ogc_cql2/ds/
csv.rs

1// SPDX-License-Identifier: Apache-2.0
2
3#![warn(missing_docs)]
4
5//! Geospatial data stored in CSV files.
6//!
7
8use crate::ds::DataSource;
9use std::path::PathBuf;
10
11/// [`DataSource`] of _Features_ and [Resources][crate::Resource] mapped from CSV rows/records.
12#[derive(Debug)]
13pub struct CSVDataSource {
14    path: PathBuf,
15}
16
17impl DataSource for CSVDataSource {
18    fn srid(&self) -> Option<u32> {
19        None
20    }
21}
22
23impl CSVDataSource {
24    /// Constructor given the file system location of an accessible CSV file.
25    pub fn from(s: &str) -> Self {
26        Self { path: s.into() }
27    }
28
29    /// Return this CSV data source path.
30    pub fn path(&self) -> &PathBuf {
31        &self.path
32    }
33}
34
35/// Macro to generate a concrete [CSVDataSource].
36///
37/// Caller must provide the following parameters:
38/// * `$vis`: Visibility specifier of the generated artifacts; e.g. `pub`.
39/// * `$name`: Prefix of the concrete data source structure name to materialize.
40///   The final name will have a 'CSV' suffix appended; eg. `Foo` -> `FooCSV`.
41/// * `$path`: Path to a readable CSV file.
42/// * `$feature`: `serde` deserializable structure that maps rows to _Features_.
43#[macro_export]
44macro_rules! gen_csv_ds {
45    ($vis:vis, $name:expr, $path:expr, $feature:expr) => {
46        ::paste::paste! {
47            /// Concrete data source.
48            #[derive(Debug)]
49            $vis struct [<$name CSV>](CSVDataSource);
50
51            impl [<$name CSV>] {
52                /// Construct a new CSV data source.
53                $vis fn new() -> Self {
54                    Self(CSVDataSource::from($path))
55                }
56
57                /// Return a file reader that deserializes rows into features.
58                $vis fn reader(&self) -> Result<::csv::Reader<::std::fs::File>, MyError> {
59                    let file = ::std::fs::File::open(self.0.path())?;
60                    Ok(::csv::Reader::from_reader(file))
61                }
62            }
63
64            impl ::core::fmt::Display for [<$name CSV>] {
65                fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
66                    write!(f, "{}CSV({})", $name, $path)
67                }
68            }
69
70            impl IterableDS for [<$name CSV>] {
71                type Item = $feature;
72                type Err = MyError;
73
74                fn iter(&self) -> Result<impl Iterator<Item = Result<$feature, Self::Err>>, Self::Err> {
75                    let file = ::std::fs::File::open(&self.0.path())?;
76                    let rdr = ::csv::Reader::from_reader(file);
77                    let it = rdr.into_deserialize().map(|res| res.map_err(MyError::from));
78                    Ok(it)
79                }
80            }
81        }
82    }
83}
ogc_cql2/ds/csv.rs

ogc_cql2/ds/
csv.rs
