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| 1 | +/** |
| 2 | + * @license |
| 3 | + * Copyright 2022 Google LLC |
| 4 | + * |
| 5 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | + * you may not use this file except in compliance with the License. |
| 7 | + * You may obtain a copy of the License at |
| 8 | + * |
| 9 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | + * |
| 11 | + * Unless required by applicable law or agreed to in writing, software |
| 12 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | + * See the License for the specific language governing permissions and |
| 15 | + * limitations under the License. |
| 16 | + */ |
| 17 | + |
| 18 | +const aliasRegExp = /^[_a-zA-Z][_a-zA-Z0-9]*(?:\.[_a-zA-Z][_a-zA-Z0-9]*)*$/; |
| 19 | + |
| 20 | +/** |
| 21 | + * An alias for aggregation results. |
| 22 | + * @internal |
| 23 | + */ |
| 24 | +export class AggregateAlias { |
| 25 | + /** |
| 26 | + * @internal |
| 27 | + * @param alias Un-escaped alias representation |
| 28 | + */ |
| 29 | + constructor(private alias: string) {} |
| 30 | + |
| 31 | + /** |
| 32 | + * Returns true if the string could be used as an alias. |
| 33 | + */ |
| 34 | + private static isValidAlias(value: string): boolean { |
| 35 | + return aliasRegExp.test(value); |
| 36 | + } |
| 37 | + |
| 38 | + /** |
| 39 | + * Return an escaped and quoted string representation of the alias. |
| 40 | + */ |
| 41 | + canonicalString(): string { |
| 42 | + let alias = this.alias.replace(/\\/g, '\\\\').replace(/`/g, '\\`'); |
| 43 | + if (!AggregateAlias.isValidAlias(alias)) { |
| 44 | + alias = '`' + alias + '`'; |
| 45 | + } |
| 46 | + return alias; |
| 47 | + } |
| 48 | +} |
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