t2_bus 0.1.0

An inter- or intra-process message bus supporting publish/subscribe and request/response.
Documentation 
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use crate::err::*;
use regex::Regex;

pub(crate) const WILDCARD: &str = "*";
pub(crate) const DOUBLE_WILDCARD: &str = "**";

lazy_static! {
    static ref RGX_TOPIC: Regex =
        Regex::new(r"^(([a-z0-9_]+|\*|\*\*)/)*([a-z0-9_]+|\*|\*\*)$").unwrap();
}

#[test]
fn test_rgx_topic() {
    assert!(RGX_TOPIC.is_match("a"));
    assert!(RGX_TOPIC.is_match("abc"));
    assert!(RGX_TOPIC.is_match("0"));
    assert!(RGX_TOPIC.is_match("a0"));
    assert!(RGX_TOPIC.is_match("0a"));
    assert!(RGX_TOPIC.is_match("*"));
    assert!(RGX_TOPIC.is_match("**"));

    assert!(!RGX_TOPIC.is_match("a/"));
    assert!(!RGX_TOPIC.is_match("0/"));
    assert!(!RGX_TOPIC.is_match("*/"));
    assert!(!RGX_TOPIC.is_match("**/"));

    assert!(RGX_TOPIC.is_match("a/b"));
    assert!(RGX_TOPIC.is_match("0/b"));
    assert!(RGX_TOPIC.is_match("a/0"));
    assert!(RGX_TOPIC.is_match("ab/b"));
    assert!(RGX_TOPIC.is_match("a/ba"));
    assert!(RGX_TOPIC.is_match("**/b"));
    assert!(RGX_TOPIC.is_match("*/b"));
    assert!(RGX_TOPIC.is_match("a/*"));
    assert!(RGX_TOPIC.is_match("a/**"));
    assert!(RGX_TOPIC.is_match("**/*"));
    assert!(RGX_TOPIC.is_match("*/**"));

    assert!(RGX_TOPIC.is_match("1/2"));
    assert!(RGX_TOPIC.is_match("a_1/2_a_"));
    assert!(RGX_TOPIC.is_match("1_/_2"));
}

pub(crate) fn parse_topic(topic_str: &str) -> BusResult<Vec<&str>> {
    if !RGX_TOPIC.is_match(topic_str) {
        return Err(BusError::InvalidTopicString(format!("Invalid topic string: {topic_str}")));
    }

    Ok(topic_str.split('/').collect::<Vec<&str>>())
}

// pub fn get_protocol(topic_str: &str) -> BusResult<&str> {
//     Ok(parse_topic(topic_str)?[0])
// }

pub fn prefix_topic(prefix: &str, topic: &str) -> String {
    match topic {
        "" => prefix.to_string(),
        _ => format!("{prefix}/{topic}"),
    }
}

// pub fn unprefix_topic(topic: &str) -> String {
//     let index_of_first_slash = topic.match_indices('/').next().unwrap().0;
//     topic[index_of_first_slash + 1..].to_string()
// }

// #[test]
// fn test_unprefix_topic() {
//     assert_eq!("a/b/c", &unprefix_topic("prefix/a/b/c"))
// }