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use json::{json_minifier::JsonMinifier, read::byte_to_char::{ByteToChar, CharsError}}; use std::{fmt, io::{Error, ErrorKind, Read}, vec::IntoIter}; pub struct JsonRead<P, R> { minifier: JsonMinifier, read: Option<R>, iter: Option<ByteToChar<R>>, predicate: P, initialized: bool, item_iter: Option<IntoIter<u8>>, item1: Option<char>, } impl<P, R: Read> JsonRead<P, R> { #[inline] pub fn new(read: R, predicate: P) -> Self { JsonRead { minifier: JsonMinifier::default(), read: Some(read), iter: None, predicate, initialized: false, item_iter: None, item1: None, } } fn get_next(&mut self) -> Result<Option<char>, CharsError> { match self.iter.as_mut().unwrap().next() { None => Ok(None), Some(item) => match item { Ok(item) => Ok(Some(item)), Err(err) => Err(err) } } } fn add_char_to_buffer(&mut self, buf: &mut [u8], buf_pos: &mut usize) { if let Some(ref mut iter) = self.item_iter { while *buf_pos < buf.len() { if let Some(byte) = iter.next() { buf[*buf_pos] = byte; *buf_pos += 1; } else { break; } } } } } impl<P, R: Read + fmt::Debug> fmt::Debug for JsonRead<P, R> { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { f.debug_struct("Filter") .field("iter", &self.iter) .field("initialized", &self.initialized) .finish() } } impl<P, R> Read for JsonRead<P, R> where R: Read, P: FnMut( &mut JsonMinifier, &char, Option<&char>, ) -> bool, { fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error> { let mut buf_pos: usize = 0; if buf.is_empty() { return Ok(0); } if !self.initialized { self.iter = Some(ByteToChar::new(self.read.take().unwrap(), buf.len())?); self.item1 = self.get_next()?; self.initialized = true; } while let Some(item) = self.item1.take() { self.item1 = self.get_next()?; if (self.predicate)( &mut self.minifier, &item, self.item1.as_ref(), ) { self.item_iter = Some(item.to_string().into_bytes().into_iter()); self.add_char_to_buffer(buf, &mut buf_pos); } if buf_pos >= buf.len() { break; } } Ok(buf_pos) } } impl From<CharsError> for Error { fn from(_: CharsError) -> Self { Error::from(ErrorKind::InvalidData) } }