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petitparser/lib/src/reflection/transform.dart

-part of reflection;
-
-/**
- * A function transforming one parser to another one.
- */
-typedef Parser TransformationHandler(Parser parser);
-
-/**
- * Transforms all parsers reachable from [parser] with the given [handler].
- * The identity function returns a copy of the the incoming parser.
- *
- * The implementation first creates a copy of each parser reachable in the
- * input grammar; then the resulting grammar is traversed until all references
- * to old parsers are replaced with the transformed ones.
- */
-Parser transformParser(Parser parser, TransformationHandler handler) {
-  var mapping = new Map.identity();
-  for (var each in allParser(parser)) {
-    mapping[each] = handler(each.copy());
-  }
-  var seen = new Set.from(mapping.values);
-  var todo = new List.from(mapping.values);
-  while (todo.isNotEmpty) {
-    var parent = todo.removeLast();
-    for (var child in parent.children) {
-      if (mapping.containsKey(child)) {
-        parent.replace(child, mapping[child]);
-      } else if (!seen.contains(child)) {
-        seen.add(child);
-        todo.add(child);
-      }
-    }
-  }
-  return mapping[parser];
-}