plugins FEATURE nacm node-instid type plugin
diff --git a/src/plugins.c b/src/plugins.c
index e669c4c..db3e565 100644
--- a/src/plugins.c
+++ b/src/plugins.c
@@ -68,6 +68,11 @@
 extern const struct lyplg_type_record plugins_xpath10[];
 
 /*
+ * ietf-netconf-acm
+ */
+extern const struct lyplg_type_record plugins_node_instanceid[];
+
+/*
  * internal extension plugins records
  */
 extern struct lyplg_ext_record plugins_metadata[];
@@ -446,6 +451,9 @@
     LY_CHECK_GOTO(ret = plugins_insert(LYPLG_TYPE, plugins_date_and_time), error);
     LY_CHECK_GOTO(ret = plugins_insert(LYPLG_TYPE, plugins_xpath10), error);
 
+    /* ietf-netconf-acm */
+    LY_CHECK_GOTO(ret = plugins_insert(LYPLG_TYPE, plugins_node_instanceid), error);
+
     /* internal extensions */
     LY_CHECK_GOTO(ret = plugins_insert(LYPLG_EXTENSION, plugins_metadata), error);
     LY_CHECK_GOTO(ret = plugins_insert(LYPLG_EXTENSION, plugins_nacm), error);
diff --git a/src/plugins_types/node_instanceid.c b/src/plugins_types/node_instanceid.c
new file mode 100644
index 0000000..60170ae
--- /dev/null
+++ b/src/plugins_types/node_instanceid.c
@@ -0,0 +1,276 @@
+/**
+ * @file node_instanceid.c
+ * @author Michal Vasko <mvasko@cesnet.cz>
+ * @brief ietf-netconf-acm node-instance-identifier type plugin.
+ *
+ * Copyright (c) 2019-2021 CESNET, z.s.p.o.
+ *
+ * This source code is licensed under BSD 3-Clause License (the "License").
+ * You may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://opensource.org/licenses/BSD-3-Clause
+ */
+
+#include "plugins_types.h"
+
+#include <assert.h>
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "libyang.h"
+
+/* additional internal headers for some useful simple macros */
+#include "common.h"
+#include "compat.h"
+#include "path.h"
+#include "plugins_internal.h" /* LY_TYPE_*_STR */
+#include "xpath.h"
+
+/**
+ * @page howtoDataLYB LYB Binary Format
+ * @subsection howtoDataLYBTypesInstanceIdentifier node-instance-identifier (ietf-netconf-acm)
+ *
+ * | Size (B) | Mandatory | Type | Meaning |
+ * | :------  | :-------: | :--: | :-----: |
+ * | string length | yes | `char *` | string JSON format of the instance-identifier |
+ */
+
+/**
+ * @brief Convert compiled path (instance-identifier) into string.
+ *
+ * @param[in] path Compiled path.
+ * @param[in] format Value format.
+ * @param[in] prefix_data Format-specific data for resolving prefixes.
+ * @param[out] str Printed instance-identifier.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+instanceid_path2str(const struct ly_path *path, LY_VALUE_FORMAT format, void *prefix_data, char **str)
+{
+    LY_ERR ret = LY_SUCCESS;
+    LY_ARRAY_COUNT_TYPE u, v;
+    char *result = NULL, quot;
+    const struct lys_module *mod = NULL;
+    ly_bool inherit_prefix = 0, d;
+    const char *strval;
+
+    switch (format) {
+    case LY_VALUE_XML:
+    case LY_VALUE_SCHEMA:
+    case LY_VALUE_SCHEMA_RESOLVED:
+        /* everything is prefixed */
+        inherit_prefix = 0;
+        break;
+    case LY_VALUE_CANON:
+    case LY_VALUE_JSON:
+    case LY_VALUE_LYB:
+        /* the same prefix is inherited and skipped */
+        inherit_prefix = 1;
+        break;
+    }
+
+    LY_ARRAY_FOR(path, u) {
+        /* new node */
+        if (!inherit_prefix || (mod != path[u].node->module)) {
+            mod = path[u].node->module;
+            ret = ly_strcat(&result, "/%s:%s", lyplg_type_get_prefix(mod, format, prefix_data), path[u].node->name);
+        } else {
+            ret = ly_strcat(&result, "/%s", path[u].node->name);
+        }
+        LY_CHECK_GOTO(ret, cleanup);
+
+        /* node predicates */
+        LY_ARRAY_FOR(path[u].predicates, v) {
+            struct ly_path_predicate *pred = &path[u].predicates[v];
+
+            switch (path[u].pred_type) {
+            case LY_PATH_PREDTYPE_NONE:
+                break;
+            case LY_PATH_PREDTYPE_POSITION:
+                /* position predicate */
+                ret = ly_strcat(&result, "[%" PRIu64 "]", pred->position);
+                break;
+            case LY_PATH_PREDTYPE_LIST:
+                /* key-predicate */
+                strval = pred->value.realtype->plugin->print(path[u].node->module->ctx, &pred->value, format, prefix_data,
+                        &d, NULL);
+
+                /* default quote */
+                quot = '\'';
+                if (strchr(strval, quot)) {
+                    quot = '"';
+                }
+                if (inherit_prefix) {
+                    /* always the same prefix as the parent */
+                    ret = ly_strcat(&result, "[%s=%c%s%c]", pred->key->name, quot, strval, quot);
+                } else {
+                    ret = ly_strcat(&result, "[%s:%s=%c%s%c]", lyplg_type_get_prefix(pred->key->module, format, prefix_data),
+                            pred->key->name, quot, strval, quot);
+                }
+                if (d) {
+                    free((char *)strval);
+                }
+                break;
+            case LY_PATH_PREDTYPE_LEAFLIST:
+                /* leaf-list-predicate */
+                strval = pred->value.realtype->plugin->print(path[u].node->module->ctx, &pred->value, format, prefix_data,
+                        &d, NULL);
+
+                /* default quote */
+                quot = '\'';
+                if (strchr(strval, quot)) {
+                    quot = '"';
+                }
+                ret = ly_strcat(&result, "[.=%c%s%c]", quot, strval, quot);
+                if (d) {
+                    free((char *)strval);
+                }
+                break;
+            }
+
+            LY_CHECK_GOTO(ret, cleanup);
+        }
+    }
+
+cleanup:
+    if (ret) {
+        free(result);
+    } else {
+        *str = result;
+    }
+    return ret;
+}
+
+/**
+ * @brief Implementation of ::lyplg_type_store_clb for the node-instance-identifier ietf-netconf-acm type.
+ */
+static LY_ERR
+lyplg_type_store_node_instanceid(const struct ly_ctx *ctx, const struct lysc_type *type, const void *value, size_t value_len,
+        uint32_t options, LY_VALUE_FORMAT format, void *prefix_data, uint32_t hints, const struct lysc_node *ctx_node,
+        struct lyd_value *storage, struct lys_glob_unres *unres, struct ly_err_item **err)
+{
+    LY_ERR ret = LY_SUCCESS;
+    struct lyxp_expr *exp = NULL;
+    uint32_t prefix_opt = 0;
+    struct ly_path *path;
+    char *canon;
+
+    /* init storage */
+    memset(storage, 0, sizeof *storage);
+    storage->realtype = type;
+
+    /* check hints */
+    ret = lyplg_type_check_hints(hints, value, value_len, type->basetype, NULL, err);
+    LY_CHECK_GOTO(ret, cleanup);
+
+    switch (format) {
+    case LY_VALUE_SCHEMA:
+    case LY_VALUE_SCHEMA_RESOLVED:
+    case LY_VALUE_XML:
+        prefix_opt = LY_PATH_PREFIX_MANDATORY;
+        break;
+    case LY_VALUE_CANON:
+    case LY_VALUE_LYB:
+    case LY_VALUE_JSON:
+        prefix_opt = LY_PATH_PREFIX_STRICT_INHERIT;
+        break;
+    }
+
+    /* parse the value */
+    ret = ly_path_parse(ctx, ctx_node, value, value_len, 0, LY_PATH_BEGIN_ABSOLUTE, prefix_opt, LY_PATH_PRED_SIMPLE, &exp);
+    if (ret) {
+        ret = ly_err_new(err, LY_EVALID, LYVE_DATA, NULL, NULL,
+                "Invalid instance-identifier \"%.*s\" value - syntax error.", (int)value_len, (char *)value);
+        goto cleanup;
+    }
+
+    if (options & LYPLG_TYPE_STORE_IMPLEMENT) {
+        /* implement all prefixes */
+        LY_CHECK_GOTO(ret = lys_compile_expr_implement(ctx, exp, format, prefix_data, 1, unres, NULL), cleanup);
+    }
+
+    /* resolve it on schema tree */
+    ret = ly_path_compile(ctx, NULL, ctx_node, NULL, exp, (ctx_node->flags & LYS_IS_OUTPUT) ?
+            LY_PATH_OPER_OUTPUT : LY_PATH_OPER_INPUT, LY_PATH_TARGET_MANY, format, prefix_data, &path);
+    if (ret) {
+        ret = ly_err_new(err, ret, LYVE_DATA, NULL, NULL,
+                "Invalid instance-identifier \"%.*s\" value - semantic error.", (int)value_len, (char *)value);
+        goto cleanup;
+    }
+
+    /* store value */
+    storage->target = path;
+
+    /* store canonical value */
+    if (format == LY_VALUE_CANON) {
+        if (options & LYPLG_TYPE_STORE_DYNAMIC) {
+            ret = lydict_insert_zc(ctx, (char *)value, &storage->_canonical);
+            options &= ~LYPLG_TYPE_STORE_DYNAMIC;
+            LY_CHECK_GOTO(ret, cleanup);
+        } else {
+            ret = lydict_insert(ctx, value, value_len, &storage->_canonical);
+            LY_CHECK_GOTO(ret, cleanup);
+        }
+    } else {
+        /* JSON format with prefix is the canonical one */
+        ret = instanceid_path2str(path, LY_VALUE_JSON, NULL, &canon);
+        LY_CHECK_GOTO(ret, cleanup);
+
+        ret = lydict_insert_zc(ctx, canon, &storage->_canonical);
+        LY_CHECK_GOTO(ret, cleanup);
+    }
+
+cleanup:
+    lyxp_expr_free(ctx, exp);
+    if (options & LYPLG_TYPE_STORE_DYNAMIC) {
+        free((void *)value);
+    }
+
+    if (ret) {
+        lyplg_type_free_instanceid(ctx, storage);
+    }
+    return ret;
+}
+
+/**
+ * @brief Plugin information for instance-identifier type implementation.
+ *
+ * Note that external plugins are supposed to use:
+ *
+ *   LYPLG_TYPES = {
+ */
+const struct lyplg_type_record plugins_node_instanceid[] = {
+    {
+        .module = "ietf-netconf-acm",
+        .revision = "2012-02-22",
+        .name = "node-instance-identifier",
+
+        .plugin.id = "libyang 2 - node-instance-identifier, version 1",
+        .plugin.store = lyplg_type_store_node_instanceid,
+        .plugin.validate = NULL,
+        .plugin.compare = lyplg_type_compare_instanceid,
+        .plugin.sort = NULL,
+        .plugin.print = lyplg_type_print_instanceid,
+        .plugin.duplicate = lyplg_type_dup_instanceid,
+        .plugin.free = lyplg_type_free_instanceid
+    },
+    {
+        .module = "ietf-netconf-acm",
+        .revision = "2018-02-14",
+        .name = "node-instance-identifier",
+
+        .plugin.id = "libyang 2 - node-instance-identifier, version 1",
+        .plugin.store = lyplg_type_store_node_instanceid,
+        .plugin.validate = NULL,
+        .plugin.compare = lyplg_type_compare_instanceid,
+        .plugin.sort = NULL,
+        .plugin.print = lyplg_type_print_instanceid,
+        .plugin.duplicate = lyplg_type_dup_instanceid,
+        .plugin.free = lyplg_type_free_instanceid
+    },
+    {0}
+};