libyang FEATURE sorting of data nodes

1. Plugin type 'lyds_tree' is integrated. Used in metadata and it is
internal, which is distinguished by the unset print callback.
Internal metadata must not be printed.
2. Leaf-list and list data instances are now automatically sorted.
3. Both the explicit and implicit YANG statement 'ordered-by system'
will cause the nodes to be ordered.
4. The first instance of the list or leaf-list of node contain
new metadata named 'lyds_tree'.
5. Data nodes are sorted only if their data types have
callback 'sort' set.
6. Sorting can be turned off so far only by adding the 'ordered-by user'
statement to the YANG model.
7. If the sort fails for some reason, the node is still inserted
as the last instance. A warning message informs about this situation.
8. The time required for sorting should be relatively small thanks to
the Red-black tree implementation.
9. Memory requirements will now increase by 40 bytes per list/leaf-list
data node, plus metadata structure overhead.

src/printer_json.c

@@ -455,6 +455,9 @@ json_print_metadata(struct jsonpr_ctx *pctx, const struct lyd_node *node, const
     }
 
     for (meta = node->meta; meta; meta = meta->next) {
+        if (!meta->value.realtype->plugin->print) {
+            continue;
+        }
         PRINT_COMMA;
         ly_print_(pctx->out, "%*s\"%s:%s\":%s", INDENT, meta->annotation->module->name, meta->name, DO_FORMAT ? " " : "");
         LY_CHECK_RET(json_print_value(pctx, LYD_CTX(node), &meta->value, NULL));
@@ -464,6 +467,30 @@ json_print_metadata(struct jsonpr_ctx *pctx, const struct lyd_node *node, const
     return LY_SUCCESS;
 }
 
+/**
+ * @brief Check if a value can be printed for at least one metadata.
+ *
+ * @param[in] node Node to check.
+ * @return 1 if node has printable meta otherwise 0.
+ */
+static ly_bool
+node_has_printable_meta(const struct lyd_node *node)
+{
+    struct lyd_meta *iter;
+
+    if (!node->meta) {
+        return 0;
+    }
+
+    LY_LIST_FOR(node->meta, iter) {
+        if (iter->value.realtype->plugin->print) {
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
 /**
  * @brief Print attributes/metadata of the given @p node. Accepts both regular as well as opaq nodes.
  *
@@ -484,7 +511,7 @@ json_print_attributes(struct jsonpr_ctx *pctx, const struct lyd_node *node, ly_b
         wdmod = ly_ctx_get_module_implemented(LYD_CTX(node), "ietf-netconf-with-defaults");
     }
 
-    if (node->schema && (node->meta || wdmod)) {
+    if (node->schema && (wdmod || node_has_printable_meta(node))) {
         if (inner) {
             LY_CHECK_RET(json_print_member2(pctx, lyd_parent(node), LY_VALUE_JSON, NULL, 1));
         } else {
@@ -793,11 +820,12 @@ json_print_leaf_list(struct jsonpr_ctx *pctx, const struct lyd_node *node)
         LY_CHECK_RET(json_print_value(pctx, LYD_CTX(node), &((const struct lyd_node_term *)node)->value, node->schema->module));
 
         if (!pctx->first_leaflist) {
+            /* decide if we will be printing metadata for these siblings */
             if ((node->flags & LYD_DEFAULT) && (pctx->options & (LYD_PRINT_WD_ALL_TAG | LYD_PRINT_WD_IMPL_TAG))) {
                 /* we have implicit OR explicit default node, get with-defaults module */
                 wdmod = ly_ctx_get_module_implemented(LYD_CTX(node), "ietf-netconf-with-defaults");
             }
-            if (node->meta || wdmod) {
+            if (wdmod || node_has_printable_meta(node)) {
                 /* we will be printing metadata for these siblings */
                 pctx->first_leaflist = node;
             }
@@ -848,7 +876,8 @@ json_print_meta_attr_leaflist(struct jsonpr_ctx *pctx)
     LEVEL_INC;
     LY_LIST_FOR(node, iter) {
         PRINT_COMMA;
-        if ((iter->schema && (iter->meta || (iter->flags & LYD_DEFAULT))) || (opaq && opaq->attr)) {
+        if ((iter->schema && (node_has_printable_meta(iter) || (iter->flags & LYD_DEFAULT))) ||
+                (opaq && opaq->attr)) {
             ly_print_(pctx->out, "%*s%s", INDENT, DO_FORMAT ? "{\n" : "{");
             LEVEL_INC;
 

src/printer_lyb.c

@@ -765,6 +765,9 @@ lyb_print_metadata(struct ly_out *out, const struct lyd_node *node, struct lyd_l
         ++count;
     }
     for (iter = node->meta; iter; iter = iter->next) {
+        if (!iter->value.realtype->plugin->print) {
+            continue;
+        }
         if (count == UINT8_MAX) {
             LOGERR(lybctx->lybctx->ctx, LY_EINT, "Maximum supported number of data node metadata is %u.", UINT8_MAX);
             return LY_EINT;
@@ -784,6 +787,10 @@ lyb_print_metadata(struct ly_out *out, const struct lyd_node *node, struct lyd_l
 
     /* write all the node metadata */
     LY_LIST_FOR(node->meta, iter) {
+        if (!iter->value.realtype->plugin->print) {
+            continue;
+        }
+
         /* model */
         LY_CHECK_RET(lyb_print_model(out, iter->annotation->module, 0, lybctx->lybctx));
 

src/printer_xml.c

@@ -209,6 +209,10 @@ xml_print_meta(struct xmlpr_ctx *pctx, const struct lyd_node *node)
     }
 
     for (meta = node->meta; meta; meta = meta->next) {
+        if (!meta->value.realtype->plugin->print) {
+            continue;
+        }
+
         /* store the module of the default namespace, NULL because there is none */
         ly_set_add(&ns_list, NULL, 0, NULL);
 

src/printer_yang.c

@@ -2148,7 +2148,7 @@ yang_print_parsed_body(struct lys_ypr_ctx *pctx, const struct lysp_module *modp)
 
     YPR_EXTRA_LINE(modp->extensions, pctx);
 
-    if (modp->exts) {
+    if (modp->exts && !(modp->exts->flags & LYS_INTERNAL)) {
         YPR_EXTRA_LINE_PRINT(pctx);
         yprp_extension_instances(pctx, LY_STMT_MODULE, 0, modp->exts, NULL);
     }

src/printer_yin.c

@@ -1285,7 +1285,9 @@ ypr_import_xmlns(struct lys_ypr_ctx *pctx, const struct lysp_module *modp, uint1
     LY_ARRAY_COUNT_TYPE u;
 
     LY_ARRAY_FOR(modp->imports, u){
-        ly_print_(pctx->out, "\n%*sxmlns:%s=\"%s\"", indent + INDENT, modp->imports[u].prefix, modp->imports[u].module->ns);
+        if (!(modp->imports[u].flags & LYS_INTERNAL)) {
+            ly_print_(pctx->out, "\n%*sxmlns:%s=\"%s\"", indent + INDENT, modp->imports[u].prefix, modp->imports[u].module->ns);
+        }
     }
 }
 

src/schema_compile_node.c

@@ -2681,12 +2681,15 @@ lys_compile_node_(struct lysc_ctx *ctx, struct lysp_node *pnode, struct lysc_nod
     /* list ordering */
     if (node->nodetype & (LYS_LIST | LYS_LEAFLIST)) {
         if ((node->flags & (LYS_CONFIG_R | LYS_IS_OUTPUT | LYS_IS_NOTIF)) && (node->flags & LYS_ORDBY_MASK)) {
+            node->flags &= ~LYS_ORDBY_MASK;
             LOGVRB("The ordered-by statement is ignored in lists representing %s (%s).",
                     (node->flags & LYS_IS_OUTPUT) ? "RPC/action output parameters" :
                     (ctx->compile_opts & LYS_IS_NOTIF) ? "notification content" : "state data", ctx->path);
-            node->flags &= ~LYS_ORDBY_MASK;
-            node->flags |= LYS_ORDBY_SYSTEM;
-        } else if (!(node->flags & LYS_ORDBY_MASK)) {
+        }
+        if (node->flags & (LYS_IS_OUTPUT | LYS_IS_NOTIF)) {
+            /* it is probably better not to order them */
+            node->flags |= LYS_ORDBY_USER;
+        } else if (!(node->flags & LYS_ORDBY_MASK) || (node->flags & LYS_CONFIG_R)) {
             /* default ordering is system */
             node->flags |= LYS_ORDBY_SYSTEM;
         }