src/doc/book/listings/ch13-functional-features/listing-13-27/src/lib.rs

   1 use std::env;
   2 use std::error::Error;
   3 use std::fs;
   4
   5 pub struct Config {
   6     pub query: String,
   7     pub filename: String,
   8     pub case_sensitive: bool,
   9 }
  10
  11 // ANCHOR: here
  12 impl Config {
  13     pub fn new(mut args: std::env::Args) -> Result<Config, &'static str> {
  14         args.next();
  15
  16         let query = match args.next() {
  17             Some(arg) => arg,
  18             None => return Err("Didn't get a query string"),
  19         };
  20
  21         let filename = match args.next() {
  22             Some(arg) => arg,
  23             None => return Err("Didn't get a file name"),
  24         };
  25
  26         let case_sensitive = env::var("CASE_INSENSITIVE").is_err();
  27
  28         Ok(Config {
  29             query,
  30             filename,
  31             case_sensitive,
  32         })
  33     }
  34 }
  35 // ANCHOR_END: here
  36
  37 pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
  38     let contents = fs::read_to_string(config.filename)?;
  39
  40     let results = if config.case_sensitive {
  41         search(&config.query, &contents)
  42     } else {
  43         search_case_insensitive(&config.query, &contents)
  44     };
  45
  46     for line in results {
  47         println!("{}", line);
  48     }
  49
  50     Ok(())
  51 }
  52
  53 pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
  54     let mut results = Vec::new();
  55
  56     for line in contents.lines() {
  57         if line.contains(query) {
  58             results.push(line);
  59         }
  60     }
  61
  62     results
  63 }
  64
  65 pub fn search_case_insensitive<'a>(
  66     query: &str,
  67     contents: &'a str,
  68 ) -> Vec<&'a str> {
  69     let query = query.to_lowercase();
  70     let mut results = Vec::new();
  71
  72     for line in contents.lines() {
  73         if line.to_lowercase().contains(&query) {
  74             results.push(line);
  75         }
  76     }
  77
  78     results
  79 }
  80
  81 #[cfg(test)]
  82 mod tests {
  83     use super::*;
  84
  85     #[test]
  86     fn case_sensitive() {
  87         let query = "duct";
  88         let contents = "\
  89 Rust:
  90 safe, fast, productive.
  91 Pick three.
  92 Duct tape.";
  93
  94         assert_eq!(vec!["safe, fast, productive."], search(query, contents));
  95     }
  96
  97     #[test]
  98     fn case_insensitive() {
  99         let query = "rUsT";
 100         let contents = "\
 101 Rust:
 102 safe, fast, productive.
 103 Pick three.
 104 Trust me.";
 105
 106         assert_eq!(
 107             vec!["Rust:", "Trust me."],
 108             search_case_insensitive(query, contents)
 109         );
 110     }
 111 }
 112
 113 fn main() {}