RustBook——Minigrep学习示例+注释
1. 代码
use std::env;
use std::process;
use minigrep;
use minigrep::Config;
fn main() {
let config = Config::new(env::args()).unwrap_or_else(|err| {
eprintln!("Problem parsing arguments: {}", err);
process::exit(1);
});
println!("Searching for '{}'", config.query);
println!("In file '{}'", config.filename);
if let Err(e) = minigrep::run(config) {
eprintln!("Application error: {}", e);
process::exit(1);
}
}
use std::env;
/// # 查询配置
/// - query: 待查询的字段
/// - filename: 待查询的文件
/// - case_sensitive: 是否大小写敏感
pub struct Config {
pub query: String,
pub filename: String,
pub case_sensitive: bool,
}
impl Config {
pub fn new(mut args: std::env::Args) -> Result<Config, &'static str> {
// args是一个Iterator,一步一步的向后取数据
// 第一个参数不要,是本程序的路径
args.next();
// 待查询的字段
let query = match args.next() {
Some(arg) => arg,
None => return Err("Didn't get a query string"),
};
// 待检索的文档
let filename = match args.next() {
Some(arg) => arg,
None => return Err("Didn't get a file name"),
};
// 1. 先检查参数中是否配置了大小写敏感
// 2. 如果没配置,再看系统环境变量中是否配置了大小写敏感
// 3. 如果都没配置,默认是大小写不敏感
let case_sensitive = match args.next() {
Some(arg) => arg == "CASE_SENSITIVE",
None => env::var("CASE_SENSITIVE").is_ok(),
};
Ok(Config { query, filename, case_sensitive })
}
}
/// # 大小写敏感查询
/// - query: 需要查询的字段
/// - contents: 需要查询的内容
fn search_case_sensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
// 获取contents的Iterator,进行过滤,保留包含query字段的行
contents.lines()
.filter(|line| line.contains(query))
.collect()
}
/// # 大小写不敏感查询
/// - query: 需要查询的字段
/// - contents: 需要查询的内容
fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
let query = query.to_lowercase();
contents.lines()
.filter(|line| line.to_lowercase().contains(&query))
.collect()
}
use std::error::Error;
use std::fs;
/// # 运行搜索
/// - config: 包括待查询的字段、待查询的文件、是否大小写敏感
pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
// 读取文件内容,如果读取失败向外返回Err
let contents = fs::read_to_string(config.filename)?;
// 根据case_sensitive参数,决定走那种查询方式
let results = if config.case_sensitive {
search_case_sensitive(&config.query, &contents)
} else {
search_case_insensitive(&config.query, &contents)
};
// 打印查询结果
for line in results {
println!("---> {}", line);
}
Ok(())
}
2. 测试
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn case_sensitive() {
let query = "duct";
let contents = "\
Rust:
safe, fast, productive.
Pick three.";
assert_eq!(vec!["safe, fast, productive."], search_case_sensitive(query, contents));
}
#[test]
fn case_insensitive() {
let query = "rUsT";
let contents = "\
Rust:
safe, fast, productive.
Pick three.
Trust me.";
assert_eq!(vec!["Rust:", "Trust me."], search_case_insensitive(query, contents));
}
}