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Merged
ehwan merged 1 commit into from
Jun 19, 2026
Merged

Remove %trace directive and runtime tracing functionality #60

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1 change: 0 additions & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -166,7 +166,6 @@ let mut context = ExprContext::new();

context.expected_token(); // Returns the expected symbols for the current state
context.can_feed(&token); // Checks if a terminal can be fed next
context.trace(); // Retrieves active `%trace` non-terminals
println!("{}", context.backtrace()); // Prints the stack trace of parser states
println!("{}", context); // Formats the state tree (requires 'tree' feature)
```
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13 changes: 0 additions & 13 deletions SYNTAX.md
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Expand Up @@ -15,7 +15,6 @@ This document provides a comprehensive guide to the grammar definition syntax us
- [Reduce Actions](#reduceaction-optional)
- [Accessing Data in Reduce Actions](#accessing-token-data-in-reduceaction)
- [Exclamation Mark (`!`) Value Discard](#exclamation-mark-)
- [Tracing Non-Terminals (`%trace`)](#tracing-non-terminals)
- [Start Symbol (`%start`)](#start-symbol-must-defined)
- [Userdata Type (`%userdata`)](#userdata-type-optional)
- [Conflict Resolution](#resolving-conflicts)
Expand Down Expand Up @@ -351,18 +350,6 @@ Expr(i32) : '('! Expr ')'! ;

---

## Tracing Non-Terminals

```
%trace NonTerm1 NonTerm2 ... ;
```

Registers non-terminals for tracing. When registered, you can query the active parsing goals at runtime using `context.trace(&parser)`, which returns a `HashSet<NonTerminals>`.

Additionally, tracing prevents the optimization engine from merging or optimizing away these non-terminal states.

---

## Start Symbol (Must Defined)

```
Expand Down
106 changes: 0 additions & 106 deletions rusty_lr_core/src/parser/deterministic/context.rs
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Expand Up @@ -754,112 +754,6 @@ impl<
)
}

/// Get set of `%trace` non-terminal symbols that current context is trying to parse.
///
/// The order of the returned set does not mean anything.
/// If the current context is attempting to recognize following grammar:
///
/// Chunk -> Statement -> IfStatement -> ReturnStatement -> ...
///
/// Then the returned set will be:
/// [`Chunk`, `Statement`, `IfStatement`, `ReturnStatement`]
/// Get set of `%trace` non-terminal symbols that current context is trying to parse.
///
/// The order of the returned set does not mean anything.
/// If the current context is attempting to recognize following grammar:
///
/// Chunk -> Statement -> IfStatement -> ReturnStatement -> ...
///
/// Then the returned set will be:
/// [`Chunk`, `Statement`, `IfStatement`, `ReturnStatement`]
pub fn trace(&self) -> crate::hash::HashSet<Data::NonTerm>
where
P::NonTerm: Hash + Eq,
{
use crate::hash::HashSet;
use crate::token::Token;

let rules = P::get_rules();
let states = P::get_states();

let mut zero_shifted_rules = BTreeSet::new();
let mut non_zero_shifted_rules = BTreeSet::new();
{
let last_state = &states[self.state_stack.last().unwrap().into_usize()];
for rule in last_state.get_rules().iter() {
if rule.shifted == 0 {
zero_shifted_rules.insert(rule.rule);
} else {
non_zero_shifted_rules.insert((rule.rule, rule.shifted));
}
}
}

let mut ret: HashSet<Data::NonTerm> = Default::default();

for &state_idx in self.state_stack.iter().rev() {
let state = &states[state_idx.into_usize()];
let ruleset = state.get_rules();

// insert new shifted rule that brings zero_shifted rules in this state
let mut new_zero_shifted_rules = Vec::new();
loop {
let zero_len0 = zero_shifted_rules.len();
let nonzero_len0 = non_zero_shifted_rules.len();

new_zero_shifted_rules.clear();

for &zero_rule in zero_shifted_rules.iter() {
let nonterm0 = rules[zero_rule].name;
for rule in ruleset.iter() {
let prod_rule = &rules[rule.rule];
if let Some(Token::NonTerm(nonterm)) = prod_rule.rule.get(rule.shifted) {
if &nonterm0 == nonterm {
if rule.shifted == 0 {
new_zero_shifted_rules.push(rule.rule);
} else {
// insert new shifted rule
non_zero_shifted_rules.insert((rule.rule, rule.shifted));
}
}
}
}
}
zero_shifted_rules.extend(new_zero_shifted_rules.iter().copied());

if zero_len0 == zero_shifted_rules.len()
&& nonzero_len0 == non_zero_shifted_rules.len()
{
break;
}
}

// push nonterminal of zero-shifted-rules into backtrace vector
for &zero_rule in zero_shifted_rules.iter() {
let nonterm0 = rules[zero_rule].name;
// do not insert auto-generated nonterminals
// since user don't need to know about them
if nonterm0.is_trace() {
ret.insert(nonterm0);
}
}

// shift to next state
zero_shifted_rules.clear();
let mut new_non_zero_shifted_rules = BTreeSet::new();
for (rule, shifted) in non_zero_shifted_rules.into_iter() {
if shifted == 1 {
zero_shifted_rules.insert(rule);
} else {
new_non_zero_shifted_rules.insert((rule, shifted - 1));
}
}
non_zero_shifted_rules = new_non_zero_shifted_rules;
}

ret
}

/// Get backtrace information for current state.
/// What current state is trying to parse, and where it comes from.
pub fn backtrace(&self) -> crate::Backtrace<P::TermClass, P::NonTerm>
Expand Down
110 changes: 0 additions & 110 deletions rusty_lr_core/src/parser/nondeterministic/context.rs
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Expand Up @@ -562,116 +562,6 @@ impl<
})
}

fn trace_impl(&self, node: usize) -> crate::hash::HashSet<Data::NonTerm>
where
Data::NonTerm: Eq + Hash,
{
use crate::hash::HashSet;
use crate::token::Token;
use std::collections::BTreeSet;

let rules = P::get_rules();
let states = P::get_states();

let mut zero_shifted_rules = BTreeSet::new();
let mut non_zero_shifted_rules = BTreeSet::new();
{
let last_state = &states[self.state(node)];
for rule in last_state.get_rules().iter() {
if rule.shifted == 0 {
zero_shifted_rules.insert(rule.rule);
} else {
non_zero_shifted_rules.insert((rule.rule, rule.shifted));
}
}
}

let mut ret: HashSet<Data::NonTerm> = Default::default();

for state in self.state_iter(node).chain(std::iter::once(0)) {
let state = &states[state];
let ruleset = &state.get_rules();

// insert new shifted rule that brings zero_shifted rules in this state
let mut new_zero_shifted_rules = Vec::new();
loop {
let zero_len0 = zero_shifted_rules.len();
let nonzero_len0 = non_zero_shifted_rules.len();

new_zero_shifted_rules.clear();

for &zero_rule in zero_shifted_rules.iter() {
let nonterm0 = rules[zero_rule].name;
for rule in ruleset.iter() {
let prod_rule = &rules[rule.rule];
if let Some(Token::NonTerm(nonterm)) = prod_rule.rule.get(rule.shifted) {
if &nonterm0 == nonterm {
if rule.shifted == 0 {
new_zero_shifted_rules.push(rule.rule);
} else {
// insert new shifted rule
non_zero_shifted_rules.insert((rule.rule, rule.shifted));
}
}
}
}
}
zero_shifted_rules.extend(new_zero_shifted_rules.iter().copied());

if zero_len0 == zero_shifted_rules.len()
&& nonzero_len0 == non_zero_shifted_rules.len()
{
break;
}
}

// push nonterminal of zero-shifted-rules into backtrace vector
for &zero_rule in zero_shifted_rules.iter() {
let nonterm0 = rules[zero_rule].name;
// do not insert auto-generated nonterminals
// since user don't need to know about them
if nonterm0.is_trace() {
ret.insert(nonterm0);
}
}

// shift to next state
zero_shifted_rules.clear();
let mut new_non_zero_shifted_rules = BTreeSet::new();
for (rule, shifted) in non_zero_shifted_rules.into_iter() {
if shifted == 1 {
zero_shifted_rules.insert(rule);
} else {
new_non_zero_shifted_rules.insert((rule, shifted - 1));
}
}
non_zero_shifted_rules = new_non_zero_shifted_rules;
}

ret
}

/// Get set of `%trace` non-terminal symbols that current context is trying to parse.
///
/// The order of the returned set does not mean anything.
/// If the current context is attempting to recognize following grammar:
///
/// Chunk -> Statement -> IfStatement -> ReturnStatement -> ...
///
/// Then the returned set will be:
/// [`Chunk`, `Statement`, `IfStatement`, `ReturnStatement`]
pub fn trace(&self) -> crate::hash::HashSet<Data::NonTerm>
where
Data::NonTerm: Copy + Eq + std::hash::Hash + NonTerminal,
{
let mut ret: crate::hash::HashSet<Data::NonTerm> = Default::default();
for &node in self.current_nodes.iter() {
let set = self.trace_impl(node);
ret.extend(set.into_iter());
}
ret
}

fn backtrace_impl(&self, node: usize) -> crate::Backtrace<P::TermClass, P::NonTerm>
where
P::Term: Clone,
Expand Down
2 changes: 0 additions & 2 deletions rusty_lr_core/src/parser/nonterminal.rs
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Expand Up @@ -9,8 +9,6 @@ pub trait NonTerminal: Copy {
fn is_augmented(&self) -> bool {
self.nonterm_type() == Some(NonTerminalType::Augmented)
}
/// whether this non-terminal is set as %trace
fn is_trace(&self) -> bool;

/// for internal use only;
/// If this non-terminal is auto-generated, gets the pattern where this non-terminal was generated from.
Expand Down
16 changes: 0 additions & 16 deletions rusty_lr_parser/src/emit.rs
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Expand Up @@ -440,7 +440,6 @@ impl Grammar {

let mut comma_separated_variants = TokenStream::new();
let mut case_as_str = TokenStream::new();
let mut nonterm_trait_is_trace_case = TokenStream::new();
let mut nonterm_type_case = TokenStream::new();
for nonterm in self.nonterminals.iter() {
let name = utils::ident_from_located(
Expand All @@ -459,16 +458,6 @@ impl Grammar {
#enum_typename::#name => #display_str,
});

let is_trace = if nonterm.name.value().as_str() == utils::AUGMENTED_NAME {
false
} else {
// non-term is auto-generated if nonterm.regex_span.is_some()
nonterm.trace
};

nonterm_trait_is_trace_case.extend(quote! {
#enum_typename::#name => #is_trace,
});
if let Some(enum_name) = &nonterm.nonterm_type {
let enum_name = format!("{:?}", enum_name);
let enum_name = Ident::new(&enum_name, Span::call_site());
Expand Down Expand Up @@ -523,11 +512,6 @@ impl Grammar {
#case_as_str
}
}
fn is_trace(&self) -> bool {
match self {
#nonterm_trait_is_trace_case
}
}
fn nonterm_type(&self) -> Option<#module_prefix::parser::nonterminal::NonTerminalType> {
match self {
#nonterm_type_case
Expand Down
13 changes: 0 additions & 13 deletions rusty_lr_parser/src/grammar.rs
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Expand Up @@ -1093,7 +1093,6 @@ impl Grammar {
ruletype_boxed: is_boxed,
rules: Vec::new(), // production rules will be added later
root_location: None,
trace: false,
protected: false,
nonterm_type: None,
};
Expand Down Expand Up @@ -1835,7 +1834,6 @@ impl Grammar {
ruletype_boxed: false,
root_location: None,
rules: vec![augmented_rule],
trace: false,
protected: true,
nonterm_type: Some(rusty_lr_core::parser::nonterminal::NonTerminalType::Augmented),
};
Expand All @@ -1849,17 +1847,6 @@ impl Grammar {
.insert(augmented_name.into_value(), augmented_idx);
}

// set `%trace`
for trace in grammar_args.traces.into_iter() {
if let Some(&nonterm_idx) = grammar.nonterminals_index.get(trace.value().as_str()) {
grammar.nonterminals[nonterm_idx].trace = true;
grammar.nonterminals[nonterm_idx].protected = true;
} else {
return Err(ParseError::NonTerminalNotDefined(trace.location()));
// no such rule
}
}

// initialize terminal classes with one-terminal-one-class
grammar.terminal_class_id.reserve(grammar.terminals.len());
grammar.terminal_classes.reserve(grammar.terminals.len());
Expand Down
3 changes: 1 addition & 2 deletions rusty_lr_parser/src/nonterminal_info.rs
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Expand Up @@ -116,8 +116,7 @@ pub struct NonTerminalInfo {
/// the location of that pattern is stored here for error reporting.
pub(crate) root_location: Option<Location>,

pub(crate) trace: bool,
/// protected from optimization removal; trace rules are always protected
/// protected from optimization removal
pub(crate) protected: bool,

/// if this non-terminal is auto-generated, the pattern that generated this rule.
Expand Down
2 changes: 0 additions & 2 deletions rusty_lr_parser/src/parser/args.rs
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Expand Up @@ -665,7 +665,6 @@ pub struct GrammarArgs {
pub glr: bool,
pub no_optim: bool,
pub dense: bool,
pub traces: Vec<Located<String>>,
pub filter: Vec<(Location, TokenStream)>,
pub location_typename: Vec<(Location, TokenStream)>,

Expand All @@ -688,7 +687,6 @@ impl Default for GrammarArgs {
glr: false,
no_optim: false,
dense: false,
traces: Vec::new(),
filter: Vec::new(),
location_typename: Vec::new(),
error_recovered: Vec::new(),
Expand Down
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