filigree 0.4.1

Filigree web application framework
Documentation 
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//! Helpers for parsing configuration

use std::env::VarError;

/// Get an environment variable with an optional prefix
pub fn prefixed_env_var(prefix: &str, key: &str) -> Result<String, VarError> {
    if prefix.is_empty() {
        std::env::var(key)
    } else {
        std::env::var(format!("{prefix}{key}"))
    }
}

/// Parse an `Option<String>`, returning an error if the value is present and fails to parse to the expected type.
pub fn parse_option<T: std::str::FromStr>(value: Option<String>) -> Result<Option<T>, T::Err> {
    match value {
        Some(v) => Ok(Some(v.parse()?)),
        None => Ok(None),
    }
}

/// Set `dest` to the value of `src`, if src is Some
pub fn merge_option_if_set<T>(dest: &mut Option<T>, src: Option<T>) {
    if src.is_some() {
        *dest = src;
    }
}