Macro path_scan 

path_scan!() { /* proc-macro */ }

path_scan! macro parses an input string using the provided patterns and returns a closure that yields the result of the first matching arm.

Patterns are specified as follows:

• "pattern string" => expression In the pattern string, placeholders like :identifier and {identifier} are captured and become available as variables.

• Multiple patterns can be combined using "pattern1" | "pattern2" => expression.

• An optional if condition may follow the pattern(s) (e.g., "pattern" if condition => expression). The arm is considered a match only if the condition evaluates to true.

• The default arm is specified as _ => expression.

Note: If an if-less default arm is not provided—that is, if a default arm without an if condition is missing— the closure returns None on failure, making the overall expression type Option<T>.

Examples

use path_scan::path_scan;

// With a default arm, the return type is a concrete type (e.g., String)
let scanner = path_scan! {
    "blog/:slug/index" => format!("blog: {}", slug),
    "other/:slug" if slug.len() == 5 => format!("short blog: {}", slug),
    _ => format!("default")
};

assert_eq!(scanner("blog/hello/index"), "blog: hello");
assert_eq!(scanner("other/short"), "short blog: short");
assert_eq!(scanner("unknown/path"), "default");

// Without a default arm, the return type is `Option<String>`
let scanner_opt = path_scan! {
    "blog/:slug/index" => format!("blog: {}", slug)
};

assert_eq!(scanner_opt("blog/world/index"), Some("blog: world".to_string()));
assert_eq!(scanner_opt("unknown/path"), None);