Add data type/schema field/schema

docs/Doxyfile

@@ -195,7 +195,7 @@ INLINE_INHERITED_MEMB  = NO
 # shortest path that makes the file name unique will be used
 # The default value is: YES.
 
-FULL_PATH_NAMES        = NO
+FULL_PATH_NAMES        = YES
 
 # The STRIP_FROM_PATH tag can be used to strip a user-defined part of the path.
 # Stripping is only done if one of the specified strings matches the left-hand
@@ -207,7 +207,7 @@ FULL_PATH_NAMES        = NO
 # will be relative from the directory where doxygen is started.
 # This tag requires that the tag FULL_PATH_NAMES is set to YES.
 
-STRIP_FROM_PATH        =
+STRIP_FROM_PATH        = ../src
 
 # The STRIP_FROM_INC_PATH tag can be used to strip a user-defined part of the
 # path mentioned in the documentation of a class, which tells the reader which

src/iceberg/CMakeLists.txt

@@ -15,7 +15,7 @@
 # specific language governing permissions and limitations
 # under the License.
 
-set(ICEBERG_SOURCES demo_table.cc)
+set(ICEBERG_SOURCES demo_table.cc schema.cc schema_field.cc type.cc)
 
 add_iceberg_lib(iceberg
                 SOURCES

src/iceberg/schema.cc

@@ -0,0 +1,47 @@
+/*
+ * 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/schema.h"
+
+#include <format>
+
+#include "iceberg/type.h"
+#include "iceberg/util/formatter.h"
+
+namespace iceberg {
+
+Schema::Schema(int32_t schema_id, std::vector<SchemaField> fields)
+    : StructType(std::move(fields)), schema_id_(schema_id) {}
+
+int32_t Schema::schema_id() const { return schema_id_; }
+
+std::string Schema::ToString() const {
+  std::string repr = "schema<";
+  for (const auto& field : fields_) {
+    std::format_to(std::back_inserter(repr), "  {}\n", field);
+  }
+  repr += ">";
+  return repr;
+}
+
+bool Schema::Equals(const Schema& other) const {
+  return schema_id_ == other.schema_id_ && fields_ == other.fields_;
+}
+
+}  // namespace iceberg

src/iceberg/schema.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
+
+/// \file iceberg/schema.h
+/// Schemas for Iceberg tables.  This header contains the definition of Schema
+/// and any utility functions.  See iceberg/type.h and iceberg/field.h as well.
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include "iceberg/iceberg_export.h"
+#include "iceberg/schema_field.h"
+#include "iceberg/type.h"
+
+namespace iceberg {
+
+/// \brief A schema for a Table.
+///
+/// A schema is a list of typed columns, along with a unique integer ID.  A
+/// Table may have different schemas over its lifetime due to schema
+/// evolution.
+class ICEBERG_EXPORT Schema : public StructType {
+ public:
+  Schema(int32_t schema_id, std::vector<SchemaField> fields);
+
+  /// \brief Get the schema ID.
+  ///
+  /// Schemas are identified by a unique ID for the purposes of schema
+  /// evolution.
+  [[nodiscard]] int32_t schema_id() const;
+
+  [[nodiscard]] std::string ToString() const;
+
+  friend bool operator==(const Schema& lhs, const Schema& rhs) { return lhs.Equals(rhs); }
+
+  friend bool operator!=(const Schema& lhs, const Schema& rhs) { return !(lhs == rhs); }
+
+ private:
+  /// \brief Compare two schemas for equality.
+  [[nodiscard]] bool Equals(const Schema& other) const;
+
+  const int32_t schema_id_;
+};
+
+}  // namespace iceberg

src/iceberg/schema_field.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 "iceberg/schema_field.h"
+
+#include <format>
+
+#include "iceberg/type.h"
+#include "iceberg/util/formatter.h"
+
+namespace iceberg {
+
+SchemaField::SchemaField(int32_t field_id, std::string name, std::shared_ptr<Type> type,
+                         bool optional)
+    : field_id_(field_id),
+      name_(std::move(name)),
+      type_(std::move(type)),
+      optional_(optional) {}
+
+SchemaField SchemaField::MakeOptional(int32_t field_id, std::string name,
+                                      std::shared_ptr<Type> type) {
+  return SchemaField(field_id, std::move(name), std::move(type), true);
+}
+
+SchemaField SchemaField::MakeRequired(int32_t field_id, std::string name,
+                                      std::shared_ptr<Type> type) {
+  return SchemaField(field_id, std::move(name), std::move(type), false);
+}
+
+int32_t SchemaField::field_id() const { return field_id_; }
+
+std::string_view SchemaField::name() const { return name_; }
+
+const std::shared_ptr<Type>& SchemaField::type() const { return type_; }
+
+bool SchemaField::optional() const { return optional_; }
+
+std::string SchemaField::ToString() const {
+  return std::format("{} ({}): {}{}", name_, field_id_, *type_,
+                     optional_ ? "" : " (required)");
+}
+
+bool SchemaField::Equals(const SchemaField& other) const {
+  return field_id_ == other.field_id_ && name_ == other.name_ && *type_ == *other.type_ &&
+         optional_ == other.optional_;
+}
+
+}  // namespace iceberg

src/iceberg/schema_field.h

@@ -0,0 +1,87 @@
+/*
+ * 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
+
+/// \file iceberg/schema_field.h
+/// A (schema) field is a name and a type and is part of a schema or nested
+/// type (e.g. a struct).
+
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <string_view>
+
+#include "iceberg/iceberg_export.h"
+#include "iceberg/type_fwd.h"
+#include "iceberg/util/formattable.h"
+
+namespace iceberg {
+
+/// \brief A type combined with a name.
+class ICEBERG_EXPORT SchemaField : public iceberg::util::Formattable {
+ public:
+  /// \brief Construct a field.
+  /// \param[in] field_id The field ID.
+  /// \param[in] name The field name.
+  /// \param[in] type The field type.
+  /// \param[in] optional Whether values of this field are required or nullable.
+  SchemaField(int32_t field_id, std::string name, std::shared_ptr<Type> type,
+              bool optional);
+
+  /// \brief Construct an optional (nullable) field.
+  static SchemaField MakeOptional(int32_t field_id, std::string name,
+                                  std::shared_ptr<Type> type);
+  /// \brief Construct a required (non-null) field.
+  static SchemaField MakeRequired(int32_t field_id, std::string name,
+                                  std::shared_ptr<Type> type);
+
+  /// \brief Get the field ID.
+  [[nodiscard]] int32_t field_id() const;
+
+  /// \brief Get the field name.
+  [[nodiscard]] std::string_view name() const;
+
+  /// \brief Get the field type.
+  [[nodiscard]] const std::shared_ptr<Type>& type() const;
+
+  /// \brief Get whether the field is optional.
+  [[nodiscard]] bool optional() const;
+
+  [[nodiscard]] std::string ToString() const;
+
+  friend bool operator==(const SchemaField& lhs, const SchemaField& rhs) {
+    return lhs.Equals(rhs);
+  }
+
+  friend bool operator!=(const SchemaField& lhs, const SchemaField& rhs) {
+    return !(lhs == rhs);
+  }
+
+ private:
+  /// \brief Compare two fields for equality.
+  [[nodiscard]] bool Equals(const SchemaField& other) const;
+
+  int32_t field_id_;
+  std::string name_;
+  std::shared_ptr<Type> type_;
+  bool optional_;
+};
+
+}  // namespace iceberg