Expose SerdByteSink in public API

5 files changed, 150 insertions, 5 deletions

diff --git a/include/serd/serd.h b/include/serd/serd.h
index dd88a23f..b724e810 100644
--- a/include/serd/serd.h
+++ b/include/serd/serd.h
@@ -102,6 +102,9 @@ typedef struct SerdWriterImpl SerdWriter;
 /// An interface that receives a stream of RDF data
 typedef struct SerdSinkImpl SerdSink;
 
+/// A sink for bytes that receives string output
+typedef struct SerdByteSinkImpl SerdByteSink;
+
 /// Return status code
 typedef enum {
   SERD_SUCCESS,        ///< No error
@@ -401,6 +404,41 @@ typedef size_t (*SerdWriteFunc)(const void* SERD_NONNULL buf,
                                 void* SERD_NONNULL       stream);
 
 /**
+   Create a new byte sink.
+
+   @param write_func Function called with bytes to consume.
+   @param stream Context parameter passed to `sink`.
+   @param block_size Number of bytes to write per call.
+*/
+SERD_API
+SerdByteSink* SERD_ALLOCATED
+serd_byte_sink_new(SerdWriteFunc SERD_NONNULL write_func,
+                   void* SERD_NULLABLE        stream,
+                   size_t                     block_size);
+
+/**
+   Write to `sink`.
+
+   Compatible with SerdWriteFunc.
+*/
+SERD_API
+size_t
+serd_byte_sink_write(const void* SERD_NONNULL   buf,
+                     size_t                     size,
+                     size_t                     nmemb,
+                     SerdByteSink* SERD_NONNULL sink);
+
+/// Flush any pending output in `sink` to the underlying write function
+SERD_API
+void
+serd_byte_sink_flush(SerdByteSink* SERD_NONNULL sink);
+
+/// Free `sink`
+SERD_API
+void
+serd_byte_sink_free(SerdByteSink* SERD_NULLABLE sink);
+
+/**
    @}
    @defgroup serd_syntax Syntax Utilities
    @{
diff --git a/meson.build b/meson.build
index 05120981..1203b176 100644
--- a/meson.build
+++ b/meson.build
@@ -92,6 +92,7 @@ c_header = files('include/serd/serd.h')
 
 sources = [
   'src/base64.c',
+  'src/byte_sink.c',
   'src/byte_source.c',
   'src/cursor.c',
   'src/env.c',
diff --git a/src/byte_sink.c b/src/byte_sink.c
new file mode 100644
index 00000000..993fb624
--- /dev/null
+++ b/src/byte_sink.c
@@ -0,0 +1,106 @@
+/*
+  Copyright 2011-2020 David Robillard <d@drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "serd_internal.h"
+#include "system.h"
+
+#include "serd/serd.h"
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct SerdByteSinkImpl {
+  SerdWriteFunc sink;
+  void*         stream;
+  char*         buf;
+  size_t        size;
+  size_t        block_size;
+};
+
+SerdByteSink*
+serd_byte_sink_new(SerdWriteFunc write_func, void* stream, size_t block_size)
+{
+  SerdByteSink* sink = (SerdByteSink*)calloc(1, sizeof(SerdByteSink));
+
+  sink->sink       = write_func;
+  sink->stream     = stream;
+  sink->block_size = block_size;
+
+  if (block_size > 1) {
+    sink->buf = (char*)serd_allocate_buffer(block_size);
+  }
+
+  return sink;
+}
+
+size_t
+serd_byte_sink_write(const void*   buf,
+                     size_t        size,
+                     size_t        nmemb,
+                     SerdByteSink* sink)
+{
+  assert(size == 1);
+  (void)size;
+
+  if (nmemb == 0) {
+    return 0;
+  }
+
+  if (sink->block_size == 1) {
+    return sink->sink(buf, 1, nmemb, sink->stream);
+  }
+
+  const size_t orig_len = nmemb;
+  while (nmemb) {
+    const size_t space = sink->block_size - sink->size;
+    const size_t n     = MIN(space, nmemb);
+
+    // Write as much as possible into the remaining buffer space
+    memcpy(sink->buf + sink->size, buf, n);
+    sink->size += n;
+    buf = (const char*)buf + n;
+    nmemb -= n;
+
+    // Flush page if buffer is full
+    if (sink->size == sink->block_size) {
+      sink->sink(sink->buf, 1, sink->block_size, sink->stream);
+      sink->size = 0;
+    }
+  }
+
+  return orig_len;
+}
+
+void
+serd_byte_sink_flush(SerdByteSink* sink)
+{
+  if (sink->block_size > 1 && sink->size > 0) {
+    sink->sink(sink->buf, 1, sink->size, sink->stream);
+    sink->size = 0;
+  }
+}
+
+void
+serd_byte_sink_free(SerdByteSink* sink)
+{
+  if (sink) {
+    serd_byte_sink_flush(sink);
+    free(sink->buf);
+    free(sink);
+  }
+}
diff --git a/src/writer.c b/src/writer.c
index 455c720c..a522e0fb 100644
--- a/src/writer.c
+++ b/src/writer.c
@@ -14,7 +14,6 @@
   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
-#include "byte_sink.h"
 #include "env.h"
 #include "node.h"
 #include "serd_internal.h"
@@ -93,7 +92,7 @@ struct SerdWriterImpl {
   SerdNode*       root_node;
   SerdURIView     root_uri;
   SerdStack       anon_stack;
-  SerdByteSink    byte_sink;
+  SerdByteSink*   byte_sink;
   SerdErrorFunc   error_func;
   void*           error_handle;
   WriteContext    context;
@@ -157,7 +156,7 @@ ctx(SerdWriter* writer, const SerdField field)
 static inline size_t
 sink(const void* buf, size_t len, SerdWriter* writer)
 {
-  return serd_byte_sink_write(buf, len, &writer->byte_sink);
+  return serd_byte_sink_write(buf, 1, len, writer->byte_sink);
 }
 
 // Write a single character, as an escape for single byte characters
@@ -965,7 +964,7 @@ serd_writer_finish(SerdWriter* writer)
   if (ctx(writer, SERD_GRAPH)) {
     write_sep(writer, SEP_GRAPH_END);
   }
-  serd_byte_sink_flush(&writer->byte_sink);
+  serd_byte_sink_flush(writer->byte_sink);
   free_context(writer);
   writer->indent  = 0;
   writer->context = WRITE_CONTEXT_NULL;
@@ -1092,7 +1091,7 @@ serd_writer_free(SerdWriter* writer)
   serd_writer_finish(writer);
   serd_stack_free(&writer->anon_stack);
   free(writer->bprefix);
-  serd_byte_sink_free(&writer->byte_sink);
+  serd_byte_sink_free(writer->byte_sink);
   serd_node_free(writer->root_node);
   free(writer);
 }
diff --git a/test/test_free_null.c b/test/test_free_null.c
index 05be8e4a..f629a285 100644
--- a/test/test_free_null.c
+++ b/test/test_free_null.c
@@ -24,6 +24,7 @@ int
 main(void)
 {
   serd_free(NULL);
+  serd_byte_sink_free(NULL);
   serd_node_free(NULL);
   serd_world_free(NULL);
   serd_env_free(NULL);