text: "use strict";
  
  const Collapser = require("./collapser");
  
  class SetCollapser extends Collapser {
    isInitTypeValid(init) {
      return init.isNewExpression() && init.get("callee").isIdentifier() && init.node.callee.name === "Set" && ( // other iterables might not be append-able
      init.node.arguments.length === 0 || init.node.arguments.length === 1 && init.get("arguments")[0].isArrayExpression());
    }
  
    isExpressionTypeValid(expr) {
      return expr.isCallExpression();
    }
  
    getExpressionChecker(objName, checkReference) {
      return expr => {
        // checks expr is of form:
        // foo.add(rval)
        const callee = expr.get("callee");
  
        if (!callee.isMemberExpression()) {
          return false;
        }
  
        const obj = callee.get("object"),
              prop = callee.get("property");
  
        if (!obj.isIdentifier() || obj.node.name !== objName || !prop.isIdentifier() || prop.node.name !== "add") {
          return false;
        }
  
        const args = expr.get("arguments");
  
        if (args.length !== 1) {
          return false;
        }
  
        if (checkReference(args[0])) {
          return false;
        }
  
        return true;
      };
    }
  
    extractAssignment(expr) {
      return expr.node.arguments[0];
    }
  
    addSuccessfully(t, arg, init) {
      if (init.arguments.length === 0) {
        init.arguments.push(t.arrayExpression());
      }
  
      init.arguments[0].elements.push(arg);
      return true;
    }
  
  }
  
  module.exports = SetCollapser;