Add serd_node_from_syntax() and serd_node_to_syntax()

8 files changed, 356 insertions, 2 deletions

diff --git a/include/serd/serd.h b/include/serd/serd.h
index 05c1ed8c..4067fa3f 100644
--- a/include/serd/serd.h
+++ b/include/serd/serd.h
@@ -1666,6 +1666,54 @@ serd_env_write_prefixes(const SerdEnv* SERD_NONNULL  env,
                         const SerdSink* SERD_NONNULL sink);
 
 /**
+   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.
+
+   @param env Environment of `str`.  This must define any abbreviations needed
+   to parse the string.
+
+   @return A newly allocated node that must be freed with serd_node_free().
+*/
+SERD_API
+SerdNode* SERD_ALLOCATED
+serd_node_from_syntax(const char* SERD_NONNULL str,
+                      SerdSyntax               syntax,
+                      SerdEnv* SERD_NULLABLE   env);
+
+/**
+   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 write as a string.
+
+   @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.
+
+   @param env Environment for the output string.  This can be used to
+   abbreviate things nicely by setting namespace prefixes.
+
+   @return A newly allocated string that must be freed with serd_free().
+*/
+SERD_API
+char* SERD_ALLOCATED
+serd_node_to_syntax(const SerdNode* SERD_NONNULL node,
+                    SerdSyntax                   syntax,
+                    const SerdEnv* SERD_NULLABLE env);
+
+/**
    @}
    @defgroup serd_byte_source Byte Source
    @{
diff --git a/meson.build b/meson.build
index c292ebb1..6711132e 100644
--- a/meson.build
+++ b/meson.build
@@ -90,6 +90,7 @@ sources = [
   'src/log.c',
   'src/n3.c',
   'src/node.c',
+  'src/node_syntax.c',
   'src/nodes.c',
   'src/read_nquads.c',
   'src/read_ntriples.c',
diff --git a/src/node_syntax.c b/src/node_syntax.c
new file mode 100644
index 00000000..626648f6
--- /dev/null
+++ b/src/node_syntax.c
@@ -0,0 +1,122 @@
+/*
+  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 "writer.h"
+
+#include "serd/serd.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static SerdStatus
+on_node_string_event(void* const handle, const SerdEvent* const event)
+{
+  if (event->type == SERD_STATEMENT) {
+    *(SerdNode**)handle =
+      serd_node_copy(serd_statement_object(event->statement.statement));
+  }
+
+  return SERD_SUCCESS;
+}
+
+static SerdNode*
+serd_node_from_syntax_in(const char* const str,
+                         const SerdSyntax  syntax,
+                         SerdEnv* const    env)
+{
+  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 + 4;
+  char* const  doc     = (char*)calloc(doc_len + 1, 1);
+
+  snprintf(doc, doc_len + 1, "%s %s .", prelude, str);
+
+  SerdNode*        object = NULL;
+  SerdWorld* const world  = serd_world_new();
+  SerdSink* const  sink   = serd_sink_new(&object, on_node_string_event, NULL);
+
+  SerdByteSource* const source = serd_byte_source_new_string(doc, NULL);
+  SerdReader* const     reader = serd_reader_new(
+    world, syntax, SERD_READ_EXACT_BLANKS, env, sink, 1024 + doc_len);
+
+  serd_reader_start(reader, source);
+  serd_reader_read_document(reader);
+  serd_reader_finish(reader);
+  serd_reader_free(reader);
+  serd_byte_source_free(source);
+  serd_sink_free(sink);
+  serd_world_free(world);
+  free(doc);
+
+  return object;
+}
+
+SerdNode*
+serd_node_from_syntax(const char* const str,
+                      const SerdSyntax  syntax,
+                      SerdEnv* const    env)
+{
+  if (env) {
+    return serd_node_from_syntax_in(str, syntax, env);
+  }
+
+  SerdEnv* const  temp_env = serd_env_new(SERD_EMPTY_STRING());
+  SerdNode* const node     = serd_node_from_syntax_in(str, syntax, temp_env);
+
+  serd_env_free(temp_env);
+  return node;
+}
+
+static char*
+serd_node_to_syntax_in(const SerdNode* const node,
+                       const SerdSyntax      syntax,
+                       const SerdEnv* const  env)
+{
+  SerdWorld* const    world  = serd_world_new();
+  SerdBuffer          buffer = {NULL, 0};
+  SerdByteSink* const out    = serd_byte_sink_new_buffer(&buffer);
+  SerdWriter* const   writer = serd_writer_new(world, syntax, 0, env, out);
+
+  char* result = NULL;
+  if (!serd_writer_write_node(writer, node) && !serd_writer_finish(writer)) {
+    result = serd_buffer_sink_finish(&buffer);
+  }
+
+  serd_writer_free(writer);
+  serd_byte_sink_free(out);
+  serd_world_free(world);
+
+  return result;
+}
+
+char*
+serd_node_to_syntax(const SerdNode* const node,
+                    const SerdSyntax      syntax,
+                    const SerdEnv* const  env)
+{
+  if (env) {
+    return serd_node_to_syntax_in(node, syntax, env);
+  }
+
+  SerdEnv* const temp_env = serd_env_new(SERD_EMPTY_STRING());
+  char* const    string   = serd_node_to_syntax_in(node, syntax, temp_env);
+
+  serd_env_free(temp_env);
+  return string;
+}
diff --git a/src/writer.c b/src/writer.c
index bfce4f9e..c6a91d78 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"
@@ -1259,6 +1261,12 @@ 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..c80fe49c
--- /dev/null
+++ b/src/writer.h
@@ -0,0 +1,20 @@
+/*
+  Copyright 2019-2020 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/serd.h"
+
+SerdStatus
+serd_writer_write_node(SerdWriter* writer, const SerdNode* node);
diff --git a/test/meson.build b/test/meson.build
index 4d9d2b43..77a9ba57 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -12,6 +12,7 @@ unit_tests = [
   'free_null',
   'log',
   'node',
+  'node_syntax',
   'nodes',
   'overflow',
   'read_chunk',
diff --git a/test/test_node.c b/test/test_node.c
index 8de81e08..466655ef 100644
--- a/test/test_node.c
+++ b/test/test_node.c
@@ -429,7 +429,7 @@ test_node_equals(void)
 }
 
 static void
-test_node_from_string(void)
+test_node_from_syntax(void)
 {
   SerdNode* const hello = serd_new_string(SERD_STRING("hello\""));
   assert(serd_node_length(hello) == 6);
@@ -547,7 +547,7 @@ main(void)
   test_base64();
   test_get_base64();
   test_node_equals();
-  test_node_from_string();
+  test_node_from_syntax();
   test_node_from_substring();
   test_simple_node();
   test_literal();
diff --git a/test/test_node_syntax.c b/test/test_node_syntax.c
new file mode 100644
index 00000000..bb394c43
--- /dev/null
+++ b/test/test_node_syntax.c
@@ -0,0 +1,154 @@
+/*
+  Copyright 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.
+*/
+
+#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)
+{
+  SerdEnv* const  env  = serd_env_new(SERD_STRING("http://example.org/base/"));
+  char* const     str  = serd_node_to_syntax(node, syntax, env);
+  SerdNode* const copy = serd_node_from_syntax(str, syntax, env);
+
+  const bool success = !strcmp(str, expected) && serd_node_equals(copy, node);
+
+  serd_node_free(copy);
+  serd_free(str);
+  serd_node_free(node);
+  serd_env_free(env);
+  return success;
+}
+
+static void
+test_common(const SerdSyntax syntax)
+{
+  static const int data[] = {4, 2};
+
+  static const SerdStringView datatype =
+    SERD_STRING("http://example.org/Datatype");
+
+  SerdNode* const num_type =
+    serd_new_uri(SERD_STRING("http://example.org/Decimal"));
+
+  assert(test(syntax, serd_new_string(SERD_STRING("node")), "\"node\""));
+
+  assert(test(syntax,
+              serd_new_plain_literal(SERD_STRING("hallo"), SERD_STRING("de")),
+              "\"hallo\"@de"));
+
+  assert(test(syntax,
+              serd_new_typed_literal(SERD_STRING("X"), datatype),
+              "\"X\"^^<http://example.org/Datatype>"));
+
+  assert(test(syntax, serd_new_blank(SERD_STRING("blank")), "_:blank"));
+  assert(test(syntax, serd_new_blank(SERD_STRING("b0")), "_:b0"));
+
+  assert(test(syntax,
+              serd_new_uri(SERD_STRING("http://example.org/")),
+              "<http://example.org/>"));
+
+  assert(test(syntax,
+              serd_new_decimal(1.25, 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_base64(data, sizeof(data), NULL),
+         "\"BAAAAAIAAAA=\"^^<http://www.w3.org/2001/XMLSchema#base64Binary>"));
+
+  serd_node_free(num_type);
+}
+
+static void
+test_ntriples(void)
+{
+  test_common(SERD_NTRIPLES);
+
+  {
+    // No relative URIs in NTriples, so converting one fails without an env
+    SerdNode* const rel = serd_new_uri(SERD_STRING("rel/uri"));
+    assert(!serd_node_to_syntax(rel, SERD_NTRIPLES, NULL));
+    assert(!serd_node_from_syntax("<rel/uri>", SERD_NTRIPLES, NULL));
+
+    // If a relative URI can be expanded then all's well
+    SerdEnv* const env = serd_env_new(SERD_STRING("http://example.org/base/"));
+    char* const    str = serd_node_to_syntax(rel, SERD_NTRIPLES, env);
+    assert(!strcmp(str, "<http://example.org/base/rel/uri>"));
+
+    SerdNode* const copy = serd_node_from_syntax(str, SERD_NTRIPLES, env);
+    assert(!strcmp(serd_node_string(copy), "http://example.org/base/rel/uri"));
+
+    serd_node_free(copy);
+    serd_env_free(env);
+    serd_free(str);
+    serd_node_free(rel);
+  }
+
+  assert(test(SERD_NTRIPLES,
+              serd_new_decimal(1.25, 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>"));
+}
+
+static void
+test_turtle(void)
+{
+  test_common(SERD_TURTLE);
+  test(SERD_TURTLE, serd_new_uri(SERD_STRING("rel/uri")), "<rel/uri>");
+  assert(test(SERD_TURTLE, serd_new_decimal(1.25, 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;
+}