schema: make leaf-list's default statement available

Make leaf-list's `default` statement available so that it can be
accessed if end-user requires reading schema nodes.

`LeafList::defaultValuesStr()` returns array of canonized string default
values.

Change-Id: Idc42cd877f1fd3d717d491d09c46b59492527bff

Author: bedrich-schindler

include/libyang-cpp/SchemaNode.hpp

@@ -169,6 +169,7 @@ class LIBYANG_CPP_EXPORT LeafList : public SchemaNode {
 public:
     bool isMandatory() const;
     types::Type valueType() const;
+    std::vector<std::string> defaultValuesStr() const;
     libyang::types::constraints::ListSize maxElements() const;
     libyang::types::constraints::ListSize minElements() const;
     std::optional<std::string> units() const;

src/SchemaNode.cpp

@@ -472,6 +472,23 @@ types::Type LeafList::valueType() const
     return types::Type{reinterpret_cast<const lysc_node_leaflist*>(m_node)->type, typeParsed, m_ctx};
 }
 
+/**
+ * @brief Retrieves the default string values for this leaf-list.
+ *
+ * @return The default values, or an empty vector if the leaf-list does not have default values.
+ *
+ * Wraps `lysc_node_leaflist::dflts`.
+ */
+std::vector<std::string> LeafList::defaultValuesStr() const
+{
+    auto dflts = reinterpret_cast<const lysc_node_leaflist*>(m_node)->dflts;
+    std::vector<std::string> res;
+    for (const auto& it : std::span(dflts, LY_ARRAY_COUNT(dflts))) {
+        res.emplace_back(lyd_value_get_canonical(m_ctx.get(), it));
+    }
+    return res;
+}
+
 /**
  * @brief Retrieves the units for this leaf.
  * @return The units, or std::nullopt if no units are available.

tests/context.cpp

@@ -733,6 +733,7 @@ TEST_CASE("context")
   +--rw iid-valid?                     instance-identifier
   +--rw iid-relaxed?                   instance-identifier
   +--rw leafListBasic*                 string
+  +--rw leafListWithDefault*           int32
   +--rw leafListWithMinMaxElements*    int32
   +--rw leafListWithUnits*             int32
   +--rw listBasic* [primary-key]

tests/example_schema.hpp

@@ -525,6 +525,14 @@ module type_module {
         ordered-by user;
     }
 
+    leaf-list leafListWithDefault {
+        type int32;
+        default -1;
+        default +512;
+        default 0x400;
+        default 04000;
+    }
+
     leaf-list leafListWithMinMaxElements {
         type int32;
         min-elements 1;

tests/schema_node.cpp

@@ -200,6 +200,7 @@ TEST_CASE("SchemaNode")
                 "/type_module:iid-valid",
                 "/type_module:iid-relaxed",
                 "/type_module:leafListBasic",
+                "/type_module:leafListWithDefault",
                 "/type_module:leafListWithMinMaxElements",
                 "/type_module:leafListWithUnits",
                 "/type_module:listBasic",
@@ -606,6 +607,12 @@ TEST_CASE("SchemaNode")
         REQUIRE(!ctx->findPath("/type_module:leafListBasic").asLeafList().isMandatory());
     }
 
+    DOCTEST_SUBCASE("LeafList::defaultValuesStr")
+    {
+        REQUIRE(ctx->findPath("/type_module:leafListWithDefault").asLeafList().defaultValuesStr() == std::vector<std::string>{"-1", "512", "1024", "2048"});
+        REQUIRE(ctx->findPath("/type_module:leafListBasic").asLeafList().defaultValuesStr().size() == 0);
+    }
+
     DOCTEST_SUBCASE("LeafList::maxElements")
     {
         REQUIRE(ctx->findPath("/type_module:leafListWithMinMaxElements").asLeafList().maxElements() == 5);