mirror of
https://github.com/astral-sh/ruff.git
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5f3da9955a
## Summary This crate now contains utilities for dealing with trivia more broadly: whitespace, newlines, "simple" trivia lexing, etc. So renaming it to reflect its increased responsibilities. To avoid conflicts, I've also renamed `Token` and `TokenKind` to `SimpleToken` and `SimpleTokenKind`.
103 lines
3 KiB
Rust
103 lines
3 KiB
Rust
use std::str::Chars;
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use ruff_text_size::{TextLen, TextSize};
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pub const EOF_CHAR: char = '\0';
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/// A [`Cursor`] over a string.
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#[derive(Debug, Clone)]
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pub struct Cursor<'a> {
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chars: Chars<'a>,
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source_length: TextSize,
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}
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impl<'a> Cursor<'a> {
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pub fn new(source: &'a str) -> Self {
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Self {
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source_length: source.text_len(),
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chars: source.chars(),
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}
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}
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/// Return the remaining input as a string slice.
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pub fn chars(&self) -> Chars<'a> {
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self.chars.clone()
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}
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/// Peeks the next character from the input stream without consuming it.
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/// Returns [`EOF_CHAR`] if the file is at the end of the file.
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pub fn first(&self) -> char {
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self.chars.clone().next().unwrap_or(EOF_CHAR)
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}
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/// Peeks the next character from the input stream without consuming it.
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/// Returns [`EOF_CHAR`] if the file is at the end of the file.
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pub fn last(&self) -> char {
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self.chars.clone().next_back().unwrap_or(EOF_CHAR)
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}
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// SAFETY: THe `source.text_len` call in `new` would panic if the string length is larger than a `u32`.
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#[allow(clippy::cast_possible_truncation)]
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pub fn text_len(&self) -> TextSize {
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TextSize::new(self.chars.as_str().len() as u32)
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}
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pub fn token_len(&self) -> TextSize {
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self.source_length - self.text_len()
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}
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pub fn start_token(&mut self) {
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self.source_length = self.text_len();
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}
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/// Returns `true` if the file is at the end of the file.
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pub fn is_eof(&self) -> bool {
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self.chars.as_str().is_empty()
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}
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/// Consumes the next character
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pub fn bump(&mut self) -> Option<char> {
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self.chars.next()
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}
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/// Consumes the next character from the back
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pub fn bump_back(&mut self) -> Option<char> {
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self.chars.next_back()
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}
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pub fn eat_char(&mut self, c: char) -> bool {
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if self.first() == c {
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self.bump();
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true
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} else {
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false
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}
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}
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pub fn eat_char_back(&mut self, c: char) -> bool {
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if self.last() == c {
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self.bump_back();
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true
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} else {
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false
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}
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}
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/// Eats symbols while predicate returns true or until the end of file is reached.
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pub fn eat_while(&mut self, mut predicate: impl FnMut(char) -> bool) {
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// It was tried making optimized version of this for eg. line comments, but
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// LLVM can inline all of this and compile it down to fast iteration over bytes.
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while predicate(self.first()) && !self.is_eof() {
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self.bump();
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}
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}
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/// Eats symbols from the back while predicate returns true or until the beginning of file is reached.
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pub fn eat_back_while(&mut self, mut predicate: impl FnMut(char) -> bool) {
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// It was tried making optimized version of this for eg. line comments, but
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// LLVM can inline all of this and compile it down to fast iteration over bytes.
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while predicate(self.last()) && !self.is_eof() {
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self.bump_back();
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}
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}
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}
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