullptr)) {}
+	Sink() : SinkWrapper(serd_sink_new(this, nullptr, nullptr)) {}
 
 	// EnvView env() const { return serd_sink_get_env(cobj()); }
 
diff --git a/src/sink.c b/src/sink.c
index e62136d9..1477412b 100644
--- a/src/sink.c
+++ b/src/sink.c
@@ -23,12 +23,13 @@
 #include <stdlib.h>
 
 SerdSink*
-serd_sink_new(void* handle, SerdEnv* env)
+serd_sink_new(void* handle, SerdFreeFunc free_handle, SerdEnv* env)
 {
 	SerdSink* sink = (SerdSink*)calloc(1, sizeof(SerdSink));
 
-	sink->handle = handle;
-	sink->env    = env;
+	sink->handle      = handle;
+	sink->free_handle = free_handle;
+	sink->env         = env;
 
 	return sink;
 }
@@ -36,7 +37,13 @@ serd_sink_new(void* handle, SerdEnv* env)
 void
 serd_sink_free(SerdSink* sink)
 {
-	free(sink);
+	if (sink) {
+		if (sink->free_handle) {
+			sink->free_handle(sink->handle);
+		}
+
+		free(sink);
+	}
 }
 
 const SerdEnv*
diff --git a/src/sink.h b/src/sink.h
index 1aeafc0a..a4349bbf 100644
--- a/src/sink.h
+++ b/src/sink.h
@@ -24,6 +24,7 @@
 */
 struct SerdSinkImpl {
 	void*             handle;
+	SerdFreeFunc      free_handle;
 	SerdEnv*          env;
 	SerdBaseFunc      base;
 	SerdPrefixFunc    prefix;
diff --git a/tests/overflow_test.c b/tests/overflow_test.c
index e3031b7e..98582597 100644
--- a/tests/overflow_test.c
+++ b/tests/overflow_test.c
@@ -58,7 +58,7 @@ main(void)
 	                      {NULL, 0}};
 
 	SerdWorld* world = serd_world_new();
-	SerdSink*  sink  = serd_sink_new(NULL, NULL);
+	SerdSink*  sink  = serd_sink_new(NULL, NULL, NULL);
 
 	for (const Test* t = tests; t->str; ++t) {
 		const SerdStatus st = test(world, sink, t->str, t->stack_size);
diff --git a/tests/read_chunk_test.c b/tests/read_chunk_test.c
index f38f4cb8..c05b3591 100644
--- a/tests/read_chunk_test.c
+++ b/tests/read_chunk_test.c
@@ -74,7 +74,7 @@ int
 main(void)
 {
 	SerdWorld* world = serd_world_new();
-	SerdSink*  sink  = serd_sink_new(NULL, NULL);
+	SerdSink*  sink  = serd_sink_new(NULL, NULL, NULL);
 	serd_sink_set_base_func(sink, on_base);
 	serd_sink_set_prefix_func(sink, on_prefix);
 	serd_sink_set_statement_func(sink, on_statement);
diff --git a/tests/serd_test.c b/tests/serd_test.c
index fe24f64a..1d05a789 100644
--- a/tests/serd_test.c
+++ b/tests/serd_test.c
@@ -106,7 +106,7 @@ test_read_chunks(void)
 	size_t            n_statements = 0;
 	FILE* const       f            = tmpfile();
 	static const char null         = 0;
-	SerdSink*         sink         = serd_sink_new(&n_statements, NULL);
+	SerdSink*         sink         = serd_sink_new(&n_statements, NULL, NULL);
 
 	assert(sink);
 	serd_sink_set_statement_func(sink, count_statements);
@@ -585,7 +585,7 @@ test_env(void)
 	assert(serd_env_set_prefix(env, b, lit));
 
 	size_t    n_prefixes          = 0;
-	SerdSink* count_prefixes_sink = serd_sink_new(&n_prefixes, NULL);
+	SerdSink* count_prefixes_sink = serd_sink_new(&n_prefixes, NULL, NULL);
 	serd_sink_set_prefix_func(count_prefixes_sink, count_prefixes);
 	serd_env_set_prefix(env, pre, eg);
 	serd_env_write_prefixes(env, count_prefixes_sink);
@@ -754,7 +754,7 @@ test_reader(const char* path)
 	SerdWorld*  world  = serd_world_new();
 
 	size_t    n_statements = 0;
-	SerdSink* sink         = serd_sink_new(&n_statements, NULL);
+	SerdSink* sink         = serd_sink_new(&n_statements, NULL, NULL);
 	serd_sink_set_statement_func(sink, count_statements);
 
 	SerdReader* reader = serd_reader_new(world, SERD_TURTLE, 0, sink, 4096);
diff --git a/tests/sink_test.c b/tests/sink_test.c
index fd38fc99..46bbd27c 100644
--- a/tests/sink_test.c
+++ b/tests/sink_test.c
@@ -20,6 +20,7 @@
 
 #include <assert.h>
 #include <stddef.h>
+#include <string.h>
 
 #define NS_EG "http://example.org/"
 
@@ -33,6 +34,12 @@ typedef struct
 	SerdStatus           return_status;
 } State;
 
+static void
+clear_state(void* ptr)
+{
+	memset(ptr, 0, sizeof(State));
+}
+
 static SerdStatus
 on_base(void* handle, const SerdNode* uri)
 {
@@ -89,7 +96,7 @@ main(void)
 		serd_statement_new(base, uri, blank, NULL, NULL);
 
 	State     state = {0, 0, 0, 0, 0, SERD_SUCCESS};
-	SerdSink* sink  = serd_sink_new(&state, env);
+	SerdSink* sink  = serd_sink_new(&state, clear_state, env);
 
 	assert(serd_sink_get_env(sink) == env);
 
@@ -121,6 +128,8 @@ main(void)
 	assert(serd_node_equals(state.last_end, blank));
 
 	serd_sink_free(sink);
+	assert(!state.last_base);
+
 	serd_statement_free(statement);
 	serd_env_free(env);
 	serd_nodes_free(nodes);