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7. Return SyntaxNodes from the Lexer

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This commit is contained in:
Ian Wrzesinski 2024-10-10 11:57:27 -04:00
parent 01186779cd
commit 1cecae0333
2 changed files with 44 additions and 37 deletions
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44
crates/typst-syntax/src/lexer.rs
View File

@ -4,12 +4,12 @@ use unicode_script::{Script, UnicodeScript};
use unicode_segmentation::UnicodeSegmentation;
use unscanny::Scanner;
use crate::{SyntaxError, SyntaxKind};
use crate::{SyntaxError, SyntaxKind, SyntaxNode};
/// Splits up a string of source code into tokens.
/// An iterator over a source code string which returns tokens.
#[derive(Clone)]
pub(super) struct Lexer<'s> {
/// The underlying scanner.
/// The scanner: contains the underlying string and location as a "cursor".
s: Scanner<'s>,
/// The mode the lexer is in. This determines which kinds of tokens it
/// produces.
@ -73,11 +73,6 @@ impl<'s> Lexer<'s> {
pub fn newline(&self) -> bool {
self.newline
}
/// Take out the last error, if any.
pub fn take_error(&mut self) -> Option<SyntaxError> {
self.error.take()
}
}
impl Lexer<'_> {
@ -97,21 +92,24 @@ impl Lexer<'_> {
/// Shared methods with all [`LexMode`].
impl Lexer<'_> {
/// Proceed to the next token and return its [`SyntaxKind`]. Note the
/// token could be a [trivia](SyntaxKind::is_trivia).
pub fn next(&mut self) -> SyntaxKind {
/// Return the next token in our text. Returns both the [`SyntaxNode`]
/// and the raw [`SyntaxKind`] to make it more ergonomic to check the kind
pub fn next(&mut self) -> (SyntaxKind, SyntaxNode) {
debug_assert!(self.error.is_none());
let start = self.s.cursor();
if self.mode == LexMode::Raw {
let Some((kind, end)) = self.raw.pop() else {
return SyntaxKind::End;
let kind = if let Some((kind, end)) = self.raw.pop() {
self.s.jump(end);
kind
} else {
SyntaxKind::End
};
self.s.jump(end);
return kind;
let node = SyntaxNode::leaf(kind, self.s.from(start));
return (kind, node);
}
self.newline = false;
self.error = None;
let start = self.s.cursor();
match self.s.eat() {
let kind = match self.s.eat() {
Some(c) if is_space(c, self.mode) => self.whitespace(start, c),
Some('/') if self.s.eat_if('/') => self.line_comment(),
Some('/') if self.s.eat_if('*') => self.block_comment(),
@ -132,13 +130,21 @@ impl Lexer<'_> {
},
None => SyntaxKind::End,
}
};
let text = self.s.from(start);
let node = match self.error.take() {
Some(error) => SyntaxNode::error(error, text),
None => SyntaxNode::leaf(kind, text),
};
(kind, node)
}
/// Eat whitespace characters greedily.
fn whitespace(&mut self, start: usize, c: char) -> SyntaxKind {
let more = self.s.eat_while(|c| is_space(c, self.mode));
let newlines = match c {
// Optimize eating a single space.
' ' if more.is_empty() => 0,
_ => count_newlines(self.s.from(start)),
};

37
crates/typst-syntax/src/parser.rs
View File

@ -185,7 +185,7 @@ fn heading(p: &mut Parser) {
whitespace_line(p);
markup(p, false, usize::MAX, |p| {
p.at_set(syntax_set!(Label, Space, RightBracket))
&& (!p.at(SyntaxKind::Space) || p.lexer.clone().next() == SyntaxKind::Label)
&& (!p.at(SyntaxKind::Space) || p.lexer.clone().next().0 == SyntaxKind::Label)
});
p.wrap(m, SyntaxKind::Heading);
}
@ -282,7 +282,7 @@ fn math_expr_prec(p: &mut Parser, min_prec: usize, stop: SyntaxKind) {
while p.directly_at(SyntaxKind::Text) && p.current_text() == "." && {
let mut copy = p.lexer.clone();
let start = copy.cursor();
let next = copy.next();
let next = copy.next().0;
let end = copy.cursor();
matches!(next, SyntaxKind::MathIdent | SyntaxKind::Text)
&& is_ident(&p.text[start..end])
@ -686,8 +686,8 @@ fn code_expr_prec(p: &mut Parser, atomic: bool, min_prec: usize) {
continue;
}
let at_field_or_method =
p.directly_at(SyntaxKind::Dot) && p.lexer.clone().next() == SyntaxKind::Ident;
let at_field_or_method = p.directly_at(SyntaxKind::Dot)
&& p.lexer.clone().next().0 == SyntaxKind::Ident;
if atomic && !at_field_or_method {
break;
@ -947,9 +947,8 @@ fn for_loop(p: &mut Parser) {
let mut seen = HashSet::new();
pattern(p, false, &mut seen, None);
let m2 = p.marker();
if p.eat_if(SyntaxKind::Comma) {
let node = &mut p[m2];
if p.at(SyntaxKind::Comma) {
let node = p.eat_and_get();
node.unexpected();
node.hint("destructuring patterns must be wrapped in parentheses");
if p.at_set(set::PATTERN) {
@ -1563,6 +1562,9 @@ struct Parser<'s> {
current_start: usize,
/// The [`SyntaxKind`] of the current token.
current: SyntaxKind,
/// The [`SyntaxNode`] of the current token, ready to be eaten and pushed
/// onto the end of `nodes`.
current_node: SyntaxNode,
/// Whether the parser has the expected set of open/close delimiters. This
/// only ever transitions from `true` to `false`.
balanced: bool,
@ -1603,13 +1605,14 @@ impl<'s> Parser<'s> {
fn new(text: &'s str, offset: usize, mode: LexMode) -> Self {
let mut lexer = Lexer::new(text, mode);
lexer.jump(offset);
let current = lexer.next();
let (current, current_node) = lexer.next();
Self {
lexer,
text,
prev_end: offset,
current_start: offset,
current,
current_node,
balanced: true,
nodes: vec![],
modes: vec![],
@ -1722,7 +1725,8 @@ impl<'s> Parser<'s> {
/// Convert the current token's [`SyntaxKind`] and eat it.
fn convert_and_eat(&mut self, kind: SyntaxKind) {
self.current = kind;
// Only need to replace the node here.
self.current_node.convert_to_kind(kind);
self.eat();
}
@ -1848,13 +1852,7 @@ impl<'s> Parser<'s> {
/// Save the current token to the `nodes` vector as an Inner or Error node.
fn save(&mut self) {
let text = self.current_text();
if self.at(SyntaxKind::Error) {
let error = self.lexer.take_error().unwrap();
self.nodes.push(SyntaxNode::error(error, text));
} else {
self.nodes.push(SyntaxNode::leaf(self.current, text));
}
self.nodes.push(self.current_node.clone());
if self.lexer.mode() == LexMode::Markup || !self.current.is_trivia() {
self.prev_end = self.current_end();
@ -1864,7 +1862,7 @@ impl<'s> Parser<'s> {
/// Find the kind of the next non-trivia token in the lexer.
fn next_non_trivia(lexer: &mut Lexer<'s>) -> SyntaxKind {
loop {
let next = lexer.next();
let next = lexer.next().0;
// Loop is terminable, because `SyntaxKind::End` is not a trivia.
if !next.is_trivia() {
break next;
@ -1876,7 +1874,7 @@ impl<'s> Parser<'s> {
/// might insert a temporary [`SyntaxKind::End`] based on our newline mode.
fn lex(&mut self) {
self.current_start = self.lexer.cursor();
self.current = self.lexer.next();
(self.current, self.current_node) = self.lexer.next();
// Special cases to handle newlines in Code.
if self.lexer.mode() == LexMode::Code
@ -1931,6 +1929,7 @@ struct PartialState {
prev_end: usize,
current_start: usize,
current: SyntaxKind,
current_node: SyntaxNode,
}
impl<'s> Parser<'s> {
@ -1975,6 +1974,7 @@ impl<'s> Parser<'s> {
self.prev_end = state.prev_end;
self.current_start = state.current_start;
self.current = state.current;
self.current_node = state.current_node;
}
/// Save a checkpoint of the parser state.
@ -1986,6 +1986,7 @@ impl<'s> Parser<'s> {
prev_end: self.prev_end,
current_start: self.current_start,
current: self.current,
current_node: self.current_node.clone(),
};
Checkpoint { node_len, state }
}