Function extract_env 

pub fn extract_env(
    file_path: &Path,
) -> TreeResult<(BTreeMap<String, String>, Vec<PathBuf>)>

Extracts environment variables and the parent path from a specified file.

This function reads the given file_path to:

1. Identify and extract environment variables specified using the export keyword.
2. Identify any parent environment file via the special # rsenv: comment. parent’s path can be relative to the child’s path.

The current working directory is temporarily changed to the directory of the file_path during the extraction process to construct correct parent paths. It is restored afterward.

Arguments

• file_path - A string slice representing the path to the .env file. The function will attempt to canonicalize this path.

Returns

A Result containing:

• A tuple with:
  • A BTreeMap with the key as the variable name and the value as its corresponding value.
  • An Option containing a Utf8PathBuf pointing to the parent env file, if specified.
• An error if there’s any problem reading the file, extracting the variables, or if the path is invalid.

Errors

This function will return an error in the following situations:

• The provided file_path is invalid.
• There’s an issue reading or processing the env file.
• The parent path specified in # rsenv: is invalid or not specified properly.