Macro url

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

A compile-time URL validation macro.

This macro takes a string literal representing a URL and validates it at compile-time. If the URL is valid, it generates the code to create a url::Url object. If the URL is invalid, it produces a compile-time error with a descriptive message.

Usage

use url_macro::url;

let valid_url = url!("https://www.example.com");
let another_valid_url = url!("http://localhost:8080/path?query=value");

// The following would cause a compile-time error:
// let invalid_url = url!("not a valid url");

Features

• Validates URLs at compile-time, preventing runtime errors from malformed URLs.
• Provides early error detection in the development process.
• Automatically converts valid URL strings into url::Url objects.
• Preserves the original span information for precise error reporting.

Limitations

• The macro only accepts string literals. Variables or expressions that evaluate to strings at runtime cannot be used with this macro.
• The macro doesn’t work in const context.

Dependencies

This macro relies on the url crate for URL parsing and validation. Ensure that your project includes this dependency.

Performance

Since the URL validation occurs at compile-time, there is no runtime performance cost associated with using this macro beyond the cost of creating a url::Url object.

Examples

Basic usage:

use url_macro::url;

let github_url = url!("https://github.com");
assert_eq!(github_url.scheme(), "https");
assert_eq!(github_url.host_str(), Some("github.com"));

let complex_url = url!("https://user:pass@example.com:8080/path/to/resource?query=value#fragment");
assert_eq!(complex_url.username(), "user");
assert_eq!(complex_url.path(), "/path/to/resource");

Compile-time error example:

use url_macro::url;

let invalid_url = url!("ftp://invalid url with spaces");
// This will produce a compile-time error

See Also

• The url crate documentation for more information on URL parsing and manipulation.