2018: day03: simplify error

aoc2018/src/day03.rs

@@ -1,7 +1,9 @@
 use std::collections::HashMap;
 use std::collections::HashSet;
+use std::error::Error;
 use std::fmt;
 
+use super::err;
 use super::Result;
 
 const INPUT: &str = include_str!("../input/day03.txt");
@@ -13,31 +15,6 @@ pub fn run() -> Result<()> {
     Ok(())
 }
 
-#[derive(Debug)]
-struct ParseError {
-    line: String,
-}
-
-impl ParseError {
-    fn new(line: &str) -> Self {
-        ParseError {
-            line: line.to_string(),
-        }
-    }
-}
-
-impl fmt::Display for ParseError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{}", self.line)
-    }
-}
-
-impl std::error::Error for ParseError {
-    fn description(&self) -> &str {
-        &self.line
-    }
-}
-
 struct Claim {
     x: usize,
     y: usize,
@@ -89,7 +66,7 @@ fn part1(input: &str) -> Result<u64> {
     let mut map: HashMap<(usize, usize), u64> = HashMap::default();
 
     for line in input.lines() {
-        let claim = parse(line).ok_or(ParseError::new(line))?;
+        let claim = parse(line).ok_or(err!("Couldn't parse line: {}", line))?;
 
         for i in 0..claim.width {
             for j in 0..claim.height {
@@ -116,7 +93,7 @@ fn part2(input: &str) -> Result<usize> {
     let mut set = HashSet::new();
 
     for line in input.lines() {
-        let claim = parse(line).ok_or(ParseError::new(line))?;
+        let claim = parse(line).ok_or(err!("Couldn't parse line: {}", line))?;
         set.insert(claim.id);
 
         for i in 0..claim.width {

aoc2018/src/lib.rs

@@ -3,3 +3,8 @@ pub mod day02;
 pub mod day03;
 
 pub type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
+
+#[macro_export]
+macro_rules! err {
+    ($($string:expr),+) => (Box::<dyn Error>::from(format!($($string),+)))
+}