src/doc/book/listings/ch13-functional-features/listing-13-20/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 ignore_case: bool,
   9 }
  10
  11 // ANCHOR: here
  12 impl Config {
  13     pub fn new(
  14         mut args: impl Iterator<Item = String>,
  15     ) -> Result<Config, &'static str> {
  16         args.next();
  17
  18         let query = match args.next() {
  19             Some(arg) => arg,
  20             None => return Err("Didn't get a query string"),
  21         };
  22
  23         let filename = match args.next() {
  24             Some(arg) => arg,
  25             None => return Err("Didn't get a file name"),
  26         };
  27
  28         let ignore_case = env::var("IGNORE_CASE").is_ok();
  29
  30         Ok(Config {
  31             query,
  32             filename,
  33             ignore_case,
  34         })
  35     }
  36 }
  37 // ANCHOR_END: here
  38
  39 pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
  40     let contents = fs::read_to_string(config.filename)?;
  41
  42     let results = if config.ignore_case {
  43         search_case_insensitive(&config.query, &contents)
  44     } else {
  45         search(&config.query, &contents)
  46     };
  47
  48     for line in results {
  49         println!("{}", line);
  50     }
  51
  52     Ok(())
  53 }
  54
  55 pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
  56     let mut results = Vec::new();
  57
  58     for line in contents.lines() {
  59         if line.contains(query) {
  60             results.push(line);
  61         }
  62     }
  63
  64     results
  65 }
  66
  67 pub fn search_case_insensitive<'a>(
  68     query: &str,
  69     contents: &'a str,
  70 ) -> Vec<&'a str> {
  71     let query = query.to_lowercase();
  72     let mut results = Vec::new();
  73
  74     for line in contents.lines() {
  75         if line.to_lowercase().contains(&query) {
  76             results.push(line);
  77         }
  78     }
  79
  80     results
  81 }
  82
  83 #[cfg(test)]
  84 mod tests {
  85     use super::*;
  86
  87     #[test]
  88     fn case_sensitive() {
  89         let query = "duct";
  90         let contents = "\
  91 Rust:
  92 safe, fast, productive.
  93 Pick three.
  94 Duct tape.";
  95
  96         assert_eq!(vec!["safe, fast, productive."], search(query, contents));
  97     }
  98
  99     #[test]
 100     fn case_insensitive() {
 101         let query = "rUsT";
 102         let contents = "\
 103 Rust:
 104 safe, fast, productive.
 105 Pick three.
 106 Trust me.";
 107
 108         assert_eq!(
 109             vec!["Rust:", "Trust me."],
 110             search_case_insensitive(query, contents)
 111         );
 112     }
 113 }