feat: add SortOrderBuilder

src/iceberg/result.h

@@ -48,6 +48,7 @@ enum class ErrorKind {
   kNotFound,
   kNotImplemented,
   kNotSupported,
+  kValidationError,
   kUnknownError,
 };
 
@@ -97,6 +98,7 @@ DEFINE_ERROR_FUNCTION(NotAllowed)
 DEFINE_ERROR_FUNCTION(NotFound)
 DEFINE_ERROR_FUNCTION(NotImplemented)
 DEFINE_ERROR_FUNCTION(NotSupported)
+DEFINE_ERROR_FUNCTION(ValidationError)
 DEFINE_ERROR_FUNCTION(UnknownError)
 
 #undef DEFINE_ERROR_FUNCTION

src/iceberg/sort_order.cc

@@ -20,9 +20,18 @@
 #include "iceberg/sort_order.h"
 
 #include <format>
+#include <memory>
+#include <optional>
 #include <ranges>
 
+#include "iceberg/exception.h"
+#include "iceberg/expression/term.h"
+#include "iceberg/result.h"
+#include "iceberg/schema.h"
+#include "iceberg/sort_field.h"
+#include "iceberg/transform.h"
 #include "iceberg/util/formatter.h"  // IWYU pragma: keep
+#include "iceberg/util/macros.h"
 
 namespace iceberg {
 
@@ -31,7 +40,7 @@ SortOrder::SortOrder(int32_t order_id, std::vector<SortField> fields)
 
 const std::shared_ptr<SortOrder>& SortOrder::Unsorted() {
   static const std::shared_ptr<SortOrder> unsorted =
-      std::make_shared<SortOrder>(/*order_id=*/0, std::vector<SortField>{});
+      std::make_shared<SortOrder>(kUnsortedOrderId, std::vector<SortField>{});
   return unsorted;
 }
 
@@ -80,4 +89,114 @@ bool SortOrder::Equals(const SortOrder& other) const {
   return order_id_ == other.order_id_ && fields_ == other.fields_;
 }
 
+// SortOrderBuilder implementation
+
+struct SortOrderBuilder::Impl {
+  const Schema* schema;
+  std::optional<int32_t> sort_id;
+  std::vector<SortField> fields;
+  bool case_sensitive{false};
+
+  explicit Impl(const Schema* schema) : schema(schema) {}
+};
+
+SortOrderBuilder::~SortOrderBuilder() = default;
+
+SortOrderBuilder::SortOrderBuilder(SortOrderBuilder&&) noexcept = default;
+
+SortOrderBuilder& SortOrderBuilder::operator=(SortOrderBuilder&&) noexcept = default;
+
+SortOrderBuilder::SortOrderBuilder(const Schema* schema)
+    : impl_(std::make_unique<Impl>(schema)) {}
+
+std::unique_ptr<SortOrderBuilder> SortOrderBuilder::BuildFromSchema(
+    const Schema* schema) {
+  return std::unique_ptr<SortOrderBuilder>(new SortOrderBuilder(schema));  // NOLINT
+}
+
+SortOrderBuilder& SortOrderBuilder::WithOrderId(int32_t sort_id) {
+  impl_->sort_id = sort_id;
+  return *this;
+}
+
+SortOrderBuilder& SortOrderBuilder::CaseSensitive(bool case_sensitive) {
+  impl_->case_sensitive = case_sensitive;
+  return *this;
+}
+
+Result<std::unique_ptr<SortOrder>> SortOrderBuilder::BuildUncheckd() {
+  if (impl_->fields.empty()) {
+    if (impl_->sort_id.has_value() && impl_->sort_id != SortOrder::kUnsortedOrderId) {
+      return InvalidArgument("Unsorted order ID must be 0");
+    }
+    return std::make_unique<SortOrder>(SortOrder::kUnsortedOrderId,
+                                       std::vector<SortField>{});
+  }
+
+  if (impl_->sort_id.has_value() && impl_->sort_id == SortOrder::kUnsortedOrderId) {
+    return InvalidArgument("Sort order ID 0 is reserved for unsorted order");
+  }
+
+  // default ID to 1 as 0 is reserved for unsorted order
+  return std::make_unique<SortOrder>(
+      impl_->sort_id.value_or(SortOrder::kInitialSortOrderId), std::move(impl_->fields));
+}
+
+Result<std::unique_ptr<SortOrder>> SortOrderBuilder::Build() {
+  ICEBERG_ASSIGN_OR_RAISE(auto sort_order, BuildUncheckd());
+  ICEBERG_RETURN_UNEXPECTED(CheckCompatibility(sort_order, impl_->schema));
+  return sort_order;
+}
+
+SortOrderBuilder& SortOrderBuilder::AddSortField(
+    int32_t source_id, const std::shared_ptr<Transform>& transform,
+    SortDirection direction, NullOrder null_order) {
+  impl_->fields.emplace_back(source_id, transform, direction, null_order);
+  return *this;
+}
+
+SortOrderBuilder& SortOrderBuilder::AddSortField(const std::shared_ptr<Term>& term,
+                                                 SortDirection direction,
+                                                 NullOrder null_order) {
+  if (auto named_ref = std::dynamic_pointer_cast<NamedReference>(term)) {
+    auto bound_ref = named_ref->Bind(*impl_->schema, impl_->case_sensitive);
+    ICEBERG_CHECK(bound_ref.has_value(), "Failed to bind named reference to schema.");
+    int32_t source_id = bound_ref.value()->field().field_id();
+    impl_->fields.emplace_back(source_id, Transform::Identity(), direction, null_order);
+  } else if (auto unbound_transform = std::dynamic_pointer_cast<UnboundTransform>(term)) {
+    auto bound_transform = unbound_transform->Bind(*impl_->schema, impl_->case_sensitive);
+    ICEBERG_CHECK(bound_transform.has_value(),
+                  "Failed to bind unbound transform to schema.");
+    int32_t source_id = bound_transform.value()->reference()->field().field_id();
+    impl_->fields.emplace_back(source_id, bound_transform.value()->transform(), direction,
+                               null_order);
+  } else {
+    throw IcebergError(std::format(
+        "Invalid term: {}, expected either a named reference or an unbound transform",
+        term ? term->ToString() : "null"));
+  }
+
+  return *this;
+}
+
+Status SortOrderBuilder::CheckCompatibility(const std::unique_ptr<SortOrder>& sort_order,
+                                            const Schema* schema) {
+  for (const auto& field : sort_order->fields()) {
+    ICEBERG_ASSIGN_OR_RAISE(auto schema_field, schema->FindFieldById(field.source_id()));
+    if (schema_field == std::nullopt) {
+      return ValidationError("Cannot find source column for sort field: {}", field);
+    }
+
+    const auto& source_type = schema_field.value().get().type();
+
+    if (!source_type->is_primitive()) {
+      return ValidationError("Cannot sort by non-primitive source field: {}",
+                             *source_type);
+    }
+
+    ICEBERG_RETURN_UNEXPECTED(field.transform()->ResultType(source_type));
+  }
+  return {};
+}
+
 }  // namespace iceberg

src/iceberg/sort_order.h

@@ -20,11 +20,15 @@
 #pragma once
 
 #include <cstdint>
+#include <memory>
 #include <span>
 #include <vector>
 
+#include "iceberg/expression/expressions.h"
+#include "iceberg/expression/term.h"
 #include "iceberg/iceberg_export.h"
 #include "iceberg/sort_field.h"
+#include "iceberg/type_fwd.h"
 #include "iceberg/util/formattable.h"
 
 namespace iceberg {
@@ -36,6 +40,7 @@ namespace iceberg {
 /// applied to the data.
 class ICEBERG_EXPORT SortOrder : public util::Formattable {
  public:
+  static constexpr int32_t kUnsortedOrderId = 0;
   static constexpr int32_t kInitialSortOrderId = 1;
 
   SortOrder(int32_t order_id, std::vector<SortField> fields);
@@ -77,4 +82,85 @@ class ICEBERG_EXPORT SortOrder : public util::Formattable {
   std::vector<SortField> fields_;
 };
 
+/// \brief A builder used to create valid SortOrder instances.
+class ICEBERG_EXPORT SortOrderBuilder {
+ public:
+  /// \brief Create a builder for a new SortOrder
+  ///
+  /// \return A new SortOrderBuilder instance initialized with Schema
+  static std::unique_ptr<SortOrderBuilder> BuildFromSchema(const Schema* schema);
+
+  /// \brief Add an expression term to the sort, ascending with the given null order.
+  SortOrderBuilder& Asc(const std::shared_ptr<Term>& term, NullOrder null_order) {
+    return AddSortField(term, SortDirection::kAscending, null_order);
+  }
+
+  /// \brief Add an expression term to the sort, descending with the given null order.
+  SortOrderBuilder& Desc(const std::shared_ptr<Term>& term, NullOrder null_order) {
+    return AddSortField(term, SortDirection::kDescending, null_order);
+  }
+
+  /// \brief Add a sort field to the sort order.
+  SortOrderBuilder& SortBy(std::string name, SortDirection direction,
+                           NullOrder null_order) {
+    return AddSortField(Expressions::Ref(std::move(name)), direction, null_order);
+  }
+
+  /// \brief Add a sort field to the sort order.
+  SortOrderBuilder& SortBy(const std::shared_ptr<Term>& term, SortDirection direction,
+                           NullOrder null_order) {
+    return AddSortField(term, direction, null_order);
+  }
+
+  /// \brief Set sort id to the sort order.
+  SortOrderBuilder& WithOrderId(int32_t sort_id);
+
+  /// \brief Set case sensitive to the sort order.
+  SortOrderBuilder& CaseSensitive(bool case_sensitive);
+
+  /// \brief Add a sort field to the sort order with the specified source field ID,
+  /// transform, direction, and null order.
+  ///
+  /// \param source_id The source field ID.
+  /// \param transform The transform to apply to the field.
+  /// \param direction The sort direction.
+  /// \param null_order The null ordering behavior (e.g., nulls first or nulls last).
+  SortOrderBuilder& AddSortField(int32_t source_id,
+                                 const std::shared_ptr<Transform>& transform,
+                                 SortDirection direction, NullOrder null_order);
+
+  /// \brief Builds a SortOrder instance.
+  ///
+  /// \return A Result containing the constructed SortOrder or an error
+  Result<std::unique_ptr<SortOrder>> Build();
+
+  /// \brief Destructor
+  ~SortOrderBuilder();
+
+  // Delete copy operations (use BuildFromSchema to create a new builder)
+  SortOrderBuilder(const SortOrderBuilder&) = delete;
+  SortOrderBuilder& operator=(const SortOrderBuilder&) = delete;
+
+  // Enable move operations
+  SortOrderBuilder(SortOrderBuilder&&) noexcept;
+  SortOrderBuilder& operator=(SortOrderBuilder&&) noexcept;
+
+ private:
+  /// \brief Private constructor for building from Schema
+  explicit SortOrderBuilder(const Schema* schema);
+
+  SortOrderBuilder& AddSortField(const std::shared_ptr<Term>& term,
+                                 SortDirection direction, NullOrder null_order);
+
+  /// \brief Builds an unchecked SortOrder instance.
+  Result<std::unique_ptr<SortOrder>> BuildUncheckd();
+
+  static Status CheckCompatibility(const std::unique_ptr<SortOrder>& sort_order,
+                                   const Schema* schema);
+
+  /// Internal state members
+  struct Impl;
+  std::unique_ptr<Impl> impl_;
+};
+
 }  // namespace iceberg

src/iceberg/test/CMakeLists.txt

@@ -73,6 +73,7 @@ add_iceberg_test(schema_test
                  partition_field_test.cc
                  partition_spec_test.cc
                  sort_field_test.cc
+                 sort_order_builder_test.cc
                  sort_order_test.cc
                  snapshot_test.cc
                  schema_util_test.cc)

src/iceberg/test/meson.build

@@ -38,6 +38,7 @@ iceberg_tests = {
             'schema_util_test.cc',
             'snapshot_test.cc',
             'sort_field_test.cc',
+            'sort_order_builder_test.cc',
             'sort_order_test.cc',
             'transform_test.cc',
             'type_test.cc',

src/iceberg/test/schema_field_test.cc

@@ -63,7 +63,7 @@ TEST(SchemaFieldTest, Equality) {
   iceberg::SchemaField field1(1, "foo", iceberg::int32(), false);
   iceberg::SchemaField field2(2, "foo", iceberg::int32(), false);
   iceberg::SchemaField field3(1, "bar", iceberg::int32(), false);
-  iceberg::SchemaField field4(1, "foo", std::make_shared<iceberg::LongType>(), false);
+  iceberg::SchemaField field4(1, "foo", iceberg::int64(), false);
   iceberg::SchemaField field5(1, "foo", iceberg::int32(), true);
   iceberg::SchemaField field6(1, "foo", iceberg::int32(), false);
 

src/iceberg/test/schema_test.cc

@@ -25,7 +25,6 @@
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
-#include "gtest/gtest.h"
 #include "iceberg/result.h"
 #include "iceberg/schema_field.h"
 #include "iceberg/test/matchers.h"