From 612e4c533527393490c8e3383d6c65dd076d70cd Mon Sep 17 00:00:00 2001
From: Andrew Wong <awong@redpanda.com>
Date: Wed, 21 Aug 2024 13:07:18 -0700
Subject: [PATCH] C++: accessors for custom attributes

Custom attributes are only settable when building a schema. There was
previously no way to get the attributes from a parsed schema. This will
be useful for reading Iceberg manifests, since we'll want to pull the
field ids for each type.
---
 lang/c++/include/avro/Node.hh     |  3 +++
 lang/c++/include/avro/NodeImpl.hh |  8 +++++++
 lang/c++/test/unittest.cc         | 38 +++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+)

diff --git a/lang/c++/include/avro/Node.hh b/lang/c++/include/avro/Node.hh
index d3840e14bd4..4141321ae93 100644
--- a/lang/c++/include/avro/Node.hh
+++ b/lang/c++/include/avro/Node.hh
@@ -168,6 +168,9 @@ public:
         doAddCustomAttribute(customAttributes);
     }
 
+    virtual size_t customAttributes() const = 0;
+    virtual const CustomAttributes& customAttributesAt(size_t index) const = 0;
+
     virtual bool isValid() const = 0;
 
     virtual SchemaResolution resolve(const Node &reader) const = 0;
diff --git a/lang/c++/include/avro/NodeImpl.hh b/lang/c++/include/avro/NodeImpl.hh
index 9bce944636b..faa9b25c8c6 100644
--- a/lang/c++/include/avro/NodeImpl.hh
+++ b/lang/c++/include/avro/NodeImpl.hh
@@ -147,6 +147,14 @@ protected:
         return nameIndex_.lookup(name, index);
     }
 
+    size_t customAttributes() const override {
+        return customAttributes_.size();
+    }
+
+    const CustomAttributes& customAttributesAt(size_t index) const override {
+        return customAttributes_.get(index);
+    }
+
     void doSetFixedSize(size_t size) override {
         sizeAttribute_.add(size);
     }
diff --git a/lang/c++/test/unittest.cc b/lang/c++/test/unittest.cc
index 2eeaa12da3b..7aed39573f8 100644
--- a/lang/c++/test/unittest.cc
+++ b/lang/c++/test/unittest.cc
@@ -497,6 +497,42 @@ struct TestSchema {
         BOOST_CHECK_EQUAL(false, cf.getAttribute("not_existing").is_initialized());
     }
 
+    void checkCustomAttributesFromNode()
+    {
+        std::string jsonWithCustomAttribute = R"(
+        {"type": "record", "name": "Test","fields":
+        [{"name": "f1", "type": "long",
+        "arrayField": [1],
+        "booleanField": true,
+        "mapField": {"key1":"value1", "key2":"value2"},
+        "nullField": null,
+        "numberField": 1.23,
+        "stringField": "field value with \"double quotes\""
+        }]}
+        )";
+        auto schema = avro::compileJsonSchemaFromString(jsonWithCustomAttribute);
+        const auto& nodePtr = schema.root();
+        BOOST_CHECK_EQUAL(nodePtr->type(), AVRO_RECORD);
+        BOOST_CHECK_EQUAL(1, nodePtr->customAttributes());
+        const auto& attrs = nodePtr->customAttributesAt(0);
+        BOOST_CHECK_EQUAL(6, attrs.attributes().size());
+        BOOST_CHECK_THROW(nodePtr->customAttributesAt(1), std::out_of_range);
+    }
+
+    void checkNoCustomAttributesFromNode()
+    {
+        std::string jsonNoCustomAttribute =
+        "{\"type\": \"record\", \"name\": \"Test\",\"fields\": "
+        "[{\"name\": \"f1\", \"type\": \"long\"}]}";
+        auto schema = avro::compileJsonSchemaFromString(jsonNoCustomAttribute);
+        const auto& nodePtr = schema.root();
+        BOOST_CHECK_EQUAL(nodePtr->type(), AVRO_RECORD);
+        BOOST_CHECK_EQUAL(1, nodePtr->customAttributes());
+        const auto& attrs = nodePtr->customAttributesAt(0);
+        BOOST_CHECK_EQUAL(0, attrs.attributes().size());
+        BOOST_CHECK_THROW(nodePtr->customAttributesAt(1), std::out_of_range);
+    }
+
     void test() {
         std::cout << "Before\n";
         schema_.toJson(std::cout);
@@ -522,6 +558,8 @@ struct TestSchema {
         checkNodeRecordWithoutCustomAttribute();
         checkNodeRecordWithCustomAttribute();
         checkCustomAttributes_getAttribute();
+        checkCustomAttributesFromNode();
+        checkNoCustomAttributesFromNode();
     }
 
     ValidSchema schema_;