use encoding_rs::{DecoderResult, UTF_8}; pub fn validate<I: Iterator<Item = u8>>(iter: I) -> bool { let mut decoder = UTF_8.new_decoder(); let mut dest = [0; 4]; for b in iter { let (status, _, _) = decoder.decode_to_utf8_without_replacement(&[b], &mut dest, false); if !valid_result(status) { return false; } } let (status, _, _) = decoder.decode_to_utf8_without_replacement(&[], &mut dest, true); valid_result(status) } fn valid_result(result: DecoderResult) -> bool { match result { DecoderResult::InputEmpty => true, DecoderResult::OutputFull => unreachable!(), DecoderResult::Malformed(_, _) => false, } } #[cfg(test)] mod tests { use super::*; #[test] fn validate_valid() { let valid = b"I am valid\xf0\x90\x8c\xbc"; assert!(validate(valid.iter().cloned())); } #[test] fn validate_invalid() { let invalid = b"I am invalid\xc3\x28"; assert!(!validate(invalid.iter().cloned())); } }