/**
 * Copyright 2018, OpenCensus Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { Resource } from './types';
/**
 * Resource represents a resource, which capture identifying information about
 * the entities for which signals (stats or traces) are reported. It further
 * provides a framework for detection of resource information from the
 * environment and progressive population as signals propagate from the core
 * instrumentation library to a backend's exporter.
 */
export declare class CoreResource {
    private static readonly MAX_LENGTH;
    private static readonly COMMA_SEPARATOR;
    private static readonly LABEL_KEY_VALUE_SPLITTER;
    private static ENV_TYPE;
    private static ENV_LABEL_MAP;
    private static readonly ERROR_MESSAGE_INVALID_CHARS;
    private static readonly ERROR_MESSAGE_INVALID_VALUE;
    /**
     * Returns a Resource. This resource information is loaded from the
     * OC_RESOURCE_TYPE and OC_RESOURCE_LABELS environment variables.
     *
     * @returns The resource.
     */
    static createFromEnvironmentVariables(): Resource;
    /**
     * Returns a Resource that runs all input resources sequentially and merges
     * their results. In case a type of label key is already set, the first set
     * value takes precedence.
     *
     * @param resources The list of the resources.
     * @returns The resource.
     */
    static mergeResources(resources: Resource[]): Resource;
    /**
     * Creates a resource type from the OC_RESOURCE_TYPE environment variable.
     *
     * OC_RESOURCE_TYPE: A string that describes the type of the resource
     * prefixed by a domain namespace, e.g. “kubernetes.io/container”.
     *
     * @param rawEnvType The resource type.
     * @returns The sanitized resource type.
     */
    private static parseResourceType;
    /**
     * Creates a label map from the OC_RESOURCE_LABELS environment variable.
     *
     * OC_RESOURCE_LABELS: A comma-separated list of labels describing the
     * source in more detail, e.g. “key1=val1,key2=val2”. Domain names and paths
     * are accepted as label keys. Values may be quoted or unquoted in general. If
     * a value contains whitespaces, =, or " characters, it must always be quoted.
     *
     * @param rawEnvLabels The resource labels as a comma-seperated list
     * of key/value pairs.
     * @returns The sanitized resource labels.
     */
    private static parseResourceLabels;
    /**
     * Returns a new, merged Resource by merging two resources. In case of
     * a collision, first resource takes precedence.
     *
     * @param resource The resource object.
     * @param otherResource The resource object.
     * @returns A new, merged Resource.
     */
    private static merge;
    /**
     * Determines whether the given String is a valid printable ASCII string with
     * a length not exceed MAX_LENGTH characters.
     *
     * @param str The String to be validated.
     * @returns Whether the String is valid.
     */
    private static isValid;
    /**
     * Determines whether the given String is a valid printable ASCII string with
     * a length greater than 0 and not exceed MAX_LENGTH characters.
     *
     * @param str The String to be validated.
     * @returns Whether the String is valid and not empty.
     */
    private static isValidAndNotEmpty;
    /** TEST_ONLY */
    static setup(): void;
}