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Simplify flatten_rule function

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This commit is contained in:
Max Brunsfeld 2017-07-13 09:59:23 -07:00
parent 7293e6f0cc
commit d646889922
1 changed files with 8 additions and 22 deletions
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30
src/compiler/prepare_grammar/flatten_grammar.cc
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@ -20,11 +20,9 @@ class FlattenRule {
private:
vector<int> precedence_stack;
vector<rules::Associativity> associativity_stack;
int last_precedence;
rules::Associativity last_associativity;
Production production;
void apply(const Rule &rule) {
void apply(const Rule &rule, bool at_end) {
rule.match(
[&](const rules::Symbol &symbol) {
production.steps.push_back(ProductionStep{
@ -47,26 +45,22 @@ class FlattenRule {
production.dynamic_precedence = metadata.params.dynamic_precedence;
}
apply(*metadata.rule);
apply(*metadata.rule, at_end);
if (metadata.params.has_precedence) {
last_precedence = precedence_stack.back();
precedence_stack.pop_back();
production.back().precedence = precedence_stack.back();
if (!at_end) production.back().precedence = precedence_stack.back();
}
if (metadata.params.has_associativity) {
last_associativity = associativity_stack.back();
associativity_stack.pop_back();
production.back().associativity = associativity_stack.back();
if (!at_end) production.back().associativity = associativity_stack.back();
}
},
[&](const rules::Seq &sequence) {
apply(*sequence.left);
last_precedence = 0;
last_associativity = rules::AssociativityNone;
apply(*sequence.right);
apply(*sequence.left, false);
apply(*sequence.right, at_end);
},
[&](const rules::Blank &blank) {},
@ -78,18 +72,10 @@ class FlattenRule {
}
public:
FlattenRule()
: precedence_stack({ 0 }),
associativity_stack({ rules::AssociativityNone }),
last_precedence(0),
last_associativity(rules::AssociativityNone) {}
FlattenRule() : precedence_stack({ 0 }), associativity_stack({ rules::AssociativityNone }) {}
Production flatten(const Rule &rule) {
apply(rule);
if (!production.empty()) {
production.back().precedence = last_precedence;
production.back().associativity = last_associativity;
}
apply(rule, true);
return production;
}
};