Move Table out of the Vector hierarchy

Author: Brian Hulette

js/src/Arrow.ts

@@ -15,7 +15,8 @@
 // specific language governing permissions and limitations
 // under the License.
 
-import { Table } from './vector/table';
+import { Table, TableRow } from './table';
+import { lit, col } from './predicate';
 import { Vector } from './vector/vector';
 import { Utf8Vector } from './vector/utf8';
 import { DictionaryVector } from './vector/dictionary';
@@ -45,8 +46,6 @@ import {
     TimestampVector,
 } from './vector/numeric';
 
-import { lit, col } from './vector/predicate';
-
 // closure compiler always erases static method names:
 // https://github.com/google/closure-compiler/issues/1776
 // set them via string indexers to save them from the mangler
@@ -55,7 +54,9 @@ Table['fromAsync'] = Table.fromAsync;
 BoolVector['pack'] = BoolVector.pack;
 
 export { read, readAsync };
-export { Table, Vector, StructRow };
+export { Table, TableRow };
+export { lit, col };
+export { Vector, StructRow };
 export { Uint64, Int64, Int128 };
 export { NumericVectorConstructor } from './vector/numeric';
 export { List, TypedArray, TypedArrayConstructor } from './vector/types';
@@ -86,7 +87,6 @@ export {
     FixedSizeListVector,
 };
 
-export { lit, col } from './vector/predicate';
 
 
 /* These exports are needed for the closure umd targets */

js/src/bin/arrow2csv.ts

@@ -98,7 +98,7 @@ files.forEach((source) => {
 });
 
 function printTable(table: Arrow.Table) {
-    let header = [...table.columns.map((_, i) => table.key(i))].map(stringify);
+    let header = [...table.columns.map((c) => c.name)].map(stringify);
     let maxColumnWidths = header.map(x => x.length);
     // Pass one to convert to strings and count max column widths
     for (let i = -1, n = table.length - 1; ++i < n;) {
@@ -132,4 +132,4 @@ function stringify(x: any) {
                                       : `${x}`;
 }
 
-})();
+})();

js/src/vector/predicate.ts renamed to js/src/predicate.ts

@@ -1,5 +1,5 @@
-import { Vector } from "../vector/vector";
-import { DictionaryVector } from "../vector/dictionary";
+import { Vector } from "./vector/vector";
+import { DictionaryVector } from "./vector/dictionary";
 
 export type ValueFunc<T> = (idx: number, cols: Vector[]) => T|null;
 export type PredicateFunc = (idx: number, cols: Vector[]) => boolean;

js/src/vector/table.ts renamed to js/src/table.ts

@@ -15,20 +15,25 @@
 // specific language governing permissions and limitations
 // under the License.
 
-import { Vector } from './vector';
-import { StructVector, StructRow } from './struct';
-import { read, readAsync } from '../reader/arrow';
+import { Vector } from './vector/vector';
+import { read, readAsync } from './reader/arrow';
 import { Predicate } from './predicate';
 
 export type NextFunc = (idx: number, cols: Vector[]) => void;
 
-export class DataFrameRow extends StructRow<any> {
-    constructor (batch: Vector[], idx: number) {
-        super(new StructVector({columns: batch}), idx);
+export class TableRow {
+    constructor (readonly batch: Vector[], readonly idx: number) {}
+    toArray() {
+        return this.batch.map((vec) => vec.get(this.idx));
     }
     toString() {
         return this.toArray().map((x) => JSON.stringify(x)).join(', ');
     }
+    *[Symbol.iterator]() {
+        for (const vec of this.batch) {
+            yield vec.get(this.idx);
+        }
+    }
 }
 
 export interface DataFrame {
@@ -46,7 +51,7 @@ function columnsFromBatches(batches: Vector[][]) {
     );
 }
 
-export class Table extends StructVector<any> implements DataFrame {
+export class Table implements DataFrame {
     static from(sources?: Iterable<Uint8Array | Buffer | string> | object | string) {
         let batches: Vector<any>[][] = [[]];
         if (sources) {
@@ -73,20 +78,20 @@ export class Table extends StructVector<any> implements DataFrame {
     readonly lengths: Uint32Array;
     readonly length: number;
     constructor(argv: { batches: Vector<any>[][] }) {
-        super({columns: columnsFromBatches(argv.batches)});
         this.batches = argv.batches;
+        this.columns = columnsFromBatches(this.batches);
         this.lengths = new Uint32Array(this.batches.map((batch) => batch[0].length));
 
         this.length = this.lengths.reduce((acc, length) => acc + length);
     }
-    get(idx: number): DataFrameRow {
+    get(idx: number): TableRow {
         let batch = 0;
         while (idx > this.lengths[batch] && batch < this.lengths.length)
             idx -= this.lengths[batch++];
 
         if (batch === this.lengths.length) throw new Error("Overflow")
 
-        else return new DataFrameRow(this.batches[batch], idx);
+        else return new TableRow(this.batches[batch], idx);
     }
     filter(predicate: Predicate): DataFrame {
         return new FilteredDataFrame(this, predicate);
@@ -116,7 +121,7 @@ export class Table extends StructVector<any> implements DataFrame {
 
             // yield all indices
             for (let idx = -1; ++idx < length;) {
-                yield new DataFrameRow(columns, idx);
+                yield new TableRow(columns, idx);
             }
         }
     }