[Expr Serde] [PR 2/X] Operation type enum conversion helper

src/iceberg/CMakeLists.txt

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

src/iceberg/expression/json_internal.cc

@@ -0,0 +1,164 @@
+/*
+ * 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 "iceberg/expression/json_internal.h"
+
+#include <format>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <nlohmann/json.hpp>
+
+#include "iceberg/expression/expressions.h"
+#include "iceberg/expression/literal.h"
+#include "iceberg/util/json_util_internal.h"
+#include "iceberg/util/macros.h"
+
+namespace iceberg {
+namespace {
+// Expression type strings
+constexpr std::string_view kTypeTrue = "true";
+constexpr std::string_view kTypeFalse = "false";
+constexpr std::string_view kTypeEq = "eq";
+constexpr std::string_view kTypeAnd = "and";
+constexpr std::string_view kTypeOr = "or";
+constexpr std::string_view kTypeNot = "not";
+constexpr std::string_view kTypeIn = "in";
+constexpr std::string_view kTypeNotIn = "not-in";
+constexpr std::string_view kTypeLt = "lt";
+constexpr std::string_view kTypeLtEq = "lt-eq";
+constexpr std::string_view kTypeGt = "gt";
+constexpr std::string_view kTypeGtEq = "gt-eq";
+constexpr std::string_view kTypeNotEq = "not-eq";
+constexpr std::string_view kTypeStartsWith = "starts-with";
+constexpr std::string_view kTypeNotStartsWith = "not-starts-with";
+constexpr std::string_view kTypeIsNull = "is-null";
+constexpr std::string_view kTypeNotNull = "not-null";
+constexpr std::string_view kTypeIsNan = "is-nan";
+constexpr std::string_view kTypeNotNan = "not-nan";
+}  // namespace
+
+/// \brief Converts a JSON type string to an Expression::Operation.
+///
+/// \param type_str The JSON type string
+/// \return The corresponding Operation or an error if unknown
+Result<Expression::Operation> OperationTypeFromString(const std::string_view type_str) {
+  if (type_str == kTypeTrue) return Expression::Operation::kTrue;
+  if (type_str == kTypeFalse) return Expression::Operation::kFalse;
+  if (type_str == kTypeAnd) return Expression::Operation::kAnd;
+  if (type_str == kTypeOr) return Expression::Operation::kOr;
+  if (type_str == kTypeNot) return Expression::Operation::kNot;
+  if (type_str == kTypeEq) return Expression::Operation::kEq;
+  if (type_str == kTypeNotEq) return Expression::Operation::kNotEq;
+  if (type_str == kTypeLt) return Expression::Operation::kLt;
+  if (type_str == kTypeLtEq) return Expression::Operation::kLtEq;
+  if (type_str == kTypeGt) return Expression::Operation::kGt;
+  if (type_str == kTypeGtEq) return Expression::Operation::kGtEq;
+  if (type_str == kTypeIn) return Expression::Operation::kIn;
+  if (type_str == kTypeNotIn) return Expression::Operation::kNotIn;
+  if (type_str == kTypeIsNull) return Expression::Operation::kIsNull;
+  if (type_str == kTypeNotNull) return Expression::Operation::kNotNull;
+  if (type_str == kTypeIsNan) return Expression::Operation::kIsNan;
+  if (type_str == kTypeNotNan) return Expression::Operation::kNotNan;
+  if (type_str == kTypeStartsWith) return Expression::Operation::kStartsWith;
+  if (type_str == kTypeNotStartsWith) return Expression::Operation::kNotStartsWith;
+
+  return JsonParseError("Unknown expression type: {}", type_str);
+}
+
+/// \brief Converts an Expression::Operation to its JSON string representation.
+///
+/// \param op The operation to convert
+/// \return The JSON type string (e.g., "eq", "lt-eq", "is-null")
+std::string_view ToStringOperationType(Expression::Operation op) {
+  switch (op) {
+    case Expression::Operation::kTrue:
+      return kTypeTrue;
+    case Expression::Operation::kFalse:
+      return kTypeFalse;
+    case Expression::Operation::kAnd:
+      return kTypeAnd;
+    case Expression::Operation::kOr:
+      return kTypeOr;
+    case Expression::Operation::kNot:
+      return kTypeNot;
+    case Expression::Operation::kEq:
+      return kTypeEq;
+    case Expression::Operation::kNotEq:
+      return kTypeNotEq;
+    case Expression::Operation::kLt:
+      return kTypeLt;
+    case Expression::Operation::kLtEq:
+      return kTypeLtEq;
+    case Expression::Operation::kGt:
+      return kTypeGt;
+    case Expression::Operation::kGtEq:
+      return kTypeGtEq;
+    case Expression::Operation::kIn:
+      return kTypeIn;
+    case Expression::Operation::kNotIn:
+      return kTypeNotIn;
+    case Expression::Operation::kIsNull:
+      return kTypeIsNull;
+    case Expression::Operation::kNotNull:
+      return kTypeNotNull;
+    case Expression::Operation::kIsNan:
+      return kTypeIsNan;
+    case Expression::Operation::kNotNan:
+      return kTypeNotNan;
+    case Expression::Operation::kStartsWith:
+      return kTypeStartsWith;
+    case Expression::Operation::kNotStartsWith:
+      return kTypeNotStartsWith;
+    default:
+      return "unknown";
+  }
+}
+
+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 booleans 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_internal.h

@@ -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.
+ */
+
+#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
+
+/// \brief Converts an operation type string to an Expression::Operation.
+///
+/// \param type_str The operation type string
+/// \return The corresponding Operation or an error if unknown
+ICEBERG_EXPORT Result<Expression::Operation> OperationTypeFromString(
+    const std::string_view type_str);
+
+/// \brief Converts an Expression::Operation to its string representation.
+///
+/// \param op The operation to convert
+/// \return The operation type string (e.g., "eq", "lt-eq", "is-null")
+ICEBERG_EXPORT std::string_view ToStringOperationType(Expression::Operation op);
+
+}  // 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 +1,85 @@
+/*
+ * 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_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 {
+ protected:
+  // Helper to test round-trip serialization
+  // Uses string comparison since expressions may have different internal identity
+  // but the same semantic meaning (i.e., ToString() output matches)
+  void TestRoundTrip(const Expression& expr) {
+    auto json = ToJson(expr);
+    auto result = ExpressionFromJson(json);
+    ASSERT_THAT(result, IsOk()) << "Failed to parse JSON: " << json.dump();
+    EXPECT_EQ(expr.ToString(), result.value()->ToString())
+        << "Round-trip failed.\nJSON: " << json.dump();
+  }
+};
+
+// 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);
+}
+
+TEST_F(ExpressionJsonTest, OpToString) {
+  EXPECT_EQ(OperationTypeFromString("true"), Expression::Operation::kTrue);
+  EXPECT_EQ("true", ToStringOperationType(Expression::Operation::kTrue));
+}
+
+}  // namespace iceberg