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import { QName, Statement, NodeLocation, toSql } from 'https://deno.land/x/pgsql_ast_parser@12.0.1/mod.ts';import { _ISchema, QueryError, _Transaction, _IDb } from '../interfaces-private.ts';
export function checkExistence(schema: _ISchema, name: QName, ifNotExists: boolean | undefined, act: () => void): boolean {    // check if object exists    const exists = schema.getObject(name, {        skipSearch: true,        nullIfNotFound: true    });    if (exists) {        if (ifNotExists) {            return false;        }        throw new QueryError(`relation "${name.name}" already exists`);    }
    // else, perform operation    act();    return true;}


export function locOf(p: Statement): NodeLocation {    return p._location ?? { start: 0, end: 0 };}
export abstract class ExecHelper {    constructor(private statement: Statement) {    }
    protected noData(t: _Transaction, name?: string) {        return {            result: {                command: name ?? this.statement.type.toUpperCase(),                fields: [],                rowCount: 0,                rows: [],                location: locOf(this.statement),            },            state: t,        };    }}