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venv/lib/python3.10/site-packages/pyarrow/include/parquet/arrow/schema.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
+
+#include <cassert>
+#include <memory>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include "arrow/result.h"
+#include "arrow/status.h"
+#include "arrow/type.h"
+#include "arrow/type_fwd.h"
+
+#include "parquet/level_conversion.h"
+#include "parquet/platform.h"
+#include "parquet/schema.h"
+
+namespace parquet {
+
+class ArrowReaderProperties;
+class ArrowWriterProperties;
+class WriterProperties;
+
+namespace arrow {
+
+/// \defgroup arrow-to-parquet-schema-conversion Functions to convert an Arrow
+/// schema into a Parquet schema.
+///
+/// @{
+
+PARQUET_EXPORT
+::arrow::Status FieldToNode(const std::shared_ptr<::arrow::Field>& field,
+                            const WriterProperties& properties,
+                            const ArrowWriterProperties& arrow_properties,
+                            schema::NodePtr* out);
+
+PARQUET_EXPORT
+::arrow::Status ToParquetSchema(const ::arrow::Schema* arrow_schema,
+                                const WriterProperties& properties,
+                                const ArrowWriterProperties& arrow_properties,
+                                std::shared_ptr<SchemaDescriptor>* out);
+
+PARQUET_EXPORT
+::arrow::Status ToParquetSchema(const ::arrow::Schema* arrow_schema,
+                                const WriterProperties& properties,
+                                std::shared_ptr<SchemaDescriptor>* out);
+
+/// @}
+
+/// \defgroup parquet-to-arrow-schema-conversion Functions to convert a Parquet
+/// schema into an Arrow schema.
+///
+/// @{
+
+PARQUET_EXPORT
+::arrow::Status FromParquetSchema(
+    const SchemaDescriptor* parquet_schema, const ArrowReaderProperties& properties,
+    const std::shared_ptr<const ::arrow::KeyValueMetadata>& key_value_metadata,
+    std::shared_ptr<::arrow::Schema>* out);
+
+PARQUET_EXPORT
+::arrow::Status FromParquetSchema(const SchemaDescriptor* parquet_schema,
+                                  const ArrowReaderProperties& properties,
+                                  std::shared_ptr<::arrow::Schema>* out);
+
+PARQUET_EXPORT
+::arrow::Status FromParquetSchema(const SchemaDescriptor* parquet_schema,
+                                  std::shared_ptr<::arrow::Schema>* out);
+
+/// @}
+
+/// \brief Bridge between an arrow::Field and parquet column indices.
+struct PARQUET_EXPORT SchemaField {
+  std::shared_ptr<::arrow::Field> field;
+  std::vector<SchemaField> children;
+
+  // Only set for leaf nodes
+  int column_index = -1;
+
+  parquet::internal::LevelInfo level_info;
+
+  bool is_leaf() const { return column_index != -1; }
+};
+
+/// \brief Bridge between a parquet Schema and an arrow Schema.
+///
+/// Expose parquet columns as a tree structure. Useful traverse and link
+/// between arrow's Schema and parquet's Schema.
+struct PARQUET_EXPORT SchemaManifest {
+  static ::arrow::Status Make(
+      const SchemaDescriptor* schema,
+      const std::shared_ptr<const ::arrow::KeyValueMetadata>& metadata,
+      const ArrowReaderProperties& properties, SchemaManifest* manifest);
+
+  const SchemaDescriptor* descr;
+  std::shared_ptr<::arrow::Schema> origin_schema;
+  std::shared_ptr<const ::arrow::KeyValueMetadata> schema_metadata;
+  std::vector<SchemaField> schema_fields;
+
+  std::unordered_map<int, const SchemaField*> column_index_to_field;
+  std::unordered_map<const SchemaField*, const SchemaField*> child_to_parent;
+
+  ::arrow::Status GetColumnField(int column_index, const SchemaField** out) const {
+    auto it = column_index_to_field.find(column_index);
+    if (it == column_index_to_field.end()) {
+      return ::arrow::Status::KeyError("Column index ", column_index,
+                                       " not found in schema manifest, may be malformed");
+    }
+    *out = it->second;
+    return ::arrow::Status::OK();
+  }
+
+  const SchemaField* GetParent(const SchemaField* field) const {
+    // Returns nullptr also if not found
+    auto it = child_to_parent.find(field);
+    if (it == child_to_parent.end()) {
+      return NULLPTR;
+    }
+    return it->second;
+  }
+
+  /// Coalesce a list of field indices (relative to the equivalent arrow::Schema) which
+  /// correspond to the column root (first node below the parquet schema's root group) of
+  /// each leaf referenced in column_indices.
+  ///
+  /// For example, for leaves `a.b.c`, `a.b.d.e`, and `i.j.k` (column_indices=[0,1,3])
+  /// the roots are `a` and `i` (return=[0,2]).
+  ///
+  /// root
+  /// -- a  <------
+  /// -- -- b  |  |
+  /// -- -- -- c  |
+  /// -- -- -- d  |
+  /// -- -- -- -- e
+  /// -- f
+  /// -- -- g
+  /// -- -- -- h
+  /// -- i  <---
+  /// -- -- j  |
+  /// -- -- -- k
+  ::arrow::Result<std::vector<int>> GetFieldIndices(
+      const std::vector<int>& column_indices) const {
+    const schema::GroupNode* group = descr->group_node();
+    std::unordered_set<int> already_added;
+
+    std::vector<int> out;
+    for (int column_idx : column_indices) {
+      if (column_idx < 0 || column_idx >= descr->num_columns()) {
+        return ::arrow::Status::IndexError("Column index ", column_idx, " is not valid");
+      }
+
+      auto field_node = descr->GetColumnRoot(column_idx);
+      auto field_idx = group->FieldIndex(*field_node);
+      if (field_idx == -1) {
+        return ::arrow::Status::IndexError("Column index ", column_idx, " is not valid");
+      }
+
+      if (already_added.insert(field_idx).second) {
+        out.push_back(field_idx);
+      }
+    }
+    return out;
+  }
+};
+
+}  // namespace arrow
+}  // namespace parquet