void visitInstanceCreationExpression()

in lib/src/rules/prefer_for_elements_to_map_fromIterable.dart [58:119]
53 lines of code
18 McCabe index (conditional complexity)

  void visitInstanceCreationExpression(InstanceCreationExpression creation) {
    var element = creation.constructorName.staticElement;
    if (element == null ||
        element.name != 'fromIterable' ||
        element.enclosingElement != context.typeProvider.mapElement) {
      return;
    }

    //
    // Ensure that the arguments have the right form.
    //
    var arguments = creation.argumentList.arguments;
    if (arguments.length != 3) {
      return;
    }

    var secondArg = arguments[1];
    var thirdArg = arguments[2];

    Expression? extractBody(FunctionExpression expression) {
      var body = expression.body;
      if (body is ExpressionFunctionBody) {
        return body.expression;
      } else if (body is BlockFunctionBody) {
        var statements = body.block.statements;
        if (statements.length == 1) {
          var statement = statements.first;
          if (statement is ReturnStatement) {
            return statement.expression;
          }
        }
      }
      return null;
    }

    FunctionExpression? extractClosure(String name, Expression argument) {
      if (argument is NamedExpression && argument.name.label.name == name) {
        var expression = argument.expression.unParenthesized;
        if (expression is FunctionExpression) {
          var parameters = expression.parameters?.parameters;
          if (parameters != null &&
              parameters.length == 1 &&
              parameters.first.isRequired) {
            if (extractBody(expression) != null) {
              return expression;
            }
          }
        }
      }
      return null;
    }

    var keyClosure =
        extractClosure('key', secondArg) ?? extractClosure('key', thirdArg);
    var valueClosure =
        extractClosure('value', thirdArg) ?? extractClosure('value', secondArg);
    if (keyClosure == null || valueClosure == null) {
      return;
    }

    rule.reportLint(creation);
  }