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Add concept of predicates for filtering dataframes
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Brian Hulette
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Jan 12, 2018
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,171 @@ | ||
| import { Vector } from "../vector/vector"; | ||
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| export type ValueFunc<T> = (idx: number, cols: Vector[]) => T|null; | ||
| export type PredicateFunc = (idx: number, cols: Vector[]) => boolean; | ||
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| export abstract class Value<T> { | ||
| eq(other: Value<T>|T): Predicate { | ||
| if (!(other instanceof Value)) other = new Literal(other); | ||
| return new Equals(this, other); | ||
| } | ||
| lteq(other: Value<T>|T): Predicate { | ||
| if (!(other instanceof Value)) other = new Literal(other); | ||
| return new LTeq(this, other); | ||
| } | ||
| gteq(other: Value<T>|T): Predicate { | ||
| if (!(other instanceof Value)) other = new Literal(other); | ||
| return new GTeq(this, other); | ||
| } | ||
| } | ||
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| class Literal<T=any> extends Value<T> { | ||
| constructor(public v: T) { super(); } | ||
| } | ||
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| class Col<T=any> extends Value<T> { | ||
| vector: Vector<T>; | ||
| colidx: number; | ||
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| constructor(public name: string) { super(); } | ||
| bind(cols: Vector[]) { | ||
| if (!this.colidx) { | ||
| // Assume column index doesn't change between calls to bind | ||
| //this.colidx = cols.findIndex(v => v.name.indexOf(this.name) != -1); | ||
| this.colidx = -1; | ||
| for (let idx = -1; ++idx < cols.length;) { | ||
| if (cols[idx].name === this.name) { | ||
| this.colidx = idx; | ||
| break; | ||
| } | ||
| } | ||
| if (this.colidx < 0) throw new Error(`Failed to bind Col "${this.name}"`) | ||
| } | ||
| this.vector = cols[this.colidx] | ||
| return this.vector.get.bind(this.vector); | ||
| } | ||
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| emitString() { return `cols[${this.colidx}].get(idx)`; } | ||
| } | ||
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| export abstract class Predicate { | ||
| abstract bind(cols: Vector[]): PredicateFunc; | ||
| and(expr: Predicate): Predicate { return new And(this, expr); } | ||
| or(expr: Predicate): Predicate { return new Or(this, expr); } | ||
| ands(): Predicate[] { return [this]; } | ||
| } | ||
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| abstract class ComparisonPredicate<T=any> extends Predicate { | ||
| constructor(public readonly left: Value<T>, public readonly right: Value<T>) { | ||
| super(); | ||
| } | ||
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| bind(cols: Vector<any>[]) { | ||
| if (this.left instanceof Literal) { | ||
| if (this.right instanceof Literal) { | ||
| return this._bindLitLit(cols, this.left, this.right); | ||
| } else { // right is a Col | ||
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| return this._bindColLit(cols, this.right as Col, this.left); | ||
| } | ||
| } else { // left is a Col | ||
| if (this.right instanceof Literal) { | ||
| return this._bindColLit(cols, this.left as Col, this.right); | ||
| } else { // right is a Col | ||
| return this._bindColCol(cols, this.left as Col, this.right as Col); | ||
| } | ||
| } | ||
| } | ||
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| protected abstract _bindLitLit(cols: Vector<any>[], left: Literal, right: Literal): PredicateFunc; | ||
| protected abstract _bindColCol(cols: Vector<any>[], left: Col , right: Col ): PredicateFunc; | ||
| protected abstract _bindColLit(cols: Vector<any>[], col: Col , lit: Literal ): PredicateFunc; | ||
| } | ||
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| abstract class CombinationPredicate extends Predicate { | ||
| constructor(public readonly left: Predicate, public readonly right: Predicate) { | ||
| super(); | ||
| } | ||
| } | ||
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| class And extends CombinationPredicate { | ||
| bind(cols: Vector[]) { | ||
| const left = this.left.bind(cols); | ||
| const right = this.right.bind(cols); | ||
| return (idx: number, cols: Vector[]) => left(idx, cols) && right(idx, cols); | ||
| } | ||
| ands() : Predicate[] { return this.left.ands().concat(this.right.ands()); } | ||
| } | ||
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| class Or extends CombinationPredicate { | ||
| bind(cols: Vector[]) { | ||
| const left = this.left.bind(cols); | ||
| const right = this.right.bind(cols); | ||
| return (idx: number, cols: Vector[]) => left(idx, cols) || right(idx, cols); | ||
| } | ||
| } | ||
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| class Equals extends ComparisonPredicate { | ||
| protected _bindLitLit(_: Vector<any>[], left: Literal, right: Literal): PredicateFunc { | ||
| const rtrn: boolean = left.v == right.v; | ||
| return () => rtrn; | ||
| } | ||
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| protected _bindColCol(cols: Vector<any>[], left: Col , right: Col ): PredicateFunc { | ||
| const left_func = left.bind(cols); | ||
| const right_func = right.bind(cols); | ||
| return (idx: number, cols: Vector[]) => left_func(idx, cols) == right_func(idx, cols); | ||
| } | ||
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| protected _bindColLit(cols: Vector<any>[], col: Col , lit: Literal ): PredicateFunc { | ||
| const col_func = col.bind(cols); | ||
| return (idx: number, cols: Vector[]) => col_func(idx, cols) == lit.v; | ||
| } | ||
| } | ||
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| class LTeq extends ComparisonPredicate { | ||
| protected _bindLitLit(_: Vector<any>[], left: Literal, right: Literal): PredicateFunc { | ||
| const rtrn: boolean = left.v <= right.v; | ||
| return () => rtrn; | ||
| } | ||
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| protected _bindColCol(cols: Vector<any>[], left: Col , right: Col ): PredicateFunc { | ||
| const left_func = left.bind(cols); | ||
| const right_func = right.bind(cols); | ||
| return (idx: number, cols: Vector[]) => left_func(idx, cols) <= right_func(idx, cols); | ||
| } | ||
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| protected _bindColLit(cols: Vector<any>[], col: Col , lit: Literal ): PredicateFunc { | ||
| const col_func = col.bind(cols); | ||
| return (idx: number, cols: Vector[]) => col_func(idx, cols) <= lit.v; | ||
| } | ||
| } | ||
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| class GTeq extends ComparisonPredicate { | ||
| protected _bindLitLit(_: Vector<any>[], left: Literal, right: Literal): PredicateFunc { | ||
| const rtrn: boolean = left.v >= right.v; | ||
| return () => rtrn; | ||
| } | ||
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| protected _bindColCol(cols: Vector<any>[], left: Col, right: Col): PredicateFunc { | ||
| const left_func = left.bind(cols); | ||
| const right_func = right.bind(cols); | ||
| return (idx: number, cols: Vector[]) => left_func(idx, cols) >= right_func(idx, cols); | ||
| } | ||
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| protected _bindColLit(cols: Vector<any>[], col: Col, lit: Literal): PredicateFunc { | ||
| const col_func = col.bind(cols); | ||
| return (idx: number, cols: Vector[]) => col_func(idx, cols) >= lit.v; | ||
| } | ||
| //eval(idx: number, cols: Vector[]) { | ||
| // return this.left.eval(idx, cols) >= this.right.eval(idx, cols); | ||
| //} | ||
| //emitString() { | ||
| // return `${this.left.emitString()} >= ${this.right.emitString()}` | ||
| //} | ||
| //createDictionaryEval(schema, lit: Literal, col: Col): (idx: number, cols: Vector[]) => boolean { | ||
| // return this.eval; | ||
| //} | ||
| } | ||
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| export function lit(n: number): Value<any> { return new Literal(n); } | ||
| export function col(n: string): Value<any> { return new Col(n); } |