Merge pull request #77 from JasminFragnaud/mtw-sentence-parsing

Add MTW sentence parser

Author: elpiel

README.md

@@ -22,6 +22,7 @@ NMEA Standard Sentences
 - GSA
 - GSV
 - MDA
+- MTW
 - MWV
 - RMC
 - VTG

src/parse.rs

@@ -108,6 +108,7 @@ pub enum ParseResult {
     GSA(GsaData),
     GSV(GsvData),
     MDA(MdaData),
+    MTW(MtwData),
     MWV(MwvData),
     RMC(RmcData),
     TXT(TxtData),

src/parser.rs

@@ -359,6 +359,7 @@ impl<'a> Nmea {
             | ParseResult::AAM(_)
             | ParseResult::ALM(_)
             | ParseResult::PGRMZ(_)
+            | ParseResult::MTW(_)
             | ParseResult::MWV(_)
             | ParseResult::MDA(_) => return Ok(FixType::Invalid),
 

src/sentences/mod.rs

@@ -11,6 +11,7 @@ mod gns;
 mod gsa;
 mod gsv;
 mod mda;
+mod mtw;
 mod mwv;
 mod rmc;
 mod rmz;
@@ -37,6 +38,7 @@ pub use {
     gsa::{parse_gsa, GsaData},
     gsv::{parse_gsv, GsvData},
     mda::{parse_mda, MdaData},
+    mtw::{parse_mtw, MtwData, MtwUnit},
     mwv::{parse_mwv, MwvData, MwvReference, MwvWindSpeedUnits},
     rmc::{parse_rmc, RmcData, RmcStatusOfFix},
     rmz::{parse_pgrmz, PgrmzData},

src/sentences/mtw.rs

@@ -0,0 +1,99 @@
+use nom::{
+    character::complete::{char, one_of},
+    combinator::opt,
+    number::complete::double,
+    sequence::preceded,
+    IResult,
+};
+
+use crate::{parse::NmeaSentence, Error, SentenceType};
+
+/// MTW - Mean Temperature of Water
+///
+/// <https://gpsd.gitlab.io/gpsd/NMEA.html#_mtw_mean_temperature_of_water>
+///
+/// ```text
+///        1   2 3
+///        |   | |
+/// $--MTW,x.x,C*hh<CR><LF>
+/// ```
+/// 1:  Temperature, degrees
+/// 2:  Unit of Measurement, (only) Celsius
+/// 3:  Mandatory NMEA checksum
+#[derive(Debug, PartialEq)]
+pub struct MtwData {
+    pub temperature: Option<f64>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum MtwUnit {
+    Celsius,
+}
+
+/// # Parse MTW message
+///
+/// Information from mtw:
+///
+/// NMEA 0183 standard Mean Temperature of Water.
+/// <https://gpsd.gitlab.io/gpsd/NMEA.html#_mtw_mean_temperature_of_water>
+///
+/// ## Example (Ignore the line break):
+/// ```text
+/// $INMTW,17.9,C*1B
+///```
+///
+/// 1:  17.9         Temperature, degrees
+/// 2:  C            Unit of Measurement, (only) Celsius
+/// 3:  *16          Mandatory NMEA checksum
+pub fn parse_mtw(sentence: NmeaSentence) -> Result<MtwData, Error> {
+    if sentence.message_id != SentenceType::MTW {
+        Err(Error::WrongSentenceHeader {
+            expected: SentenceType::MTW,
+            found: sentence.message_id,
+        })
+    } else {
+        Ok(do_parse_mtw(sentence.data)?.1)
+    }
+}
+
+fn do_parse_mtw(i: &str) -> IResult<&str, MtwData> {
+    let (i, temperature_value) = opt(double)(i)?;
+    preceded(char(','), one_of("C"))(i)?;
+    Ok((
+        i,
+        MtwData {
+            temperature: temperature_value,
+        },
+    ))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::parse::parse_nmea_sentence;
+
+    #[test]
+    fn test_parse_mtw() {
+        let s = parse_nmea_sentence("$INMTW,17.9,C*1B").unwrap();
+        assert_eq!(s.checksum, s.calc_checksum());
+        assert_eq!(s.checksum, 0x1B);
+        let mtw_data = parse_mtw(s).unwrap();
+        assert_eq!(Some(17.9), mtw_data.temperature);
+    }
+
+    #[test]
+    fn test_parse_mtw_invalid_unit() {
+        let s = parse_nmea_sentence("$INMTW,17.9,x*20").unwrap();
+        assert_eq!(s.checksum, s.calc_checksum());
+        assert_eq!(s.checksum, 0x20);
+        assert_eq!(true, parse_mtw(s).is_err());
+    }
+
+    #[test]
+    fn test_parse_mtw_invalid_temp() {
+        let s = parse_nmea_sentence("$INMTW,x.9,C*65").unwrap();
+        assert_eq!(s.checksum, s.calc_checksum());
+        assert_eq!(s.checksum, 0x65);
+        assert_eq!(true, parse_mtw(s).is_err());
+    }
+}