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import { _Transaction, asTable, _ISchema, NotSupported, CreateIndexColDef, _ITable, CreateIndexDef, _IStatement, _IStatementExecutor, asView, _IView, QueryError } from '../../interfaces-private.ts';import { CreateViewStatement, SelectedColumn } from 'https://deno.land/x/pgsql_ast_parser@12.0.1/mod.ts';import { ExecHelper } from '../exec-utils.ts';import { ignore } from '../../utils.ts';import { View } from '../../schema/view.ts';import { buildSelect } from '../select.ts';
export class CreateView extends ExecHelper implements _IStatementExecutor {    private schema: _ISchema;    private drop: boolean;    existing: _IView | null;    toRegister: View;

    constructor(st: _IStatement, p: CreateViewStatement) {        super(p);        this.schema = st.schema.getThisOrSiblingFor(p.name);        // check existence        this.existing = asView(this.schema.getObject(p.name, { nullIfNotFound: true }));        ignore(p.orReplace);        this.drop = !!(p.orReplace && this.existing);
        let view = buildSelect(p.query);
        // optional column mapping        if (p.columnNames?.length) {            if (p.columnNames.length > view.columns.length) {                throw new QueryError('CREATE VIEW specifies more column names than columns', '42601');            }            view = view.select(view.columns.map<string | SelectedColumn>((x, i) => {                const alias = p.columnNames?.[i]?.name;                if (!alias) {                    return x.id!;                }                return {                    expr: { type: 'ref', name: x.id! },                    alias: { name: alias },                }            }));        }
        this.toRegister = new View(this.schema, p.name.name, view);    }
    execute(t: _Transaction) {        // commit pending data before making changes        //  (because does not support further rollbacks)        t = t.fullCommit();
        // drop if needed        if (this.existing && this.drop) {            this.existing.drop(t);        }
        // view creation        this.toRegister.register();
        // new implicit transaction        t = t.fork();        return this.noData(t, 'CREATE');    }}