radiance · commit

perf(lang): Narrow speculative parser snapshots

a084814327fdb33b1827f62b1a57dbbf887d43102d6ea048dd434937cad69ba2

Save only parser fields that speculative parsing can mutate. Avoid copying the fixed parser error array for generic arguments, returns, and panic expressions.

Alexis Sellier committed 20 days ago 1 parent 88ab8cc1

lib/std/lang/parser.rad +23 -3

    count: u32,
}

/// Snapshot of parser state for speculative parsing.
record SavedState {
    parser: Parser,
    /// Scanner position before speculative parsing.
    scanner: scanner::Scanner,
    /// Current token before speculative parsing.
    current: scanner::Token,
    /// Previous token before speculative parsing.
    previous: scanner::Token,
    /// Number of parser errors before speculative parsing.
    /// Error entries at or above this count are inactive.
    errorCount: u32,
    /// Parsing context before speculative parsing.
    context: Context,
    /// Arena position before speculative parsing.
    arena: u32,
    /// Next node identifier before speculative parsing.
    nextId: u32,
}

/// Operator metadata for precedence climbing.
record OpInfo {

}

/// Save parser state for speculative parsing.
fn saveState(p: *Parser) -> SavedState {
    return SavedState {
        parser: *p,
        scanner: p.scanner,
        current: p.current,
        previous: p.previous,
        errorCount: p.errors.count,
        context: p.context,
        arena: alloc::save(&p.arena.arena),
        nextId: p.arena.nextId,
    };
}

/// Restore parser state from a snapshot, fully undoing any
/// side effects of a failed speculative parse.
fn restoreState(p: *mut Parser, s: *SavedState) {
    set *p = s.parser;
    set p.scanner = s.scanner;
    set p.current = s.current;
    set p.previous = s.previous;
    set p.errors.count = s.errorCount;
    set p.context = s.context;
    alloc::restore(&mut p.arena.arena, s.arena);
    set p.arena.nextId = s.nextId;
}

/// Report a parser error.

85	85		count: u32,
86	86		}
87	87
88	88		/// Snapshot of parser state for speculative parsing.
89	89		record SavedState {
90		-	parser: Parser,
	90	+	/// Scanner position before speculative parsing.
	91	+	scanner: scanner::Scanner,
	92	+	/// Current token before speculative parsing.
	93	+	current: scanner::Token,
	94	+	/// Previous token before speculative parsing.
	95	+	previous: scanner::Token,
	96	+	/// Number of parser errors before speculative parsing.
	97	+	/// Error entries at or above this count are inactive.
	98	+	errorCount: u32,
	99	+	/// Parsing context before speculative parsing.
	100	+	context: Context,
	101	+	/// Arena position before speculative parsing.
91	102		arena: u32,
	103	+	/// Next node identifier before speculative parsing.
92	104		nextId: u32,
93	105		}
94	106
95	107		/// Operator metadata for precedence climbing.
96	108		record OpInfo {

1116	1128		}
1117	1129
1118	1130		/// Save parser state for speculative parsing.
1119	1131		fn saveState(p: *Parser) -> SavedState {
1120	1132		return SavedState {
1121		-	parser: *p,
	1133	+	scanner: p.scanner,
	1134	+	current: p.current,
	1135	+	previous: p.previous,
	1136	+	errorCount: p.errors.count,
	1137	+	context: p.context,
1122	1138		arena: alloc::save(&p.arena.arena),
1123	1139		nextId: p.arena.nextId,
1124	1140		};
1125	1141		}
1126	1142
1127	1143		/// Restore parser state from a snapshot, fully undoing any
1128	1144		/// side effects of a failed speculative parse.
1129	1145		fn restoreState(p: mut Parser, s: SavedState) {
1130		-	set *p = s.parser;
	1146	+	set p.scanner = s.scanner;
	1147	+	set p.current = s.current;
	1148	+	set p.previous = s.previous;
	1149	+	set p.errors.count = s.errorCount;
	1150	+	set p.context = s.context;
1131	1151		alloc::restore(&mut p.arena.arena, s.arena);
1132	1152		set p.arena.nextId = s.nextId;
1133	1153		}
1134	1154
1135	1155		/// Report a parser error.