Function parse_optional_value

alpm-srcinfo/src/pkgbuild_bridge/mod.rs:155–169

Ensures a combination of [`Keyword`] and [`Value`] uses a [`Value::Single`] and parses the value as a specific, but optional type. Returns [`None`] if `value` is **empty**. # Errors Returns a error for `keyword` if `value` is not [`Value::Single`] or cannot be parsed as the specific type.

(
    keyword: &Keyword,
    value: &'a Value,
    mut parser: P,
)

///
/// Returns a error for `keyword` if `value` is not [`Value::Single`] or cannot be parsed as the
/// specific type.
fn parse_optional_value<'a, O, P: Parser<&'a str, O, ErrMode<ContextError>>>(
    keyword: &Keyword,
    value: &'a Value,
    mut parser: P,
) -> Result<Option<O>, BridgeError> {
    let input = ensure_single_value(keyword, value)?;

    if input.trim().is_empty() {
        return Ok(None);
    }

    Ok(Some(
        parser.parse(input).map_err(|err| (keyword.clone(), err))?,
    ))
}

/// Parses a [`Value`] as a [`Vec`] of specific types.