gpx 0.4.1

//! tracksegment handles parsing of GPX-spec track segments.

use errors::*;
use std::io::Read;
use xml::reader::XmlEvent;

use parser::verify_starting_tag;
use parser::waypoint;
use parser::Context;

use TrackSegment;

/// consume consumes a GPX track segment from the `reader` until it ends.
pub fn consume<R: Read>(context: &mut Context<R>) -> Result<TrackSegment> {
    let mut segment: TrackSegment = Default::default();
    verify_starting_tag(context, "trkseg")?;

    loop {
        let next_event = {
            if let Some(next) = context.reader.peek() {
                next.clone()
            } else {
                break;
            }
        };

        match next_event.chain_err(|| Error::from("error while parsing tracksegment event"))? {
            XmlEvent::StartElement { ref name, .. } => match name.local_name.as_ref() {
                "trkpt" => segment.points.push(waypoint::consume(context, "trkpt")?),
                child => {
                    bail!(ErrorKind::InvalidChildElement(
                        String::from(child),
                        "tracksegment"
                    ));
                }
            },
            XmlEvent::EndElement { ref name } => {
                ensure!(
                    name.local_name == "trkseg",
                    ErrorKind::InvalidClosingTag(name.local_name.clone(), "trksegment")
                );
                context.reader.next(); //consume the end tag
                return Ok(segment);
            }
            _ => {
                context.reader.next(); //consume and ignore this event
            }
        }
    }

    bail!(ErrorKind::MissingClosingTag("tracksegment"));
}

#[cfg(test)]
mod tests {
    use geo::euclidean_length::EuclideanLength;
    use std::io::BufReader;

    use super::consume;
    use GpxVersion;

    #[test]
    fn consume_full_trkseg() {
        let segment = consume!(
            "
            <trkseg>
                <trkpt lon=\"-77.0365\" lat=\"38.8977\">
                    <name>The White House</name>
                </trkpt>
                <trkpt lon=\"-71.063611\" lat=\"42.358056\">
                    <name>Boston, Massachusetts</name>
                </trkpt>
                <trkpt lon=\"-69.7832\" lat=\"44.31055\">
                    <name>Augusta, Maine</name>
                </trkpt>
            </trkseg>",
            GpxVersion::Gpx11
        );

        assert!(segment.is_ok());
        let segment = segment.unwrap();

        assert_eq!(segment.points.len(), 3);

        let linestring = segment.linestring();
        assert_approx_eq!(linestring.euclidean_length(), 9.2377437);
    }

    #[test]
    fn consume_empty() {
        let segment = consume!("<trkseg></trkseg>", GpxVersion::Gpx11);

        assert!(segment.is_ok());
        let segment = segment.unwrap();

        assert_eq!(segment.points.len(), 0);
    }
}