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Implement no associative infix op for precedence!{} #413

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70e19f5
Add no associative infix for precedence!{}
A4-Tacks Aug 8, 2025
d446221
arithmetic_no_associative: add failing test case
kevinmehall Nov 2, 2025
7e0a7e4
Add some right associative failing tests
A4-Tacks Nov 3, 2025
e1df838
Add some nested no associative tests
A4-Tacks Nov 3, 2025
5ceb109
Implement a test passed no associative
A4-Tacks Nov 3, 2025
97ddb2f
Remove debug prints
A4-Tacks Nov 6, 2025
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71 changes: 51 additions & 20 deletions peg-macros/translate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -878,20 +878,36 @@ fn compile_expr(context: &Context, e: &SpannedExpr, result_used: bool) -> TokenS
));
}
(&Expr::Marker(la), &Expr::Marker(ra)) if op.elements.len() >= 3 => {
//infix
let new_prec = match (la, ra) {
(true, false) => prec + 1, // left associative
(false, true) => prec, // right associative
// infix
let (assoc, new_prec) = match (la, ra) {
(true, false) => (true, prec + 1), // left associative
(false, true) => (true, prec), // right associative
(false, false) => (false, prec + 1), // no associative
_ => return report_error(op_span, "precedence rules must use `@` and `(@)` to indicate associativity".to_string())
};
let assoc_prec = if assoc { -1 } else { prec };

let no_assoc_trap = if !assoc {
quote_spanned! { op_span =>
if #prec == __assoc_prec {
::peg::RuleResult::Failed
} else
}
} else {
quote!()
};

post_rules.push(
labeled_seq(context, &op.elements[1..op.elements.len()-1], {
quote_spanned!{ op_span =>
if let ::peg::RuleResult::Matched(__pos, #r_arg) = __recurse(__pos, #new_prec, __state, __err_state) {
#no_assoc_trap
if let ::peg::RuleResult::Matched(__pos, (__assoc_prec_bound, #r_arg)) = __recurse(__pos, #new_prec, __state, __err_state) {
let #l_arg = __infix_result;
__infix_result = #action;
::peg::RuleResult::Matched(__pos, ())
::peg::RuleResult::Matched(
__pos,
__assoc_prec.max(__assoc_prec_bound).max(#assoc_prec),
)
} else { ::peg::RuleResult::Failed }
}
})
Expand All @@ -906,7 +922,7 @@ fn compile_expr(context: &Context, e: &SpannedExpr, result_used: bool) -> TokenS
quote_spanned! { op_span =>
let #l_arg = __infix_result;
__infix_result = #action;
::peg::RuleResult::Matched(__pos, ())
::peg::RuleResult::Matched(__pos, -1)
}
},
));
Expand All @@ -920,8 +936,8 @@ fn compile_expr(context: &Context, e: &SpannedExpr, result_used: bool) -> TokenS
pre_rules.push(
labeled_seq(context, &op.elements[..op.elements.len()-1], {
quote_spanned!{ op_span =>
if let ::peg::RuleResult::Matched(__pos, #r_arg) = __recurse(__pos, #new_prec, __state, __err_state) {
::peg::RuleResult::Matched(__pos, #action)
if let ::peg::RuleResult::Matched(__pos, (__assoc_prec, #r_arg)) = __recurse(__pos, #new_prec, __state, __err_state) {
::peg::RuleResult::Matched(__pos, (__assoc_prec, #action))
} else { ::peg::RuleResult::Failed }
}
})
Expand All @@ -930,7 +946,7 @@ fn compile_expr(context: &Context, e: &SpannedExpr, result_used: bool) -> TokenS
_ => {
// atom
pre_rules.push(labeled_seq(context, &op.elements, {
quote_spanned! { op_span => ::peg::RuleResult::Matched(__pos, #action) }
quote_spanned! { op_span => ::peg::RuleResult::Matched(__pos, (-1, #action)) }
}));
}
};
Expand All @@ -940,8 +956,8 @@ fn compile_expr(context: &Context, e: &SpannedExpr, result_used: bool) -> TokenS
level_code.push(quote_spanned! { span =>
if #prec >= __min_prec {
#(
if let ::peg::RuleResult::Matched(__pos, ()) = #post_rules {
return (__infix_result, ::peg::RuleResult::Matched(__pos, ()));
if let ::peg::RuleResult::Matched(__pos, __assoc_prec) = #post_rules {
return (__infix_result, ::peg::RuleResult::Matched(__pos, __assoc_prec));
}
)*
}
Expand All @@ -967,23 +983,24 @@ fn compile_expr(context: &Context, e: &SpannedExpr, result_used: bool) -> TokenS
err_state: &mut ::peg::error::ErrorState,
min_prec: i32,
lpos: usize,
prefix_atom: &dyn Fn(usize, &mut S, &mut ::peg::error::ErrorState, &dyn Fn(usize, i32, &mut S, &mut ::peg::error::ErrorState) -> ::peg::RuleResult<T>) -> ::peg::RuleResult<T>,
level_code: &dyn Fn(usize, usize, i32, T, &mut S, &mut ::peg::error::ErrorState, &dyn Fn(usize, i32, &mut S, &mut ::peg::error::ErrorState) -> ::peg::RuleResult<T>) -> (T, ::peg::RuleResult<()>),
) -> ::peg::RuleResult<T> {
prefix_atom: &dyn Fn(usize, &mut S, &mut ::peg::error::ErrorState, &dyn Fn(usize, i32, &mut S, &mut ::peg::error::ErrorState) -> ::peg::RuleResult<(i32, T)>) -> ::peg::RuleResult<(i32, T)>,
level_code: &dyn Fn(usize, usize, i32, i32, T, &mut S, &mut ::peg::error::ErrorState, &dyn Fn(usize, i32, &mut S, &mut ::peg::error::ErrorState) -> ::peg::RuleResult<(i32, T)>) -> (T, ::peg::RuleResult<i32>),
) -> ::peg::RuleResult<(i32, T)> {
let initial = {
prefix_atom(lpos, state, err_state, &|pos, min_prec, state, err_state| {
__infix_parse(state, err_state, min_prec, pos, prefix_atom, level_code)
})
};

if let ::peg::RuleResult::Matched(pos, mut infix_result) = initial {
if let ::peg::RuleResult::Matched(pos, (mut assoc_prec, mut infix_result)) = initial {
#enter
let mut repeat_pos = pos;
loop {
let (val, res) = level_code(
repeat_pos,
lpos,
min_prec,
assoc_prec,
infix_result,
state,
err_state,
Expand All @@ -993,21 +1010,35 @@ fn compile_expr(context: &Context, e: &SpannedExpr, result_used: bool) -> TokenS
);
infix_result = val;

if let ::peg::RuleResult::Matched(pos, ()) = res {
if let ::peg::RuleResult::Matched(pos, assoc_prec_bound) = res {
repeat_pos = pos;
assoc_prec = assoc_prec_bound;
continue;
}

break;
}
#leave
::peg::RuleResult::Matched(repeat_pos, infix_result)
::peg::RuleResult::Matched(repeat_pos, (assoc_prec, infix_result))
} else {
::peg::RuleResult::Failed
}
}
fn __infix_parse_result<T, S>(
state: &mut S,
err_state: &mut ::peg::error::ErrorState,
min_prec: i32,
lpos: usize,
prefix_atom: &dyn Fn(usize, &mut S, &mut ::peg::error::ErrorState, &dyn Fn(usize, i32, &mut S, &mut ::peg::error::ErrorState) -> ::peg::RuleResult<(i32, T)>) -> ::peg::RuleResult<(i32, T)>,
level_code: &dyn Fn(usize, usize, i32, i32, T, &mut S, &mut ::peg::error::ErrorState, &dyn Fn(usize, i32, &mut S, &mut ::peg::error::ErrorState) -> ::peg::RuleResult<(i32, T)>) -> (T, ::peg::RuleResult<i32>),
) -> ::peg::RuleResult<T> {
match __infix_parse(state, err_state, 0, lpos, prefix_atom, level_code) {
::peg::RuleResult::Matched(__pos, (_, __v)) => ::peg::RuleResult::Matched(__pos, __v),
::peg::RuleResult::Failed => ::peg::RuleResult::Failed,
}
}

__infix_parse(__state, __err_state, 0, __pos,
__infix_parse_result(__state, __err_state, 0, __pos,
&|__pos, __state, __err_state, __recurse| {
let __lpos = __pos;
#(
Expand All @@ -1018,7 +1049,7 @@ fn compile_expr(context: &Context, e: &SpannedExpr, result_used: bool) -> TokenS

::peg::RuleResult::Failed
},
&|__pos, __lpos, __min_prec, mut __infix_result, __state, __err_state, __recurse| {
&|__pos, __lpos, __min_prec, __assoc_prec, mut __infix_result, __state, __err_state, __recurse| {
#(#level_code)*
(__infix_result, ::peg::RuleResult::Failed)
}
Expand Down
87 changes: 87 additions & 0 deletions tests/pass/arithmetic_no_associative.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,87 @@
extern crate peg;

peg::parser!(grammar arithmetic() for str {
pub(crate) rule no_assoc() = precedence! {
(@) "||" @ {}
@ "@@" (@) {}
--
@ "<" @ {}
@ ">" @ {}
--
@ "?" {}
--
"-" @ {}
--
@ "." @ {}
--
"x" {}
}
});

#[test]
fn main() {
assert!(arithmetic::no_assoc("x<x").is_ok());
assert!(arithmetic::no_assoc("x>x").is_ok());
assert!(arithmetic::no_assoc("-x").is_ok());
assert!(arithmetic::no_assoc("x?").is_ok());

assert!(arithmetic::no_assoc("x||x").is_ok());
assert!(arithmetic::no_assoc("x<x||x").is_ok());
assert!(arithmetic::no_assoc("x||x<x").is_ok());
assert!(arithmetic::no_assoc("x<x||x<x").is_ok());
assert!(arithmetic::no_assoc("x<x||x<x||x<x").is_ok());
assert!(arithmetic::no_assoc("x@@x").is_ok());
assert!(arithmetic::no_assoc("x<x@@x").is_ok());
assert!(arithmetic::no_assoc("x@@x<x").is_ok());
assert!(arithmetic::no_assoc("x<x@@x<x").is_ok());
assert!(arithmetic::no_assoc("x<x@@x<x@@x<x").is_ok());

assert!(arithmetic::no_assoc("-x?").is_ok());
assert!(arithmetic::no_assoc("x<-x").is_ok());
assert!(arithmetic::no_assoc("-x<x").is_ok());
assert!(arithmetic::no_assoc("-x<-x").is_ok());
assert!(arithmetic::no_assoc("x<x?").is_ok());
assert!(arithmetic::no_assoc("x?<x").is_ok());
assert!(arithmetic::no_assoc("x?<x?").is_ok());
assert!(arithmetic::no_assoc("x<-x?").is_ok());
assert!(arithmetic::no_assoc("x?<-x?").is_ok());
assert!(arithmetic::no_assoc("-x?<-x?").is_ok());

assert!(arithmetic::no_assoc("x.x").is_ok());
assert!(arithmetic::no_assoc("x.x<x").is_ok());
assert!(arithmetic::no_assoc("x<x.x").is_ok());
assert!(arithmetic::no_assoc("x.x<x.x").is_ok());
assert!(arithmetic::no_assoc("x||x.x<x.x").is_ok());
assert!(arithmetic::no_assoc("x.x||x.x<x.x").is_ok());
assert!(arithmetic::no_assoc("x.x||x<x.x").is_ok());

assert!(arithmetic::no_assoc("x<x<x").is_err());
assert!(arithmetic::no_assoc("x<x>x").is_err());
assert!(arithmetic::no_assoc("x?<x<x").is_err());
assert!(arithmetic::no_assoc("-x<x<x").is_err());
assert!(arithmetic::no_assoc("x<-x<x").is_err());
assert!(arithmetic::no_assoc("x<x?<x").is_err());
assert!(arithmetic::no_assoc("x<x?<-x").is_err());
assert!(arithmetic::no_assoc("x<x?<x?").is_err());

assert!(arithmetic::no_assoc("x<x<x||x").is_err());
assert!(arithmetic::no_assoc("x<x<x||x<x").is_err());
assert!(arithmetic::no_assoc("x||x<x<x").is_err());
assert!(arithmetic::no_assoc("x<x||x<x<x").is_err());
assert!(arithmetic::no_assoc("x<x<x@@x").is_err());
assert!(arithmetic::no_assoc("x<x<x@@x<x").is_err());
assert!(arithmetic::no_assoc("x@@x<x<x").is_err());
assert!(arithmetic::no_assoc("x<x@@x<x<x").is_err());

assert!(arithmetic::no_assoc("x<x.x.x").is_err());
assert!(arithmetic::no_assoc("x||x<x.x.x").is_err());
assert!(arithmetic::no_assoc("x@@x<x.x.x").is_err());
assert!(arithmetic::no_assoc("x.x<x.x.x").is_err());
assert!(arithmetic::no_assoc("x.x<x||x.x.x").is_err());
assert!(arithmetic::no_assoc("x.x<x@@x.x.x").is_err());
assert!(arithmetic::no_assoc("x.x.x<x").is_err());
assert!(arithmetic::no_assoc("x.x.x<x.x").is_err());
assert!(arithmetic::no_assoc("x.x.x<x.x||x").is_err());
assert!(arithmetic::no_assoc("x.x.x<x.x||x.x").is_err());
assert!(arithmetic::no_assoc("x.x.x<x||x.x").is_err());
}
1 change: 1 addition & 0 deletions tests/pass/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ mod arithmetic_ast;
mod arithmetic_infix;
mod arithmetic_infix_ast;
mod arithmetic_infix_ast_span;
mod arithmetic_no_associative;
mod arithmetic_with_left_recursion;
mod assembly_ast_dyn_type_param_bounds;
mod borrow_from_input;
Expand Down