OrdinalMeta.js

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements.  See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership.  The ASF licenses this file
* to you 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 {createHashMap, isObject, map} from 'zrender/src/core/util';

/**
 * @constructor
 * @param {Object} [opt]
 * @param {Object} [opt.categories=[]]
 * @param {Object} [opt.needCollect=false]
 * @param {Object} [opt.deduplication=false]
 */
function OrdinalMeta(opt) {

    /**
     * @readOnly
     * @type {Array.<string>}
     */
    this.categories = opt.categories || [];

    /**
     * @private
     * @type {boolean}
     */
    this._needCollect = opt.needCollect;

    /**
     * @private
     * @type {boolean}
     */
    this._deduplication = opt.deduplication;

    /**
     * @private
     * @type {boolean}
     */
    this._map;
}

/**
 * @param {module:echarts/model/Model} axisModel
 * @return {module:echarts/data/OrdinalMeta}
 */
OrdinalMeta.createByAxisModel = function (axisModel) {
    var option = axisModel.option;
    var data = option.data;
    var categories = data && map(data, getName);

    return new OrdinalMeta({
        categories: categories,
        needCollect: !categories,
        // deduplication is default in axis.
        deduplication: option.dedplication !== false
    });
};

var proto = OrdinalMeta.prototype;

/**
 * @param {string} category
 * @return {number} ordinal
 */
proto.getOrdinal = function (category) {
    return getOrCreateMap(this).get(category);
};

/**
 * @param {*} category
 * @return {number} The ordinal. If not found, return NaN.
 */
proto.parseAndCollect = function (category) {
    var index;
    var needCollect = this._needCollect;

    // The value of category dim can be the index of the given category set.
    // This feature is only supported when !needCollect, because we should
    // consider a common case: a value is 2017, which is a number but is
    // expected to be tread as a category. This case usually happen in dataset,
    // where it happent to be no need of the index feature.
    if (typeof category !== 'string' && !needCollect) {
        return category;
    }

    // Optimize for the scenario:
    // category is ['2012-01-01', '2012-01-02', ...], where the input
    // data has been ensured not duplicate and is large data.
    // Notice, if a dataset dimension provide categroies, usually echarts
    // should remove duplication except user tell echarts dont do that
    // (set axis.deduplication = false), because echarts do not know whether
    // the values in the category dimension has duplication (consider the
    // parallel-aqi example)
    if (needCollect && !this._deduplication) {
        index = this.categories.length;
        this.categories[index] = category;
        return index;
    }

    var map = getOrCreateMap(this);
    index = map.get(category);

    if (index == null) {
        if (needCollect) {
            index = this.categories.length;
            this.categories[index] = category;
            map.set(category, index);
        }
        else {
            index = NaN;
        }
    }

    return index;
};

// Consider big data, do not create map until needed.
function getOrCreateMap(ordinalMeta) {
    return ordinalMeta._map || (
        ordinalMeta._map = createHashMap(ordinalMeta.categories)
    );
}

function getName(obj) {
    if (isObject(obj) && obj.value != null) {
        return obj.value;
    }
    else {
        return obj + '';
    }
}

export default OrdinalMeta;