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Merged
zharinov merged 2 commits into from
Dec 8, 2025
Merged

refactor: Parser #87

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7723e36
refactor: Parser
zharinov Dec 8, 2025
00f2b9c
Merge branch 'master' into refactor/parser
zharinov Dec 8, 2025
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110 changes: 47 additions & 63 deletions crates/plotnik-lib/src/parser/core.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,8 @@ use super::ast::Root;
use super::cst::token_sets::ROOT_EXPR_FIRST;
use super::cst::{SyntaxKind, SyntaxNode, TokenSet};
use super::lexer::{Token, token_text};
use crate::diagnostics::{DiagnosticKind, Diagnostics};

use crate::Error;
use crate::diagnostics::{DiagnosticKind, Diagnostics};

#[derive(Debug)]
pub struct ParseResult {
Expand All @@ -19,13 +18,12 @@ pub struct ParseResult {

#[derive(Debug, Clone, Copy)]
pub(super) struct OpenDelimiter {
#[allow(dead_code)] // for future mismatch detection (e.g., `(]`)
#[allow(dead_code)] // for future mismatch detection
pub kind: SyntaxKind,
pub span: TextRange,
}

/// Trivia tokens (whitespace, comments) are buffered and flushed as leading trivia
/// when starting a new node. This gives predictable trivia attachment without backtracking.
/// Trivia tokens are buffered and flushed when starting a new node.
pub struct Parser<'src> {
pub(super) source: &'src str,
pub(super) tokens: Vec<Token>,
Expand Down Expand Up @@ -101,7 +99,6 @@ impl<'src> Parser<'src> {
self.fatal_error.is_some()
}

/// Returns `Error` at EOF (acts as sentinel).
pub(super) fn current(&self) -> SyntaxKind {
self.nth(0)
}
Expand All @@ -112,7 +109,6 @@ impl<'src> Parser<'src> {

pub(super) fn nth(&self, lookahead: usize) -> SyntaxKind {
self.ensure_progress();

self.tokens
.get(self.pos + lookahead)
.map_or(SyntaxKind::Error, |t| t.kind)
Expand Down Expand Up @@ -203,7 +199,6 @@ impl<'src> Parser<'src> {
self.builder.start_node(kind.into());
}

/// Wrap previously-parsed content using checkpoint.
pub(super) fn start_node_at(&mut self, checkpoint: Checkpoint, kind: SyntaxKind) {
self.builder.start_node_at(checkpoint, kind.into());
}
Expand All @@ -219,9 +214,7 @@ impl<'src> Parser<'src> {

pub(super) fn bump(&mut self) {
assert!(!self.eof(), "bump called at EOF");

self.reset_debug_fuel();

self.consume_exec_fuel();

let token = self.tokens[self.pos];
Expand All @@ -232,11 +225,8 @@ impl<'src> Parser<'src> {

pub(super) fn skip_token(&mut self) {
assert!(!self.eof(), "skip_token called at EOF");

self.reset_debug_fuel();

self.consume_exec_fuel();

self.pos += 1;
}

Expand All @@ -249,47 +239,31 @@ impl<'src> Parser<'src> {
}
}

/// On mismatch: emit diagnostic but don't consume (allows parent recovery).
/// On mismatch: emit diagnostic but don't consume.
pub(super) fn expect(&mut self, kind: SyntaxKind, what: &str) -> bool {
if self.eat(kind) {
return true;
}
let msg = format!("expected {}", what);
self.error_msg(DiagnosticKind::UnexpectedToken, &msg);
self.error_msg(
DiagnosticKind::UnexpectedToken,
format!("expected {}", what),
);
false
}

/// Returns the suppression span for the current context.
///
/// If inside a delimiter (tree/seq/alt), returns a span from the delimiter's
/// start to the end of source. This ensures all errors within the same
/// delimiter context can suppress each other based on priority.
/// At root level, returns the current token's span.
pub(super) fn current_suppression_span(&self) -> TextRange {
self.delimiter_stack
.last()
.map(|d| {
let source_end = TextSize::from(self.source.len() as u32);
TextRange::new(d.span.start(), source_end)
})
.map(|d| TextRange::new(d.span.start(), TextSize::from(self.source.len() as u32)))
.unwrap_or_else(|| self.current_span())
}

fn error_impl(&mut self, kind: DiagnosticKind, message: Option<&str>) {
let range = self.current_span();
let pos = range.start();
fn should_report(&mut self, pos: TextSize) -> bool {
if self.last_diagnostic_pos == Some(pos) {
return;
return false;
}
self.last_diagnostic_pos = Some(pos);

let suppression = self.current_suppression_span();
let builder = self.diagnostics.report(kind, range);
let builder = match message {
Some(msg) => builder.message(msg),
None => builder,
};
builder.suppression_range(suppression).emit();
true
}

fn bump_as_error(&mut self) {
Expand All @@ -300,22 +274,42 @@ impl<'src> Parser<'src> {
}
}

/// Emit diagnostic with default message for the kind.
fn get_error_ranges(&mut self) -> Option<(TextRange, TextRange)> {
let range = self.current_span();
if !self.should_report(range.start()) {
return None;
}
let suppression = self.current_suppression_span();
Some((range, suppression))
}

pub(super) fn error(&mut self, kind: DiagnosticKind) {
self.error_impl(kind, None);
let Some((range, suppression)) = self.get_error_ranges() else {
return;
};
self.diagnostics
.report(kind, range)
.suppression_range(suppression)
.emit();
}

/// Emit diagnostic with custom message detail.
pub(super) fn error_msg(&mut self, kind: DiagnosticKind, message: &str) {
self.error_impl(kind, Some(message));
pub(super) fn error_msg(&mut self, kind: DiagnosticKind, message: impl Into<String>) {
let Some((range, suppression)) = self.get_error_ranges() else {
return;
};
self.diagnostics
.report(kind, range)
.message(message)
.suppression_range(suppression)
.emit();
}

pub(super) fn error_and_bump(&mut self, kind: DiagnosticKind) {
self.error(kind);
self.bump_as_error();
}

pub(super) fn error_and_bump_msg(&mut self, kind: DiagnosticKind, message: &str) {
pub(super) fn error_and_bump_msg(&mut self, kind: DiagnosticKind, message: impl Into<String>) {
self.error_msg(kind, message);
self.bump_as_error();
}
Expand Down Expand Up @@ -359,14 +353,11 @@ impl<'src> Parser<'src> {
true
}

fn at_def_start(&mut self) -> bool {
pub(super) fn at_def_start(&mut self) -> bool {
let kind = self.peek();
// Named def: UpperIdent followed by =
if kind == SyntaxKind::Id && self.peek_nth(1) == SyntaxKind::Equals {
return true;
}
// Anonymous def: tokens that can validly start a root-level expression
// (excludes LowerIdent, Dot, Negation which only make sense inside trees)
ROOT_EXPR_FIRST.contains(kind)
}

Expand Down Expand Up @@ -400,8 +391,6 @@ impl<'src> Parser<'src> {
self.delimiter_stack.pop()
}

/// Error for unclosed delimiters - uses full span from opening to current position.
/// This enables proper cascading error suppression.
pub(super) fn error_unclosed_delimiter(
&mut self,
kind: DiagnosticKind,
Expand All @@ -410,12 +399,10 @@ impl<'src> Parser<'src> {
open_range: TextRange,
) {
let current = self.current_span();
let pos = current.start();
if self.last_diagnostic_pos == Some(pos) {
if !self.should_report(current.start()) {
return;
}
self.last_diagnostic_pos = Some(pos);
// Full span from opening delimiter to current position for suppression
// Use full range for easier downstream error suppression
let full_range = TextRange::new(open_range.start(), current.end());
self.diagnostics
.report(kind, full_range)
Expand All @@ -425,12 +412,11 @@ impl<'src> Parser<'src> {
}

pub(super) fn last_non_trivia_end(&self) -> Option<TextSize> {
for i in (0..self.pos).rev() {
if !self.tokens[i].kind.is_trivia() {
return Some(self.tokens[i].span.end());
}
}
None
self.tokens[..self.pos]
.iter()
.rev()
.find(|t| !t.kind.is_trivia())
.map(|t| t.span.end())
}

pub(super) fn error_with_fix(
Expand All @@ -441,11 +427,9 @@ impl<'src> Parser<'src> {
fix_description: impl Into<String>,
fix_replacement: impl Into<String>,
) {
let pos = range.start();
if self.last_diagnostic_pos == Some(pos) {
if !self.should_report(range.start()) {
return;
}
self.last_diagnostic_pos = Some(pos);
self.diagnostics
.report(kind, range)
.message(message)
Expand Down