[Expr Serde] [PR 1/X] basic plumbing for serde support for expressions

src/iceberg/CMakeLists.txt

@@ -31,6 +31,7 @@ set(ICEBERG_SOURCES
     expression/expression.cc
     expression/expressions.cc
     expression/inclusive_metrics_evaluator.cc
+    expression/json_serde.cc
     expression/literal.cc
     expression/manifest_evaluator.cc
     expression/predicate.cc

src/iceberg/expression/json_serde.cc

@@ -0,0 +1,64 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include <format>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <nlohmann/json.hpp>
+
+#include "iceberg/expression/expressions.h"
+#include "iceberg/expression/json_serde_internal.h"
+#include "iceberg/expression/literal.h"
+#include "iceberg/util/json_util_internal.h"
+#include "iceberg/util/macros.h"
+
+namespace iceberg {
+
+Result<std::shared_ptr<Expression>> ExpressionFromJson(const nlohmann::json& json) {
+  // Handle boolean
+  if (json.is_boolean()) {
+    return json.get<bool>() ? std::static_pointer_cast<Expression>(True::Instance())
+                            : std::static_pointer_cast<Expression>(False::Instance());
+  }
+  return JsonParseError("Only boolean are currently supported");
+}
+
+nlohmann::json ToJson(const Expression& expr) {
+  switch (expr.op()) {
+    case Expression::Operation::kTrue:
+      return true;
+
+    case Expression::Operation::kFalse:
+      return false;
+    default:
+      throw std::logic_error("Only booleans are currently supported");
+  }
+}
+
+#define ICEBERG_DEFINE_FROM_JSON(Model)                                        \
+  template <>                                                                  \
+  Result<std::shared_ptr<Model>> FromJson<Model>(const nlohmann::json& json) { \
+    return Model##FromJson(json);                                              \
+  }
+
+ICEBERG_DEFINE_FROM_JSON(Expression)
+
+}  // namespace iceberg

src/iceberg/expression/json_serde_internal.h

@@ -0,0 +1,51 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#pragma once
+
+#include <nlohmann/json_fwd.hpp>
+
+#include "iceberg/expression/expression.h"
+#include "iceberg/iceberg_export.h"
+#include "iceberg/result.h"
+
+/// \file iceberg/expression/json_internal.h
+/// JSON serialization and deserialization for expressions.
+
+namespace iceberg {
+
+template <typename Model>
+Result<Model> FromJson(const nlohmann::json& json);
+
+#define ICEBERG_DECLARE_JSON_SERDE(Model)                                             \
+  ICEBERG_EXPORT Result<std::shared_ptr<Model>> Model##FromJson(                      \
+      const nlohmann::json& json);                                                    \
+                                                                                      \
+  template <typename Model>                                                           \
+  ICEBERG_EXPORT Result<std::shared_ptr<Model>> FromJson(const nlohmann::json& json); \
+                                                                                      \
+  ICEBERG_EXPORT nlohmann::json ToJson(const Model& model);
+
+/// \note Don't forget to add `ICEBERG_DEFINE_FROM_JSON` to the end of
+/// `json_internal.cc` to define the `FromJson` function for the model.
+ICEBERG_DECLARE_JSON_SERDE(Expression)
+
+#undef ICEBERG_DECLARE_JSON_SERDE
+
+}  // namespace iceberg

src/iceberg/test/CMakeLists.txt

@@ -88,6 +88,7 @@ add_iceberg_test(table_test
 add_iceberg_test(expression_test
                  SOURCES
                  aggregate_test.cc
+                 expression_json_test.cc
                  expression_test.cc
                  expression_visitor_test.cc
                  inclusive_metrics_evaluator_test.cc

src/iceberg/test/expression_json_test.cc

@@ -0,0 +1,68 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include <memory>
+#include <vector>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <nlohmann/json.hpp>
+
+#include "iceberg/expression/expression.h"
+#include "iceberg/expression/expressions.h"
+#include "iceberg/expression/json_serde_internal.h"
+#include "iceberg/expression/literal.h"
+#include "iceberg/expression/predicate.h"
+#include "iceberg/expression/term.h"
+#include "iceberg/test/matchers.h"
+
+namespace iceberg {
+
+class ExpressionJsonTest : public ::testing::Test {};
+
+// Test boolean constant expressions
+TEST_F(ExpressionJsonTest, TrueExpression) {
+  auto expr = True::Instance();
+  auto json = ToJson(*expr);
+
+  // True should serialize as JSON boolean true
+  EXPECT_TRUE(json.is_boolean());
+  EXPECT_TRUE(json.get<bool>());
+
+  // Parse back
+  auto result = ExpressionFromJson(json);
+  ASSERT_THAT(result, IsOk());
+  EXPECT_EQ(result.value()->op(), Expression::Operation::kTrue);
+}
+
+TEST_F(ExpressionJsonTest, FalseExpression) {
+  auto expr = False::Instance();
+  auto json = ToJson(*expr);
+
+  // False should serialize as JSON boolean false
+  EXPECT_TRUE(json.is_boolean());
+  EXPECT_FALSE(json.get<bool>());
+
+  // Parse back
+  auto result = ExpressionFromJson(json);
+  ASSERT_THAT(result, IsOk());
+  EXPECT_EQ(result.value()->op(), Expression::Operation::kFalse);
+}
+
+}  // namespace iceberg