// basic tokens
WHITESPACE = _{ " " | "\t" | "\r" | "\n" }
ASCII_UPPER_ALPHA = _{ 'A'..'Z' }
// basic rule == rand number of recognized or unrecognized tokens
metar_report = { SOI ~ token* ~ EOI }
//time formatfrom HHMMSSZ
time = { ASCII_DIGIT{6} ~ "Z" }
// station is 4 chars uppercase
station = { SOI ~ ASCII_UPPER_ALPHA{4} ~ EOI }
// expected wind format is DDDSS(GGG)?(KT|MPS), so:
wind_dir= {ASCII_DIGIT{3}} // 3 digits
wind_speed= { ASCII_DIGIT{2,3} } // 2 or 3 digits
wind_gust = {"G"~ASCII_DIGIT{2,3} } // optional G+num
wind_units= {"KT" | "MPS"}
wind = {wind_dir~wind_speed ~ wind_gust?~wind_units}//? baceuse might be absent
// visibility for abbreviations+nums
visibility = {(ASCII_ALPHA)?~ // one upperc prefix char
//num + "" + num + "/" + num; num + "/" + num; or num
((ASCII_DIGIT+ ~ " " ~ ASCII_DIGIT+ ~ "/" ~ ASCII_DIGIT+) | (ASCII_DIGIT+ ~ "/" ~ ASCII_DIGIT+)
| (ASCII_DIGIT+)) ~ "SM" // num + somethin
}
cloud_cover = { "FEW" | "SCT" | "BKN" | "OVC" } //type of cloud
cloud_alt = { ASCII_DIGIT{3} } //altitude
clouds = {cloud_cover~cloud_alt | "CLR" | "SKC"}//cloud type + altitude or clear
temp = { "M"? ~ ASCII_DIGIT{2} } //temp (M if minus)
dew = { "M"? ~ ASCII_DIGIT{2} } //dew point (M if minus)
temp_dew = { temp ~ "/" ~ dew } // temp/dew point
// pressure A + 4 dig
pressure = { "A" ~ ASCII_DIGIT{4} }
// all RMK+something until eol
remarks = { "RMK" ~ (!NEWLINE ~ ANY)* }
//known words from docunentation(just in case:) might delete if i find optimalsolution)
known_keyword = {"COR" | "AUTO" | "AMD" | "TEMPO" | "NOSIG" }
//other tokens >2 upper chars
uppercase_token = @{ ASCII_UPPER_ALPHA{2,} }
// sep
separator = _{ WHITESPACE+ }
// known tokens
token = _{station| time| wind|visibility|clouds|temp_dew| pressure|remarks| known_keyword| uppercase_token| separator| unknown_token}
//until whitespace - any symbols >1 times
unknown_token = @{ (!WHITESPACE ~ ANY)+ }