[oilshell] Print JSON parse errors to stderr.

We could expose a proper API, but this is OK for now.

Author: Andy Chu

decoder.c

@@ -247,16 +247,12 @@ PyObject *_internal_decode(_YajlDecoder *self, char *buffer, unsigned int buflen
     yajl_status yrc;
     yrc = yajl_parse(parser, (const unsigned char *)(buffer), buflen);
     if (yrc != yajl_status_ok) {
-        //fprintf(stderr, "YAJL ERROR %s\n", yajl_status_to_string(yrc));
-        PyErr_SetString(PyExc_ValueError, yajl_status_to_string(yrc));
-        return NULL;
+        goto error;
     }
 
     yrc = yajl_complete_parse(parser);
     if (yrc != yajl_status_ok) {
-        //fprintf(stderr, "YAJL ERROR %s\n", yajl_status_to_string(yrc));
-        PyErr_SetString(PyExc_ValueError, yajl_status_to_string(yrc));
-        return NULL;
+        goto error;
     }
 
     yajl_free(parser);
@@ -268,4 +264,17 @@ PyObject *_internal_decode(_YajlDecoder *self, char *buffer, unsigned int buflen
     PyObject *root = self->root;
     self->root = NULL;
     return root;
+
+    unsigned char* str;
+error:
+    // TODO: It would be nice to make these parse errors more consistent with
+    // Oil.  And maybe return them rather than printing on stderr.
+    str = yajl_get_error(parser, 1, buffer, buflen);
+    fprintf(stderr, "%s", (const char *) str); 
+    yajl_free_error(parser, str);  
+    yajl_free(parser);
+
+    //fprintf(stderr, "YAJL ERROR %s\n", yajl_status_to_string(yrc));
+    PyErr_SetString(PyExc_ValueError, yajl_status_to_string(yrc));
+    return NULL;
 }

tests/unit.py

@@ -284,6 +284,8 @@ def testAll(self):
         rel_path = 'yajl/test/parsing/cases'
         cases = os.listdir(rel_path)
         for case in cases:
+            if not case.endswith('.json'):
+                continue
             print(case)
             # TODO: This causes SystemError!
             if case == 'deep_arrays.json':
@@ -293,7 +295,7 @@ def testAll(self):
                 try:
                     obj = yajl.load(f)
                 except ValueError as e:
-                    print('\t%s: %s' % (case, e))
+                    print('\t%s:\n%s' % (case, e))
                 else:
                     try:
                         j = yajl.dumps(obj)