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fix: recursion depth tracking and sequence quantifier navigation #227

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Merged
zharinov merged 1 commit into from
Jan 3, 2026
Merged

fix: recursion depth tracking and sequence quantifier navigation #227

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1 change: 1 addition & 0 deletions crates/plotnik-lib/src/compile/navigation.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -91,6 +91,7 @@ pub fn repeat_nav_for(first_nav: Option<Nav>) -> Option<Nav> {
Some(Nav::DownSkip) => Some(Nav::NextSkip),
Some(Nav::DownExact) => Some(Nav::NextExact),
Some(nav @ (Nav::Next | Nav::NextSkip | Nav::NextExact)) => Some(nav),
None | Some(Nav::Stay) => Some(Nav::Next),
_ => None,
}
}
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11 changes: 11 additions & 0 deletions crates/plotnik-lib/src/emit/codegen_tests.rs
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Expand Up @@ -235,6 +235,17 @@ fn quantifiers_repeat_navigation() {
"#});
}

/// Regression test: sequence quantifiers in called definitions need sibling navigation.
/// Previously, `{...}*` compiled without navigation, causing infinite loops.
#[test]
fn quantifiers_sequence_in_called_def() {
snap!(indoc! {r#"
Item = (identifier) @name
Collect = {(Item) @item}* @items
Test = (parent (Collect))
"#});
}

// ============================================================================
// 5. SEQUENCES
// ============================================================================
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2 changes: 1 addition & 1 deletion ...nik-lib/src/emit/snapshots/plotnik_lib__emit__codegen_tests__captures_wrapper_struct.snap
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Expand Up @@ -59,7 +59,7 @@ Test:
25 ε [EndObj Push] 37
27 ε [EndObj Set(M2)] 25
29 ▷ (number) [Node Set(M1)] 27
31 (identifier) [Node Set(M0)] 29
31 ▷ (identifier) [Node Set(M0)] 29
33 ε [Obj] 31
35 ε [Obj] 33
37 ε 35, 11
2 changes: 1 addition & 1 deletion ...es/plotnik-lib/src/emit/snapshots/plotnik_lib__emit__codegen_tests__quantifiers_plus.snap
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Expand Up @@ -37,5 +37,5 @@ Test:
08 ▶
09 ε [EndObj] 08
11 ε [EndArr Set(M0)] 09
13 (identifier) [Node Push] 15
13 ▷ (identifier) [Node Push] 15
15 ε 13, 11
2 changes: 1 addition & 1 deletion ...-lib/src/emit/snapshots/plotnik_lib__emit__codegen_tests__quantifiers_plus_nongreedy.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -37,5 +37,5 @@ Test:
08 ▶
09 ε [EndObj] 08
11 ε [EndArr Set(M0)] 09
13 (identifier) [Node Push] 15
13 ▷ (identifier) [Node Push] 15
15 ε 11, 13
80 changes: 80 additions & 0 deletions .../emit/snapshots/plotnik_lib__emit__codegen_tests__quantifiers_sequence_in_called_def.snap
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@@ -0,0 +1,80 @@
---
source: crates/plotnik-lib/src/emit/codegen_tests.rs
---
Item = (identifier) @name
Collect = {(Item) @item}* @items
Test = (parent (Collect))
---
[flags]
linked = false

[strings]
S0 "Beauty will save the world"
S1 "name"
S2 "item"
S3 "items"
S4 "Item"
S5 "Collect"
S6 "Test"
S7 "identifier"
S8 "parent"

[type_defs]
T0 = <Node>
T1 = Struct M0:1 ; { name }
T2 = Struct M1:2 ; { name, item }
T3 = ArrayStar(T2) ; T2*
T4 = Struct M3:1 ; { items }

[type_members]
M0: S1 → T0 ; name: <Node>
M1: S1 → T0 ; name: <Node>
M2: S2 → T0 ; item: <Node>
M3: S3 → T3 ; items: T3

[type_names]
N0: S4 → T1 ; Item
N1: S5 → T4 ; Collect
N2: S6 → T4 ; Test

[entrypoints]
Collect = 09 :: T4
Item = 01 :: T1
Test = 16 :: T4

[transitions]
00 ε ◼

Item:
01 ε 02
02 ε [Obj] 04
04 (identifier) [Node Set(M0)] 06
06 ε [EndObj] 08
08 ▶

Collect:
09 ε 10
10 ε [Obj] 12
12 ε [Arr] 14
14 ε 35, 28

Test:
16 ε 17
17 ε [Obj] 19
19 (parent) 20
20 ▽ (Collect) 21 ⯇
21 △ 22
22 ε [EndObj] 24
24 ▶
25 ▶
26 ε [EndObj] 25
28 ε [EndArr Set(M3)] 26
30 ε [EndObj Push] 44
32 ε [Set(M2)] 30
34 (Item) 32 ⯇
35 ε [Obj] 34
37 ε [EndObj Push] 44
39 ε [Set(M2)] 37
41 ▷ (Item) 39 ⯇
42 ε [Obj] 41
44 ε 42, 28
2 changes: 1 addition & 1 deletion ...es/plotnik-lib/src/emit/snapshots/plotnik_lib__emit__codegen_tests__quantifiers_star.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -38,5 +38,5 @@ Test:
09 ε [EndObj] 08
11 ε [EndArr Set(M0)] 09
13 (identifier) [Node Push] 17
15 (identifier) [Node Push] 17
15 ▷ (identifier) [Node Push] 17
17 ε 15, 11
2 changes: 1 addition & 1 deletion ...-lib/src/emit/snapshots/plotnik_lib__emit__codegen_tests__quantifiers_star_nongreedy.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -38,5 +38,5 @@ Test:
09 ε [EndObj] 08
11 ε [EndArr Set(M0)] 09
13 (identifier) [Node Push] 17
15 (identifier) [Node Push] 17
15 ▷ (identifier) [Node Push] 17
17 ε 11, 15
2 changes: 2 additions & 0 deletions crates/plotnik-lib/src/engine/checkpoint.rs
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Expand Up @@ -13,6 +13,8 @@ pub struct Checkpoint {
pub effect_watermark: usize,
/// Frame arena state at checkpoint.
pub frame_index: Option<u32>,
/// Recursion depth at checkpoint.
pub recursion_depth: u32,
/// Resume point (raw step index).
pub ip: u16,
}
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11 changes: 9 additions & 2 deletions crates/plotnik-lib/src/engine/vm.rs
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Expand Up @@ -133,9 +133,10 @@ impl<'t> VM<'t> {
self.emit_effect(effect_op, tracer);
}

self.matched_node = None;

// Only clear matched_node for non-epsilon transitions.
// For epsilon, preserve matched_node from previous match or return.
if !m.is_epsilon() {
self.matched_node = None;
self.navigate_and_match(m, tracer)?;
}

Expand Down Expand Up @@ -213,6 +214,7 @@ impl<'t> VM<'t> {
descendant_index: self.cursor.descendant_index(),
effect_watermark: self.effects.len(),
frame_index: self.frames.current(),
recursion_depth: self.recursion_depth,
ip: m.successor(i).get(),
});
tracer.trace_checkpoint_created(self.ip);
Expand Down Expand Up @@ -296,6 +298,10 @@ impl<'t> VM<'t> {
// Prune frames (O(1) amortized)
self.frames.prune(self.checkpoints.max_frame_ref());

// Set matched_node to current cursor position so effects after
// a Call can capture the node that the callee matched.
self.matched_node = Some(self.cursor.node());

self.ip = return_addr;
Ok(())
}
Expand All @@ -306,6 +312,7 @@ impl<'t> VM<'t> {
self.cursor.goto_descendant(cp.descendant_index);
self.effects.truncate(cp.effect_watermark);
self.frames.restore(cp.frame_index);
self.recursion_depth = cp.recursion_depth;
self.ip = cp.ip;
Err(RuntimeError::Backtracked)
}
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