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//! High level reader interface use blob::{BlobDecode, BlobReader}; use elements::Element; use error::Result; use rayon::prelude::*; use std::fs::File; use std::io::{BufReader, Read}; use std::path::Path; /// A reader for PBF files that gives access to the stored elements: nodes, ways and relations. #[derive(Clone, Debug)] pub struct ElementReader<R: Read + Send> { blob_iter: BlobReader<R>, } impl<R: Read + Send> ElementReader<R> { /// Creates a new `ElementReader`. /// /// # Example /// ``` /// use osmpbf::*; /// /// # fn foo() -> Result<()> { /// let f = std::fs::File::open("tests/test.osm.pbf")?; /// let buf_reader = std::io::BufReader::new(f); /// /// let reader = ElementReader::new(buf_reader); /// /// # Ok(()) /// # } /// # foo().unwrap(); /// ``` pub fn new(reader: R) -> ElementReader<R> { ElementReader { blob_iter: BlobReader::new(reader), } } /// Decodes the PBF structure sequentially and calls the given closure on each element. /// Consider using `par_map_reduce` instead if you need better performance. /// /// # Errors /// Returns the first Error encountered while parsing the PBF structure. /// /// # Example /// ``` /// use osmpbf::*; /// /// # fn foo() -> Result<()> { /// let reader = ElementReader::from_path("tests/test.osm.pbf")?; /// let mut ways = 0_u64; /// /// // Increment the counter by one for each way. /// reader.for_each(|element| { /// if let Element::Way(_) = element { /// ways += 1; /// } /// })?; /// /// println!("Number of ways: {}", ways); /// /// # Ok(()) /// # } /// # foo().unwrap(); /// ``` pub fn for_each<F>(self, mut f: F) -> Result<()> where F: for<'a> FnMut(Element<'a>), { //TODO do something useful with header blocks for blob in self.blob_iter { match blob?.decode() { Ok(BlobDecode::OsmHeader(_)) | Ok(BlobDecode::Unknown(_)) => {} Ok(BlobDecode::OsmData(block)) => { block.for_each_element(&mut f); } Err(e) => return Err(e), } } Ok(()) } /// Parallel map/reduce. Decodes the PBF structure in parallel, calls the closure `map_op` on /// each element and then reduces the number of results to one item with the closure /// `reduce_op`. Similarly to the `init` argument in the `fold` method on iterators, the /// `identity` closure should produce an identity value that is inserted into `reduce_op` when /// necessary. The number of times that this identity value is inserted should not alter the /// result. /// /// # Errors /// Returns the first Error encountered while parsing the PBF structure. /// /// # Example /// ``` /// use osmpbf::*; /// /// # fn foo() -> Result<()> { /// let reader = ElementReader::from_path("tests/test.osm.pbf")?; /// /// // Count the ways /// let ways = reader.par_map_reduce( /// |element| { /// match element { /// Element::Way(_) => 1, /// _ => 0, /// } /// }, /// || 0_u64, // Zero is the identity value for addition /// |a, b| a + b // Sum the partial results /// )?; /// /// println!("Number of ways: {}", ways); /// # Ok(()) /// # } /// # foo().unwrap(); /// ``` pub fn par_map_reduce<MP, RD, ID, T>(self, map_op: MP, identity: ID, reduce_op: RD) -> Result<T> where MP: for<'a> Fn(Element<'a>) -> T + Sync + Send, RD: Fn(T, T) -> T + Sync + Send, ID: Fn() -> T + Sync + Send, T: Send, { self.blob_iter .par_bridge() .map(|blob| match blob?.decode() { Ok(BlobDecode::OsmHeader(_)) | Ok(BlobDecode::Unknown(_)) => Ok(identity()), Ok(BlobDecode::OsmData(block)) => Ok(block .elements() .map(|e| map_op(e)) .fold(identity(), |a, b| reduce_op(a, b))), Err(e) => Err(e), }) .reduce( || Ok(identity()), |a, b| match (a, b) { (Ok(x), Ok(y)) => Ok(reduce_op(x, y)), (x, y) => x.and(y), }, ) } } impl ElementReader<BufReader<File>> { /// Tries to open the file at the given path and constructs an `ElementReader` from this. /// /// # Errors /// Returns the same errors that `std::fs::File::open` returns. /// /// # Example /// ``` /// use osmpbf::*; /// /// # fn foo() -> Result<()> { /// let reader = ElementReader::from_path("tests/test.osm.pbf")?; /// # Ok(()) /// # } /// # foo().unwrap(); /// ``` pub fn from_path<P: AsRef<Path>>(path: P) -> Result<Self> { Ok(ElementReader { blob_iter: BlobReader::from_path(path)?, }) } }