WIP: Add serd_node_from_syntax() and serd_node_to_syntax()

7 files changed, 319 insertions, 2 deletions

diff --git a/serd/serd.h b/serd/serd.h
index bac74adc..a43acbca 100644
--- a/serd/serd.h
+++ b/serd/serd.h
@@ -671,6 +671,44 @@ serd_uri_serialise_relative(const SerdURI* uri,
 */
 
 /**
+   Create a node from a string representation in `syntax`.
+
+   The string should be a node as if written as an object in the given syntax,
+   without any extra quoting or punctuation, which is the format returned by
+   serd_node_to_syntax().  These two functions, when used with #SERD_TURTLE,
+   can be used to round-trip any node to a string and back.
+
+   @param str String representation of a node.
+
+   @param syntax Syntax to use.  Should be either SERD_TURTLE or SERD_NTRIPLES
+   (the others are redundant).  Note that namespaced (CURIE) nodes and relative
+   URIs can not be expressed in NTriples.
+
+   @return A newly allocated node that must be freed with serd_node_free().
+*/
+SERD_API
+SerdNode*
+serd_node_from_syntax(const char* str, SerdSyntax syntax);
+
+/**
+   Return a string representation of `node` in `syntax`.
+
+   The returned string represents that node as if written as an object in the
+   given syntax, without any extra quoting or punctuation.
+
+   @param node Node to serialise.
+
+   @param syntax Syntax to use.  Should be either SERD_TURTLE or SERD_NTRIPLES
+   (the others are redundant).  Note that namespaced (CURIE) nodes and relative
+   URIs can not be expressed in NTriples.
+
+   @return A newly allocated string that must be freed with serd_free().
+*/
+SERD_API
+char*
+serd_node_to_syntax(const SerdNode* node, SerdSyntax syntax);
+
+/**
    Create a new "simple" node that is just a string.
 
    This can be used to create blank, CURIE, or URI nodes from an already
diff --git a/src/node_syntax.c b/src/node_syntax.c
new file mode 100644
index 00000000..10483188
--- /dev/null
+++ b/src/node_syntax.c
@@ -0,0 +1,97 @@
+/*
+  Copyright 2011-2020 David Robillard <http://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 "writer.h"
+
+#include "serd/serd.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static SerdStatus
+on_node_string_event(void* handle, const SerdEvent* event)
+{
+	if (event->type == SERD_STATEMENT) {
+		*(SerdNode**)handle = serd_node_copy(
+		    serd_statement_object(event->statement.statement));
+	}
+
+	return SERD_SUCCESS;
+}
+
+SerdNode*
+serd_node_from_syntax(const char* str, const SerdSyntax syntax)
+{
+	static const char* const prelude =
+	    "_:s <http://www.w3.org/2000/01/rdf-schema#object>";
+
+	const size_t str_len = strlen(str);
+	const size_t doc_len = strlen(prelude) + str_len + 3;
+	char* const  doc     = (char*)calloc(doc_len + 1, 1);
+
+	snprintf(doc, doc_len + 1, "%s %s .", prelude, str);
+
+	SerdNode*   object = NULL;
+	SerdWorld*  world  = serd_world_new();
+	SerdSink*   sink   = serd_sink_new(&object, NULL);
+
+	SerdByteSource* byte_source = serd_byte_source_new_string(doc, NULL);
+
+	SerdReader* reader = serd_reader_new(
+	    world, syntax, SERD_READ_EXACT_BLANKS, sink, 1024 + doc_len);
+
+	serd_world_set_log_func(world, serd_quiet_error_func, NULL);
+	serd_sink_set_event_func(sink, on_node_string_event);
+	serd_reader_start(reader, byte_source);
+	serd_reader_read_document(reader);
+	serd_reader_finish(reader);
+	serd_byte_source_free(byte_source);
+	serd_reader_free(reader);
+	serd_sink_free(sink);
+	serd_world_free(world);
+	free(doc);
+
+	return object;
+}
+
+char*
+serd_node_to_syntax(const SerdNode* node, const SerdSyntax syntax)
+{
+	SerdWorld*    world  = serd_world_new();
+	SerdBuffer    buffer = {NULL, 0};
+	SerdByteSink* bsink  = serd_byte_sink_new_buffer(&buffer);
+	SerdWriter*   writer = serd_writer_new(world, syntax, 0, NULL, bsink);
+
+	serd_world_set_log_func(world, serd_quiet_error_func, NULL);
+
+	SerdStatus st = serd_writer_write_node(writer, node);
+	if (!st) {
+		st = serd_writer_finish(writer);
+	}
+
+	serd_buffer_sink_finish(&buffer);
+	serd_writer_free(writer);
+	serd_byte_sink_free(bsink);
+	serd_world_free(world);
+
+	if (st) {
+		serd_free(buffer.buf);
+		return NULL;
+	}
+
+	return (char*)buffer.buf;
+}
diff --git a/src/writer.c b/src/writer.c
index ed3be4e7..7acf7922 100644
--- a/src/writer.c
+++ b/src/writer.c
@@ -14,6 +14,8 @@
   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
+#include "writer.h"
+
 #include "byte_sink.h"
 #include "env.h"
 #include "node.h"
@@ -1049,6 +1051,12 @@ serd_writer_on_event(SerdWriter* writer, const SerdEvent* event)
 }
 
 SerdStatus
+serd_writer_write_node(SerdWriter* writer, const SerdNode* node)
+{
+	return write_node(writer, node, SERD_OBJECT, 0);
+}
+
+SerdStatus
 serd_writer_finish(SerdWriter* writer)
 {
 	SerdStatus st = SERD_SUCCESS;
diff --git a/src/writer.h b/src/writer.h
new file mode 100644
index 00000000..e86fc775
--- /dev/null
+++ b/src/writer.h
@@ -0,0 +1,21 @@
+/*
+  Copyright 2019-2020 David Robillard <http://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/serd.h"
+
+SerdStatus
+serd_writer_write_node(SerdWriter* writer, const SerdNode* node);
+
diff --git a/tests/node_syntax_test.c b/tests/node_syntax_test.c
new file mode 100644
index 00000000..739a8b94
--- /dev/null
+++ b/tests/node_syntax_test.c
@@ -0,0 +1,150 @@
+/*
+  Copyright 2020 David Robillard <http://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.
+*/
+
+#undef NDEBUG
+
+#include "serd/serd.h"
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+static bool
+test(const SerdSyntax syntax, SerdNode* const node, const char* const expected)
+{
+	char* const     str  = serd_node_to_syntax(node, syntax);
+	SerdNode* const copy = serd_node_from_syntax(str, syntax);
+
+	const bool success = !strcmp(str, expected) && serd_node_equals(copy, node);
+
+	serd_node_free(copy);
+	serd_free(str);
+	serd_node_free(node);
+	return success;
+}
+
+static void
+test_common(const SerdSyntax syntax)
+{
+	static const int data[] = {4, 2};
+
+	SerdNode* const datatype = serd_new_uri("http://example.org/Datatype");
+	SerdNode* const num_type = serd_new_uri("http://example.org/Decimal");
+
+	assert(test(syntax, serd_new_string("node"), "\"node\""));
+
+	assert(test(syntax, serd_new_plain_literal("hallo", "de"), "\"hallo\"@de"));
+
+	assert(test(syntax,
+	            serd_new_typed_literal("X", datatype),
+	            "\"X\"^^<http://example.org/Datatype>"));
+
+	assert(test(syntax, serd_new_blank("blank"), "_:blank"));
+	assert(test(syntax, serd_new_blank("b0"), "_:b0"));
+
+	assert(test(syntax,
+	            serd_new_uri("http://example.org/"),
+	            "<http://example.org/>"));
+
+	assert(test(syntax,
+	            serd_new_decimal(1.25, 4, 2, num_type),
+	            "\"1.25\"^^<http://example.org/Decimal>"));
+
+	assert(test(syntax,
+	            serd_new_double(1.25),
+	            "\"1.25E0\"^^<http://www.w3.org/2001/XMLSchema#double>"));
+
+	assert(test(syntax,
+	            serd_new_float(1.25),
+	            "\"1.25E0\"^^<http://www.w3.org/2001/XMLSchema#float>"));
+
+	assert(test(syntax,
+	            serd_new_integer(1234, num_type),
+	            "\"1234\"^^<http://example.org/Decimal>"));
+
+	assert(test(
+	    syntax,
+	    serd_new_blob(data, sizeof(data), false, NULL),
+	    "\"BAAAAAIAAAA=\"^^<http://www.w3.org/2001/XMLSchema#base64Binary>"));
+
+	serd_node_free(num_type);
+	serd_node_free(datatype);
+}
+
+static void
+test_ntriples(void)
+{
+	SerdNode* const datatype = serd_new_uri("http://example.org/Datatype");
+	SerdNode* const num_type = serd_new_uri("http://example.org/Decimal");
+
+	test_common(SERD_NTRIPLES);
+
+	{
+		// No namespace prefixes in NTriples
+		SerdNode* const curie = serd_new_curie("cu:rie");
+		assert(!serd_node_to_syntax(curie, SERD_NTRIPLES));
+		serd_node_free(curie);
+	}
+
+	{
+		// No relative URIs in NTriples
+		SerdNode* const uri = serd_new_uri("rel/uri");
+		assert(!serd_node_to_syntax(uri, SERD_NTRIPLES));
+		serd_node_free(uri);
+	}
+
+	assert(test(SERD_NTRIPLES,
+	            serd_new_decimal(1.25, 4, 2, NULL),
+	            "\"1.25\"^^<http://www.w3.org/2001/XMLSchema#decimal>"));
+
+	assert(test(SERD_NTRIPLES,
+	            serd_new_integer(1234, NULL),
+	            "\"1234\"^^<http://www.w3.org/2001/XMLSchema#integer>"));
+
+	assert(test(SERD_NTRIPLES,
+	            serd_new_boolean(true),
+	            "\"true\"^^<http://www.w3.org/2001/XMLSchema#boolean>"));
+
+	assert(test(SERD_NTRIPLES,
+	            serd_new_boolean(false),
+	            "\"false\"^^<http://www.w3.org/2001/XMLSchema#boolean>"));
+
+	serd_node_free(num_type);
+	serd_node_free(datatype);
+}
+
+static void
+test_turtle(void)
+{
+	test_common(SERD_TURTLE);
+
+	assert(test(SERD_TURTLE, serd_new_curie("cu:rie"), "cu:rie"));
+	assert(test(SERD_TURTLE, serd_new_uri("rel/uri"), "<rel/uri>"));
+	assert(test(SERD_TURTLE, serd_new_decimal(1.25, 4, 2, NULL), "1.25"));
+	assert(test(SERD_TURTLE, serd_new_integer(1234, NULL), "1234"));
+	assert(test(SERD_TURTLE, serd_new_boolean(true), "true"));
+	assert(test(SERD_TURTLE, serd_new_boolean(false), "false"));
+}
+
+int
+main(void)
+{
+	test_ntriples();
+	test_turtle();
+
+	return 0;
+}
diff --git a/tests/serd_test.c b/tests/serd_test.c
index 9f85136e..2acf24b0 100644
--- a/tests/serd_test.c
+++ b/tests/serd_test.c
@@ -375,7 +375,7 @@ test_node_equals(void)
 }
 
 static void
-test_node_from_string(void)
+test_node_from_syntax(void)
 {
 	assert(!serd_new_string(NULL));
 
@@ -748,7 +748,7 @@ main(void)
 	test_strerror();
 	test_uri_parsing();
 	test_node_equals();
-	test_node_from_string();
+	test_node_from_syntax();
 	test_node_from_substring();
 	test_simple_node();
 	test_literal();
diff --git a/wscript b/wscript
index aa799da5..2d10f77c 100644
--- a/wscript
+++ b/wscript
@@ -177,6 +177,7 @@ lib_source = ['src/base64.c',
               'src/model.c',
               'src/n3.c',
               'src/node.c',
+              'src/node_syntax.c',
               'src/nodes.c',
               'src/normalise.c',
               'src/range.c',
@@ -265,6 +266,7 @@ def build(bld):
                      ('free_null_test', 'tests/free_null_test.c'),
                      ('int_math_test', 'tests/int_math_test.c'),
                      ('model_test', 'tests/model_test.c'),
+                     ('node_syntax_test', 'tests/node_syntax_test.c'),
                      ('nodes_test', 'tests/nodes_test.c'),
                      ('overflow_test', 'tests/overflow_test.c'),
                      ('read_chunk_test', 'tests/read_chunk_test.c'),
@@ -708,6 +710,7 @@ def test(tst):
         check(['./free_null_test'])
         check(['./int_math_test'])
         check(['./model_test'])
+        check(['./node_syntax_test'])
         check(['./nodes_test'])
         check(['./overflow_test'])
         check(['./read_chunk_test'])