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// <== THERE MUST BE NO ACTUAL IMPORTS OTHER THAN IMPORT TYPES (dependency loop)// ... use 'kind-of' dependency injection belowimport type { _ISelection, IValue, _IIndex, _ISchema, _IDb, _Transaction, _SelectExplanation, _Explainer, Stats, nil, _IAlias } from '../interfaces-private.ts';import type { buildSelection } from './selection.ts';import type { buildAlias } from './alias.ts';import type { buildFilter } from './build-filter.ts';import type { buildGroupBy } from './aggregation.ts';import type { buildLimit } from './limit.ts';import type { buildUnion } from './union.ts';import type { buildOrderBy } from './order-by.ts';import type { buildDistinct } from './distinct.ts';
import { Expr, SelectedColumn, SelectStatement, LimitStatement, OrderByStatement, ExprRef } from 'https://deno.land/x/pgsql_ast_parser@12.0.1/mod.ts';import { RestrictiveIndex } from './restrictive-index.ts';
interface Fns {    buildSelection: typeof buildSelection;    buildAlias: typeof buildAlias;    buildLimit: typeof buildLimit;    buildUnion: typeof buildUnion;    buildFilter: typeof buildFilter;    buildGroupBy: typeof buildGroupBy;    buildOrderBy: typeof buildOrderBy;    buildDistinct: typeof buildDistinct;}let fns: Fns;export function initialize(init: Fns) {    fns = init;}
export abstract class DataSourceBase<T> implements _ISelection<T> {    abstract enumerate(t: _Transaction): Iterable<T>;    abstract entropy(t: _Transaction): number;    abstract readonly columns: ReadonlyArray<IValue<any>>;    abstract getColumn(column: string, nullIfNotFound?: boolean): IValue<any>;    abstract hasItem(value: T, t: _Transaction): boolean;    abstract getIndex(forValue: IValue): _IIndex<any> | null | undefined;    abstract explain(e: _Explainer): _SelectExplanation;    abstract isOriginOf(a: IValue<any>): boolean;    abstract stats(t: _Transaction): Stats | null;    abstract get isExecutionWithNoResult(): boolean    isAggregation(): boolean {        return false;    }    // abstract get name(): string;

    get db() {        return this.ownerSchema.db;    }
    constructor(readonly ownerSchema: _ISchema) {    }
    listColumns(): Iterable<IValue> {        return this.columns;    }
    listSelectableIdentities(): Iterable<IValue> {        return this.columns;    }
    select(select: (string | SelectedColumn)[] | nil): _ISelection<any> {        let sel: SelectedColumn[] | nil;        if (select?.some(v => typeof v === 'string')) {            sel = select.map<SelectedColumn>(v => typeof v !== 'string'                ? v                : {                    expr: { type: 'ref', name: v },                })        } else {            sel = select as SelectedColumn[] | nil;        }        return fns.buildSelection(this, sel);    }

    selectAlias(alias: string): _IAlias | nil {        return null;    }

    filter(filter: Expr | undefined | null): _ISelection {        if (!filter) {            return this;        }        const plan = fns.buildFilter(this, filter, 'WHERE');        return plan;    }
    groupBy(grouping: Expr[] | nil): _ISelection {        if (!grouping?.length) {            return this;        }        const plan = fns.buildGroupBy(this, grouping);        return plan;    }

    setAlias(alias?: string): _ISelection<any> {        return fns.buildAlias(this, alias);    }
    limit(limit: LimitStatement): _ISelection {        if (!limit?.limit && !limit?.offset) {            return this;        }        return fns.buildLimit(this, limit)    }
    orderBy(orderBy: OrderByStatement[] | nil): _ISelection<any> {        if (!orderBy?.length) {            return this;        }        return fns.buildOrderBy(this, orderBy);    }
    distinct(exprs?: Expr[]): _ISelection<any> {        return fns.buildDistinct(this, exprs);    }
    union(right: _ISelection<any>): _ISelection<any> {        return fns.buildUnion(this, right);    }
}

export abstract class TransformBase<T> extends DataSourceBase<T> {

    constructor(readonly base: _ISelection) {        super(base.ownerSchema);    }
    get isExecutionWithNoResult(): boolean {        return false;    }
    entropy(t: _Transaction): number {        return this.base.entropy(t);    }
    isOriginOf(a: IValue<any>): boolean {        return a.origin === this || this.base?.isOriginOf(a);    }}
export abstract class FilterBase<T> extends TransformBase<T> {
    isAggregation(): boolean {        return false;    }
    constructor(_base: _ISelection<T>) {        super(_base);    }
    get columns(): ReadonlyArray<IValue<any>> {        return this.base.columns;    }
    selectAlias(alias: string): nil | _IAlias {        // this is a filter... that the alias returned by the unfiltered datasource will        // be valid for the filtered datasource (aliases are only listing columns)        return this.base.selectAlias(alias);    }
    /**    private _columns: IValue[];    private _columnMappings: Map<IValue, IValue>;    get columns(): ReadonlyArray<IValue<any>> {        this.initCols();        return this._columns;        // return this.base.columns;    }
    private initCols() {        if (this._columns) {            return;        }        this._columns = [];        this._columnMappings = new Map();        for (const c of this.base.columns) {            const nc = c.setOrigin(this);            this._columns.push(nc);            this._columnMappings.set(c, nc);        }    }
    getColumn(column: string, nullIfNotFound?: boolean): IValue<any> {        if (!this.base) { // istanbul ignore next            throw new Error('Should not call .getColumn() on join');        }        if (!('columns' in this.base)) { // istanbul ignore next            throw new Error('Should not call getColumn() on table');        }        this.initCols();        const col = this.base.getColumn(column, nullIfNotFound);        return col && this._columnMappings.get(col);    }     */
    getColumn(column: string | ExprRef): IValue;    getColumn(column: string | ExprRef, nullIfNotFound?: boolean): IValue | nil;    getColumn(column: string | ExprRef, nullIfNotFound?: boolean): IValue<any> | nil {        if (!this.base) { // istanbul ignore next            throw new Error('Should not call .getColumn() on join');        }        if (!('columns' in this.base)) { // istanbul ignore next            throw new Error('Should not call getColumn() on table');        }        return this.base.getColumn(column, nullIfNotFound);    }
    getIndex(...forValue: IValue<any>[]): _IIndex<any> | null | undefined {        const index = this.base.getIndex(...forValue);        if (!index) {            return null;        }        return new RestrictiveIndex(index, this);    }}