data: add support for lyd_attr to DNode

Add new DNodeAttrs class mapped to access the lyd_attr structure in a
DNode, and unit tests for it.

Fixes: #77
Signed-off-by: nvxf <68589039+nvxf@users.noreply.github.com>
Signed-off-by: Samuel Gauthier <samuel.gauthier@6wind.com>

Author: nvxf

cffi/cdefs.h

@@ -1042,5 +1042,56 @@ LY_ERR lyd_new_implicit_all(struct lyd_node **, const struct ly_ctx *, uint32_t,
 
 LY_ERR lyd_new_meta(const struct ly_ctx *, struct lyd_node *, const struct lys_module *, const char *, const char *, ly_bool, struct lyd_meta **);
 
+struct ly_opaq_name {
+    const char *name;
+    const char *prefix;
+
+    union {
+        const char *module_ns;
+        const char *module_name;
+    };
+};
+
+struct lyd_node_opaq {
+    union {
+        struct lyd_node node;
+
+        struct {
+            uint32_t hash;
+            uint32_t flags;
+            const struct lysc_node *schema;
+            struct lyd_node_inner *parent;
+            struct lyd_node *next;
+            struct lyd_node *prev;
+            struct lyd_meta *meta;
+            void *priv;
+        };
+    };
+
+    struct lyd_node *child;
+
+    struct ly_opaq_name name;
+    const char *value;
+    uint32_t hints;
+    LY_VALUE_FORMAT format;
+    void *val_prefix_data;
+
+    struct lyd_attr *attr;
+    const struct ly_ctx *ctx;
+};
+
+struct lyd_attr {
+    struct lyd_node_opaq *parent;
+    struct lyd_attr *next;
+    struct ly_opaq_name name;
+    const char *value;
+    uint32_t hints;
+    LY_VALUE_FORMAT format;
+    void *val_prefix_data;
+};
+
+LY_ERR lyd_new_attr(struct lyd_node *, const char *, const char *, const char *, struct lyd_attr **);
+void lyd_free_attr_single(const struct ly_ctx *ctx, struct lyd_attr *attr);
+
 /* from libc, needed to free allocated strings */
 void free(void *);

libyang/__init__.py

@@ -13,6 +13,7 @@
     DLeafList,
     DList,
     DNode,
+    DNodeAttrs,
     DNotif,
     DRpc,
 )

libyang/data.py

@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: MIT
 
 import logging
-from typing import IO, Any, Dict, Iterator, Optional, Union
+from typing import IO, Any, Dict, Iterator, Optional, Tuple, Union
 
 from _libyang import ffi, lib
 from .keyed_list import KeyedList
@@ -190,13 +190,69 @@ def diff_flags(with_defaults: bool = False) -> int:
     return flags
 
 
+# -------------------------------------------------------------------------------------
+class DNodeAttrs:
+    __slots__ = ("context", "parent", "cdata", "__dict__")
+
+    def __init__(self, context: "libyang.Context", parent: "libyang.DNode"):
+        self.context = context
+        self.parent = parent
+        self.cdata = []  # C type: "struct lyd_attr *"
+
+    def get(self, name: str) -> Optional[str]:
+        for attr_name, attr_value in self:
+            if attr_name == name:
+                return attr_value
+        return None
+
+    def set(self, name: str, value: str):
+        attrs = ffi.new("struct lyd_attr **")
+        ret = lib.lyd_new_attr(
+            self.parent.cdata,
+            ffi.NULL,
+            str2c(name),
+            str2c(value),
+            attrs,
+        )
+        if ret != lib.LY_SUCCESS:
+            raise self.context.error("cannot create attr")
+        self.cdata.append(attrs[0])
+
+    def remove(self, name: str):
+        for attr in self.cdata:
+            if self._get_attr_name(attr) == name:
+                lib.lyd_free_attr_single(self.context.cdata, attr)
+                self.cdata.remove(attr)
+                break
+
+    def __contains__(self, name: str) -> bool:
+        for attr_name, _ in self:
+            if attr_name == name:
+                return True
+        return False
+
+    def __iter__(self) -> Iterator[Tuple[str, str]]:
+        for attr in self.cdata:
+            name = self._get_attr_name(attr)
+            yield (name, c2str(attr.value))
+
+    def __len__(self) -> int:
+        return len(self.cdata)
+
+    @staticmethod
+    def _get_attr_name(cdata) -> str:
+        if cdata.name.prefix != ffi.NULL:
+            return f"{c2str(cdata.name.prefix)}:{c2str(cdata.name.name)}"
+        return c2str(cdata.name.name)
+
+
 # -------------------------------------------------------------------------------------
 class DNode:
     """
     Data tree node.
     """
 
-    __slots__ = ("context", "cdata", "free_func", "__dict__")
+    __slots__ = ("context", "cdata", "attributes", "free_func", "__dict__")
 
     def __init__(self, context: "libyang.Context", cdata):
         """
@@ -207,6 +263,7 @@ def __init__(self, context: "libyang.Context", cdata):
         """
         self.context = context
         self.cdata = cdata  # C type: "struct lyd_node *"
+        self.attributes = None
         self.free_func = None  # type: Callable[DNode]
 
     def meta(self):
@@ -254,6 +311,11 @@ def new_meta(self, name: str, value: str, clear_dflt: bool = False):
         if ret != lib.LY_SUCCESS:
             raise self.context.error("cannot create meta")
 
+    def attrs(self) -> DNodeAttrs:
+        if not self.attributes:
+            self.attributes = DNodeAttrs(self.context, self)
+        return self.attributes
+
     def add_defaults(
         self,
         no_config: bool = False,

tests/test_data.py

@@ -16,6 +16,7 @@
     DLeaf,
     DList,
     DNode,
+    DNodeAttrs,
     DNotif,
     DRpc,
     IOType,
@@ -950,13 +951,86 @@ def test_dnode_insert_sibling(self):
         self.assertIsInstance(sibling, DLeaf)
         self.assertEqual(sibling.cdata, dnode2.cdata)
 
-    def test_dnode_new_opaq_find_one(self):
+    def _create_opaq_hostname(self):
         root = self.ctx.create_data_path(path="/yolo-system:conf")
         root.new_path(
             "hostname",
             None,
             opt_opaq=True,
         )
-        dnode = root.find_one("/yolo-system:conf/hostname")
+        return root.find_one("/yolo-system:conf/hostname")
+
+    def test_dnode_new_opaq_find_one(self):
+        dnode = self._create_opaq_hostname()
 
         self.assertIsInstance(dnode, DLeaf)
+
+    def test_dnode_attrs(self):
+        dnode = self._create_opaq_hostname()
+        attrs = dnode.attrs()
+
+        self.assertIsInstance(attrs, DNodeAttrs)
+
+    def test_dnode_attrs_set(self):
+        dnode = self._create_opaq_hostname()
+        attrs = dnode.attrs()
+
+        self.assertEqual(len(attrs.cdata), 0)
+        attrs.set("ietf-netconf:operation", "remove")
+
+        self.assertEqual(len(attrs.cdata), 1)
+
+    def test_dnode_attrs_get(self):
+        dnode = self._create_opaq_hostname()
+        attrs = dnode.attrs()
+
+        attrs.set("ietf-netconf:operation", "remove")
+
+        value = attrs.get("ietf-netconf:operation")
+        self.assertEqual(value, "remove")
+
+    def test_dnode_attrs__len(self):
+        dnode = self._create_opaq_hostname()
+        attrs = dnode.attrs()
+
+        self.assertEqual(len(attrs), 0)
+        attrs.set("ietf-netconf:operation", "remove")
+
+        self.assertEqual(len(attrs), 1)
+
+    def test_dnode_attrs__contains(self):
+        dnode = self._create_opaq_hostname()
+        attrs = dnode.attrs()
+
+        attrs.set("ietf-netconf:operation", "remove")
+
+        self.assertTrue("ietf-netconf:operation" in attrs)
+
+    def test_dnode_attrs_remove(self):
+        dnode = self._create_opaq_hostname()
+        attrs = dnode.attrs()
+
+        attrs.set("ietf-netconf:operation", "remove")
+        attrs.remove("ietf-netconf:operation")
+
+        self.assertEqual(len(attrs), 0)
+
+    def test_dnode_attrs_set_and_remove_multiple(self):
+        dnode = self._create_opaq_hostname()
+        attrs = dnode.attrs()
+
+        attrs.set("ietf-netconf:operation", "remove")
+        attrs.set("something:else", "test")
+        attrs.set("no_prefix", "test")
+        self.assertEqual(len(attrs), 3)
+
+        attrs.remove("something:else")
+        self.assertEqual(len(attrs), 2)
+        self.assertIn("no_prefix", attrs)
+        self.assertIn("ietf-netconf:operation", attrs)
+
+        attrs.remove("no_prefix")
+        self.assertEqual(len(attrs), 1)
+
+        attrs.remove("ietf-netconf:operation")
+        self.assertEqual(len(attrs), 0)