envsubst

A simple Rust library for variables substitution.

This library provide helper functions for string manipulation, taking values from a context environment map and substituting all matching placeholders.

Its name and logic is similar to the envsubst GNU utility, but this only supports braces-delimited variables (i.e. ${foo}) and takes replacement values from an explicit map of variables.

License

Licensed under either of

• MIT license - http://opensource.org/licenses/MIT
• Apache License, Version 2.0 - http://www.apache.org/licenses/LICENSE-2.0

at your option.

lib.rs:

Variables substitution in string templates.

This library provide helper functions for string manipulation, taking values from a context environment map and substituting all matching placeholders.

Its name and logic is similar to the envsubst GNU utility, but this only supports braces-delimited variables (i.e. ${foo}) and takes replacement values from an explicit map of variables.

Example

let base_url = "${protocol}://${hostname}/${endpoint}";
assert!(envsubst::is_templated(base_url));

let mut context = std::collections::HashMap::new();
context.insert("protocol".to_string(), "https".to_string());
context.insert("hostname".to_string(), "example.com".to_string());
context.insert("endpoint".to_string(), "login".to_string());
assert!(envsubst::validate_vars(&context).is_ok());

let final_url = envsubst::substitute(base_url, &context).unwrap();
assert!(!envsubst::is_templated(&final_url));
assert_eq!(final_url, "https://example.com/login");