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import { _ISchema, _Transaction, _ISequence, _IStatementExecutor, _IStatement, asSeq, asIndex, _INamedIndex } from '../../interfaces-private.ts';import { DropStatement } from 'https://deno.land/x/pgsql_ast_parser@12.0.1/mod.ts';import { ExecHelper } from '../exec-utils.ts';import { ignore, notNil } from '../../utils.ts';
export class DropIndex extends ExecHelper implements _IStatementExecutor {    private idx: _INamedIndex<any>[];

    constructor({ schema }: _IStatement, statement: DropStatement) {        super(statement);
        this.idx = notNil(statement.names.map(x => asIndex(schema.getObject(x, {            nullIfNotFound: statement.ifExists,        }))));
        if (this.idx.length) {            ignore(statement.concurrently);        } else {            ignore(statement);        }    }
    execute(t: _Transaction) {        // commit pending data before making changes        //  (because the index sequence creation does support further rollbacks)        t = t.fullCommit();
        // alter the sequence        for (const idx of this.idx) {            idx.onTable.dropIndex(t, idx.name);        }
        // new implicit transaction        t = t.fork();
        return this.noData(t, 'DROP');    }}