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#![deny(missing_docs)] //! # METAR parsing library for Rust //! //! ## Quick usage //! //! This simple usage will print out the parsed data from the METAR. //! //! ```rust //! extern crate metar; //! //! fn main() { //! let metar = "EGHI 282120Z 19015KT 140V220 6000 RA SCT006 BKN009 16/14 Q1006"; //! let r = metar::Metar::parse(metar).unwrap(); //! println!("{:#?}", r); //! } //! ``` //! //! ## Issues? //! //! METARs are complicated structures. If you come across a METAR that doesn't parse //! correctly, please open an issue and include the METAR. This will aid in debugging //! the issue significantly. //! //! ## Definition of a METAR //! //! A METAR can be defined with the following Backus-Naur Form description: //! //! ```bnf //! <metar> ::= <station> ' ' <observationtime> ' ' <method> ' ' <wind> ' ' <wind_varying> <cloudsvis> ' ' <temps> ' ' <pressure> <remark> //! //! <station> ::= <letter><letter><letter><letter> //! //! <method> ::= '' | 'AUTO' | 'COR' //! //! <observationtime> ::= <obs_day><obs_hour><obs_minute> 'Z' //! <obs_day> ::= <obs_day_1><digit> | '3' <obs_day_2> //! <obs_day_1> ::= '0' | '1' | '2' //! <obs_day_2> ::= '0' | '1' //! <obs_hour> ::= <obs_hour_1><digit> | '2' <obs_hour_2> //! <obs_hour_1> ::= '0' | '1' //! <obs_hour_2> ::= '0' | '1' | '2' | '3' //! <obs_minute> ::= <obs_minute_1><digit> //! <obs_minute_1> ::= '0' | '1' | '2' | '3' | '4' | '5' //! //! <wind> ::= <wind_dir><digit><digit><wind_gusts> 'KT' //! | <wind_dir><digit><digit><wind_gusts> 'MPS' //! <wind_dir> ::= <angle> | 'VRB' //! <wind_gusts> ::= '' | 'G' <digit><digit> //! //! <wind_varying> ::= '' | <angle> 'V' <angle> ' ' //! //! <angle> ::= <angle_1><digit><digit> | '3' <angle_2><digit> | '360' //! <angle_1> ::= '0' | '1' | '2' //! <angle_2> ::= '0' | '1' | '2' | '3' | '4' | '5' //! //! <cloudsvis> ::= 'CAVOK' | <visibility> <rvr> <weather> <clouds> //! <visibility> ::= <digit><digit><digit><digit> | <digit><digit> 'SM' //! <clouds> ::= 'CLR' | 'SKC' | 'NCD' | 'NSC' | <cloud_description_list> | <vertical_visibility> //! <rvr> ::= <rvr_entry> | <rvr_entry><rvr> //! <rvr_entry> ::= 'R' <runway_number> '/' <rvr_vis> <rvr_trend> //! <runway_number> ::= <angle_1><digit><runway_modifier> | '3' <angle_2><runway_modifier> //! <runway_modifier> ::= '' | 'L' | 'C' | 'R' //! <rvr_vis> ::= 'P' <digit><digit><digit><digit> | 'M' <digit><digit><digit><digit> //! <rvr_trend> ::= 'D' | 'U' | 'N' //! //! <cloud_description_list> ::= <cloud_description> | <cloud_description> <cloud_description_list> //! <cloud_description> ::= <cloud_density> <cloud_floor> <cloud_type> //! <cloud_density> ::= 'FEW' | 'SCT' | 'BKN' | 'OVC' | '///' //! <cloud_floor> ::= <digit><digit><digit> | '///' //! <cloud_type> ::= '' | 'CB' | 'TCU' | '///' //! //! <vertical_visibility> ::= 'VV' <vertical_visibility_distance> //! <vertical_visibility_distance> ::= '///' | <digit><digit><digit> //! //! <weather> ::= <weather_cond> | <weather_cond> <weather> //! <weather_cond> ::= <weather_intesity><weather_descriptor><weather_preceipitation> //! | <weather_obscuration> //! | <weather_other> //! | <weather_preceipitation><weather_timing> //! <weather_intesity> ::= '' | '+' | '-' | 'VC' //! <weather_descriptor> ::= '' | 'MI' | 'PR' | 'BC' | 'DR' | 'BL' | 'SH' | 'TS' | 'FZ' //! <weather_preceipitation> ::= 'RA' | 'DZ' | 'SN' | 'SG' | 'IC' | 'PL' | 'GR' | 'GS' | 'UP' //! <weather_obscuration> ::= 'FG' | 'VA' | 'BR' | 'HZ' | 'DU' | 'FU' | 'SA' | 'PY' //! <weather_other> ::= 'SQ' | 'PO' | 'DS' | 'SS' | 'FC' //! <weather_timing> ::= 'B' <weather_timing_time> 'E' <weather_timing_time> //! | 'B' <weather_timing_time> //! | 'E' <weather_timing_time> //! <weather_timing_time> ::= <digit><digit> | <digit><digit><digit><digit> //! //! //! <temps> ::= <temperature> '/' <temperature> //! <temperature> ::= 'M' <digit><digit> //! | <digit><digit> //! //! <pressure> ::= 'Q' <digit><digit><digit><digit> //! | 'A' <digit><digit><digit><digit> //! //! <remark> ::= ' RMK' ... //! //! <digit> ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' //! ``` mod types; mod parsers; use std::fmt; pub use types::*; pub use parsers::errors::*; #[derive(PartialEq, Clone, Debug)] /// A complete METAR pub struct Metar<'a> { /// The station making the METAR measurement pub station: &'a str, /// The measurement time pub time: Time, /// The current wind information pub wind: Wind, /// The current visibility pub visibility: Visibility, /// The current clouds pub clouds: Clouds, /// The current clouds pub cloud_layers: Vec<CloudLayer>, /// The current vertical visibility, in feet pub vert_visibility: Option<VertVisibility>, /// The current weather conditions pub weather: Vec<Weather>, /// The current temperature pub temperature: i32, /// The current dewpoint pub dewpoint: i32, /// The current air pressure pub pressure: Pressure, /// Any remarks made about the METAR pub remarks: Option<&'a str>, } #[derive(PartialEq, Eq, Clone, Debug)] /// An error when parsing a METAR pub struct MetarError<'a> { /// The string being parsed pub string: &'a str, /// The start index of the error pub start: usize, /// The length of the error'd section pub length: usize, /// The current parser state (what it was expecting to read) pub parser_state: ParseState, /// The error from the internal parser pub error: ParserError, } impl<'a> MetarError<'a> { fn new(string: &'a str, start: usize, length: usize, parser_state: ParseState, error: ParserError) -> Self { Self { string, start, length, parser_state, error, } } } impl<'a> fmt::Display for MetarError<'a> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let mut caret = String::new(); for _ in 0..self.start { caret.push(' '); } caret.push('^'); for _ in 1..self.length { caret.push('~'); } write!(f, "{}\n{}\n{}", self.string, caret, self.error) } } impl fmt::Display for ParserError { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { match self { Self::Station(e) => write!(f, "{}", e), Self::ObservationTime(e) => write!(f, "{}", e), Self::Wind(e) => write!(f, "{}", e), Self::WindVarying(e) => write!(f, "{}", e), Self::CloudVisibility(e) => write!(f, "{}", e), Self::Temperature(e) => write!(f, "{}", e), Self::Pressure(e) => write!(f, "{}", e), } } } #[derive(PartialEq, Eq, Clone, Debug)] /// An error from an internal parser pub enum ParserError { /// An error from the station parser Station(StationError), /// An error from the observation time parser ObservationTime(ObservationTimeError), /// An error from the wind parser Wind(WindError), /// An error from the wind varying parser WindVarying(WindVaryingError), /// An error from the cloud/visibility parser CloudVisibility(CloudVisibilityError), /// An error from the temperature parser Temperature(TemperatureError), /// An error from the pressure parser Pressure(PressureError), } /// Find the words in a string by splitting into an array of usize tuples with the start index and /// length of each word fn find_words<'a>(s: &'a str) -> Vec<(usize, usize)> { let mut words = Vec::new(); let chs: Vec<_> = s.chars().collect(); let mut start_idx = 0; let mut last_read_ws = false; let len = chs.len(); for i in 0..len { if chs[i].is_whitespace() && !last_read_ws { last_read_ws = true; words.push((start_idx, i - start_idx)); } if !chs[i].is_whitespace() { if last_read_ws { start_idx = i; } last_read_ws = false; } } if !last_read_ws { words.push((start_idx, len - start_idx)); } words } #[derive(Copy, Clone, Debug, Eq, PartialEq)] /// The state of the parser, used in error messages to describe the expected next occurence when it /// wasn't reached. pub enum ParseState { /// Expected an ICAO station Station, /// Expected an observation time ObservationTime, /// Expected either a recording method ('AUTO') or wind information MethodOrWind, /// Expected information about wind variation or cloud and visibility information WindVaryingOrCloudsVis, /// Expected cloud and visibility information or temperatures CloudVisOrTemps, /// Expected air pressure Pressure, /// Expected either remarks or the METAR end RemarksOrEnd, } impl<'a> Metar<'a> { /// Parse a string into a METAR pub fn parse(data: &'a str) -> Result<Self, MetarError> { let mut metar = Metar { station: "XXXX", time: Time { date: 0, hour: 0, minute: 0, }, wind: Wind { dir: WindDirection::Heading(0), speed: WindSpeed::Knot(0), varying: None, gusting: None, }, visibility: Visibility::Metres(10000), clouds: Clouds::SkyClear, cloud_layers: Vec::new(), vert_visibility: None, weather: Vec::new(), temperature: 0, dewpoint: 0, pressure: Pressure::Hectopascals(0), remarks: None, }; let mut state = ParseState::Station; let words = find_words(data); for word_idx in words { let word = &data[word_idx.0..word_idx.0 + word_idx.1]; match state { ParseState::Station => { let r = parsers::parse_station(word); if let Ok(data) = r { metar.station = data; state = ParseState::ObservationTime; } else if let Err(e) = r { return Err(MetarError::new(data, word_idx.0 + e.0, e.1, state, ParserError::Station(e.2))); } }, ParseState::ObservationTime => { let r = parsers::parse_obs_time(word); if let Ok(data) = r { metar.time = data; state = ParseState::MethodOrWind; } else if let Err(e) = r { return Err(MetarError::new(data, word_idx.0 + e.0, e.1, state, ParserError::ObservationTime(e.2))); } }, ParseState::MethodOrWind => { if word == "AUTO" || word == "COR" { // Method - just ignore for now continue; } let r = parsers::parse_wind(word); if let Ok(data) = r { metar.wind = data; state = ParseState::WindVaryingOrCloudsVis; } else if let Err(e) = r { return Err(MetarError::new(data, word_idx.0 + e.0, e.1, state, ParserError::Wind(e.2))); } }, ParseState::WindVaryingOrCloudsVis => { // Treat as wind varying let r = parsers::parse_wind_varying(word); if let Ok(data) = r { metar.wind.varying = Some(data); state = ParseState::CloudVisOrTemps; } else if let Err(e) = r { if let (_s, _l, WindVaryingError::NotWindVarying) = e { // Parse cloud/vis data let r = parsers::parse_cloud_visibility_info(word); if let Ok(data) = r { match data { parsers::CloudVisibilityInfo::CloudLayer(layer) => { metar.clouds = Clouds::CloudLayers; metar.cloud_layers.push(layer); }, parsers::CloudVisibilityInfo::Clouds(clouds) => { metar.clouds = clouds; }, parsers::CloudVisibilityInfo::RVR(..) => { }, parsers::CloudVisibilityInfo::VerticalVisibility(vv) => { metar.vert_visibility = Some(vv); metar.clouds = Clouds::Undetermined; }, parsers::CloudVisibilityInfo::Visibility(visibility) => { match visibility { Visibility::StatuteMiles(dist) => { match metar.visibility { Visibility::StatuteMiles(prevdist) => { metar.visibility = Visibility::StatuteMiles(prevdist + dist); }, _ => { metar.visibility = visibility; } } }, _ => { metar.visibility = visibility; } } }, parsers::CloudVisibilityInfo::Weather(wx) => { metar.weather.push(wx); }, }; } else if let Err(e) = r { return Err(MetarError::new(data, word_idx.0 + e.0, e.1, state, ParserError::CloudVisibility(e.2))); } state = ParseState::CloudVisOrTemps; continue; } else { return Err(MetarError::new(data, word_idx.0 + e.0, e.1, state, ParserError::WindVarying(e.2))); } } }, ParseState::CloudVisOrTemps => { // Treat as temperatures let r = parsers::parse_temperatures(word); if let Ok(data) = r { metar.temperature = data.0; metar.dewpoint = data.1; state = ParseState::Pressure; } else if let Err(e) = r { if let (_s, _l, TemperatureError::NotTemperatureDewpointPair) = e { let r = parsers::parse_cloud_visibility_info(word); if let Ok(data) = r { match data { parsers::CloudVisibilityInfo::CloudLayer(layer) => { metar.clouds = Clouds::CloudLayers; metar.cloud_layers.push(layer); }, parsers::CloudVisibilityInfo::Clouds(clouds) => { metar.clouds = clouds; }, parsers::CloudVisibilityInfo::RVR(..) => { }, parsers::CloudVisibilityInfo::VerticalVisibility(vv) => { metar.vert_visibility = Some(vv); metar.clouds = Clouds::Undetermined; }, parsers::CloudVisibilityInfo::Visibility(visibility) => { match visibility { Visibility::StatuteMiles(dist) => { match metar.visibility { Visibility::StatuteMiles(prevdist) => { metar.visibility = Visibility::StatuteMiles(prevdist + dist); }, _ => { metar.visibility = visibility; } } }, _ => { metar.visibility = visibility; } } }, parsers::CloudVisibilityInfo::Weather(wx) => { metar.weather.push(wx); }, }; } else if let Err(e) = r { return Err(MetarError::new(data, word_idx.0 + e.0, e.1, state, ParserError::CloudVisibility(e.2))); } state = ParseState::CloudVisOrTemps; continue; } else { return Err(MetarError::new(data, word_idx.0 + e.0, e.1, state, ParserError::Temperature(e.2))); } } }, ParseState::Pressure => { let r = parsers::parse_pressure(word); if let Ok(data) = r { metar.pressure = data; state = ParseState::RemarksOrEnd; } else if let Err(e) = r { return Err(MetarError::new(data, word_idx.0 + e.0, e.1, state, ParserError::Pressure(e.2))); } }, ParseState::RemarksOrEnd => { metar.remarks = Some(&data[word_idx.0..]); break; }, } } Ok(metar) } } #[cfg(test)] mod tests { use super::*; #[test] fn test_find_words() { let r = find_words("The quick brown fox."); assert_eq!(r, [(0, 3), (4, 5), (10, 5), (16, 4)]); } }