Remove use of shared_ptr in choice, repeat, and seq factories

src/compiler/rules/seq.cc

@@ -8,28 +8,6 @@ Seq::Seq(const Rule &left, const Rule &right) :
   left(std::make_shared<Rule>(left)),
   right(std::make_shared<Rule>(right)) {}
 
-std::shared_ptr<Rule> Seq::build(const std::vector<Rule> &rules) {
-  Rule result;
-  for (const auto &rule : rules) {
-    rule.match(
-      [](Blank) {},
-      [&](Metadata metadata) {
-        if (!metadata.rule->is<Blank>()) {
-          result = Seq{result, rule};
-        }
-      },
-      [&](auto) {
-        if (result.is<Blank>()) {
-          result = rule;
-        } else {
-          result = Seq{result, rule};
-        }
-      }
-    );
-  }
-  return std::make_shared<Rule>(result);
-}
-
 bool Seq::operator==(const Seq &other) const {
   return left->operator==(*other.left) && right->operator==(*other.right);
 }