Add "longhand" mode to write rdf:type predicates normally

12 files changed, 75 insertions, 1 deletions

diff --git a/doc/man/serd-pipe.1 b/doc/man/serd-pipe.1
index 4d475985..7f91de29 100644
--- a/doc/man/serd-pipe.1
+++ b/doc/man/serd-pipe.1
@@ -167,6 +167,11 @@ Escape all non-ASCII characters.
 Write expanded URIs instead of prefixed names.
 .It Cm lax
 Tolerate corrupt UTF-8 and write replacements.
+.It Cm longhand
+Avoid using the
+.Ql a
+shorthand for
+.Ql rdf:type .
 .It Cm terse
 Write terser output with fewer, longer lines.
 .It Cm verbatim
diff --git a/include/serd/writer.h b/include/serd/writer.h
index 91baa7e8..5e8f5e6e 100644
--- a/include/serd/writer.h
+++ b/include/serd/writer.h
@@ -80,6 +80,13 @@ typedef enum {
      carefully, since it can result in data loss.
   */
   SERD_WRITE_LAX = 1U << 4U,
+
+  /**
+     Write rdf:type as a normal predicate.
+
+     This disables the special "a" syntax in Turtle and TriG.
+  */
+  SERD_WRITE_LONGHAND = 1U << 5U,
 } SerdWriterFlag;
 
 /// Bitwise OR of #SerdWriterFlag values
diff --git a/src/writer.c b/src/writer.c
index 0b0574d5..30b8bb4e 100644
--- a/src/writer.c
+++ b/src/writer.c
@@ -841,7 +841,7 @@ write_uri_node(SerdWriter* const     writer,
   const bool           has_scheme = serd_uri_string_has_scheme(string.data);
 
   if (supports_abbrev(writer)) {
-    if (field == SERD_PREDICATE &&
+    if (!(writer->flags & SERD_WRITE_LONGHAND) && field == SERD_PREDICATE &&
         serd_node_equals(node, writer->world->rdf_type)) {
       return esink("a", 1, writer);
     }
diff --git a/test/extra/longhand/blank_object.ttl b/test/extra/longhand/blank_object.ttl
new file mode 100644
index 00000000..270e406b
--- /dev/null
+++ b/test/extra/longhand/blank_object.ttl
@@ -0,0 +1,2 @@
+@prefix eg: <http://example.org/> .
+eg:s eg:p1 [ eg:p11 1 ; eg:p12 2 ] ; eg:p2 [ eg:p23 3 ; eg:p24 4 ] .
diff --git a/test/extra/longhand/blank_subject.ttl b/test/extra/longhand/blank_subject.ttl
new file mode 100644
index 00000000..5e3303f9
--- /dev/null
+++ b/test/extra/longhand/blank_subject.ttl
@@ -0,0 +1,2 @@
+@prefix eg: <http://example.org/> .
+[] eg:p1 1 ; eg:p2 2 .
diff --git a/test/extra/longhand/collection_object.ttl b/test/extra/longhand/collection_object.ttl
new file mode 100644
index 00000000..3310c418
--- /dev/null
+++ b/test/extra/longhand/collection_object.ttl
@@ -0,0 +1,2 @@
+@prefix eg: <http://example.org/> .
+eg:s eg:p1 ( 1 2 ) ; eg:p2 ( 3 4 ) .
diff --git a/test/extra/longhand/collection_subject.ttl b/test/extra/longhand/collection_subject.ttl
new file mode 100644
index 00000000..43670620
--- /dev/null
+++ b/test/extra/longhand/collection_subject.ttl
@@ -0,0 +1,2 @@
+@prefix eg: <http://example.org/> .
+( 1 2 ) eg:p3 3 ; eg:p4 4 .
diff --git a/test/extra/longhand/longhand.ttl b/test/extra/longhand/longhand.ttl
new file mode 100644
index 00000000..b756ce91
--- /dev/null
+++ b/test/extra/longhand/longhand.ttl
@@ -0,0 +1,13 @@
+@prefix eg: <http://example.org/eg#> .
+@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+
+[]
+	rdf:type eg:Node ;
+	eg:with [
+		rdf:type eg:NodeChild ;
+		eg:having (
+			[
+				rdf:type eg:ListItem
+			]
+		)
+	] .
diff --git a/test/extra/longhand/manifest.ttl b/test/extra/longhand/manifest.ttl
new file mode 100644
index 00000000..313ca846
--- /dev/null
+++ b/test/extra/longhand/manifest.ttl
@@ -0,0 +1,16 @@
+@prefix mf: <http://www.w3.org/2001/sw/DataAccess/tests/test-manifest#> .
+@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
+@prefix rdft: <http://www.w3.org/ns/rdftest#> .
+
+<>
+	a mf:Manifest ;
+	rdfs:comment "Serd longhand writing test suite" ;
+	mf:entries (
+		<#write-longhand>
+	) .
+
+<#write-longhand>
+	a rdft:TestTurtleEval ;
+	mf:action <shorthand.ttl> ;
+	mf:name "write-longhand" ;
+	mf:result <longhand.ttl> .
diff --git a/test/extra/longhand/shorthand.ttl b/test/extra/longhand/shorthand.ttl
new file mode 100644
index 00000000..d563021e
--- /dev/null
+++ b/test/extra/longhand/shorthand.ttl
@@ -0,0 +1,13 @@
+@prefix eg: <http://example.org/eg#> .
+@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
+
+[]
+	a eg:Node ;
+	eg:with [
+		a eg:NodeChild ;
+		eg:having (
+			[
+				a eg:ListItem
+			]
+		)
+	] .
diff --git a/test/meson.build b/test/meson.build
index 43fc7211..c186b6e4 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -507,6 +507,17 @@ test_suites = {
     files('extra/lax/manifest.ttl'),
     ns_serdtest + 'lax/',
   ],
+  'longhand_forward': [
+    files('extra/longhand/manifest.ttl'),
+    ns_serdtest + 'longhand/',
+    '--',
+    ['-O', 'longhand'],
+  ],
+  'longhand_reverse': [
+    '--reverse',
+    files('extra/longhand/manifest.ttl'),
+    ns_serdtest + 'longhand/',
+  ],
   'pattern': [
     files('extra/pattern/manifest.ttl'),
     ns_serdtest + 'pattern/',
diff --git a/tools/console.c b/tools/console.c
index 2a861d1b..0f66a2f1 100644
--- a/tools/console.c
+++ b/tools/console.c
@@ -294,6 +294,7 @@ serd_set_output_option(const SerdStringView   name,
     {"ascii", SERD_WRITE_ASCII},
     {"expanded", SERD_WRITE_EXPANDED},
     {"lax", SERD_WRITE_LAX},
+    {"longhand", SERD_WRITE_LONGHAND},
     {"terse", SERD_WRITE_TERSE},
     {"verbatim", SERD_WRITE_VERBATIM},
     {NULL, SERD_WRITE_ASCII},