Rust Project: Minigrep

mini-grep

A simple, grep-like command-line tool written in Rust. It allows you to search for a specific string pattern within a text file.

Initial primary release! Will integrate more functions and capabilities in the future.

Features

• Search for a text pattern in a specified file.
• Case-sensitive search by default.
• Case-insensitive search can be enabled via an environment variable.

Usage

To use mini-grep, you need to provide two arguments: a search pattern and the path to the file you want to search in.

Basic Search (Case-Sensitive)

To perform a case-sensitive search, run the program with the following command structure:

cargo run -- <pattern> <file_path>

Example:

cargo run -- "hello" poem.txt

This command will search for the exact word “hello” in the poem.txt file and print any lines that contain it.

Case-Insensitive Search

You can perform a case-insensitive search by setting the IGNORE_CASE environment variable before running the command.

On Linux/macOS:

IGNORE_CASE=1 cargo run -- <pattern> <file_path>

On Windows (PowerShell):

$env:IGNORE_CASE=1; cargo run -- <pattern> <file_path>

Example:

IGNORE_CASE=1 cargo run -- "rUsT" poem.txt

This command will search for “rUsT” (and “rust”, “Rust”, “RUST”, etc.) in poem.txt and print all matching lines, regardless of their casing.

Todo List

• feat: add iterator for function programming
• Add recursive search for folders
• Add Regex search
• Add fuzzy search

Code

Just as a toy implementation… Still needs to be improved.

// main.rs
\use mini_grep::{Config, run};
use std::{env, process};

fn main() {
    let config = Config::build(env::args()).unwrap_or_else(|err| {
        eprintln!("Problem parsing arguments: {err}");
        process::exit(1);
    });
    println!("Searching for \"{}\" in file {}...", config.query, config.file_path);

    if let Err(e) = run(config) {
        eprintln!("Application error: {e}");
        process::exit(1);
    }
}

// lib.rs
use std::error::Error;
use std::{env, fs};
pub struct Config {
    pub query: String,
    pub file_path: String,
    pub ignore_case: bool,
}
impl Config {
    pub fn build(mut args: impl Iterator<Item = String>) -> Result<Config, &'static str> {
        args.next();
        let query = match args.next() {
            Some(arg) => arg,
            None => return Err("Didn't get a query string"),
        };
        let file_path = match args.next() {
            Some(arg) => arg,
            None => return Err("Didn't get a file path"),
        };
        let ignore_case = env::var("IGNORE_CASE").is_ok();
        Ok(Config {
            query,
            file_path,
            ignore_case,
        })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents =
        fs::read_to_string(config.file_path).expect("Should have been able to read the file");
    let results = if config.ignore_case {
        search_case_insensitive(&config.query, &contents)
    } else {
        search(&config.query, &contents)
    };

    for line in results {
        println!("{line}");
    }
    Ok(())
}

// public core function: search for minigrep
pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents
        .lines()
        .filter(|line| line.contains(&query))
        .collect()
}

// public core function: search while case sensitive
pub 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()
}

// test module
#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn one_result() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.";
        assert_eq!(vec!["safe, fast, productive."], search(query, contents));
    }

    #[test]
    fn case_sensitive() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Duct tape.";
        assert_eq!(vec!["safe, fast, productive."], search(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)
        );
    }
}