unwrap unchecked

benchmark.txt

@@ -5,3 +5,4 @@
  95 FxHashMap
  71 mmap, reduced UTF8 parsing (names)
  50 manual number parsing
+ 48 unchecked unwrap

src/main.rs

@@ -29,9 +29,9 @@ fn main() {
         let line = &mmap[pointer..pointer + length];
 
         let mut split = line.split(|&c| c == b';');
-        let station = split.next().unwrap();
+        let station = unsafe { split.next().unwrap_unchecked() };
-        let number = split.next().unwrap();
+        let number = unsafe { split.next().unwrap_unchecked() };
-        let parsed = parse_number(number);
+        let parsed = unsafe { parse_number(number) };
         // panic!();
 
         data.entry(station)
@@ -70,8 +70,9 @@ fn main() {
     println!("}}");
 }
 
-fn parse_number(number: &[u8]) -> i64 {
+unsafe fn parse_number(number: &[u8]) -> i64 {
-    let sign = if *number.first().unwrap() == b'-' {
+    unsafe {
+        let sign = if *number.first().unwrap_unchecked() == b'-' {
             -1
         } else {
             1
@@ -80,9 +81,9 @@ fn parse_number(number: &[u8]) -> i64 {
         let mut iter = number.iter().rev();
 
         // 48: ASCII '0'
-    let mut result = (iter.next().unwrap() - 48) as i64;
+        let mut result = (iter.next().unwrap_unchecked() - 48) as i64;
         iter.next(); // skip '.'
-    result += ((iter.next().unwrap() - 48) as i64) * 10;
+        result += ((iter.next().unwrap_unchecked() - 48) as i64) * 10;
 
         if let Some(hundreds) = iter.next()
             && *hundreds != b'-'
@@ -92,6 +93,7 @@ fn parse_number(number: &[u8]) -> i64 {
 
         sign * result
     }
+}
 
 #[cfg(test)]
 mod tests {
@@ -100,6 +102,6 @@ mod tests {
     #[test]
     fn test_parse_number() {
         let input = [49, 53, 46, 51]; // "15.3"
-        assert_eq!(parse_number(&input), 153);
+        assert_eq!(unsafe { parse_number(&input) }, 153);
     }
 }