adopt InternMap

Author: mbostock

package.json

@@ -43,7 +43,7 @@
     "tape-await": "^0.1.2"
   },
   "dependencies": {
-    "d3-array": "^2.8.0",
+    "d3-array": "^2.10.0",
     "d3-axis": "^2.0.0",
     "d3-color": "^2.0.0",
     "d3-interpolate": "^2.0.1",

src/facet.js

@@ -1,4 +1,4 @@
-import {cross, groups} from "d3-array";
+import {cross, groups, InternMap} from "d3-array";
 import {create} from "d3-selection";
 import {Mark, first, second} from "./mark.js";
 
@@ -164,7 +164,7 @@ function facetMap(channels) {
 
 class FacetMap {
   constructor() {
-    this._ = new Map();
+    this._ = new InternMap();
   }
   has(key) {
     return this._.has(key);
@@ -190,7 +190,7 @@ class FacetMap2 extends FacetMap {
   set([key1, key2], value) {
     const map = super.get(key1);
     if (map) map.set(key2, value);
-    else super.set(key1, new Map([[key2, value]]));
+    else super.set(key1, new InternMap([[key2, value]]));
     return this;
   }
 }

src/group.js

@@ -1,13 +1,14 @@
-// Unlike d3.group, this implicitly coerces to a primitive value if possible via
-// valueOf; for example Date is coerced to a number. And, this returns an
-// iterable of subsets of the given index rather than a map.
+import {InternMap} from "d3-array";
+
+// Like d3.group, but takes an array of values instead of accessor, only
+// supports one level of grouping, and returns an iterable of subsets of the
+// given index rather than a map.
 export function group(index, values) {
-  const groups = new Map();
+  const groups = new InternMap();
   for (const i of index) {
     const value = values[i];
-    const key = value !== null && typeof value === "object" ? value.valueOf() : value;
-    const group = groups.get(key);
-    if (group === undefined) groups.set(key, [i]);
+    const group = groups.get(value);
+    if (group === undefined) groups.set(value, [i]);
     else group.push(i);
   }
   return groups.values();

src/transforms/stack.js

@@ -1,15 +1,16 @@
+import {InternMap} from "d3-array";
 import {valueof} from "../mark";
 
 // TODO configurable series order
 export function stackX(data, {x, y, ...options}) {
   const X = valueof(data, x);
   const Y = valueof(data, y);
   const n = X.length;
-  const X0 = new Map();
+  const X0 = new InternMap();
   const X1 = new Float64Array(n);
   const X2 = new Float64Array(n);
   for (let i = 0; i < n; ++i) {
-    const k = Y[i] && Y[i].valueOf();
+    const k = Y[i];
     const x1 = X1[i] = X0.has(k) ? X0.get(k) : 0;
     const x2 = X2[i] = x1 + +X[i];
     X0.set(k, isNaN(x2) ? x1 : x2);
@@ -22,11 +23,11 @@ export function stackY(data, {x, y, ...options}) {
   const X = valueof(data, x);
   const Y = valueof(data, y);
   const n = X.length;
-  const Y0 = new Map();
+  const Y0 = new InternMap();
   const Y1 = new Float64Array(n);
   const Y2 = new Float64Array(n);
   for (let i = 0; i < n; ++i) {
-    const k = X[i] && X[i].valueOf();
+    const k = X[i];
     const y1 = Y1[i] = Y0.has(k) ? Y0.get(k) : 0;
     const y2 = Y2[i] = y1 + +Y[i];
     Y0.set(k, isNaN(y2) ? y1 : y2);

yarn.lock

@@ -326,7 +326,7 @@ cssstyle@^2.2.0:
   dependencies:
     cssom "~0.3.6"
 
-d3-array@2, d3-array@>=2.5, d3-array@^2.3.0, d3-array@^2.8.0:
+d3-array@2, d3-array@>=2.5, d3-array@^2.10.0, d3-array@^2.3.0:
   version "2.10.0"
   resolved "https://registry.yarnpkg.com/d3-array/-/d3-array-2.10.0.tgz#dedf198fe55ea761d196ae40b15dd42e2deaf0b2"
   integrity sha512-TygE7/GvpL0092Pa/cS/kcyQ4E+I8KCkw3uCpQOFc4xi4IWNE67xST56H1Tz/FTYUqABULSEAmeLrGAmuLN8Xg==