Add model and serd-sort utility

With all the new functionality, the complexity of the serd-pipe command-line
interface is starting to push the limits of available flags. So, instead of
grafting on further options to control a model, this commit adds a new tool,
serd-sort, which acts somewhat like a stripped-down serd-pipe that stores
statements in a model in memory.

This keeps the complexity (including the user-facing complexity) of any one
tool down, since other more focused tools can be used for streaming tasks in a
pipeline.

In other words, abandon Swissarmyknifeism, take a page from the Unix
philosophy, and try to expose the model functionality to the command-line in a
dedicated focused tool.  The model implementation is tested by using this tool
to run a subset of the usual test suites, and a special suite to test statement
sorting.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/string.c b/src/string.c
index b8227100..ac964705 100644
--- a/src/string.c
+++ b/src/string.c
@@ -64,6 +64,10 @@ serd_strerror(const SerdStatus status)
     return "Invalid literal";
   case SERD_BAD_PATTERN:
     return "Invalid statement pattern";
+  case SERD_BAD_CURSOR:
+    return "Invalid cursor";
+  case SERD_BAD_INDEX:
+    return "No suitable model index available";
   }
 
   return "Unknown error";