crates/lang/src/lst_parser.rs

@@ -1,6 +1,12 @@
 use drop_bomb::DropBomb;
 
-use self::{error::SyntaxError, events::Event, input::Input, syntax_kind::SyntaxKind};
+use self::{
+    error::SyntaxError,
+    events::{Event, NodeKind},
+    input::Input,
+    syntax_kind::SyntaxKind,
+};
+use std::cell::Cell;
 
 pub mod syntax_kind;
 #[cfg(test)]
@@ -12,11 +18,13 @@ pub mod grammar;
 pub mod input;
 pub mod output;
 
+const PARSER_STEP_LIMIT: u32 = 4096;
+
 pub struct Parser<'src, 'toks> {
     input: Input<'src, 'toks>,
     pos: usize,
     events: Vec<Event>,
-    errors: Vec<SyntaxError>,
+    steps: Cell<u32>,
 }
 
 impl<'src, 'toks> Parser<'src, 'toks> {
@@ -25,15 +33,16 @@ impl<'src, 'toks> Parser<'src, 'toks> {
             input,
             pos: 0,
             events: Vec::new(),
-            errors: Vec::new(),
+            steps: Cell::new(0),
         }
     }
 
-    pub fn finish(self) -> (Vec<Event>, Vec<SyntaxError>) {
-        (self.events, self.errors)
+    pub fn finish(self) -> Vec<Event> {
+        self.events
     }
 
     pub(crate) fn nth(&self, n: usize) -> SyntaxKind {
+        self.step();
         self.input.kind(self.pos + n)
     }
 
@@ -44,6 +53,7 @@ impl<'src, 'toks> Parser<'src, 'toks> {
     }
 
     pub(crate) fn current(&self) -> SyntaxKind {
+        self.step();
         self.input.kind(self.pos)
     }
 
@@ -80,6 +90,12 @@ impl<'src, 'toks> Parser<'src, 'toks> {
     fn push_ev(&mut self, event: Event) {
         self.events.push(event)
     }
+
+    fn step(&self) {
+        let steps = self.steps.get();
+        assert!(steps <= PARSER_STEP_LIMIT, "the parser seems stuck...");
+        self.steps.set(steps + 1);
+    }
 }
 
 pub(crate) struct Marker {
@@ -95,12 +111,13 @@ impl Marker {
         }
     }
 
-    pub(crate) fn complete(mut self, p: &mut Parser<'_, '_>, kind: SyntaxKind) -> CompletedMarker {
+    fn complete_node(mut self, p: &mut Parser, kind: NodeKind) -> CompletedMarker {
         self.bomb.defuse();
         match &mut p.events[self.pos] {
-            Event::Start { kind: slot, .. } => *slot = kind,
+            Event::Start { kind: slot, .. } => *slot = kind.clone(),
             _ => unreachable!(),
         }
+
         p.push_ev(Event::Finish);
 
         CompletedMarker {
@@ -109,9 +126,12 @@ impl Marker {
         }
     }
 
-    pub(crate) fn complete_err(mut self, p: &mut Parser, kind: SyntaxError) -> CompletedMarker {
-        p.errors.push(kind);
-        self.complete(p, SyntaxKind::PARSE_ERR)
+    pub(crate) fn complete(self, p: &mut Parser<'_, '_>, kind: SyntaxKind) -> CompletedMarker {
+        self.complete_node(p, NodeKind::Syntax(kind))
+    }
+
+    pub(crate) fn error(self, p: &mut Parser, kind: SyntaxError) -> CompletedMarker {
+        self.complete_node(p, NodeKind::Error(kind))
     }
 
     pub(crate) fn abandon(mut self, p: &mut Parser<'_, '_>) {
@@ -119,7 +139,7 @@ impl Marker {
         if self.pos == p.events.len() - 1 {
             match p.events.pop() {
                 Some(Event::Start {
-                    kind: SyntaxKind::TOMBSTONE,
+                    kind: NodeKind::Syntax(SyntaxKind::TOMBSTONE),
                     forward_parent: None,
                 }) => (),
                 _ => unreachable!(),
@@ -130,7 +150,7 @@ impl Marker {
 
 pub(crate) struct CompletedMarker {
     pos: usize,
-    kind: SyntaxKind,
+    kind: NodeKind,
 }
 
 impl CompletedMarker {

crates/lang/src/lst_parser/error.rs

@@ -1,6 +1,6 @@
 use crate::lst_parser::syntax_kind::SyntaxKind;
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq, Eq, Clone)]
 pub enum SyntaxError {
     Expected(Vec<SyntaxKind>),
     PipelineNeedsSink,

crates/lang/src/lst_parser/events.rs

@@ -1,22 +1,69 @@
 use crate::lst_parser::syntax_kind::SyntaxKind;
 
+use super::error::SyntaxError;
+
 #[derive(Debug)]
 pub enum Event {
     Start {
-        kind: SyntaxKind,
+        kind: NodeKind,
         forward_parent: Option<usize>,
     },
     Finish,
     Eat {
         count: usize,
     },
-    Error,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum NodeKind {
+    Syntax(SyntaxKind),
+    Error(SyntaxError),
+}
+
+impl NodeKind {
+    pub fn is_syntax(&self) -> bool {
+        matches!(self, Self::Syntax(_))
+    }
+
+    pub fn is_error(&self) -> bool {
+        matches!(self, Self::Error(_))
+    }
+}
+
+impl From<SyntaxKind> for NodeKind {
+    fn from(value: SyntaxKind) -> Self {
+        NodeKind::Syntax(value)
+    }
+}
+
+impl From<SyntaxError> for NodeKind {
+    fn from(value: SyntaxError) -> Self {
+        NodeKind::Error(value)
+    }
+}
+
+impl PartialEq<SyntaxKind> for NodeKind {
+    fn eq(&self, other: &SyntaxKind) -> bool {
+        match self {
+            NodeKind::Syntax(s) => s == other,
+            NodeKind::Error(_) => false,
+        }
+    }
+}
+
+impl PartialEq<SyntaxError> for NodeKind {
+    fn eq(&self, other: &SyntaxError) -> bool {
+        match self {
+            NodeKind::Syntax(_) => false,
+            NodeKind::Error(e) => e == other,
+        }
+    }
 }
 
 impl Event {
     pub(crate) fn tombstone() -> Self {
         Self::Start {
-            kind: SyntaxKind::TOMBSTONE,
+            kind: SyntaxKind::TOMBSTONE.into(),
             forward_parent: None,
         }
     }

crates/lang/src/lst_parser/grammar/expression.rs

@@ -35,7 +35,7 @@ pub fn parenthesized_expr(p: &mut Parser) -> Option<CompletedMarker> {
         let par_expr = p.start("parenthesized");
         expression(p, false);
         if !p.eat(R_PAREN) {
-            return Some(par_expr.complete_err(p, SyntaxError::Expected(vec![R_PAREN])));
+            return Some(par_expr.error(p, SyntaxError::Expected(vec![R_PAREN])));
         }
 
         return Some(par_expr.complete(p, PARENTHESIZED_EXPR));

crates/lang/src/lst_parser/grammar/expression/collection/vec.rs

@@ -21,7 +21,7 @@ pub fn vec_matrix_list(p: &mut Parser) -> CompletedMarker {
         start.complete(p, LIST)
     } else {
         row_start.abandon(p);
-        start.complete_err(p, SyntaxError::Expected(vec![EXPR, R_BRACK]))
+        start.error(p, SyntaxError::Expected(vec![EXPR, R_BRACK]))
     }
 }
 

crates/lang/src/lst_parser/grammar/expression/pipeline.rs

@@ -16,7 +16,7 @@ pub fn pipeline(p: &mut Parser, start_expr: CompletedMarker) -> Option<Completed
 
     loop {
         if expression(p, true).is_none() {
-            return Some(pipeline_marker.complete_err(p, SyntaxError::PipelineNeedsSink));
+            return Some(pipeline_marker.error(p, SyntaxError::PipelineNeedsSink));
         }
         if !pipe(p) {
             return Some(pipeline_marker.complete(p, PIPELINE));

crates/lang/src/lst_parser/output.rs

@@ -1,3 +1,4 @@
+use clap::builder;
 use owo_colors::{unset_override, OwoColorize};
 use rowan::{GreenNode, GreenNodeBuilder, GreenNodeData, GreenTokenData, Language, NodeOrToken};
 use std::mem;
@@ -7,7 +8,10 @@ use crate::lst_parser::{
     syntax_kind::{Lang, SyntaxKind},
 };
 
-use super::{error::SyntaxError, events::Event};
+use super::{
+    error::SyntaxError,
+    events::{Event, NodeKind},
+};
 
 pub struct Output {
     pub green_node: GreenNode,
@@ -23,6 +27,7 @@ impl std::fmt::Debug for Output {
     }
 }
 
+const INDENT_STR: &str = "    ";
 fn debug_print_green_node(
     node: NodeOrToken<&GreenNodeData, &GreenTokenData>,
     f: &mut dyn std::fmt::Write,
@@ -31,7 +36,7 @@ fn debug_print_green_node(
     colored: bool,
 ) -> std::fmt::Result {
     for _ in 0..lvl {
-        f.write_str("    ")?;
+        f.write_str(INDENT_STR)?;
     }
 
     if !colored {
@@ -68,7 +73,7 @@ fn debug_print_green_node(
                 debug_print_green_node(c, f, lvl + 1, errs, colored)?;
             }
             for _ in 0..lvl {
-                f.write_str("    ")?;
+                f.write_str(INDENT_STR)?;
             }
             if kind != SyntaxKind::PARSE_ERR {
                 write!(f, "{}", "}\n".yellow())
@@ -123,10 +128,11 @@ impl Output {
     }
     pub fn from_parser_output(
         mut raw_toks: Vec<(SyntaxKind, &str)>,
-        (mut events, errs): (Vec<Event>, Vec<SyntaxError>),
+        mut events: Vec<Event>,
     ) -> Self {
         let mut builder = GreenNodeBuilder::new();
         let mut fw_parents = Vec::new();
+        let mut errors = Vec::new();
         raw_toks.reverse();
 
         for i in 0..events.len() {
@@ -170,8 +176,15 @@ impl Output {
                     }
 
                     for kind in fw_parents.drain(..).rev() {
-                        if kind != SyntaxKind::TOMBSTONE {
-                            builder.start_node(kind.into());
+                        match kind {
+                            NodeKind::Syntax(kind) if kind != SyntaxKind::TOMBSTONE => {
+                                builder.start_node(kind.into())
+                            }
+                            NodeKind::Error(err) => {
+                                errors.push(err);
+                                builder.start_node(SyntaxKind::PARSE_ERR.into())
+                            }
+                            _ => {}
                         }
                     }
                 }
@@ -180,13 +193,12 @@ impl Output {
                     let (tok, text): (SyntaxKind, &str) = raw_toks.pop().unwrap();
                     builder.token(tok.into(), text);
                 }),
-                Event::Error => todo!(),
             }
         }
 
         Self {
             green_node: builder.finish(),
-            errors: errs,
+            errors,
         }
     }
 }

flake.nix

@@ -27,8 +27,7 @@
         pkgs = nixpkgs.legacyPackages.${system};
         toolchain = with fenix.packages.${system};
           combine [
-            default.toolchain
-            rust-analyzer
+            complete.toolchain
           ];
       in {
         default = devenv.lib.mkShell {
@@ -39,24 +38,14 @@
               config,
               ...
             }: {
-              # languages.rust = {
-              #   enable = true;
-              #   channel = "nightly";
-              #   components = [
-              #     "rustc"
-              #     "cargo"
-              #     "clippy"
-              #     "rustfmt"
-              #     "rust-src"
-              #     "rust-analyzer"
-              #   ];
-              # };
-
               pre-commit.hooks = {
                 clippy.enable = false;
                 rustfmt.enable = true;
               };
 
+              env = {
+                RUST_BACKTRACE = 1;
+              };
               packages = with pkgs; [
                 just
                 nushell