WIP: Add headers for type/field/schema

Author: lidavidm

src/iceberg/schema.h

@@ -0,0 +1,60 @@
+/*
+ * 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.
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include "iceberg/iceberg_export.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<Field> 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;
+
+  /// \brief Get a user-readable string representation of the schema.
+  [[nodiscard]] std::string ToString() const;
+
+  /// \brief Compare two schemas for equality.
+  [[nodiscard]] bool Equals(const Schema& other) 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); }
+};
+
+}  // namespace iceberg

src/iceberg/type.h

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+/*
+ * 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/type.h
+/// Data types for Iceberg.
+
+#include <memory>
+#include <span>
+#include <string>
+#include <vector>
+
+#include "iceberg/iceberg_export.h"
+#include "iceberg/type_fwd.h"
+
+namespace iceberg {
+
+/// \brief A type combined with a name.
+class ICEBERG_EXPORT Field {
+ 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.
+  Field(int32_t field_id, std::string name, std::shared_ptr<Type> type, bool optional);
+
+  /// \brief Construct an optional (nullable) field.
+  static Field MakeOptional(int32_t field_id, std::string name,
+                            std::shared_ptr<Type> type);
+  /// \brief Construct a required (non-null) field.
+  static Field 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;
+
+  /// \brief Get a user-readable string representation of the field.
+  [[nodiscard]] std::string ToString() const;
+
+  /// \brief Compare two fields for equality.
+  [[nodiscard]] bool Equals(const Field& other) const;
+
+  friend bool operator==(const Field& lhs, const Field& rhs) { return lhs.Equals(rhs); }
+
+  friend bool operator!=(const Field& lhs, const Field& rhs) { return !(lhs == rhs); }
+};
+
+/// \brief Interface for a data type for a field.
+class ICEBERG_EXPORT Type {
+ public:
+  virtual ~Type() = default;
+
+  /// \brief Get the type ID.
+  [[nodiscard]] virtual TypeId type_id() const = 0;
+
+  /// \brief Get a user-readable string representation of the type.
+  [[nodiscard]] virtual std::string ToString() const = 0;
+
+  /// \brief Compare two types for equality.
+  [[nodiscard]] virtual bool Equals(const Type& other) const = 0;
+
+  /// \brief Is this a primitive type (may not have child fields)?
+  [[nodiscard]] virtual bool is_primitive() const = 0;
+
+  /// \brief Is this a nested type (may have child fields)?
+  [[nodiscard]] virtual bool is_nested() const = 0;
+
+  friend bool operator==(const Type& lhs, const Type& rhs) { return lhs.Equals(rhs); }
+
+  friend bool operator!=(const Type& lhs, const Type& rhs) { return !(lhs == rhs); }
+};
+
+/// \brief A data type that may not have child fields.
+class ICEBERG_EXPORT PrimitiveType : public Type {
+ public:
+  bool is_primitive() const override { return true; }
+  bool is_nested() const override { return false; }
+};
+
+/// \brief A data type that may have child fields.
+class ICEBERG_EXPORT NestedType : public Type {
+ public:
+  bool is_primitive() const override { return false; }
+  bool is_nested() const override { return true; }
+};
+
+/// \brief A data type representing a boolean.
+class ICEBERG_EXPORT BooleanType : public PrimitiveType {
+ public:
+  BooleanType() = default;
+  ~BooleanType() = default;
+
+  TypeId type_id() const override;
+
+  std::string ToString() const override;
+
+  bool Equals(const Type& other) const override;
+};
+
+/// \brief A data type representing a struct with nested fields.
+class ICEBERG_EXPORT StructType : public NestedType {
+ public:
+  explicit StructType(std::vector<Field> fields);
+
+  StructType() = default;
+  ~StructType() = default;
+
+  /// \brief Get a view of the child fields.
+  [[nodiscard]] std::span<Field> fields() const;
+  /// \brief Get a field by index.
+  const Field& GetFieldByIndex(int i) const;
+  /// \brief Get a field by name.
+  const Field& GetFieldByName(std::string_view name) const;
+
+  TypeId type_id() const override;
+
+  std::string ToString() const override;
+
+  bool Equals(const Type& other) const override;
+};
+
+}  // namespace iceberg

src/iceberg/type_fwd.h

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+/*
+ * 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/type_fwd.h
+/// Forward declarations and enum definitions.
+
+namespace iceberg {
+
+/// \brief A data type.
+///
+/// This is not a complete data type by itself because some types are nested
+/// and/or parameterized.
+enum class TypeId {
+  kBoolean,
+  kInt32,
+  kInt64,
+  kFloat32,
+  kFloat64,
+  kDecimal,
+  kDate,
+  kTime,
+  kTimestamp,
+  kTimestampTz,
+  kString,
+  kFixed,
+  kStruct,
+  kList,
+  kMap,
+};
+
+class BooleanType;
+class Field;
+class NestedType;
+class PrimitiveType;
+class Schema;
+class StructType;
+class Type;
+
+}  // namespace iceberg