@finos/legend-graph
Version:
Legend graph and graph manager
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text/typescript
/**
* Copyright (c) 2020-present, Goldman Sachs
*
* 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 { CORE_HASH_STRUCTURE } from '../../../../../../../graph/Core_HashUtils.js';
import { type Hashable, type Pair, hashArray } from '@finos/legend-shared';
import type { Operation, TableAlias } from './RelationalOperationElement.js';
import type { Database } from './Database.js';
export const SELF_JOIN_TABLE_NAME = '{target}';
export const SELF_JOIN_SCHEMA_NAME = 'default';
export const SELF_JOIN_ALIAS_PREFIX = 't_';
export class Join implements Hashable {
owner!: Database;
name: string;
/**
* Target is used to show the direction of the join. Since cross table join is symmetrical in nature,
* the direction is not required at all, whereas for self-join, the direction really matters
*/
target?: TableAlias | undefined;
/**
* This is an optimization for looking up tables/views involved in a join.
* Normally, it has 2 pairs (A,B) and (B,A)
*/
aliases: Pair<TableAlias, TableAlias>[] = [];
operation: Operation;
constructor(name: string, operation: Operation) {
this.name = name;
this.operation = operation;
}
get hashCode(): string {
return hashArray([
CORE_HASH_STRUCTURE.DATABASE_JOIN,
this.name,
this.operation,
]);
}
}