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import { _ISelection, QueryError, AggregationComputer, IValue, _IType, _Transaction, AggregationGroupComputer } from '../../interfaces-private.ts';import { ExprCall } from 'https://deno.land/x/pgsql_ast_parser@12.0.1/mod.ts';import { withSelection } from '../../parser/context.ts';import { buildValue } from '../../parser/expression-builder.ts';import { nullIsh } from '../../utils.ts';import { Types } from '../../datatypes/index.ts';

class JsonAggExpr implements AggregationComputer<any[]> {
    constructor(private exp: IValue, readonly type: _IType) {    }
    createGroup(t: _Transaction): AggregationGroupComputer<any[]> {        let full: any[][] = [];        return {            feedItem: (item) => {                const value = this.exp.get(item, t);                if (!nullIsh(value)) {                    full.push(value);                }            },            finish: () => full.length === 0 ? null : full,        }    }}

export function buildJsonAgg(this: void, base: _ISelection, call: ExprCall, fn: 'json_agg' | 'jsonb_agg') {    return withSelection(base, () => {        const args = call.args;        if (args.length !== 1) {            throw new QueryError(fn + ' expects one argument, given ' + args.length);        }        const type = fn === 'json_agg' ? Types.json : Types.jsonb;        const what = buildValue(args[0]);        return new JsonAggExpr(what, type);    });}