| 1 | import {Operator} from 'vega-dataflow';
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| 2 | import {compare, inherits} from 'vega-util';
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| 3 |
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| 4 | /**
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| 5 | * Generates a comparator function.
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| 6 | * @constructor
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| 7 | * @param {object} params - The parameters for this operator.
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| 8 | * @param {Array<string|function>} params.fields - The fields to compare.
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| 9 | * @param {Array<string>} [params.orders] - The sort orders.
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| 10 | * Each entry should be one of "ascending" (default) or "descending".
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| 11 | */
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| 12 | export default function Compare(params) {
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| 13 | Operator.call(this, null, update, params);
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| 14 | }
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| 15 |
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| 16 | inherits(Compare, Operator);
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| 17 |
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| 18 | function update(_) {
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| 19 | return (this.value && !_.modified())
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| 20 | ? this.value
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| 21 | : compare(_.fields, _.orders);
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| 22 | }
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