use crate::fallback::{
is_ident_continue, is_ident_start, Group, LexError, Literal, Span, TokenStream,
};
use crate::{Delimiter, Punct, Spacing, TokenTree};
use std::char;
use std::str::{Bytes, CharIndices, Chars};
#[derive(Copy, Clone, Eq, PartialEq)]
pub(crate) struct Cursor<'a> {
pub rest: &'a str,
#[cfg(span_locations)]
pub off: u32,
}
impl<'a> Cursor<'a> {
fn advance(&self, bytes: usize) -> Cursor<'a> {
let (_front, rest) = self.rest.split_at(bytes);
Cursor {
rest,
#[cfg(span_locations)]
off: self.off + _front.chars().count() as u32,
}
}
fn starts_with(&self, s: &str) -> bool {
self.rest.starts_with(s)
}
fn is_empty(&self) -> bool {
self.rest.is_empty()
}
fn len(&self) -> usize {
self.rest.len()
}
fn as_bytes(&self) -> &'a [u8] {
self.rest.as_bytes()
}
fn bytes(&self) -> Bytes<'a> {
self.rest.bytes()
}
fn chars(&self) -> Chars<'a> {
self.rest.chars()
}
fn char_indices(&self) -> CharIndices<'a> {
self.rest.char_indices()
}
fn parse(&self, tag: &str) -> Result<Cursor<'a>, Reject> {
if self.starts_with(tag) {
Ok(self.advance(tag.len()))
} else {
Err(Reject)
}
}
}
pub(crate) struct Reject;
type PResult<'a, O> = Result<(Cursor<'a>, O), Reject>;
fn skip_whitespace(input: Cursor) -> Cursor {
let mut s = input;
while !s.is_empty() {
let byte = s.as_bytes()[0];
if byte == b'/' {
if s.starts_with("//")
&& (!s.starts_with("///") || s.starts_with("////"))
&& !s.starts_with("//!")
{
let (cursor, _) = take_until_newline_or_eof(s);
s = cursor;
continue;
} else if s.starts_with("/**/") {
s = s.advance(4);
continue;
} else if s.starts_with("/*")
&& (!s.starts_with("/**") || s.starts_with("/***"))
&& !s.starts_with("/*!")
{
match block_comment(s) {
Ok((rest, _)) => {
s = rest;
continue;
}
Err(Reject) => return s,
}
}
}
match byte {
b' ' | 0x09..=0x0d => {
s = s.advance(1);
continue;
}
b if b <= 0x7f => {}
_ => {
let ch = s.chars().next().unwrap();
if is_whitespace(ch) {
s = s.advance(ch.len_utf8());
continue;
}
}
}
return s;
}
s
}
fn block_comment(input: Cursor) -> PResult<&str> {
if !input.starts_with("/*") {
return Err(Reject);
}
let mut depth = 0;
let bytes = input.as_bytes();
let mut i = 0;
let upper = bytes.len() - 1;
while i < upper {
if bytes[i] == b'/' && bytes[i + 1] == b'*' {
depth += 1;
i += 1; } else if bytes[i] == b'*' && bytes[i + 1] == b'/' {
depth -= 1;
if depth == 0 {
return Ok((input.advance(i + 2), &input.rest[..i + 2]));
}
i += 1; }
i += 1;
}
Err(Reject)
}
fn is_whitespace(ch: char) -> bool {
ch.is_whitespace() || ch == '\u{200e}' || ch == '\u{200f}'
}
fn word_break(input: Cursor) -> Result<Cursor, Reject> {
match input.chars().next() {
Some(ch) if is_ident_continue(ch) => Err(Reject),
Some(_) | None => Ok(input),
}
}
pub(crate) fn token_stream(mut input: Cursor) -> Result<TokenStream, LexError> {
let mut trees = Vec::new();
let mut stack = Vec::new();
loop {
input = skip_whitespace(input);
if let Ok((rest, tt)) = doc_comment(input) {
trees.extend(tt);
input = rest;
continue;
}
#[cfg(span_locations)]
let lo = input.off;
let first = match input.bytes().next() {
Some(first) => first,
None => match stack.last() {
None => return Ok(TokenStream { inner: trees }),
#[cfg(span_locations)]
Some((lo, _frame)) => {
return Err(LexError {
span: Span { lo: *lo, hi: *lo },
})
}
#[cfg(not(span_locations))]
Some(_frame) => return Err(LexError { span: Span {} }),
},
};
if let Some(open_delimiter) = match first {
b'(' => Some(Delimiter::Parenthesis),
b'[' => Some(Delimiter::Bracket),
b'{' => Some(Delimiter::Brace),
_ => None,
} {
input = input.advance(1);
let frame = (open_delimiter, trees);
#[cfg(span_locations)]
let frame = (lo, frame);
stack.push(frame);
trees = Vec::new();
} else if let Some(close_delimiter) = match first {
b')' => Some(Delimiter::Parenthesis),
b']' => Some(Delimiter::Bracket),
b'}' => Some(Delimiter::Brace),
_ => None,
} {
let frame = match stack.pop() {
Some(frame) => frame,
None => return Err(lex_error(input)),
};
#[cfg(span_locations)]
let (lo, frame) = frame;
let (open_delimiter, outer) = frame;
if open_delimiter != close_delimiter {
return Err(lex_error(input));
}
input = input.advance(1);
let mut g = Group::new(open_delimiter, TokenStream { inner: trees });
g.set_span(Span {
#[cfg(span_locations)]
lo,
#[cfg(span_locations)]
hi: input.off,
});
trees = outer;
trees.push(TokenTree::Group(crate::Group::_new_stable(g)));
} else {
let (rest, mut tt) = match leaf_token(input) {
Ok((rest, tt)) => (rest, tt),
Err(Reject) => return Err(lex_error(input)),
};
tt.set_span(crate::Span::_new_stable(Span {
#[cfg(span_locations)]
lo,
#[cfg(span_locations)]
hi: rest.off,
}));
trees.push(tt);
input = rest;
}
}
}
fn lex_error(cursor: Cursor) -> LexError {
#[cfg(not(span_locations))]
let _ = cursor;
LexError {
span: Span {
#[cfg(span_locations)]
lo: cursor.off,
#[cfg(span_locations)]
hi: cursor.off,
},
}
}
fn leaf_token(input: Cursor) -> PResult<TokenTree> {
if let Ok((input, l)) = literal(input) {
Ok((input, TokenTree::Literal(crate::Literal::_new_stable(l))))
} else if let Ok((input, p)) = punct(input) {
Ok((input, TokenTree::Punct(p)))
} else if let Ok((input, i)) = ident(input) {
Ok((input, TokenTree::Ident(i)))
} else {
Err(Reject)
}
}
fn ident(input: Cursor) -> PResult<crate::Ident> {
if ["r\"", "r#\"", "r##", "b\"", "b\'", "br\"", "br#"]
.iter()
.any(|prefix| input.starts_with(prefix))
{
Err(Reject)
} else {
ident_any(input)
}
}
fn ident_any(input: Cursor) -> PResult<crate::Ident> {
let raw = input.starts_with("r#");
let rest = input.advance((raw as usize) << 1);
let (rest, sym) = ident_not_raw(rest)?;
if !raw {
let ident = crate::Ident::new(sym, crate::Span::call_site());
return Ok((rest, ident));
}
if sym == "_" {
return Err(Reject);
}
let ident = crate::Ident::_new_raw(sym, crate::Span::call_site());
Ok((rest, ident))
}
fn ident_not_raw(input: Cursor) -> PResult<&str> {
let mut chars = input.char_indices();
match chars.next() {
Some((_, ch)) if is_ident_start(ch) => {}
_ => return Err(Reject),
}
let mut end = input.len();
for (i, ch) in chars {
if !is_ident_continue(ch) {
end = i;
break;
}
}
Ok((input.advance(end), &input.rest[..end]))
}
pub(crate) fn literal(input: Cursor) -> PResult<Literal> {
let rest = literal_nocapture(input)?;
let end = input.len() - rest.len();
Ok((rest, Literal::_new(input.rest[..end].to_string())))
}
fn literal_nocapture(input: Cursor) -> Result<Cursor, Reject> {
if let Ok(ok) = string(input) {
Ok(ok)
} else if let Ok(ok) = byte_string(input) {
Ok(ok)
} else if let Ok(ok) = byte(input) {
Ok(ok)
} else if let Ok(ok) = character(input) {
Ok(ok)
} else if let Ok(ok) = float(input) {
Ok(ok)
} else if let Ok(ok) = int(input) {
Ok(ok)
} else {
Err(Reject)
}
}
fn literal_suffix(input: Cursor) -> Cursor {
match ident_not_raw(input) {
Ok((input, _)) => input,
Err(Reject) => input,
}
}
fn string(input: Cursor) -> Result<Cursor, Reject> {
if let Ok(input) = input.parse("\"") {
cooked_string(input)
} else if let Ok(input) = input.parse("r") {
raw_string(input)
} else {
Err(Reject)
}
}
fn cooked_string(input: Cursor) -> Result<Cursor, Reject> {
let mut chars = input.char_indices().peekable();
while let Some((i, ch)) = chars.next() {
match ch {
'"' => {
let input = input.advance(i + 1);
return Ok(literal_suffix(input));
}
'\r' => match chars.next() {
Some((_, '\n')) => {}
_ => break,
},
'\\' => match chars.next() {
Some((_, 'x')) => {
if !backslash_x_char(&mut chars) {
break;
}
}
Some((_, 'n')) | Some((_, 'r')) | Some((_, 't')) | Some((_, '\\'))
| Some((_, '\'')) | Some((_, '"')) | Some((_, '0')) => {}
Some((_, 'u')) => {
if !backslash_u(&mut chars) {
break;
}
}
Some((_, ch @ '\n')) | Some((_, ch @ '\r')) => {
let mut last = ch;
loop {
if last == '\r' && chars.next().map_or(true, |(_, ch)| ch != '\n') {
return Err(Reject);
}
match chars.peek() {
Some((_, ch)) if ch.is_whitespace() => {
last = *ch;
chars.next();
}
_ => break,
}
}
}
_ => break,
},
_ch => {}
}
}
Err(Reject)
}
fn byte_string(input: Cursor) -> Result<Cursor, Reject> {
if let Ok(input) = input.parse("b\"") {
cooked_byte_string(input)
} else if let Ok(input) = input.parse("br") {
raw_string(input)
} else {
Err(Reject)
}
}
fn cooked_byte_string(mut input: Cursor) -> Result<Cursor, Reject> {
let mut bytes = input.bytes().enumerate();
while let Some((offset, b)) = bytes.next() {
match b {
b'"' => {
let input = input.advance(offset + 1);
return Ok(literal_suffix(input));
}
b'\r' => match bytes.next() {
Some((_, b'\n')) => {}
_ => break,
},
b'\\' => match bytes.next() {
Some((_, b'x')) => {
if !backslash_x_byte(&mut bytes) {
break;
}
}
Some((_, b'n')) | Some((_, b'r')) | Some((_, b't')) | Some((_, b'\\'))
| Some((_, b'0')) | Some((_, b'\'')) | Some((_, b'"')) => {}
Some((newline, b @ b'\n')) | Some((newline, b @ b'\r')) => {
let mut last = b as char;
let rest = input.advance(newline + 1);
let mut chars = rest.char_indices();
loop {
if last == '\r' && chars.next().map_or(true, |(_, ch)| ch != '\n') {
return Err(Reject);
}
match chars.next() {
Some((_, ch)) if ch.is_whitespace() => last = ch,
Some((offset, _)) => {
input = rest.advance(offset);
bytes = input.bytes().enumerate();
break;
}
None => return Err(Reject),
}
}
}
_ => break,
},
b if b < 0x80 => {}
_ => break,
}
}
Err(Reject)
}
fn raw_string(input: Cursor) -> Result<Cursor, Reject> {
let mut chars = input.char_indices();
let mut n = 0;
while let Some((i, ch)) = chars.next() {
match ch {
'"' => {
n = i;
break;
}
'#' => {}
_ => return Err(Reject),
}
}
while let Some((i, ch)) = chars.next() {
match ch {
'"' if input.rest[i + 1..].starts_with(&input.rest[..n]) => {
let rest = input.advance(i + 1 + n);
return Ok(literal_suffix(rest));
}
'\r' => match chars.next() {
Some((_, '\n')) => {}
_ => break,
},
_ => {}
}
}
Err(Reject)
}
fn byte(input: Cursor) -> Result<Cursor, Reject> {
let input = input.parse("b'")?;
let mut bytes = input.bytes().enumerate();
let ok = match bytes.next().map(|(_, b)| b) {
Some(b'\\') => match bytes.next().map(|(_, b)| b) {
Some(b'x') => backslash_x_byte(&mut bytes),
Some(b'n') | Some(b'r') | Some(b't') | Some(b'\\') | Some(b'0') | Some(b'\'')
| Some(b'"') => true,
_ => false,
},
b => b.is_some(),
};
if !ok {
return Err(Reject);
}
let (offset, _) = bytes.next().ok_or(Reject)?;
if !input.chars().as_str().is_char_boundary(offset) {
return Err(Reject);
}
let input = input.advance(offset).parse("'")?;
Ok(literal_suffix(input))
}
fn character(input: Cursor) -> Result<Cursor, Reject> {
let input = input.parse("'")?;
let mut chars = input.char_indices();
let ok = match chars.next().map(|(_, ch)| ch) {
Some('\\') => match chars.next().map(|(_, ch)| ch) {
Some('x') => backslash_x_char(&mut chars),
Some('u') => backslash_u(&mut chars),
Some('n') | Some('r') | Some('t') | Some('\\') | Some('0') | Some('\'') | Some('"') => {
true
}
_ => false,
},
ch => ch.is_some(),
};
if !ok {
return Err(Reject);
}
let (idx, _) = chars.next().ok_or(Reject)?;
let input = input.advance(idx).parse("'")?;
Ok(literal_suffix(input))
}
macro_rules! next_ch {
($chars:ident @ $pat:pat $(| $rest:pat)*) => {
match $chars.next() {
Some((_, ch)) => match ch {
$pat $(| $rest)* => ch,
_ => return false,
},
None => return false,
}
};
}
fn backslash_x_char<I>(chars: &mut I) -> bool
where
I: Iterator<Item = (usize, char)>,
{
next_ch!(chars @ '0'..='7');
next_ch!(chars @ '0'..='9' | 'a'..='f' | 'A'..='F');
true
}
fn backslash_x_byte<I>(chars: &mut I) -> bool
where
I: Iterator<Item = (usize, u8)>,
{
next_ch!(chars @ b'0'..=b'9' | b'a'..=b'f' | b'A'..=b'F');
next_ch!(chars @ b'0'..=b'9' | b'a'..=b'f' | b'A'..=b'F');
true
}
fn backslash_u<I>(chars: &mut I) -> bool
where
I: Iterator<Item = (usize, char)>,
{
next_ch!(chars @ '{');
let mut value = 0;
let mut len = 0;
for (_, ch) in chars {
let digit = match ch {
'0'..='9' => ch as u8 - b'0',
'a'..='f' => 10 + ch as u8 - b'a',
'A'..='F' => 10 + ch as u8 - b'A',
'_' if len > 0 => continue,
'}' if len > 0 => return char::from_u32(value).is_some(),
_ => return false,
};
if len == 6 {
return false;
}
value *= 0x10;
value += u32::from(digit);
len += 1;
}
false
}
fn float(input: Cursor) -> Result<Cursor, Reject> {
let mut rest = float_digits(input)?;
if let Some(ch) = rest.chars().next() {
if is_ident_start(ch) {
rest = ident_not_raw(rest)?.0;
}
}
word_break(rest)
}
fn float_digits(input: Cursor) -> Result<Cursor, Reject> {
let mut chars = input.chars().peekable();
match chars.next() {
Some(ch) if ch >= '0' && ch <= '9' => {}
_ => return Err(Reject),
}
let mut len = 1;
let mut has_dot = false;
let mut has_exp = false;
while let Some(&ch) = chars.peek() {
match ch {
'0'..='9' | '_' => {
chars.next();
len += 1;
}
'.' => {
if has_dot {
break;
}
chars.next();
if chars
.peek()
.map(|&ch| ch == '.' || is_ident_start(ch))
.unwrap_or(false)
{
return Err(Reject);
}
len += 1;
has_dot = true;
}
'e' | 'E' => {
chars.next();
len += 1;
has_exp = true;
break;
}
_ => break,
}
}
if !(has_dot || has_exp) {
return Err(Reject);
}
if has_exp {
let token_before_exp = if has_dot {
Ok(input.advance(len - 1))
} else {
Err(Reject)
};
let mut has_sign = false;
let mut has_exp_value = false;
while let Some(&ch) = chars.peek() {
match ch {
'+' | '-' => {
if has_exp_value {
break;
}
if has_sign {
return token_before_exp;
}
chars.next();
len += 1;
has_sign = true;
}
'0'..='9' => {
chars.next();
len += 1;
has_exp_value = true;
}
'_' => {
chars.next();
len += 1;
}
_ => break,
}
}
if !has_exp_value {
return token_before_exp;
}
}
Ok(input.advance(len))
}
fn int(input: Cursor) -> Result<Cursor, Reject> {
let mut rest = digits(input)?;
if let Some(ch) = rest.chars().next() {
if is_ident_start(ch) {
rest = ident_not_raw(rest)?.0;
}
}
word_break(rest)
}
fn digits(mut input: Cursor) -> Result<Cursor, Reject> {
let base = if input.starts_with("0x") {
input = input.advance(2);
16
} else if input.starts_with("0o") {
input = input.advance(2);
8
} else if input.starts_with("0b") {
input = input.advance(2);
2
} else {
10
};
let mut len = 0;
let mut empty = true;
for b in input.bytes() {
match b {
b'0'..=b'9' => {
let digit = (b - b'0') as u64;
if digit >= base {
return Err(Reject);
}
}
b'a'..=b'f' => {
let digit = 10 + (b - b'a') as u64;
if digit >= base {
break;
}
}
b'A'..=b'F' => {
let digit = 10 + (b - b'A') as u64;
if digit >= base {
break;
}
}
b'_' => {
if empty && base == 10 {
return Err(Reject);
}
len += 1;
continue;
}
_ => break,
};
len += 1;
empty = false;
}
if empty {
Err(Reject)
} else {
Ok(input.advance(len))
}
}
fn punct(input: Cursor) -> PResult<Punct> {
let (rest, ch) = punct_char(input)?;
if ch == '\'' {
if ident_any(rest)?.0.starts_with("'") {
Err(Reject)
} else {
Ok((rest, Punct::new('\'', Spacing::Joint)))
}
} else {
let kind = match punct_char(rest) {
Ok(_) => Spacing::Joint,
Err(Reject) => Spacing::Alone,
};
Ok((rest, Punct::new(ch, kind)))
}
}
fn punct_char(input: Cursor) -> PResult<char> {
if input.starts_with("//") || input.starts_with("/*") {
return Err(Reject);
}
let mut chars = input.chars();
let first = match chars.next() {
Some(ch) => ch,
None => {
return Err(Reject);
}
};
let recognized = "~!@#$%^&*-=+|;:,<.>/?'";
if recognized.contains(first) {
Ok((input.advance(first.len_utf8()), first))
} else {
Err(Reject)
}
}
fn doc_comment(input: Cursor) -> PResult<Vec<TokenTree>> {
#[cfg(span_locations)]
let lo = input.off;
let (rest, (comment, inner)) = doc_comment_contents(input)?;
let span = crate::Span::_new_stable(Span {
#[cfg(span_locations)]
lo,
#[cfg(span_locations)]
hi: rest.off,
});
let mut scan_for_bare_cr = comment;
while let Some(cr) = scan_for_bare_cr.find('\r') {
let rest = &scan_for_bare_cr[cr + 1..];
if !rest.starts_with('\n') {
return Err(Reject);
}
scan_for_bare_cr = rest;
}
let mut trees = Vec::new();
trees.push(TokenTree::Punct(Punct::new('#', Spacing::Alone)));
if inner {
trees.push(Punct::new('!', Spacing::Alone).into());
}
let mut stream = vec![
TokenTree::Ident(crate::Ident::new("doc", span)),
TokenTree::Punct(Punct::new('=', Spacing::Alone)),
TokenTree::Literal(crate::Literal::string(comment)),
];
for tt in stream.iter_mut() {
tt.set_span(span);
}
let group = Group::new(Delimiter::Bracket, stream.into_iter().collect());
trees.push(crate::Group::_new_stable(group).into());
for tt in trees.iter_mut() {
tt.set_span(span);
}
Ok((rest, trees))
}
fn doc_comment_contents(input: Cursor) -> PResult<(&str, bool)> {
if input.starts_with("//!") {
let input = input.advance(3);
let (input, s) = take_until_newline_or_eof(input);
Ok((input, (s, true)))
} else if input.starts_with("/*!") {
let (input, s) = block_comment(input)?;
Ok((input, (&s[3..s.len() - 2], true)))
} else if input.starts_with("///") {
let input = input.advance(3);
if input.starts_with("/") {
return Err(Reject);
}
let (input, s) = take_until_newline_or_eof(input);
Ok((input, (s, false)))
} else if input.starts_with("/**") && !input.rest[3..].starts_with('*') {
let (input, s) = block_comment(input)?;
Ok((input, (&s[3..s.len() - 2], false)))
} else {
Err(Reject)
}
}
fn take_until_newline_or_eof(input: Cursor) -> (Cursor, &str) {
let chars = input.char_indices();
for (i, ch) in chars {
if ch == '\n' {
return (input.advance(i), &input.rest[..i]);
} else if ch == '\r' && input.rest[i + 1..].starts_with('\n') {
return (input.advance(i + 1), &input.rest[..i]);
}
}
(input.advance(input.len()), input.rest)
}