src/doc/book/listings/ch12-an-io-project/listing-12-12/src/main.rs

   1 use std::env;
   2 use std::fs;
   3 use std::process;
   4 // ANCHOR: here
   5 use std::error::Error;
   6
   7 // --snip--
   8
   9 // ANCHOR_END: here
  10
  11 fn main() {
  12     let args: Vec<String> = env::args().collect();
  13
  14     let config = Config::build(&args).unwrap_or_else(|err| {
  15         println!("Problem parsing arguments: {err}");
  16         process::exit(1);
  17     });
  18
  19     println!("Searching for {}", config.query);
  20     println!("In file {}", config.file_path);
  21
  22     run(config);
  23 }
  24
  25 // ANCHOR: here
  26 fn run(config: Config) -> Result<(), Box<dyn Error>> {
  27     let contents = fs::read_to_string(config.file_path)?;
  28
  29     println!("With text:\n{contents}");
  30
  31     Ok(())
  32 }
  33 // ANCHOR_END: here
  34
  35 struct Config {
  36     query: String,
  37     file_path: String,
  38 }
  39
  40 impl Config {
  41     fn build(args: &[String]) -> Result<Config, &'static str> {
  42         if args.len() < 3 {
  43             return Err("not enough arguments");
  44         }
  45
  46         let query = args[1].clone();
  47         let file_path = args[2].clone();
  48
  49         Ok(Config { query, file_path })
  50     }
  51 }