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use crate::header_generated::flat_geobuf::*;
use crate::packed_r_tree::{self, PackedRTree};
use crate::properties_reader::FgbFeature;
use crate::MAGIC_BYTES;
use geozero::error::{GeozeroError, Result};
use geozero::{FeatureProcessor, ReadSeek};
use std::io::SeekFrom;
pub struct FgbReader<'a> {
reader: &'a mut dyn ReadSeek,
fbs: FgbFeature,
feature_base: u64,
item_filter: Option<Vec<packed_r_tree::SearchResultItem>>,
count: usize,
feat_no: usize,
}
impl<'a> FgbReader<'a> {
pub fn open<R: 'a + ReadSeek>(reader: &'a mut R) -> Result<Self> {
let mut magic_buf: [u8; 8] = [0; 8];
reader.read_exact(&mut magic_buf)?;
if magic_buf != MAGIC_BYTES {
return Err(GeozeroError::GeometryFormat);
}
let mut size_buf: [u8; 4] = [0; 4];
reader.read_exact(&mut size_buf)?;
let header_size = u32::from_le_bytes(size_buf) as usize;
let mut header_buf = Vec::with_capacity(header_size);
header_buf.resize(header_size, 0);
reader.read_exact(&mut header_buf)?;
Ok(FgbReader {
reader,
fbs: FgbFeature {
header_buf,
feature_buf: Vec::new(),
},
feature_base: 0,
item_filter: None,
count: 0,
feat_no: 0,
})
}
pub fn header(&self) -> Header {
self.fbs.header()
}
pub fn select_all(&mut self) -> Result<usize> {
let header = self.fbs.header();
let count = header.features_count() as usize;
let index_size = PackedRTree::index_size(count, header.index_node_size());
self.feature_base = self.reader.seek(SeekFrom::Current(index_size as i64))?;
self.count = count;
Ok(count)
}
pub fn select_bbox(&mut self, min_x: f64, min_y: f64, max_x: f64, max_y: f64) -> Result<usize> {
let header = self.fbs.header();
let list = PackedRTree::stream_search(
&mut self.reader,
header.features_count() as usize,
PackedRTree::DEFAULT_NODE_SIZE,
min_x,
min_y,
max_x,
max_y,
)?;
self.feature_base = self.reader.seek(SeekFrom::Current(0))?;
self.count = list.len();
self.item_filter = Some(list);
Ok(self.count)
}
pub fn features_count(&self) -> usize {
self.count
}
pub fn next(&mut self) -> Result<Option<&FgbFeature>> {
if self.feat_no >= self.count {
return Ok(None);
}
if let Some(filter) = &self.item_filter {
let item = &filter[self.feat_no];
self.reader
.seek(SeekFrom::Start(self.feature_base + item.offset as u64))?;
}
self.feat_no += 1;
let mut size_buf: [u8; 4] = [0; 4];
self.reader.read_exact(&mut size_buf)?;
let feature_size = u32::from_le_bytes(size_buf);
self.fbs.feature_buf.resize(feature_size as usize, 0);
self.reader.read_exact(&mut self.fbs.feature_buf)?;
Ok(Some(&self.fbs))
}
pub fn cur_feature(&self) -> &FgbFeature {
&self.fbs
}
pub fn process_features<W: FeatureProcessor>(&mut self, out: &mut W) -> Result<()> {
out.dataset_begin(self.fbs.header().name())?;
let mut cnt = 0;
while let Some(feature) = self.next()? {
feature.process(out, cnt)?;
cnt += 1;
}
out.dataset_end()
}
}
mod inspect {
use super::*;
impl FgbReader<'_> {
pub fn process_index<P: FeatureProcessor>(&mut self, processor: &mut P) -> Result<()> {
let features_count = self.header().features_count() as usize;
let index_node_size = self.header().index_node_size();
let index = PackedRTree::from_buf(&mut self.reader, features_count, index_node_size)?;
index.process_index(processor)
}
}
#[test]
fn dump_index() -> Result<()> {
use geozero_core::geojson::GeoJsonWriter;
use std::fs::File;
use std::io::{BufReader, BufWriter};
let mut filein = BufReader::new(File::open("../../test/data/countries.fgb")?);
let mut fgb = FgbReader::open(&mut filein)?;
let mut fout = BufWriter::new(File::create("/tmp/countries-index.json")?);
fgb.process_index(&mut GeoJsonWriter::new(&mut fout))?;
Ok(())
}
}