use std::{char, cmp, io, str};
use serde::iter::LineColIterator;
use super::error::{Error, ErrorCode, Result};
pub trait Read {
fn next(&mut self) -> io::Result<Option<u8>>;
fn peek(&mut self) -> io::Result<Option<u8>>;
fn discard(&mut self);
fn position(&self) -> Position;
fn peek_position(&self) -> Position;
fn parse_str<'s>(
&'s mut self,
scratch: &'s mut Vec<u8>
) -> Result<&'s str>;
}
pub struct Position {
pub line: usize,
pub column: usize,
}
pub struct IteratorRead<Iter>
where Iter: Iterator<Item = io::Result<u8>>,
{
iter: LineColIterator<Iter>,
ch: Option<u8>,
}
pub struct SliceRead<'a> {
slice: &'a [u8],
index: usize,
}
pub struct StrRead<'a> {
delegate: SliceRead<'a>,
}
impl<Iter> IteratorRead<Iter>
where Iter: Iterator<Item = io::Result<u8>>,
{
pub fn new(iter: Iter) -> Self {
IteratorRead {
iter: LineColIterator::new(iter),
ch: None,
}
}
}
impl<Iter> Read for IteratorRead<Iter>
where Iter: Iterator<Item = io::Result<u8>>,
{
#[inline]
fn next(&mut self) -> io::Result<Option<u8>> {
match self.ch.take() {
Some(ch) => Ok(Some(ch)),
None => {
match self.iter.next() {
Some(Err(err)) => Err(err),
Some(Ok(ch)) => Ok(Some(ch)),
None => Ok(None),
}
}
}
}
#[inline]
fn peek(&mut self) -> io::Result<Option<u8>> {
match self.ch {
Some(ch) => Ok(Some(ch)),
None => {
match self.iter.next() {
Some(Err(err)) => Err(err),
Some(Ok(ch)) => {
self.ch = Some(ch);
Ok(self.ch)
}
None => Ok(None),
}
}
}
}
#[inline]
fn discard(&mut self) {
self.ch = None;
}
fn position(&self) -> Position {
Position {
line: self.iter.line(),
column: self.iter.col(),
}
}
fn peek_position(&self) -> Position {
self.position()
}
fn parse_str<'s>(
&'s mut self,
scratch: &'s mut Vec<u8>
) -> Result<&'s str> {
loop {
let ch = match try!(self.next()) {
Some(ch) => ch,
None => {
return error(self, ErrorCode::EOFWhileParsingString);
}
};
if !ESCAPE[ch as usize] {
scratch.push(ch);
continue;
}
match ch {
b'"' => {
return as_str(self, scratch);
}
b'\\' => {
try!(parse_escape(self, scratch));
}
_ => {
return error(self, ErrorCode::InvalidUnicodeCodePoint);
}
}
}
}
}
impl<'a> SliceRead<'a> {
pub fn new(slice: &'a [u8]) -> Self {
SliceRead {
slice: slice,
index: 0,
}
}
fn position_of_index(&self, i: usize) -> Position {
let mut pos = Position {
line: 1,
column: 0,
};
for ch in &self.slice[..i] {
match *ch {
b'\n' => {
pos.line += 1;
pos.column = 0;
}
_ => {
pos.column += 1;
}
}
}
pos
}
fn parse_str_bytes<'s, T, F>(
&'s mut self,
scratch: &'s mut Vec<u8>,
result: F
) -> Result<T>
where T: 's,
F: FnOnce(&'s Self, &'s [u8]) -> Result<T>,
{
let mut start = self.index;
loop {
while self.index < self.slice.len() &&
!ESCAPE[self.slice[self.index] as usize] {
self.index += 1;
}
if self.index == self.slice.len() {
return error(self, ErrorCode::EOFWhileParsingString);
}
match self.slice[self.index] {
b'"' => {
let string = if scratch.is_empty() {
&self.slice[start..self.index]
} else {
scratch.extend_from_slice(&self.slice[start .. self.index]);
scratch as &[u8]
};
self.index += 1;
return result(self, string);
}
b'\\' => {
scratch.extend_from_slice(&self.slice[start..self.index]);
self.index += 1;
try!(parse_escape(self, scratch));
start = self.index;
}
_ => {
return error(self, ErrorCode::InvalidUnicodeCodePoint);
}
}
}
}
}
impl<'a> Read for SliceRead<'a> {
#[inline]
fn next(&mut self) -> io::Result<Option<u8>> {
Ok(if self.index < self.slice.len() {
let ch = self.slice[self.index];
self.index += 1;
Some(ch)
} else {
None
})
}
#[inline]
fn peek(&mut self) -> io::Result<Option<u8>> {
Ok(if self.index < self.slice.len() {
Some(self.slice[self.index])
} else {
None
})
}
#[inline]
fn discard(&mut self) {
self.index += 1;
}
fn position(&self) -> Position {
self.position_of_index(self.index)
}
fn peek_position(&self) -> Position {
self.position_of_index(cmp::min(self.slice.len(), self.index + 1))
}
fn parse_str<'s>(
&'s mut self,
scratch: &'s mut Vec<u8>
) -> Result<&'s str> {
self.parse_str_bytes(scratch, as_str)
}
}
impl<'a> StrRead<'a> {
pub fn new(s: &'a str) -> Self {
StrRead {
delegate: SliceRead::new(s.as_bytes()),
}
}
}
impl<'a> Read for StrRead<'a> {
#[inline]
fn next(&mut self) -> io::Result<Option<u8>> {
self.delegate.next()
}
#[inline]
fn peek(&mut self) -> io::Result<Option<u8>> {
self.delegate.peek()
}
#[inline]
fn discard(&mut self) {
self.delegate.discard();
}
fn position(&self) -> Position {
self.delegate.position()
}
fn peek_position(&self) -> Position {
self.delegate.peek_position()
}
fn parse_str<'s>(
&'s mut self,
scratch: &'s mut Vec<u8>
) -> Result<&'s str> {
self.delegate.parse_str_bytes(scratch, |_, bytes| {
Ok(unsafe { str::from_utf8_unchecked(bytes) })
})
}
}
const CT: bool = true; const QU: bool = true; const BS: bool = true; const O: bool = false;
#[cfg_attr(rustfmt, rustfmt_skip)]
static ESCAPE: [bool; 256] = [
CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, O, O, QU, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, BS, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, ];
fn error<R: Read, T>(read: &R, reason: ErrorCode) -> Result<T> {
let pos = read.position();
Err(Error::syntax(reason, pos.line, pos.column))
}
fn as_str<'s, R: Read>(read: &R, slice: &'s [u8]) -> Result<&'s str> {
str::from_utf8(slice)
.or_else(|_| error(read, ErrorCode::InvalidUnicodeCodePoint))
}
fn parse_escape<R: Read>(read: &mut R, scratch: &mut Vec<u8>) -> Result<()> {
let ch = match try!(read.next()) {
Some(ch) => ch,
None => {
return error(read, ErrorCode::EOFWhileParsingString);
}
};
match ch {
b'"' => scratch.push(b'"'),
b'\\' => scratch.push(b'\\'),
b'/' => scratch.push(b'/'),
b'b' => scratch.push(b'\x08'),
b'f' => scratch.push(b'\x0c'),
b'n' => scratch.push(b'\n'),
b'r' => scratch.push(b'\r'),
b't' => scratch.push(b'\t'),
b'u' => {
let c =
match try!(decode_hex_escape(read)) {
0xDC00...0xDFFF => {
return error(read, ErrorCode::LoneLeadingSurrogateInHexEscape);
}
n1 @ 0xD800...0xDBFF => {
match (try!(read.next()),
try!(read.next())) {
(Some(b'\\'), Some(b'u')) => (),
_ => {
return error(read, ErrorCode::UnexpectedEndOfHexEscape);
}
}
let n2 = try!(decode_hex_escape(read));
if n2 < 0xDC00 || n2 > 0xDFFF {
return error(read, ErrorCode::LoneLeadingSurrogateInHexEscape);
}
let n = (((n1 - 0xD800) as u32) << 10 |
(n2 - 0xDC00) as u32) +
0x1_0000;
match char::from_u32(n as u32) {
Some(c) => c,
None => {
return error(read, ErrorCode::InvalidUnicodeCodePoint);
}
}
}
n => {
match char::from_u32(n as u32) {
Some(c) => c,
None => {
return error(read, ErrorCode::InvalidUnicodeCodePoint);
}
}
}
};
let mut buf = String::new();
buf.push(c);
scratch.extend(buf.bytes());
}
_ => {
return error(read, ErrorCode::InvalidEscape);
}
}
Ok(())
}
fn decode_hex_escape<R: Read>(read: &mut R) -> Result<u16> {
let mut i = 0;
let mut n = 0;
while i < 4 && try!(read.peek()).is_some() {
n = match try!(read.next()).unwrap_or(b'\x00') {
c @ b'0'...b'9' => n * 16_u16 + ((c as u16) - (b'0' as u16)),
b'a' | b'A' => n * 16_u16 + 10_u16,
b'b' | b'B' => n * 16_u16 + 11_u16,
b'c' | b'C' => n * 16_u16 + 12_u16,
b'd' | b'D' => n * 16_u16 + 13_u16,
b'e' | b'E' => n * 16_u16 + 14_u16,
b'f' | b'F' => n * 16_u16 + 15_u16,
_ => {
return error(read, ErrorCode::InvalidEscape);
}
};
i += 1;
}
if i != 4 {
return error(read, ErrorCode::InvalidEscape);
}
Ok(n)
}