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1850 lines (1744 loc) · 63.4 KB
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//! This module takes care of lexing Python source text.
//!
//! This means source code is scanned and translated into separate tokens. The rules
//! governing what is and is not a valid token are defined in the Python reference
//! guide section on [Lexical analysis].
//!
//! The primary function in this module is [`lex`], which takes a string slice
//! and returns an iterator over the tokens in the source code. The tokens are currently returned
//! as a `Result<Spanned, LexicalError>`, where [`Spanned`] is a tuple containing the
//! start and end [`TextSize`] and a [`Tok`] denoting the token.
//!
//! # Example
//!
//! ```
//! use rustpython_parser::{lexer::lex, Tok, Mode, StringKind};
//!
//! let source = "x = 'RustPython'";
//! let tokens = lex(source, Mode::Module)
//! .map(|tok| tok.expect("Failed to lex"))
//! .collect::<Vec<_>>();
//!
//! for (token, range) in tokens {
//! println!(
//! "{token:?}@{range:?}",
//! );
//! }
//! ```
//!
//! [Lexical analysis]: https://docs.python.org/3/reference/lexical_analysis.html
use crate::{
soft_keywords::SoftKeywordTransformer,
string::FStringErrorType,
text_size::{TextLen, TextRange, TextSize},
token::{StringKind, Tok},
Mode,
};
use log::trace;
use num_bigint::BigInt;
use num_traits::{Num, Zero};
use std::{char, cmp::Ordering, ops::Index, slice::SliceIndex, str::FromStr};
use unic_emoji_char::is_emoji_presentation;
use unic_ucd_ident::{is_xid_continue, is_xid_start};
// Indentations are tracked by a stack of indentation levels. IndentationLevel keeps
// track of the number of tabs and spaces at the current level.
#[derive(Clone, Copy, PartialEq, Debug, Default)]
struct IndentationLevel {
tabs: u32,
spaces: u32,
}
impl IndentationLevel {
fn compare_strict(
&self,
other: &IndentationLevel,
location: TextSize,
) -> Result<Ordering, LexicalError> {
// We only know for sure that we're smaller or bigger if tabs
// and spaces both differ in the same direction. Otherwise we're
// dependent on the size of tabs.
match self.tabs.cmp(&other.tabs) {
Ordering::Less => {
if self.spaces <= other.spaces {
Ok(Ordering::Less)
} else {
Err(LexicalError {
location,
error: LexicalErrorType::TabError,
})
}
}
Ordering::Greater => {
if self.spaces >= other.spaces {
Ok(Ordering::Greater)
} else {
Err(LexicalError {
location,
error: LexicalErrorType::TabError,
})
}
}
Ordering::Equal => Ok(self.spaces.cmp(&other.spaces)),
}
}
}
// The indentations stack is used to keep track of the current indentation level.
// Similar to the CPython implementation, the Indentations stack always has at
// least one level which is never popped. See Reference 2.1.8.
#[derive(Debug)]
struct Indentations {
indent_stack: Vec<IndentationLevel>,
}
impl Indentations {
fn is_empty(&self) -> bool {
self.indent_stack.len() == 1
}
fn push(&mut self, indent: IndentationLevel) {
self.indent_stack.push(indent);
}
fn pop(&mut self) -> Option<IndentationLevel> {
if self.is_empty() {
return None;
}
self.indent_stack.pop()
}
fn current(&self) -> &IndentationLevel {
self.indent_stack
.last()
.expect("Indentations must have at least one level")
}
}
impl Default for Indentations {
fn default() -> Self {
Self {
indent_stack: vec![IndentationLevel::default()],
}
}
}
// A CharWindow is a sliding window over an iterator of chars. It is used to
// allow for look-ahead when scanning tokens from the source code.
struct CharWindow<T: Iterator<Item = char>, const N: usize> {
source: T,
window: [Option<char>; N],
}
impl<T, const N: usize> CharWindow<T, N>
where
T: Iterator<Item = char>,
{
fn new(source: T) -> Self {
Self {
source,
window: [None; N],
}
}
fn slide(&mut self) -> Option<char> {
self.window.rotate_left(1);
let next = self.source.next();
*self.window.last_mut().expect("never empty") = next;
next
}
}
impl<T, const N: usize, Idx> Index<Idx> for CharWindow<T, N>
where
T: Iterator<Item = char>,
Idx: SliceIndex<[Option<char>]>,
{
type Output = Idx::Output;
fn index(&self, index: Idx) -> &Self::Output {
&self.window[index]
}
}
/// A lexer for Python source code.
pub struct Lexer<T: Iterator<Item = char>> {
// Contains the source code to be lexed.
window: CharWindow<T, 3>,
// Are we at the beginning of a line?
at_begin_of_line: bool,
// Amount of parenthesis.
nesting: usize,
// Indentation levels.
indentations: Indentations,
// Pending list of tokens to be returned.
pending: Vec<Spanned>,
// The current location.
location: TextSize,
}
// generated in build.rs, in gen_phf()
/// A map of keywords to their tokens.
pub static KEYWORDS: phf::Map<&'static str, Tok> =
include!(concat!(env!("OUT_DIR"), "/keywords.rs"));
/// Contains a Token along with its `range`.
pub type Spanned = (Tok, TextRange);
/// The result of lexing a token.
pub type LexResult = Result<Spanned, LexicalError>;
/// Create a new lexer from a source string.
///
/// # Examples
///
/// ```
/// use rustpython_parser::{Mode, lexer::lex};
///
/// let source = "def hello(): return 'world'";
/// let lexer = lex(source, Mode::Module);
///
/// for token in lexer {
/// println!("{:?}", token);
/// }
/// ```
#[inline]
pub fn lex(source: &str, mode: Mode) -> impl Iterator<Item = LexResult> + '_ {
lex_starts_at(source, mode, TextSize::default())
}
/// Create a new lexer from a source string, starting at a given location.
/// You probably want to use [`lex`] instead.
pub fn lex_starts_at(
source: &str,
mode: Mode,
start_offset: TextSize,
) -> SoftKeywordTransformer<Lexer<std::str::Chars<'_>>> {
SoftKeywordTransformer::new(Lexer::new(source.chars(), start_offset), mode)
}
impl<T> Lexer<T>
where
T: Iterator<Item = char>,
{
/// Create a new lexer from T and a starting location. You probably want to use
/// [`lex`] instead.
pub fn new(input: T, start: TextSize) -> Self {
let mut lxr = Lexer {
at_begin_of_line: true,
nesting: 0,
indentations: Indentations::default(),
// Usually we have less than 5 tokens pending.
pending: Vec::with_capacity(5),
location: start,
window: CharWindow::new(input),
};
// Fill the window.
lxr.window.slide();
lxr.window.slide();
lxr.window.slide();
// TODO: Handle possible mismatch between BOM and explicit encoding declaration.
// spell-checker:ignore feff
if let Some('\u{feff}') = lxr.window[0] {
lxr.window.slide();
lxr.location += '\u{feff}'.text_len();
}
lxr
}
/// Lex an identifier. Also used for keywords and string/bytes literals with a prefix.
fn lex_identifier(&mut self) -> LexResult {
// Detect potential string like rb'' b'' f'' u'' r''
match self.window[..3] {
[Some(c), Some('"' | '\''), ..] => {
if let Ok(kind) = StringKind::try_from(c) {
return self.lex_string(kind);
}
}
[Some(c1), Some(c2), Some('"' | '\'')] => {
if let Ok(kind) = StringKind::try_from([c1, c2]) {
return self.lex_string(kind);
}
}
_ => {}
};
let start_pos = self.get_pos();
let mut name = String::with_capacity(8);
while self.is_identifier_continuation() {
name.push(self.next_char().unwrap());
}
let end_pos = self.get_pos();
if let Some(tok) = KEYWORDS.get(&name) {
Ok((tok.clone(), TextRange::new(start_pos, end_pos)))
} else {
Ok((Tok::Name { name }, TextRange::new(start_pos, end_pos)))
}
}
/// Numeric lexing. The feast can start!
fn lex_number(&mut self) -> LexResult {
let start_pos = self.get_pos();
match self.window[..2] {
[Some('0'), Some('x' | 'X')] => {
// Hex! (0xdeadbeef)
self.next_char();
self.next_char();
self.lex_number_radix(start_pos, 16)
}
[Some('0'), Some('o' | 'O')] => {
// Octal style! (0o377)
self.next_char();
self.next_char();
self.lex_number_radix(start_pos, 8)
}
[Some('0'), Some('b' | 'B')] => {
// Binary! (0b_1110_0101)
self.next_char();
self.next_char();
self.lex_number_radix(start_pos, 2)
}
_ => self.lex_normal_number(),
}
}
/// Lex a hex/octal/decimal/binary number without a decimal point.
fn lex_number_radix(&mut self, start_pos: TextSize, radix: u32) -> LexResult {
let value_text = self.radix_run(radix);
let end_pos = self.get_pos();
let value = BigInt::from_str_radix(&value_text, radix).map_err(|e| LexicalError {
error: LexicalErrorType::OtherError(format!("{e:?}")),
location: start_pos,
})?;
Ok((Tok::Int { value }, TextRange::new(start_pos, end_pos)))
}
/// Lex a normal number, that is, no octal, hex or binary number.
fn lex_normal_number(&mut self) -> LexResult {
let start_pos = self.get_pos();
let start_is_zero = self.window[0] == Some('0');
// Normal number:
let mut value_text = self.radix_run(10);
// If float:
if self.window[0] == Some('.') || self.at_exponent() {
// Take '.':
if self.window[0] == Some('.') {
if self.window[1] == Some('_') {
return Err(LexicalError {
error: LexicalErrorType::OtherError("Invalid Syntax".to_owned()),
location: self.get_pos(),
});
}
value_text.push(self.next_char().unwrap());
value_text.push_str(&self.radix_run(10));
}
// 1e6 for example:
if let Some('e' | 'E') = self.window[0] {
if self.window[1] == Some('_') {
return Err(LexicalError {
error: LexicalErrorType::OtherError("Invalid Syntax".to_owned()),
location: self.get_pos(),
});
}
value_text.push(self.next_char().unwrap().to_ascii_lowercase());
// Optional +/-
if matches!(self.window[0], Some('-' | '+')) {
if self.window[1] == Some('_') {
return Err(LexicalError {
error: LexicalErrorType::OtherError("Invalid Syntax".to_owned()),
location: self.get_pos(),
});
}
value_text.push(self.next_char().unwrap());
}
value_text.push_str(&self.radix_run(10));
}
let value = f64::from_str(&value_text).map_err(|_| LexicalError {
error: LexicalErrorType::OtherError("Invalid decimal literal".to_owned()),
location: self.get_pos(),
})?;
// Parse trailing 'j':
if matches!(self.window[0], Some('j' | 'J')) {
self.next_char();
let end_pos = self.get_pos();
Ok((
Tok::Complex {
real: 0.0,
imag: value,
},
TextRange::new(start_pos, end_pos),
))
} else {
let end_pos = self.get_pos();
Ok((Tok::Float { value }, TextRange::new(start_pos, end_pos)))
}
} else {
// Parse trailing 'j':
if matches!(self.window[0], Some('j' | 'J')) {
self.next_char();
let end_pos = self.get_pos();
let imag = f64::from_str(&value_text).unwrap();
Ok((
Tok::Complex { real: 0.0, imag },
TextRange::new(start_pos, end_pos),
))
} else {
let end_pos = self.get_pos();
let value = value_text.parse::<BigInt>().unwrap();
if start_is_zero && !value.is_zero() {
// leading zeros in decimal integer literals are not permitted
return Err(LexicalError {
error: LexicalErrorType::OtherError("Invalid Token".to_owned()),
location: self.get_pos(),
});
}
Ok((Tok::Int { value }, TextRange::new(start_pos, end_pos)))
}
}
}
/// Consume a sequence of numbers with the given radix,
/// the digits can be decorated with underscores
/// like this: '1_2_3_4' == '1234'
fn radix_run(&mut self, radix: u32) -> String {
let mut value_text = String::new();
loop {
if let Some(c) = self.take_number(radix) {
value_text.push(c);
} else if self.window[0] == Some('_')
&& Lexer::<T>::is_digit_of_radix(self.window[1], radix)
{
self.next_char();
} else {
break;
}
}
value_text
}
/// Consume a single character with the given radix.
fn take_number(&mut self, radix: u32) -> Option<char> {
let take_char = Lexer::<T>::is_digit_of_radix(self.window[0], radix);
take_char.then(|| self.next_char().unwrap())
}
/// Test if a digit is of a certain radix.
fn is_digit_of_radix(c: Option<char>, radix: u32) -> bool {
match radix {
2 => matches!(c, Some('0'..='1')),
8 => matches!(c, Some('0'..='7')),
10 => matches!(c, Some('0'..='9')),
16 => matches!(c, Some('0'..='9') | Some('a'..='f') | Some('A'..='F')),
other => unimplemented!("Radix not implemented: {}", other),
}
}
/// Test if we face '[eE][-+]?[0-9]+'
fn at_exponent(&self) -> bool {
match self.window[..2] {
[Some('e' | 'E'), Some('+' | '-')] => matches!(self.window[2], Some('0'..='9')),
[Some('e' | 'E'), Some('0'..='9')] => true,
_ => false,
}
}
/// Lex a single comment.
#[cfg(feature = "full-lexer")]
fn lex_comment(&mut self) -> LexResult {
let start_pos = self.get_pos();
let mut value = String::new();
loop {
match self.window[0] {
Some('\n' | '\r') | None => {
let end_pos = self.get_pos();
return Ok((Tok::Comment(value), TextRange::new(start_pos, end_pos)));
}
Some(_) => {}
}
value.push(self.next_char().unwrap());
}
}
/// Discard comment if full-lexer is not enabled.
#[cfg(not(feature = "full-lexer"))]
fn lex_comment(&mut self) {
loop {
match self.window[0] {
Some('\n' | '\r') | None => {
return;
}
Some(_) => {}
}
self.next_char().unwrap();
}
}
/// Lex a string literal.
fn lex_string(&mut self, kind: StringKind) -> LexResult {
let start_pos = self.get_pos();
for _ in 0..u32::from(kind.prefix_len()) {
self.next_char();
}
let quote_char = self.next_char().unwrap();
let mut string_content = String::with_capacity(5);
// If the next two characters are also the quote character, then we have a triple-quoted
// string; consume those two characters and ensure that we require a triple-quote to close
let triple_quoted = if self.window[..2] == [Some(quote_char); 2] {
self.next_char();
self.next_char();
true
} else {
false
};
loop {
match self.next_char() {
Some(c) => {
if c == '\\' {
if let Some(next_c) = self.next_char() {
string_content.push('\\');
string_content.push(next_c);
continue;
}
}
if c == '\n' && !triple_quoted {
return Err(LexicalError {
error: LexicalErrorType::OtherError(
"EOL while scanning string literal".to_owned(),
),
location: self.get_pos(),
});
}
if c == quote_char {
if triple_quoted {
// Look ahead at the next two characters; if we have two more
// quote_chars, it's the end of the string; consume the remaining
// closing quotes and break the loop
if self.window[..2] == [Some(quote_char); 2] {
self.next_char();
self.next_char();
break;
}
} else {
break;
}
}
string_content.push(c);
}
None => {
return Err(LexicalError {
error: if triple_quoted {
LexicalErrorType::Eof
} else {
LexicalErrorType::StringError
},
location: self.get_pos(),
});
}
}
}
let end_pos = self.get_pos();
let tok = Tok::String {
value: string_content,
kind,
triple_quoted,
};
Ok((tok, TextRange::new(start_pos, end_pos)))
}
// Checks if the character c is a valid starting character as described
// in https://docs.python.org/3/reference/lexical_analysis.html#identifiers
fn is_identifier_start(&self, c: char) -> bool {
match c {
'a'..='z' | 'A'..='Z' | '_' => true,
_ => is_xid_start(c),
}
}
// Checks if the character c is a valid continuation character as described
// in https://docs.python.org/3/reference/lexical_analysis.html#identifiers
fn is_identifier_continuation(&self) -> bool {
match self.window[0] {
Some('a'..='z' | 'A'..='Z' | '_' | '0'..='9') => true,
Some(c) => is_xid_continue(c),
_ => false,
}
}
// This is the main entry point. Call this function to retrieve the next token.
// This function is used by the iterator implementation.
fn inner_next(&mut self) -> LexResult {
// top loop, keep on processing, until we have something pending.
while self.pending.is_empty() {
// Detect indentation levels
if self.at_begin_of_line {
self.handle_indentations()?;
}
self.consume_normal()?;
}
Ok(self.pending.remove(0))
}
// Given we are at the start of a line, count the number of spaces and/or tabs until the first character.
fn eat_indentation(&mut self) -> Result<IndentationLevel, LexicalError> {
// Determine indentation:
let mut spaces: u32 = 0;
let mut tabs: u32 = 0;
loop {
match self.window[0] {
Some(' ') => {
/*
if tabs != 0 {
// Don't allow spaces after tabs as part of indentation.
// This is technically stricter than python3 but spaces after
// tabs is even more insane than mixing spaces and tabs.
return Some(Err(LexicalError {
error: LexicalErrorType::OtherError("Spaces not allowed as part of indentation after tabs".to_owned()),
location: self.get_pos(),
}));
}
*/
self.next_char();
spaces += 1;
}
Some('\t') => {
if spaces != 0 {
// Don't allow tabs after spaces as part of indentation.
// This is technically stricter than python3 but spaces before
// tabs is even more insane than mixing spaces and tabs.
return Err(LexicalError {
error: LexicalErrorType::TabsAfterSpaces,
location: self.get_pos(),
});
}
self.next_char();
tabs += 1;
}
Some('#') => {
let _comment = self.lex_comment();
#[cfg(feature = "full-lexer")]
self.emit(_comment?);
spaces = 0;
tabs = 0;
}
Some('\x0C') => {
// Form feed character!
// Reset indentation for the Emacs user.
self.next_char();
spaces = 0;
tabs = 0;
}
Some('\n' | '\r') => {
// Empty line!
#[cfg(feature = "full-lexer")]
let tok_start = self.get_pos();
self.next_char();
#[cfg(feature = "full-lexer")]
let tok_end = self.get_pos();
#[cfg(feature = "full-lexer")]
self.emit((Tok::NonLogicalNewline, TextRange::new(tok_start, tok_end)));
spaces = 0;
tabs = 0;
}
None => {
spaces = 0;
tabs = 0;
break;
}
_ => {
self.at_begin_of_line = false;
break;
}
}
}
Ok(IndentationLevel { tabs, spaces })
}
// Push/pop indents/dedents based on the current indentation level.
fn handle_indentations(&mut self) -> Result<(), LexicalError> {
let indentation_level = self.eat_indentation()?;
if self.nesting != 0 {
return Ok(());
}
// Determine indent or dedent:
let current_indentation = self.indentations.current();
let ordering = indentation_level.compare_strict(current_indentation, self.get_pos())?;
match ordering {
Ordering::Equal => {
// Same same
}
Ordering::Greater => {
// New indentation level:
self.indentations.push(indentation_level);
let tok_pos = self.get_pos();
self.emit((
Tok::Indent,
TextRange::new(
tok_pos
- TextSize::new(indentation_level.spaces)
- TextSize::new(indentation_level.tabs),
tok_pos,
),
));
}
Ordering::Less => {
// One or more dedentations
// Pop off other levels until col is found:
loop {
let current_indentation = self.indentations.current();
let ordering =
indentation_level.compare_strict(current_indentation, self.get_pos())?;
match ordering {
Ordering::Less => {
self.indentations.pop();
let tok_pos = self.get_pos();
self.emit((Tok::Dedent, TextRange::empty(tok_pos)));
}
Ordering::Equal => {
// We arrived at proper level of indentation.
break;
}
Ordering::Greater => {
return Err(LexicalError {
error: LexicalErrorType::IndentationError,
location: self.get_pos(),
});
}
}
}
}
}
Ok(())
}
// Take a look at the next character, if any, and decide upon the next steps.
fn consume_normal(&mut self) -> Result<(), LexicalError> {
if let Some(c) = self.window[0] {
// Identifiers are the most common case.
if self.is_identifier_start(c) {
let identifier = self.lex_identifier()?;
self.emit(identifier);
} else {
self.consume_character(c)?;
}
} else {
// We reached end of file.
let tok_pos = self.get_pos();
// First of all, we need all nestings to be finished.
if self.nesting > 0 {
return Err(LexicalError {
error: LexicalErrorType::Eof,
location: tok_pos,
});
}
// Next, insert a trailing newline, if required.
if !self.at_begin_of_line {
self.at_begin_of_line = true;
self.emit((Tok::Newline, TextRange::empty(tok_pos)));
}
// Next, flush the indentation stack to zero.
while !self.indentations.is_empty() {
self.indentations.pop();
self.emit((Tok::Dedent, TextRange::empty(tok_pos)));
}
self.emit((Tok::EndOfFile, TextRange::empty(tok_pos)));
}
Ok(())
}
// Dispatch based on the given character.
fn consume_character(&mut self, c: char) -> Result<(), LexicalError> {
match c {
'0'..='9' => {
let number = self.lex_number()?;
self.emit(number);
}
'#' => {
let _comment = self.lex_comment();
#[cfg(feature = "full-lexer")]
self.emit(_comment?);
}
'"' | '\'' => {
let string = self.lex_string(StringKind::String)?;
self.emit(string);
}
'=' => {
let tok_start = self.get_pos();
self.next_char();
match self.window[0] {
Some('=') => {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::EqEqual, TextRange::new(tok_start, tok_end)));
}
_ => {
let tok_end = self.get_pos();
self.emit((Tok::Equal, TextRange::new(tok_start, tok_end)));
}
}
}
'+' => {
let tok_start = self.get_pos();
self.next_char();
if let Some('=') = self.window[0] {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::PlusEqual, TextRange::new(tok_start, tok_end)));
} else {
let tok_end = self.get_pos();
self.emit((Tok::Plus, TextRange::new(tok_start, tok_end)));
}
}
'*' => {
let tok_start = self.get_pos();
self.next_char();
match self.window[0] {
Some('=') => {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::StarEqual, TextRange::new(tok_start, tok_end)));
}
Some('*') => {
self.next_char();
match self.window[0] {
Some('=') => {
self.next_char();
let tok_end = self.get_pos();
self.emit((
Tok::DoubleStarEqual,
TextRange::new(tok_start, tok_end),
));
}
_ => {
let tok_end = self.get_pos();
self.emit((Tok::DoubleStar, TextRange::new(tok_start, tok_end)));
}
}
}
_ => {
let tok_end = self.get_pos();
self.emit((Tok::Star, TextRange::new(tok_start, tok_end)));
}
}
}
'/' => {
let tok_start = self.get_pos();
self.next_char();
match self.window[0] {
Some('=') => {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::SlashEqual, TextRange::new(tok_start, tok_end)));
}
Some('/') => {
self.next_char();
match self.window[0] {
Some('=') => {
self.next_char();
let tok_end = self.get_pos();
self.emit((
Tok::DoubleSlashEqual,
TextRange::new(tok_start, tok_end),
));
}
_ => {
let tok_end = self.get_pos();
self.emit((Tok::DoubleSlash, TextRange::new(tok_start, tok_end)));
}
}
}
_ => {
let tok_end = self.get_pos();
self.emit((Tok::Slash, TextRange::new(tok_start, tok_end)));
}
}
}
'%' => {
let tok_start = self.get_pos();
self.next_char();
if let Some('=') = self.window[0] {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::PercentEqual, TextRange::new(tok_start, tok_end)));
} else {
let tok_end = self.get_pos();
self.emit((Tok::Percent, TextRange::new(tok_start, tok_end)));
}
}
'|' => {
let tok_start = self.get_pos();
self.next_char();
if let Some('=') = self.window[0] {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::VbarEqual, TextRange::new(tok_start, tok_end)));
} else {
let tok_end = self.get_pos();
self.emit((Tok::Vbar, TextRange::new(tok_start, tok_end)));
}
}
'^' => {
let tok_start = self.get_pos();
self.next_char();
if let Some('=') = self.window[0] {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::CircumflexEqual, TextRange::new(tok_start, tok_end)));
} else {
let tok_end = self.get_pos();
self.emit((Tok::CircumFlex, TextRange::new(tok_start, tok_end)));
}
}
'&' => {
let tok_start = self.get_pos();
self.next_char();
if let Some('=') = self.window[0] {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::AmperEqual, TextRange::new(tok_start, tok_end)));
} else {
let tok_end = self.get_pos();
self.emit((Tok::Amper, TextRange::new(tok_start, tok_end)));
}
}
'-' => {
let tok_start = self.get_pos();
self.next_char();
match self.window[0] {
Some('=') => {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::MinusEqual, TextRange::new(tok_start, tok_end)));
}
Some('>') => {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::Rarrow, TextRange::new(tok_start, tok_end)));
}
_ => {
let tok_end = self.get_pos();
self.emit((Tok::Minus, TextRange::new(tok_start, tok_end)));
}
}
}
'@' => {
let tok_start = self.get_pos();
self.next_char();
if let Some('=') = self.window[0] {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::AtEqual, TextRange::new(tok_start, tok_end)));
} else {
let tok_end = self.get_pos();
self.emit((Tok::At, TextRange::new(tok_start, tok_end)));
}
}
'!' => {
let tok_start = self.get_pos();
self.next_char();
if let Some('=') = self.window[0] {
self.next_char();
let tok_end = self.get_pos();
self.emit((Tok::NotEqual, TextRange::new(tok_start, tok_end)));
} else {
return Err(LexicalError {
error: LexicalErrorType::UnrecognizedToken { tok: '!' },
location: tok_start,
});
}
}
'~' => {
self.eat_single_char(Tok::Tilde);
}
'(' => {
self.eat_single_char(Tok::Lpar);
self.nesting += 1;
}
')' => {
self.eat_single_char(Tok::Rpar);
if self.nesting == 0 {
return Err(LexicalError {
error: LexicalErrorType::NestingError,
location: self.get_pos(),
});
}
self.nesting -= 1;
}
'[' => {
self.eat_single_char(Tok::Lsqb);
self.nesting += 1;
}
']' => {
self.eat_single_char(Tok::Rsqb);
if self.nesting == 0 {
return Err(LexicalError {
error: LexicalErrorType::NestingError,
location: self.get_pos(),
});
}
self.nesting -= 1;