Move syntax name/extension utilities to public API

4 files changed, 117 insertions, 59 deletions

diff --git a/include/serd/serd.h b/include/serd/serd.h
index 57f5af75..766844be 100644
--- a/include/serd/serd.h
+++ b/include/serd/serd.h
@@ -73,14 +73,6 @@ extern "C" {
    @{
 */
 
-/// RDF syntax type
-typedef enum {
-  SERD_TURTLE   = 1, ///< Terse triples http://www.w3.org/TR/turtle
-  SERD_NTRIPLES = 2, ///< Line-based triples http://www.w3.org/TR/n-triples/
-  SERD_NQUADS   = 3, ///< Line-based quads http://www.w3.org/TR/n-quads/
-  SERD_TRIG     = 4  ///< Terse quads http://www.w3.org/TR/trig/
-} SerdSyntax;
-
 /// Flags indicating certain string properties relevant to serialisation
 typedef enum {
   SERD_HAS_NEWLINE  = 1u << 0u, ///< Contains line breaks ('\\n' or '\\r')
@@ -309,6 +301,49 @@ typedef size_t (*SerdWriteFunc)(const void* SERD_NONNULL buf,
 
 /**
    @}
+   @defgroup serd_syntax Syntax Utilities
+   @{
+*/
+
+/// Syntax supported by serd
+typedef enum {
+  SERD_TURTLE   = 1, ///< Terse triples http://www.w3.org/TR/turtle
+  SERD_NTRIPLES = 2, ///< Line-based triples http://www.w3.org/TR/n-triples/
+  SERD_NQUADS   = 3, ///< Line-based quads http://www.w3.org/TR/n-quads/
+  SERD_TRIG     = 4  ///< Terse quads http://www.w3.org/TR/trig/
+} SerdSyntax;
+
+/**
+   Get a syntax by name.
+
+   Case-insensitive, supports "Turtle", "NTriples", "NQuads", and "TriG".  Zero
+   is returned if the name is not recognized.
+*/
+SERD_PURE_API
+SerdSyntax
+serd_syntax_by_name(const char* SERD_NONNULL name);
+
+/**
+   Guess a syntax from a filename.
+
+   This uses the file extension to guess the syntax of a file.  Zero is
+   returned if the extension is not recognized.
+*/
+SERD_PURE_API
+SerdSyntax
+serd_guess_syntax(const char* SERD_NONNULL filename);
+
+/**
+   Return whether a syntax can represent multiple graphs.
+
+   @return True for #SERD_NQUADS and #SERD_TRIG, false otherwise.
+*/
+SERD_CONST_API
+bool
+serd_syntax_has_graphs(SerdSyntax syntax);
+
+/**
+   @}
    @defgroup serd_uri URI
    @{
 */
diff --git a/meson.build b/meson.build
index 0e1e9471..2708b5a7 100644
--- a/meson.build
+++ b/meson.build
@@ -98,6 +98,7 @@ sources = [
   'src/reader.c',
   'src/sink.c',
   'src/string.c',
+  'src/syntax.c',
   'src/system.c',
   'src/uri.c',
   'src/writer.c',
diff --git a/src/serdi.c b/src/serdi.c
index 61fb8f09..e46ef5e5 100644
--- a/src/serdi.c
+++ b/src/serdi.c
@@ -15,7 +15,6 @@
 */
 
 #include "serd_config.h"
-#include "string_utils.h"
 #include "system.h"
 
 #include "serd/serd.h"
@@ -32,52 +31,10 @@
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
 
 #define SERDI_ERROR(msg) fprintf(stderr, "serdi: " msg)
 #define SERDI_ERRORF(fmt, ...) fprintf(stderr, "serdi: " fmt, __VA_ARGS__)
 
-typedef struct {
-  SerdSyntax  syntax;
-  const char* name;
-  const char* extension;
-} Syntax;
-
-static const Syntax syntaxes[] = {{SERD_TURTLE, "turtle", ".ttl"},
-                                  {SERD_NTRIPLES, "ntriples", ".nt"},
-                                  {SERD_NQUADS, "nquads", ".nq"},
-                                  {SERD_TRIG, "trig", ".trig"},
-                                  {(SerdSyntax)0, NULL, NULL}};
-
-static SerdSyntax
-get_syntax(const char* const name)
-{
-  for (const Syntax* s = syntaxes; s->name; ++s) {
-    if (!serd_strncasecmp(s->name, name, strlen(name))) {
-      return s->syntax;
-    }
-  }
-
-  SERDI_ERRORF("unknown syntax `%s'\n", name);
-  return (SerdSyntax)0;
-}
-
-static SERD_PURE_FUNC
-SerdSyntax
-guess_syntax(const char* const filename)
-{
-  const char* ext = strrchr(filename, '.');
-  if (ext) {
-    for (const Syntax* s = syntaxes; s->name; ++s) {
-      if (!serd_strncasecmp(s->extension, ext, strlen(ext))) {
-        return s->syntax;
-      }
-    }
-  }
-
-  return (SerdSyntax)0;
-}
-
 static int
 print_version(void)
 {
@@ -223,7 +180,7 @@ main(int argc, char** argv)
           return missing_arg(prog, 'i');
         }
 
-        if (!(input_syntax = get_syntax(argv[a]))) {
+        if (!(input_syntax = serd_syntax_by_name(argv[a]))) {
           return print_usage(prog, true);
         }
         break;
@@ -245,7 +202,7 @@ main(int argc, char** argv)
           return missing_arg(prog, 'o');
         }
 
-        if (!(output_syntax = get_syntax(argv[a]))) {
+        if (!(output_syntax = serd_syntax_by_name(argv[a]))) {
           return print_usage(prog, true);
         }
         break;
@@ -282,15 +239,13 @@ main(int argc, char** argv)
 
   const char* input = argv[a++];
 
-  if (!input_syntax && !(input_syntax = guess_syntax(input))) {
+  if (!input_syntax && !(input_syntax = serd_guess_syntax(input))) {
     input_syntax = SERD_TRIG;
   }
 
+  const bool input_has_graphs = serd_syntax_has_graphs(input_syntax);
   if (!output_syntax) {
-    output_syntax =
-      ((input_syntax == SERD_TURTLE || input_syntax == SERD_NTRIPLES)
-         ? SERD_NTRIPLES
-         : SERD_NQUADS);
+    output_syntax = input_has_graphs ? SERD_NQUADS : SERD_NTRIPLES;
   }
 
   const SerdWriterFlags writer_flags =
@@ -298,7 +253,7 @@ main(int argc, char** argv)
 
   SerdNode* base = NULL;
   if (a < argc) { // Base URI given on command line
-    base = serd_new_uri(SERD_STRING((const char*)argv[a]));
+    base = serd_new_uri(SERD_STRING(argv[a]));
   } else if (!from_string && !from_stdin) { // Use input file URI
     base = serd_new_file_uri(SERD_STRING(input), SERD_EMPTY_STRING());
   }
diff --git a/src/syntax.c b/src/syntax.c
new file mode 100644
index 00000000..61814709
--- /dev/null
+++ b/src/syntax.c
@@ -0,0 +1,67 @@
+/*
+  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 "string_utils.h"
+
+#include "serd/serd.h"
+
+#include <stdbool.h>
+#include <string.h>
+
+typedef struct {
+  const char* name;
+  const char* extension;
+  SerdSyntax  syntax;
+} Syntax;
+
+static const Syntax syntaxes[] = {
+  {"turtle", ".ttl", SERD_TURTLE},
+  {"ntriples", ".nt", SERD_NTRIPLES},
+  {"nquads", ".nq", SERD_NQUADS},
+  {"trig", ".trig", SERD_TRIG},
+  {NULL, NULL, (SerdSyntax)0},
+};
+
+SerdSyntax
+serd_syntax_by_name(const char* const name)
+{
+  for (const Syntax* s = syntaxes; s->name; ++s) {
+    if (!serd_strncasecmp(s->name, name, strlen(name))) {
+      return s->syntax;
+    }
+  }
+  return (SerdSyntax)0;
+}
+
+SerdSyntax
+serd_guess_syntax(const char* const filename)
+{
+  const char* ext = strrchr(filename, '.');
+  if (ext) {
+    for (const Syntax* s = syntaxes; s->name; ++s) {
+      if (!serd_strncasecmp(s->extension, ext, strlen(ext))) {
+        return s->syntax;
+      }
+    }
+  }
+  return (SerdSyntax)0;
+}
+
+bool
+serd_syntax_has_graphs(const SerdSyntax syntax)
+{
+  return syntax == SERD_NQUADS || syntax == SERD_TRIG;
+}