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import { _ISelection, IValue, _IIndex, _ITable, _Transaction, _Explainer, _SelectExplanation, IndexKey, IndexOp, Stats } from '../interfaces-private.ts';import { FilterBase } from './transform-base.ts';import { nullIsh } from '../utils.ts';
export class EqFilter<T = any> extends FilterBase<T> {
    private index: _IIndex;    private opDef: IndexOp;
    entropy(t: _Transaction): number {        return this.index.entropy({ ...this.opDef, t });    }

    stats(t: _Transaction): Stats | null {        const stats = this.index.stats(t, [this.equalsCst]);        if (this.op === 'eq' || !stats) {            return stats;        }        // if neq, then compute from eq and all        const all = this.index.stats(t);        if (!all) {            return null;        }        return {            count: all.count - stats.count,        };    }
    hasItem(item: T, t: _Transaction) {        const val = this.onValue.get(item, t);        if (nullIsh(val)) {            return false;        }        const eq = this.onValue.type.equals(val, this.equalsCst);        if (nullIsh(eq)) {            return false;        }        return this.op === 'eq' ? !!eq : !eq;    }
    constructor(private onValue: IValue<T>        , private equalsCst: any        , private op: 'eq' | 'neq'        , private matchNull: boolean) {        super(onValue.origin!);        if (onValue.index!.expressions.length !== 1) {            throw new Error('Unexpected index equality expressions count mismatch');        }
        this.index = this.onValue.index!;        this.opDef = {            type: op,            key: [equalsCst],            t: null as any,            matchNull: this.matchNull,        }    }
    *enumerate(t: _Transaction): Iterable<T> {        for (const item of this.index.enumerate({ ...this.opDef, t })) {            yield item;        }    }
    explain(e: _Explainer): _SelectExplanation {        return {            id: e.idFor(this),            _: this.op,            entropy: this.entropy(e.transaction),            on: this.onValue.index!.explain(e),        };    }}