refactor: error handling

Author: beeb

src/days/mod.rs

@@ -1,10 +1,8 @@
-use std::{fmt::Display, fs::read_to_string};
+use std::{fmt::Display, fs, path::Path, time::Instant};
 
-use anyhow::{anyhow, Result};
+use anyhow::{anyhow, Context, Result};
 use winnow::{PResult, Parser as _};
 
-use crate::Instant;
-
 pub mod day01;
 pub mod day02;
 pub mod day03;
@@ -44,26 +42,25 @@ pub trait Day {
 
     fn part_2(input: &Self::Input) -> Self::Output2;
 
-    fn parse_file(fp: &str) -> Result<Self::Input> {
-        let input_string = read_to_string(fp)?;
+    fn parse_file(path: impl AsRef<Path>) -> Result<Self::Input> {
+        let input_string = fs::read_to_string(path).context("reading the input file")?;
         let input = Self::parser
             .parse(&input_string)
-            .map_err(|e| anyhow!(e.to_string()))?;
+            .map_err(|e| anyhow!(e.to_string()))
+            .context("running the parser")?;
         Ok(input)
     }
 
     #[allow(clippy::cast_precision_loss)]
-    fn run_day(fp: &str) {
-        match Self::parse_file(fp) {
-            Err(e) => println!("{e:?}"),
-            Ok(input) => {
-                let before1 = Instant::now();
-                println!("Part 1: {}", Self::part_1(&input));
-                println!("Part 1 took {:?}", before1.elapsed());
-                let before2 = Instant::now();
-                println!("Part 2: {}", Self::part_2(&input));
-                println!("Part 2 took {:?}", before2.elapsed());
-            }
-        }
+    fn run_day(path: impl AsRef<Path>) -> Result<()> {
+        let input = Self::parse_file(path)?;
+
+        let before1 = Instant::now();
+        println!("Part 1: {}", Self::part_1(&input));
+        println!("Part 1 took {:?}", before1.elapsed());
+        let before2 = Instant::now();
+        println!("Part 2: {}", Self::part_2(&input));
+        println!("Part 2 took {:?}", before2.elapsed());
+        Ok(())
     }
 }

src/main.rs

@@ -1,4 +1,4 @@
-use std::{fs, time::Instant};
+use std::fs;
 
 use anyhow::{bail, Context as _, Result};
 use chrono::{Datelike, Local};
@@ -47,18 +47,15 @@ fn main() -> Result<()> {
     match cli.command {
         Commands::Run { day, all } => {
             if all {
-                run_all_days();
-                return Ok(());
+                return run_all_days();
             }
             if let Some(day) = day {
-                run_day(parse_day(&day)?);
-                return Ok(());
+                return run_day(parse_day(&day)?);
             }
             println!("No day parameter specified, attempting to run today's code");
             let now_day = get_today()?;
             println!("Running day {now_day}");
-            run_day(now_day);
-            Ok(())
+            run_day(now_day)
         }
         Commands::GetInput { day, all } => {
             if all {
@@ -95,11 +92,11 @@ fn parse_day(day: &str) -> Result<u32> {
     Ok(out)
 }
 
-fn run_all_days() {
-    (1..=25).for_each(run_day);
+fn run_all_days() -> Result<()> {
+    (1..=25).try_for_each(run_day)
 }
 
-fn run_day(day: u32) {
+fn run_day(day: u32) -> Result<()> {
     println!("======== DAY {day} ========");
     // I'd like to do this with a macro, but I'm not sure how to do it.
     let input_fp = &format!("inputs/day{day:02}.txt");