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Add options to specify cache type #338

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Add options to specify cache type #338

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42e9fbb
add options to specify cache type
stevefan1999-personal Apr 5, 2023
d4dd5cf
Merge remote-tracking branch 'upstream/master' into patch-no-std-macros
stevefan1999-personal Apr 10, 2023
ec4a36b
fold the similar lines into optional matching for cache
stevefan1999-personal Apr 10, 2023
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62 changes: 40 additions & 22 deletions peg-macros/analysis.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,10 @@ impl LeftRecursionError {
}

impl<'a> LeftRecursionVisitor<'a> {
fn check(grammar: &'a Grammar, rules: &HashMap<String, &'a Rule>) -> (HashMap<String, bool>, Vec<LeftRecursionError>) {
fn check(
grammar: &'a Grammar,
rules: &HashMap<String, &'a Rule>,
) -> (HashMap<String, bool>, Vec<LeftRecursionError>) {
let mut visitor = LeftRecursionVisitor {
rules,
errors: Vec::new(),
Expand All @@ -64,7 +67,9 @@ impl<'a> LeftRecursionVisitor<'a> {
for rule in grammar.iter_rules() {
let nullable = visitor.walk_rule(rule);
debug_assert!(visitor.stack.is_empty());
rule_nullability.entry(rule.name.to_string()).or_insert(nullable);
rule_nullability
.entry(rule.name.to_string())
.or_insert(nullable);
}

(rule_nullability, visitor.errors)
Expand Down Expand Up @@ -98,20 +103,18 @@ impl<'a> LeftRecursionVisitor<'a> {
let mut recursive_loop = self.stack[loop_start..].to_vec();
recursive_loop.push(name.clone());
match rule.cache {
None | Some(Cache::Simple) =>
self.errors.push(LeftRecursionError {
path: recursive_loop,
span: rule_ident.span(),
}),
_ => ()

None | Some(Cache::Simple(_)) => self.errors.push(LeftRecursionError {
path: recursive_loop,
span: rule_ident.span(),
}),
_ => (),
}
return false;
}
self.walk_rule(rule)
} else {
// Missing rule would have already been reported
false
false
}
}

Expand All @@ -138,7 +141,11 @@ impl<'a> LeftRecursionVisitor<'a> {
true
}

Repeat { ref inner, ref bound, .. } => {
Repeat {
ref inner,
ref bound,
..
} => {
let inner_nullable = self.walk_expr(inner);
inner_nullable | !bound.has_lower_bound()
}
Expand All @@ -161,10 +168,12 @@ impl<'a> LeftRecursionVisitor<'a> {
}
}

nullable
nullable
}

LiteralExpr(_) | PatternExpr(_) | MethodExpr(_, _) | FailExpr(_) | MarkerExpr(_) => false,
LiteralExpr(_) | PatternExpr(_) | MethodExpr(_, _) | FailExpr(_) | MarkerExpr(_) => {
false
}

PositionExpr => true,
}
Expand All @@ -188,9 +197,11 @@ impl LoopNullabilityError {
}
}


impl<'a> LoopNullabilityVisitor<'a> {
fn check(grammar: &'a Grammar, rule_nullability: &HashMap<String, bool>) -> Vec<LoopNullabilityError> {
fn check(
grammar: &'a Grammar,
rule_nullability: &HashMap<String, bool>,
) -> Vec<LoopNullabilityError> {
let mut visitor = LoopNullabilityVisitor {
rule_nullability,
errors: Vec::new(),
Expand All @@ -203,7 +214,6 @@ impl<'a> LoopNullabilityVisitor<'a> {
visitor.errors
}


/// Walk an expr and its children analyzing the nullability of loop bodies.
///
/// Returns true if the rule is known to match completely without consuming
Expand All @@ -220,7 +230,7 @@ impl<'a> LoopNullabilityVisitor<'a> {
let name = rule_ident.to_string();
*self.rule_nullability.get(&name).unwrap_or(&false)
}

ActionExpr(ref elems, ..) => {
let mut nullable = true;
for elem in elems {
Expand All @@ -242,15 +252,21 @@ impl<'a> LoopNullabilityVisitor<'a> {
true
}

Repeat { ref inner, ref bound, ref sep } => {
Repeat {
ref inner,
ref bound,
ref sep,
} => {
let inner_nullable = self.walk_expr(inner);
let sep_nullable = sep.as_ref().map_or(true, |sep| self.walk_expr(sep));

// The entire purpose of this analysis: report errors if the loop body is nullable
if inner_nullable && sep_nullable && !bound.has_upper_bound() {
self.errors.push(LoopNullabilityError { span: this_expr.span });
self.errors.push(LoopNullabilityError {
span: this_expr.span,
});
}

inner_nullable | !bound.has_lower_bound()
}

Expand All @@ -269,10 +285,12 @@ impl<'a> LoopNullabilityVisitor<'a> {
}
}

nullable
nullable
}

LiteralExpr(_) | PatternExpr(_) | MethodExpr(_, _) | FailExpr(_) | MarkerExpr(_) => false,
LiteralExpr(_) | PatternExpr(_) | MethodExpr(_, _) | FailExpr(_) | MarkerExpr(_) => {
false
}
PositionExpr => true,
}
}
Expand Down
21 changes: 14 additions & 7 deletions peg-macros/ast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,8 +28,8 @@ pub enum Item {

#[derive(Debug)]
pub enum Cache {
Simple,
Recursive
Simple(Option<TokenStream>),
Recursive(Option<TokenStream>),
}

#[derive(Debug)]
Expand Down Expand Up @@ -77,7 +77,11 @@ pub enum Expr {
MethodExpr(Ident, TokenStream),
ChoiceExpr(Vec<SpannedExpr>),
OptionalExpr(Box<SpannedExpr>),
Repeat { inner: Box<SpannedExpr>, bound: BoundedRepeat, sep: Option<Box<SpannedExpr>> },
Repeat {
inner: Box<SpannedExpr>,
bound: BoundedRepeat,
sep: Option<Box<SpannedExpr>>,
},
PosAssertExpr(Box<SpannedExpr>),
NegAssertExpr(Box<SpannedExpr>),
ActionExpr(Vec<TaggedExpr>, Option<Group>),
Expand All @@ -93,7 +97,10 @@ pub enum Expr {

impl Expr {
pub fn at(self, sp: Span) -> SpannedExpr {
SpannedExpr { expr: self, span:sp }
SpannedExpr {
expr: self,
span: sp,
}
}
}

Expand Down Expand Up @@ -127,14 +134,14 @@ impl BoundedRepeat {
pub fn has_lower_bound(&self) -> bool {
match self {
BoundedRepeat::None | BoundedRepeat::Both(None, _) => false,
BoundedRepeat::Plus | BoundedRepeat::Exact(_) | BoundedRepeat::Both(Some(_), _) => true
BoundedRepeat::Plus | BoundedRepeat::Exact(_) | BoundedRepeat::Both(Some(_), _) => true,
}
}

pub fn has_upper_bound(&self) -> bool {
match self {
BoundedRepeat::None | BoundedRepeat::Plus | BoundedRepeat::Both(_, None) => false,
BoundedRepeat::Exact(_) | BoundedRepeat::Both(_, Some(_)) => true
BoundedRepeat::None | BoundedRepeat::Plus | BoundedRepeat::Both(_, None) => false,
BoundedRepeat::Exact(_) | BoundedRepeat::Both(_, Some(_)) => true,
}
}
}
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