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//! Parsing utilities.  Format-specific parsing is in various other modules.
use std::error::Error as StdError;
use std::str::FromStr;

use anyhow::{anyhow, Result};

pub mod bindata;
pub mod dates;
#[cfg(test)]
mod test_dates;

pub use bindata::decode_hex_i64_pair;

/// Trim a string, and convert to None if it is empty.
pub fn trim_opt<'a>(s: &'a str) -> Option<&'a str> {
    let s2 = s.trim();
    if s2.is_empty() {
        None
    } else {
        Some(s2)
    }
}

/// Trim a string, and convert to None if it is empty.
pub fn trim_owned(s: &str) -> Option<String> {
    return trim_opt(s).map(|s| s.to_owned());
}

/// Parse a possibly-empty string into an option.
pub fn parse_opt<T: FromStr>(s: &str) -> Result<Option<T>>
where
    T::Err: StdError + Sync + Send + 'static,
{
    let so = trim_opt(s);
    // we can't just use map because we need to propagate errors
    Ok(match so {
        None => None,
        Some(s) => Some(match s.parse() {
            Ok(v) => v,
            Err(e) => return Err(anyhow!("error parsing ‘{}’: {}", s, e)),
        }),
    })
}