1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81

// 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.

//! Parquet schema definitions and methods to print and parse schema.
//!
//! * [`SchemaDescriptor`] describes the data types of the columns stored in a file
//! * [`ColumnDescriptor`]: Describes the schema of a single (leaf) column.
//! * [`ColumnPath`]: Represents the location of a column in the schema (e.g. a nested field)
//!
//! Parquet distinguishes
//! between "logical" and "physical" data types.
//! For instance, strings (logical type) are stored as byte arrays (physical type).
//! Likewise, temporal types like dates, times, timestamps, etc. (logical type)
//! are stored as integers (physical type).
//!
//! [`SchemaDescriptor`]: types::SchemaDescriptor
//! [`ColumnDescriptor`]: types::ColumnDescriptor
//! [`ColumnPath`]: types::ColumnPath
//!
//! # Example
//!
//! ```rust
//! use parquet::{
//!     basic::{ConvertedType, Repetition, Type as PhysicalType},
//!     schema::{parser, printer, types::Type},
//! };
//! use std::sync::Arc;
//!
//! // Create the following schema:
//! //
//! // message schema {
//! //   OPTIONAL BYTE_ARRAY a (UTF8);
//! //   REQUIRED INT32 b;
//! // }
//!
//! let field_a = Type::primitive_type_builder("a", PhysicalType::BYTE_ARRAY)
//!     .with_converted_type(ConvertedType::UTF8)
//!     .with_repetition(Repetition::OPTIONAL)
//!     .build()
//!     .unwrap();
//!
//! let field_b = Type::primitive_type_builder("b", PhysicalType::INT32)
//!     .with_repetition(Repetition::REQUIRED)
//!     .build()
//!     .unwrap();
//!
//! let schema = Type::group_type_builder("schema")
//!     .with_fields(vec![Arc::new(field_a), Arc::new(field_b)])
//!     .build()
//!     .unwrap();
//!
//! let mut buf = Vec::new();
//!
//! // Print schema into buffer
//! printer::print_schema(&mut buf, &schema);
//!
//! // Parse schema from the string
//! let string_schema = String::from_utf8(buf).unwrap();
//! let parsed_schema = parser::parse_message_type(&string_schema).unwrap();
//!
//! assert_eq!(schema, parsed_schema);
//! ```

pub mod parser;
pub mod printer;
pub mod types;
pub mod visitor;