feat: add name mapping

src/iceberg/CMakeLists.txt

@@ -23,6 +23,7 @@ set(ICEBERG_SOURCES
     expression/expression.cc
     file_reader.cc
     json_internal.cc
+    name_mapping.cc
     partition_field.cc
     partition_spec.cc
     schema.cc
@@ -36,7 +37,6 @@ set(ICEBERG_SOURCES
     transform.cc
     transform_function.cc
     type.cc
-    snapshot.cc
     util/murmurhash3_internal.cc
     util/timepoint.cc)
 

src/iceberg/name_mapping.cc

@@ -0,0 +1,267 @@
+/*
+ * 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/name_mapping.h"
+
+#include <format>
+#include <sstream>
+
+#include "iceberg/util/formatter_internal.h"
+
+namespace iceberg {
+
+namespace {
+
+// Helper function to join a list of field names with a dot
+std::string JoinByDot(std::span<const std::string> parts) {
+  std::stringstream ss;
+  for (size_t i = 0; i < parts.size(); ++i) {
+    if (i > 0) {
+      ss << ".";
+    }
+    ss << parts[i];
+  }
+  return ss.str();
+}
+
+// Helper class to recursively index MappedField by field id
+struct IndexByIdVisitor {
+  std::unordered_map<int32_t, MappedFieldConstRef> field_by_id;
+
+  void Visit(const MappedField& field) {
+    field_by_id.emplace(field.field_id, std::cref(field));
+    if (field.nested_mapping != nullptr) {
+      Visit(*field.nested_mapping);
+    }
+  }
+
+  void Visit(const MappedFields& fields) {
+    for (const auto& field : fields.fields()) {
+      Visit(field);
+    }
+  }
+
+  void Visit(const NameMapping& name_mapping) { Visit(name_mapping.AsMappedFields()); }
+};
+
+// Helper class to recursively index MappedField by field name
+struct IndexByNameVisitor {
+  std::unordered_map<std::string, MappedFieldConstRef> field_by_name;
+
+  void Visit(const MappedField& field) {
+    for (const auto& name : field.names) {
+      field_by_name.emplace(name, std::cref(field));
+    }
+
+    if (field.nested_mapping != nullptr) {
+      IndexByNameVisitor nested_visitor;
+      nested_visitor.Visit(*field.nested_mapping);
+
+      for (const auto& [name, mapped_field] : nested_visitor.field_by_name) {
+        for (const auto& prefix : field.names) {
+          std::vector<std::string> parts = {prefix, name};
+          field_by_name.emplace(JoinByDot(parts), std::cref(mapped_field));
+        }
+      }
+    }
+  }
+
+  void Visit(const MappedFields& fields) {
+    for (const auto& field : fields.fields()) {
+      Visit(field);
+    }
+  }
+
+  void Visit(const NameMapping& name_mapping) { Visit(name_mapping.AsMappedFields()); }
+};
+
+}  // namespace
+
+MappedFields::MappedFields(std::vector<MappedField> fields)
+    : fields_(std::move(fields)) {}
+
+std::unique_ptr<MappedFields> MappedFields::Make(std::vector<MappedField> fields) {
+  return std::unique_ptr<MappedFields>(new MappedFields(std::move(fields)));
+}
+
+std::optional<MappedFieldConstRef> MappedFields::Field(int32_t id) const {
+  const auto& id_to_field = LazyIdToField();
+  if (auto it = id_to_field.find(id); it != id_to_field.cend()) {
+    return it->second;
+  }
+  return std::nullopt;
+}
+
+std::optional<int32_t> MappedFields::Id(std::string_view name) const {
+  const auto& name_to_id = LazyNameToId();
+  if (auto it = name_to_id.find(name); it != name_to_id.cend()) {
+    return it->second;
+  }
+  return std::nullopt;
+}
+
+size_t MappedFields::Size() const { return fields_.size(); }
+
+std::span<const MappedField> MappedFields::fields() const { return fields_; }
+
+const std::unordered_map<std::string_view, int32_t>& MappedFields::LazyNameToId() const {
+  if (name_to_id_.empty() && !fields_.empty()) {
+    for (const auto& field : fields_) {
+      for (const auto& name : field.names) {
+        name_to_id_.emplace(name, field.field_id);
+      }
+    }
+  }
+  return name_to_id_;
+}
+
+const std::unordered_map<int32_t, MappedFieldConstRef>& MappedFields::LazyIdToField()
+    const {
+  if (id_to_field_.empty() && !fields_.empty()) {
+    for (const auto& field : fields_) {
+      id_to_field_.emplace(field.field_id, std::cref(field));
+    }
+  }
+  return id_to_field_;
+}
+
+NameMapping::NameMapping(std::unique_ptr<MappedFields> mapping)
+    : mapping_(std::move(mapping)) {}
+
+std::optional<MappedFieldConstRef> NameMapping::Find(int32_t id) {
+  const auto& fields_by_id = LazyFieldsById();
+  if (auto iter = fields_by_id.find(id); iter != fields_by_id.cend()) {
+    return iter->second;
+  }
+  return std::nullopt;
+}
+
+std::optional<MappedFieldConstRef> NameMapping::Find(std::span<const std::string> names) {
+  if (names.empty()) {
+    return std::nullopt;
+  }
+  return Find(JoinByDot(names));
+}
+
+std::optional<MappedFieldConstRef> NameMapping::Find(const std::string& name) {
+  const auto& fields_by_name = LazyFieldsByName();
+  if (auto iter = fields_by_name.find(name); iter != fields_by_name.cend()) {
+    return iter->second;
+  }
+  return std::nullopt;
+}
+
+const MappedFields& NameMapping::AsMappedFields() const {
+  if (mapping_ == nullptr) {
+    const static std::unique_ptr<MappedFields> kEmptyFields = MappedFields::Make({});
+    return *kEmptyFields;
+  }
+  return *mapping_;
+}
+
+const std::unordered_map<int32_t, MappedFieldConstRef>& NameMapping::LazyFieldsById()
+    const {
+  if (fields_by_id_.empty()) {
+    IndexByIdVisitor visitor;
+    visitor.Visit(AsMappedFields());
+    fields_by_id_ = std::move(visitor.field_by_id);
+  }
+  return fields_by_id_;
+}
+
+const std::unordered_map<std::string, MappedFieldConstRef>&
+NameMapping::LazyFieldsByName() const {
+  if (fields_by_name_.empty()) {
+    IndexByNameVisitor visitor;
+    visitor.Visit(AsMappedFields());
+    fields_by_name_ = std::move(visitor.field_by_name);
+  }
+  return fields_by_name_;
+}
+
+std::unique_ptr<NameMapping> NameMapping::MakeEmpty() {
+  return std::unique_ptr<NameMapping>(new NameMapping(MappedFields::Make({})));
+}
+
+std::unique_ptr<NameMapping> NameMapping::Make(std::unique_ptr<MappedFields> fields) {
+  return std::unique_ptr<NameMapping>(new NameMapping(std::move(fields)));
+}
+
+std::unique_ptr<NameMapping> NameMapping::Make(std::vector<MappedField> fields) {
+  return Make(MappedFields::Make(std::move(fields)));
+}
+
+bool operator==(const MappedField& lhs, const MappedField& rhs) {
+  if (lhs.field_id != rhs.field_id) {
+    return false;
+  }
+  if (lhs.names != rhs.names) {
+    return false;
+  }
+  if (lhs.nested_mapping == nullptr && rhs.nested_mapping == nullptr) {
+    return true;
+  }
+  if (lhs.nested_mapping == nullptr || rhs.nested_mapping == nullptr) {
+    return false;
+  }
+  return *lhs.nested_mapping == *rhs.nested_mapping;
+}
+
+bool operator==(const MappedFields& lhs, const MappedFields& rhs) {
+  if (lhs.Size() != rhs.Size()) {
+    return false;
+  }
+  auto lhs_fields = lhs.fields();
+  auto rhs_fields = rhs.fields();
+  for (size_t i = 0; i < lhs.Size(); ++i) {
+    if (lhs_fields[i] != rhs_fields[i]) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool operator==(const NameMapping& lhs, const NameMapping& rhs) {
+  return lhs.AsMappedFields() == rhs.AsMappedFields();
+}
+
+std::string ToString(const MappedField& field) {
+  return std::format(
+      "({} -> {}{})", field.names, field.field_id,
+      field.nested_mapping ? std::format(", {}", ToString(*field.nested_mapping)) : "");
+}
+
+std::string ToString(const MappedFields& fields) {
+  return std::format("{}", fields.fields());
+}
+
+std::string ToString(const NameMapping& name_mapping) {
+  const auto& fields = name_mapping.AsMappedFields();
+  if (fields.Size() == 0) {
+    return "[]";
+  }
+  std::string repr = "[\n";
+  for (const auto& field : fields.fields()) {
+    std::format_to(std::back_inserter(repr), "  {}\n", ToString(field));
+  }
+  repr += "]";
+  return repr;
+}
+
+}  // namespace iceberg