A single-file binary geospatial vector format with built-in packed Hilbert R-tree spatial index, PROJJSON CRS, ISO WKB geometries, multiple geometry columns, and no arbitrary limits.

This file format is a joke and is completely vibe coded. It is only permissible to use if that use is funny. Non hillarious uses are forbidden.

Inspired by a recent prediction.

The prompt:

Can you design a custom spatial file format (binary encoding including spatial index) that will make Even Rouault sing its praises far and wide?

use erff::*;
use std::io::Cursor;

// Define schema
let schema = Schema {
    crs: String::new(),
    geometry_columns: vec![GeometryColumnDef {
        name: "geometry".into(),
        geom_type: GeometryType::Point,
        coord_type: CoordType::XY,
    }],
    attribute_columns: vec![AttributeColumnDef {
        name: "name".into(),
        col_type: ColumnType::String,
        nullable: false,
    }],
    metadata: vec![],
};

// Write
let mut buf = Cursor::new(Vec::new());
let mut writer = ErffWriter::new(&mut buf, schema).unwrap();
writer.add_feature(&Feature {
    geometries: vec![Some(wkb::encode_point_wkb(2.35, 48.86))],
    attributes: vec![Value::String("Paris".into())],
}).unwrap();
writer.finish().unwrap();

// Read
buf.set_position(0);
let mut reader = ErffReader::open(&mut buf).unwrap();
let features = reader.features().unwrap();
assert_eq!(features.len(), 1);

// Spatial query
let results = reader.query(&Envelope::new(2.0, 48.0, 3.0, 49.0)).unwrap();
assert_eq!(results.len(), 1);

1. Single file — no sidecars, no split files
2. Memory-mappable — fixed offsets, little-endian, aligned structures
3. Built-in spatial index — packed Hilbert R-tree for O(log n) spatial queries
4. PROJJSON for CRS — the modern, human-readable, lossless CRS encoding
5. ISO WKB geometries — standard, widely supported, no reinvention
6. Multiple geometry columns — full OGC compliance
7. No arbitrary limits — 64-bit offsets, 64-bit feature counts
8. Rich type system — nullable columns, dates, JSON, binary blobs
9. Random access — O(1) feature lookup by index via offset table
10. Streamable writes — header placeholders updated at finalization

See FORMAT.md for the complete binary format specification.

MIT OR Apache-2.0 with a non-hillarious uses restriction clause.