Parser Capstone

Command Parser

Convert Text into an Enum

A parser can turn raw command text into an enum so later code handles typed cases instead of strings.

Program

Play the program to choose a command string and route the parsed enum.

command_enum_parser.rs 
enum Command {
    Add(String),
    Done(String),
    Unknown,
}

fn main() {
    let input = ;
    let command = parse_command(input);
    let message = describe(command);
    println!("{message}");
}

fn parse_command(input: &str) -> Command {
    match input.split_once(':') {
        Some(("add", value)) => Command::Add(value.to_string()),
        Some(("done", value)) => Command::Done(value.to_string()),
        _ => Command::Unknown,
    }
}

fn describe(command: Command) -> String {
    match command {
        Command::Add(value) => format!("add:{value}"),
        Command::Done(value) => format!("done:{value}"),
        Command::Unknown => "unknown".to_string(),
    }
}

enum Command {
    Add(String),
    Done(String),
    Unknown,
}

fn main() {
    let input = ;
    let command = parse_command(input);
    let message = describe(command);
    println!("{message}");
}

fn parse_command(input: &str) -> Command {
    match input.split_once(':') {
        Some(("add", value)) => Command::Add(value.to_string()),
        Some(("done", value)) => Command::Done(value.to_string()),
        _ => Command::Unknown,
    }
}

fn describe(command: Command) -> String {
    match command {
        Command::Add(value) => format!("add:{value}"),
        Command::Done(value) => format!("done:{value}"),
        Command::Unknown => "unknown".to_string(),
    }
}

enum Command {
    Add(String),
    Done(String),
    Unknown,
}

fn main() {
    let input = ;
    let command = parse_command(input);
    let message = describe(command);
    println!("{message}");
}

fn parse_command(input: &str) -> Command {
    match input.split_once(':') {
        Some(("add", value)) => Command::Add(value.to_string()),
        Some(("done", value)) => Command::Done(value.to_string()),
        _ => Command::Unknown,
    }
}

fn describe(command: Command) -> String {
    match command {
        Command::Add(value) => format!("add:{value}"),
        Command::Done(value) => format!("done:{value}"),
        Command::Unknown => "unknown".to_string(),
    }
}
enum parser `parse_command` converts raw text into a typed `Command` value.
payload `Add` and `Done` carry the parsed task name as owned `String` data.
routing `describe` matches the enum instead of reparsing the original string.