phf_codegen abbreviated timezone parser

build.rs

@@ -0,0 +1,72 @@
+use std::env;
+use std::fs::File;
+use std::io::{BufRead, BufReader, BufWriter, Write};
+use std::path::Path;
+use regex::Regex;
+use chrono::{FixedOffset};
+use lazy_static::lazy_static;
+
+lazy_static! {
+    static ref FULL_PATTERN: Regex = Regex::new(r"([A-Z]+)\s\t.+\s\tUTC([−+±]\d{2}(?::\d{2})?)").unwrap();
+    static ref OFFSET_PATTERN: Regex = Regex::new(r"([−+±])(\d{2}(?::\d{2})?)").unwrap();
+}
+
+const HOUR: u32 = 3600;
+
+fn parse_offset(raw_offset: &str) -> i32 {
+    let capture = OFFSET_PATTERN.captures(raw_offset).expect("RegEx failed to match offset");
+    println!("{}: {}", raw_offset, capture.get(1).expect("First group capture failed").as_str());
+
+    let is_west = capture.get(1).unwrap().as_str() == "−";
+    let time = capture.get(2).expect("Second group capture failed").as_str();
+    let (hours, minutes) = if time.contains(':') {
+        let mut split = time.split(':');
+        let hours = split.next().unwrap().parse::<u32>().unwrap();
+        let minutes = split.next().unwrap().parse::<u32>().unwrap();
+
+        (hours, minutes)
+    } else {
+        // Minutes not specified, assume 0
+        (time.parse::<u32>().unwrap(), 0)
+    };
+
+    let value = (hours * HOUR) + (minutes * 60);
+    return if is_west { value as i32 * -1 } else { value as i32 };
+}
+
+fn main() {
+    let path = Path::new(&env::var("OUT_DIR").unwrap()).join("codegen.rs");
+    let raw_tz = BufReader::new(File::open("./src/abbr_tz").unwrap());
+
+    let mut file = BufWriter::new(File::create(&path).unwrap());
+
+    let mut builder: phf_codegen::Map<String> = phf_codegen::Map::new();
+
+    for line in raw_tz.lines() {
+        let line = line.unwrap();
+        if line.starts_with('#') {
+            continue;
+        }
+
+        let capture = FULL_PATTERN.captures(&line).expect("RegEx failed to match line");
+
+        let abbreviation = capture.get(1).unwrap().as_str();
+        let raw_offset = capture.get(2).unwrap().as_str();
+
+        let offset = if !raw_offset.starts_with('±') {
+            parse_offset(raw_offset)
+        } else {
+            0
+        };
+
+        builder.entry(String::from(abbreviation), &format!("\"{}\"", offset).to_string());
+    }
+
+    write!(
+        &mut file,
+        "static TIMEZONES: phf::Map<&'static str, &'static str> = {}",
+        builder.build()
+    )
+        .unwrap();
+    write!(&mut file, ";\n").unwrap();
+}