feat: make use of Symbol.species to allow creating new matrices in any class

- defaults to the current constructor
- views override it to return a new Matrix

Author: targos

src/abstractMatrix.js

@@ -18,6 +18,10 @@ function abstractMatrix(superCtor) {
      * @param {number} [nColumns] - Number of columns of the new matrix
      */
     class Matrix extends superCtor {
+        static get [Symbol.species]() {
+            return this;
+        }
+
         /**
          * Constructs a Matrix with the chosen dimensions from a 1D array
          * @param {number} newRows - Number of rows
@@ -339,7 +343,7 @@ function abstractMatrix(superCtor) {
         repeat(rowRep, colRep) {
             rowRep = rowRep || 1;
             colRep = colRep || 1;
-            var matrix = new this.constructor(this.rows * rowRep, this.columns * colRep);
+            var matrix = new this.constructor[Symbol.species](this.rows * rowRep, this.columns * colRep);
             for (var i = 0; i < rowRep; i++) {
                 for (var j = 0; j < colRep; j++) {
                     matrix.setSubMatrix(this, this.rows * i, this.columns * j);
@@ -929,7 +933,7 @@ function abstractMatrix(superCtor) {
             var n = this.columns;
             var p = other.columns;
 
-            var result = new this.constructor(m, p);
+            var result = new this.constructor[Symbol.species](m, p);
 
             var Bcolj = new Array(n);
             for (var j = 0; j < p; j++) {
@@ -1010,7 +1014,7 @@ function abstractMatrix(superCtor) {
             var p = other.rows;
             var q = other.columns;
 
-            var result = new this.constructor(m * p, n * q);
+            var result = new this.constructor[Symbol.species](m * p, n * q);
             for (var i = 0; i < m; i++) {
                 for (var j = 0; j < n; j++) {
                     for (var k = 0; k < p; k++) {
@@ -1028,7 +1032,7 @@ function abstractMatrix(superCtor) {
          * @returns {Matrix}
          */
         transpose() {
-            var result = new this.constructor(this.columns, this.rows);
+            var result = new this.constructor[Symbol.species](this.columns, this.rows);
             for (var i = 0; i < this.rows; i++) {
                 for (var j = 0; j < this.columns; j++) {
                     result.set(j, i, this.get(i, j));
@@ -1075,7 +1079,7 @@ function abstractMatrix(superCtor) {
             if ((startRow > endRow) || (startColumn > endColumn) || (startRow < 0) || (startRow >= this.rows) || (endRow < 0) || (endRow >= this.rows) || (startColumn < 0) || (startColumn >= this.columns) || (endColumn < 0) || (endColumn >= this.columns)) {
                 throw new RangeError('Argument out of range');
             }
-            var newMatrix = new this.constructor(endRow - startRow + 1, endColumn - startColumn + 1);
+            var newMatrix = new this.constructor[Symbol.species](endRow - startRow + 1, endColumn - startColumn + 1);
             for (var i = startRow; i <= endRow; i++) {
                 for (var j = startColumn; j <= endColumn; j++) {
                     newMatrix[i - startRow][j - startColumn] = this.get(i, j);
@@ -1098,7 +1102,7 @@ function abstractMatrix(superCtor) {
                 throw new RangeError('Argument out of range');
             }
 
-            var newMatrix = new this.constructor(indices.length, endColumn - startColumn + 1);
+            var newMatrix = new this.constructor[Symbol.species](indices.length, endColumn - startColumn + 1);
             for (var i = 0; i < indices.length; i++) {
                 for (var j = startColumn; j <= endColumn; j++) {
                     if (indices[i] < 0 || indices[i] >= this.rows) {
@@ -1124,7 +1128,7 @@ function abstractMatrix(superCtor) {
                 throw new RangeError('Argument out of range');
             }
 
-            var newMatrix = new this.constructor(endRow - startRow + 1, indices.length);
+            var newMatrix = new this.constructor[Symbol.species](endRow - startRow + 1, indices.length);
             for (var i = 0; i < indices.length; i++) {
                 for (var j = startRow; j <= endRow; j++) {
                     if (indices[i] < 0 || indices[i] >= this.columns) {

src/matrix.js

@@ -1,10 +1,14 @@
 'use strict';
 
+require('./symbol-species');
 var abstractMatrix = require('./abstractMatrix');
 var util = require('./util');
 
 class Matrix extends abstractMatrix(Array) {
     constructor(nRows, nColumns) {
+        if (arguments.length === 1 && typeof nRows === 'number') {
+            return new Array(nRows);
+        }
         if (Matrix.isMatrix(nRows)) {
             return nRows.clone();
         } else if (Number.isInteger(nRows) && nRows > 0) { // Create an empty matrix
@@ -37,11 +41,6 @@ class Matrix extends abstractMatrix(Array) {
         this.columns = nColumns;
     }
 
-    // Native array methods should return instances of Array, not Matrix
-    static get [Symbol.species]() {
-        return Array;
-    }
-
     set(rowIndex, columnIndex, value) {
         this[rowIndex][columnIndex] = value;
         return this;
@@ -56,7 +55,7 @@ class Matrix extends abstractMatrix(Array) {
      * @returns {Matrix}
      */
     clone() {
-        var newMatrix = new this.constructor(this.rows, this.columns);
+        var newMatrix = new this.constructor[Symbol.species](this.rows, this.columns);
         for (var row = 0; row < this.rows; row++) {
             for (var column = 0; column < this.columns; column++) {
                 newMatrix.set(row, column, this.get(row, column));

src/symbol-species.js

@@ -0,0 +1,5 @@
+'use strict';
+
+if (!Symbol.species) {
+    Symbol.species = Symbol.for('@@species');
+}

src/views/base.js

@@ -1,6 +1,7 @@
 'use strict';
 
 var abstractMatrix = require('../abstractMatrix');
+var Matrix;
 
 class BaseView extends abstractMatrix() {
     constructor(matrix, rows, columns) {
@@ -9,6 +10,13 @@ class BaseView extends abstractMatrix() {
         this.rows = rows;
         this.columns = columns;
     }
+
+    static get [Symbol.species]() {
+        if (!Matrix) {
+            Matrix = require('../matrix');
+        }
+        return Matrix;
+    }
 }
 
 module.exports = BaseView;