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use jetscii::ByteSubstring;
use std::io::{self, Write};
lazy_static! {
static ref OPEN: ByteSubstring<'static> = ByteSubstring::new(b"<p");
static ref CLOSE: ByteSubstring<'static> = ByteSubstring::new(b"</p>");
}
const OPEN_LEN: usize = 2;
const CLOSE_LEN: usize = 4;
pub struct ParagraphPasser<'w> {
out: &'w mut dyn Write,
paras_left: usize,
depth: usize,
has_ended: bool,
}
impl<'w> ParagraphPasser<'w> {
pub fn new(into: &'w mut dyn Write, count: usize) -> ParagraphPasser<'w> {
ParagraphPasser {
out: into,
paras_left: count,
depth: 0,
has_ended: false,
}
}
fn close_para(&mut self, buf: &mut &[u8], past_end_idx: usize) -> io::Result<()> {
self.out.write_all(&buf[..past_end_idx])?;
*buf = &buf[past_end_idx..];
if self.depth == 1 {
self.paras_left -= 1;
}
self.depth -= 1;
Ok(())
}
}
impl<'w> Write for ParagraphPasser<'w> {
fn write(&mut self, mut buf: &[u8]) -> io::Result<usize> {
let mut full_len = buf.len();
if !self.has_ended {
if buf.ends_with(b"</p") {
full_len -= 3;
} else if buf.ends_with(b"</") || buf.ends_with(b"<p") {
full_len -= 2;
} else if buf.ends_with(b"<") {
full_len -= 1;
}
buf = &buf[..full_len];
let mut open_idx = OPEN.find(buf);
let mut close_idx = CLOSE.find(buf);
while !self.has_ended && !buf.is_empty() {
match (open_idx.take(), close_idx.take(), self.paras_left == 0) {
(Some(oi), Some(_), true) |
(Some(oi), None, true) => {
self.out.write_all(&buf[..oi])?;
self.has_ended = true;
}
(Some(oi), Some(ci), false) => {
if oi < ci {
self.depth += 1;
let mut toi = oi;
while let Some(mut next_oi) = OPEN.find(&buf[toi + OPEN_LEN..]) {
next_oi += toi + OPEN_LEN;
if next_oi < ci {
self.depth += 1;
} else {
break;
}
toi = next_oi;
}
}
let past_end = ci + CLOSE_LEN;
self.close_para(&mut buf, past_end)?;
if oi < ci {
open_idx = OPEN.find(buf);
} else {
open_idx = Some(oi - past_end);
}
close_idx = CLOSE.find(buf);
}
(Some(_), None, false) => {
self.out.write_all(buf)?;
self.depth += 1;
buf = &buf[..0];
}
(None, Some(ci), _) => {
let past_end = ci + CLOSE_LEN;
self.close_para(&mut buf, past_end)?;
close_idx = CLOSE.find(buf);
}
(None, None, _) => {
self.out.write_all(buf)?;
buf = &buf[..0];
}
}
}
}
return Ok(full_len);
}
fn flush(&mut self) -> io::Result<()> {
self.out.flush()
}
}