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Fix edge case in flatten rule

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This commit is contained in:
Max Brunsfeld 2019-01-11 17:43:42 -08:00
parent c76a155174
commit 6f242fda0c
1 changed files with 11 additions and 6 deletions
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17
cli/src/generate/prepare_grammar/flatten_grammar.rs
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@ -31,13 +31,15 @@ impl RuleFlattener {
self.production
}
fn apply(&mut self, rule: Rule, at_end: bool) {
fn apply(&mut self, rule: Rule, at_end: bool) -> bool {
match rule {
Rule::Seq(members) => {
let mut result = false;
let last_index = members.len() - 1;
for (i, member) in members.into_iter().enumerate() {
self.apply(member, i == last_index && at_end);
result |= self.apply(member, i == last_index && at_end);
}
result
}
Rule::Metadata { rule, params } => {
let mut has_precedence = false;
@ -62,11 +64,11 @@ impl RuleFlattener {
self.production.dynamic_precedence = params.dynamic_precedence;
}
self.apply(*rule, at_end);
let did_push = self.apply(*rule, at_end);
if has_precedence {
self.precedence_stack.pop();
if !at_end {
if did_push && !at_end {
self.production.steps.last_mut().unwrap().precedence =
self.precedence_stack.last().cloned().unwrap_or(0);
}
@ -74,7 +76,7 @@ impl RuleFlattener {
if has_associativity {
self.associativity_stack.pop();
if !at_end {
if did_push && !at_end {
self.production.steps.last_mut().unwrap().associativity =
self.associativity_stack.last().cloned();
}
@ -83,6 +85,8 @@ impl RuleFlattener {
if has_alias {
self.alias_stack.pop();
}
did_push
}
Rule::Symbol(symbol) => {
self.production.steps.push(ProductionStep {
@ -91,8 +95,9 @@ impl RuleFlattener {
associativity: self.associativity_stack.last().cloned(),
alias: self.alias_stack.last().cloned(),
});
true
}
_ => (),
_ => false,
}
}
}