feat: basic table scan planning

src/iceberg/CMakeLists.txt

@@ -39,6 +39,7 @@ set(ICEBERG_SOURCES
     sort_order.cc
     statistics_file.cc
     table_metadata.cc
+    table_scan.cc
     transform.cc
     transform_function.cc
     type.cc

src/iceberg/manifest_entry.h

@@ -291,7 +291,7 @@ struct ICEBERG_EXPORT ManifestEntry {
   std::optional<int64_t> file_sequence_number;
   /// Field id: 2
   /// File path, partition tuple, metrics, ...
-  DataFile data_file;
+  std::shared_ptr<DataFile> data_file;
 
   inline static const SchemaField kStatus =
       SchemaField::MakeRequired(0, "status", std::make_shared<IntType>());

src/iceberg/manifest_reader.h

@@ -34,6 +34,7 @@ namespace iceberg {
 /// \brief Read manifest entries from a manifest file.
 class ICEBERG_EXPORT ManifestReader {
  public:
+  virtual ~ManifestReader() = default;
   virtual Result<std::span<std::unique_ptr<ManifestEntry>>> Entries() const = 0;
 
  private:
@@ -43,10 +44,27 @@ class ICEBERG_EXPORT ManifestReader {
 /// \brief Read manifest files from a manifest list file.
 class ICEBERG_EXPORT ManifestListReader {
  public:
+  virtual ~ManifestListReader() = default;
   virtual Result<std::span<std::unique_ptr<ManifestFile>>> Files() const = 0;
 
  private:
   std::unique_ptr<StructLikeReader> reader_;
 };
 
+/// \brief Creates a reader for the manifest list.
+/// \param file_path Path to the manifest list file.
+/// \return A Result containing the reader or an error.
+Result<std::unique_ptr<ManifestListReader>> CreateManifestListReader(
+    const std::string& file_path) {
+  return NotImplemented("CreateManifestListReader is not implemented yet.");
+}
+
+/// \brief Creates a reader for a manifest file.
+/// \param file_path Path to the manifest file.
+/// \return A Result containing the reader or an error.
+Result<std::unique_ptr<ManifestReader>> CreateManifestReader(
+    const std::string& file_path) {
+  return NotImplemented("CreateManifestReader is not implemented yet.");
+}
+
 }  // namespace iceberg

src/iceberg/table.h

@@ -88,21 +88,20 @@ class ICEBERG_EXPORT Table {
   /// \return a vector of history entries
   virtual const std::vector<std::shared_ptr<HistoryEntry>>& history() const = 0;
 
-  /// \brief Create a new table scan for this table
+  /// \brief Create a new table scan builder for this table
   ///
-  /// Once a table scan is created, it can be refined to project columns and filter data.
-  virtual std::unique_ptr<TableScan> NewScan() const = 0;
+  /// Once a table scan builder is created, it can be refined to project columns and
+  /// filter data.
+  virtual std::unique_ptr<TableScanBuilder> NewScan() const = 0;
 
   /// \brief Create a new append API to add files to this table and commit
   virtual std::shared_ptr<AppendFiles> NewAppend() = 0;
 
   /// \brief Create a new transaction API to commit multiple table operations at once
   virtual std::unique_ptr<Transaction> NewTransaction() = 0;
 
-  /// TODO(wgtmac): design of FileIO is not finalized yet. We intend to use an
-  /// IO-less design in the core library.
   // /// \brief Returns a FileIO to read and write table data and metadata files
-  // virtual std::shared_ptr<FileIO> io() const = 0;
+  virtual std::shared_ptr<FileIO> io() const = 0;
 
   /// \brief Returns a LocationProvider to provide locations for new data files
   virtual std::unique_ptr<LocationProvider> location_provider() const = 0;

src/iceberg/table_scan.cc

@@ -0,0 +1,116 @@
+/*
+ * 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/table_scan.h"
+
+#include "iceberg/manifest_entry.h"
+#include "iceberg/manifest_list.h"
+#include "iceberg/manifest_reader.h"
+#include "iceberg/schema.h"
+#include "iceberg/schema_field.h"
+#include "iceberg/snapshot.h"
+#include "iceberg/table.h"
+#include "iceberg/util/macros.h"
+
+namespace iceberg {
+
+TableScanBuilder::TableScanBuilder(const Table& table) : table_(table) {}
+
+TableScanBuilder& TableScanBuilder::WithColumnNames(
+    std::vector<std::string> column_names) {
+  column_names_ = std::move(column_names);
+  return *this;
+}
+
+TableScanBuilder& TableScanBuilder::WithSnapshotId(int64_t snapshot_id) {
+  snapshot_id_ = snapshot_id;
+  return *this;
+}
+
+TableScanBuilder& TableScanBuilder::WithFilter(std::shared_ptr<Expression> filter) {
+  filter_ = std::move(filter);
+  return *this;
+}
+
+Result<std::unique_ptr<TableScan>> TableScanBuilder::Build() {
+  std::shared_ptr<Snapshot> snapshot;
+  if (snapshot_id_) {
+    ICEBERG_ASSIGN_OR_RAISE(snapshot, table_.snapshot(*snapshot_id_));
+  } else {
+    snapshot = table_.current_snapshot();
+  }
+  if (snapshot == nullptr) {
+    return InvalidArgument("No snapshot found for table {}", table_.name());
+  }
+
+  std::shared_ptr<Schema> schema;
+  if (snapshot->schema_id) {
+    const auto& schemas = table_.schemas();
+    if (auto it = schemas.find(*snapshot->schema_id); it != schemas.end()) {
+      schema = it->second;
+    } else {
+      return InvalidArgument("Schema {} in snapshot {} is not found",
+                             *snapshot->schema_id, snapshot->snapshot_id);
+    }
+  } else {
+    schema = table_.schema();
+  }
+
+  std::vector<SchemaField> projected_fields;
+  projected_fields.reserve(column_names_.size());
+  for (const auto& column_name : column_names_) {
+    auto field_opt = schema->GetFieldByName(column_name);
+    if (!field_opt) {
+      return InvalidArgument("Column {} not found in schema", column_name);
+    }
+    projected_fields.emplace_back(field_opt.value().get());
+  }
+
+  auto projected_schema =
+      std::make_shared<Schema>(std::move(projected_fields), schema->schema_id());
+  TableScan::ScanContext context{.snapshot = std::move(snapshot),
+                                 .projected_schema = std::move(projected_schema),
+                                 .filter = std::move(filter_)};
+  return std::make_unique<TableScan>(std::move(context), table_.io());
+}
+
+TableScan::TableScan(ScanContext context, std::shared_ptr<FileIO> file_io)
+    : context_(std::move(context)), file_io_(std::move(file_io)) {}
+
+Result<std::vector<std::shared_ptr<FileScanTask>>> TableScan::PlanFiles() const {
+  ICEBERG_ASSIGN_OR_RAISE(auto manifest_list_reader,
+                          CreateManifestListReader(context_.snapshot->manifest_list));
+  ICEBERG_ASSIGN_OR_RAISE(auto manifest_files, manifest_list_reader->Files());
+
+  std::vector<std::shared_ptr<FileScanTask>> tasks;
+  for (const auto& manifest_file : manifest_files) {
+    ICEBERG_ASSIGN_OR_RAISE(auto manifest_reader,
+                            CreateManifestReader(manifest_file->manifest_path));
+    ICEBERG_ASSIGN_OR_RAISE(auto manifests, manifest_reader->Entries());
+
+    for (const auto& manifest : manifests) {
+      const auto& data_file = manifest->data_file;
+      tasks.emplace_back(
+          std::make_shared<FileScanTask>(data_file, 0, data_file->file_size_in_bytes));
+    }
+  }
+  return tasks;
+}
+
+}  // namespace iceberg

src/iceberg/table_scan.h

@@ -0,0 +1,96 @@
+/*
+ * 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 <string>
+#include <vector>
+
+#include "iceberg/manifest_entry.h"
+#include "iceberg/type_fwd.h"
+
+namespace iceberg {
+
+/// \brief Builder class for creating TableScan instances.
+class ICEBERG_EXPORT TableScanBuilder {
+ public:
+  /// \brief Constructs a TableScanBuilder for the given table.
+  /// \param table Reference to the table to scan.
+  explicit TableScanBuilder(const Table& table);
+
+  /// \brief Sets the snapshot ID to scan.
+  /// \param snapshot_id The ID of the snapshot.
+  /// \return Reference to the builder.
+  TableScanBuilder& WithSnapshotId(int64_t snapshot_id);
+
+  /// \brief Selects columns to include in the scan.
+  /// \param column_names A list of column names. If empty, all columns will be selected.
+  /// \return Reference to the builder.
+  TableScanBuilder& WithColumnNames(std::vector<std::string> column_names);
+
+  /// \brief Applies a filter expression to the scan.
+  /// \param filter Filter expression to use.
+  /// \return Reference to the builder.
+  TableScanBuilder& WithFilter(std::shared_ptr<Expression> filter);
+
+  /// \brief Builds and returns a TableScan instance.
+  /// \return A Result containing the TableScan or an error.
+  Result<std::unique_ptr<TableScan>> Build();
+
+ private:
+  const Table& table_;
+  std::vector<std::string> column_names_;
+  std::optional<int64_t> snapshot_id_;
+  std::shared_ptr<Expression> filter_;
+};
+
+/// \brief Represents a configured scan operation on a table.
+class ICEBERG_EXPORT TableScan {
+ public:
+  /// \brief Scan context holding snapshot and scan-specific metadata.
+  struct ScanContext {
+    std::shared_ptr<Snapshot> snapshot;        ///< Snapshot to scan.
+    std::shared_ptr<Schema> projected_schema;  ///< Projected schema.
+    std::shared_ptr<Expression> filter;        ///< Filter expression to apply.
+  };
+
+  /// \brief Constructs a TableScan with the given context and file I/O.
+  /// \param context Scan context including snapshot, schema, and filter.
+  /// \param file_io File I/O instance for reading manifests and data files.
+  TableScan(ScanContext context, std::shared_ptr<FileIO> file_io);
+
+  /// \brief Plans the scan tasks by resolving manifests and data files.
+  ///
+  /// Returns a list of file scan tasks if successful.
+  /// \return A Result containing scan tasks or an error.
+  Result<std::vector<std::shared_ptr<FileScanTask>>> PlanFiles() const;
+
+ private:
+  ScanContext context_;
+  std::shared_ptr<FileIO> file_io_;
+};
+
+/// \brief Represents a task to scan a portion of a data file.
+struct ICEBERG_EXPORT FileScanTask {
+  std::shared_ptr<DataFile> data_file;  ///< Data file metadata.
+  uint64_t start;                       ///< Start byte offset.
+  uint64_t length;                      ///< Length in bytes to scan.
+};
+
+}  // namespace iceberg

src/iceberg/type_fwd.h

@@ -92,6 +92,7 @@ class LocationProvider;
 class SortField;
 class SortOrder;
 class Table;
+class FileIO;
 class Transaction;
 class Transform;
 class TransformFunction;
@@ -109,6 +110,12 @@ class NameMapping;
 enum class SnapshotRefType;
 enum class TransformType;
 
+class Expression;
+
+struct FileScanTask;
+class TableScan;
+class TableScanBuilder;
+
 /// ----------------------------------------------------------------------------
 /// TODO: Forward declarations below are not added yet.
 /// ----------------------------------------------------------------------------
@@ -120,11 +127,13 @@ class MetadataUpdate;
 class UpdateRequirement;
 
 class AppendFiles;
-class TableScan;
 
 struct DataFile;
 struct ManifestEntry;
 struct ManifestFile;
 struct ManifestList;
 
+class ManifestReader;
+class ManifestListReader;
+
 }  // namespace iceberg