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import { _ISchema, _Transaction, SchemaField, NotSupported, _ITable, _IStatementExecutor, asTable, QueryError, _IStatement } from '../../interfaces-private.ts';import { AlterTableStatement } from 'https://deno.land/x/pgsql_ast_parser@12.0.1/mod.ts';import { ignore } from '../../utils.ts';import { ExecHelper } from '../exec-utils.ts';
export class Alter extends ExecHelper implements _IStatementExecutor {
    private table: _ITable;
    constructor({ schema }: _IStatement, private p: AlterTableStatement) {        super(p);        this.table = asTable(schema.getObject(p.table));        ignore(p.only);    }
    execute(t: _Transaction) {
        let ignored = 0;
        // commit pending data before making changes        //  (because  does not support further rollbacks)        t = t.fullCommit();

        for (const change of this.p.changes) {            function ignoreChange() {                ignore(change);                ignored++;            }            switch (change.type) {                case 'rename':                    this.table.rename(change.to.name);                    break;                case 'add column': {                    const col = this.table.selection.getColumn(change.column.name.name, true);                    if (col) {                        if (change.ifNotExists) {                            ignoreChange();                            break;                        } else {                            throw new QueryError('Column already exists: ' + col.id);                        }                    } else {                        ignore(change.ifNotExists);                    }                    this.table.addColumn(change.column, t);                    break;                }                case 'drop column':                    const col = this.table.getColumnRef(change.column.name, change.ifExists);                    if (!col) {                        ignoreChange();                    } else {                        col.drop(t);                    }                    break;                case 'drop constraint':                    const cst = this.table.getConstraint(change.constraint.name);                    if (change.ifExists && !cst) {                        ignoreChange();                        break;                    }                    if (!cst) {                        throw new QueryError(`constraint "${change.constraint.name}" of relation "${this.table.name}" does not exist`, '42704')                    }                    cst.uninstall(t);                    break;                case 'rename column':                    this.table.getColumnRef(change.column.name)                        .rename(change.to.name, t);                    break;                case 'alter column':                    this.table.getColumnRef(change.column.name)                        .alter(change.alter, t);                    break;                case 'rename constraint':                    throw new NotSupported('rename constraint');                case 'add constraint':                    this; this.table.addConstraint(change.constraint, t);                    break;                case 'owner':                    // owner change statements are not supported.                    // however, in order to support, pg_dump, we're just ignoring them.                    ignoreChange();                    break;                default:                    throw NotSupported.never(change, 'alter request');
            }        }

        // new implicit transaction        t = t.fork();        return this.noData(t, 'ALTER');    }}