improve long fmt ser

src/serde.rs

@@ -13,7 +13,7 @@ mod io_writer {
  use crate::serde::ser;
 
  /// Serializes a value to a writer.
- pub fn to_writer<W, T>(writer: &mut W, value: &T)
+ pub fn to_writer<W, T>(writer: W, value: &T)
  -> Result<(), EncodeError<io::Error>>
  where
  W: io::Write,

src/serde/ser.rs

@@ -472,26 +472,35 @@ impl<W: enc::Write> fmt::Write for FmtWriter<'_, W> {
  }
 
  match self.state {
- State::Short => {
- if self.buf.len() - self.pos >= input.len() {
- self.buf[self.pos..][..input.len()]
- .copy_from_slice(input.as_bytes());
- self.pos += input.len();
- } else {
- self.state = State::Segment;
- try_!(types::UncheckedStr::unbounded(self.inner));
- try_!(types::UncheckedStr(&self.buf[..self.pos]).encode(self.inner));
- try_!(input.encode(self.inner));
- }
-
- Ok(())
+ State::Short => if self.pos + input.len() > self.buf.len() {
+ self.state = State::Segment;
+ try_!(types::UncheckedStr::unbounded(self.inner));
  },
- State::Segment => {
+ State::Segment => (),
+ State::Error(_) => return Err(fmt::Error)
+ }
+
+ loop {
+ if let Some(buf) = self.buf.get_mut(self.pos..)
+ .and_then(|buf| buf.get_mut(..input.len()))
+ {
+ buf.copy_from_slice(input.as_bytes());
+ self.pos += input.len();
+ break
+ }
+
+ if self.pos > 0 {
+ try_!(types::UncheckedStr(&self.buf[..self.pos]).encode(self.inner));
+ self.pos = 0;
+ }
+
+ if input.len() > self.buf.len() {
  try_!(input.encode(self.inner));
- Ok(())
- },
- State::Error(_) => Err(fmt::Error)
+ break
+ }
  }
+
+ Ok(())
  }
 }
 
@@ -513,9 +522,18 @@ impl<W: enc::Write> FmtWriter<'_, W> {
  #[inline]
  fn flush(self) -> Result<(), enc::Error<W::Error>> {
  match self.state {
- State::Short => types::UncheckedStr(&self.buf[..self.pos]).encode(self.inner),
- State::Segment => types::UncheckedStr::end(self.inner),
- State::Error(err) => Err(err)
+ State::Short | State::Segment => {
+ if matches!(self.state, State::Short) || self.pos != 0 {
+ types::UncheckedStr(&self.buf[..self.pos]).encode(self.inner)?;
+ }
+
+ if matches!(self.state, State::Segment) {
+ types::UncheckedStr::end(self.inner)?;
+ }
+
+ Ok(())
+ },
+ State::Error(err) => Err(err),
  }
  }
 }