Add d3.set

Taking inspiration from d3.map, d3.set is a simple shim for ES6 sets.

Makefile

@@ -34,6 +34,7 @@ d3.core.js: \
 	src/core/class.js \
 	src/core/array.js \
 	src/core/map.js \
+	src/core/set.js \
 	src/core/identity.js \
 	src/core/true.js \
 	src/core/functor.js \

d3.js

@@ -104,6 +104,40 @@ d3 = function() {
     }
   });
   var d3_map_prefix = "\0", d3_map_prefixCode = d3_map_prefix.charCodeAt(0);
+  d3.set = function(array) {
+    var set = new d3_Set();
+    if (array) for (var i = 0; i < array.length; i++) set.add(array[i]);
+    return set;
+  };
+  function d3_Set() {}
+  d3_class(d3_Set, {
+    has: function(value) {
+      return d3_set_prefix + value in this;
+    },
+    add: function(value) {
+      this[d3_set_prefix + value] = true;
+      return value;
+    },
+    remove: function(value) {
+      value = d3_set_prefix + value;
+      return value in this && delete this[value];
+    },
+    values: function() {
+      var values = [];
+      this.forEach(function(value) {
+        values.push(value);
+      });
+      return values;
+    },
+    forEach: function(f) {
+      for (var value in this) {
+        if (value.charCodeAt(0) === d3_set_prefixCode) {
+          f.call(this, value.substring(1));
+        }
+      }
+    }
+  });
+  var d3_set_prefix = "\0", d3_set_prefixCode = d3_set_prefix.charCodeAt(0);
   function d3_identity(d) {
     return d;
   }

src/core/set.js

@@ -0,0 +1,38 @@
+d3.set = function(array) {
+  var set = new d3_Set();
+  if (array) for (var i = 0; i < array.length; i++) set.add(array[i]);
+  return set;
+};
+
+function d3_Set() {}
+
+d3_class(d3_Set, {
+  has: function(value) {
+    return d3_set_prefix + value in this;
+  },
+  add: function(value) {
+    this[d3_set_prefix + value] = true;
+    return value;
+  },
+  remove: function(value) {
+    value = d3_set_prefix + value;
+    return value in this && delete this[value];
+  },
+  values: function() {
+    var values = [];
+    this.forEach(function(value) {
+      values.push(value);
+    });
+    return values;
+  },
+  forEach: function(f) {
+    for (var value in this) {
+      if (value.charCodeAt(0) === d3_set_prefixCode) {
+        f.call(this, value.substring(1));
+      }
+    }
+  }
+});
+
+var d3_set_prefix = "\0", // prevent collision with built-ins
+    d3_set_prefixCode = d3_set_prefix.charCodeAt(0);

test/core/set-test.js

@@ -0,0 +1,133 @@
+require("../env");
+
+var vows = require("vows"),
+    assert = require("assert");
+
+var suite = vows.describe("d3.set");
+
+suite.addBatch({
+  "constructor": {
+    "set() returns an empty set": function() {
+      var set = d3.set();
+      assert.deepEqual(set.values(), []);
+    },
+    "set(null) returns an empty set": function() {
+      var set = d3.set(null);
+      assert.deepEqual(set.values(), []);
+    },
+    "set(array) adds array entries": function() {
+      var set = d3.set(["foo"]);
+      assert.isTrue(set.has("foo"));
+      var set = d3.set(["foo", "bar"]);
+      assert.isTrue(set.has("foo"));
+      assert.isTrue(set.has("bar"));
+    }
+  },
+  "forEach": {
+    "empty sets have an empty values array": function() {
+      var set = d3.set();
+      assert.deepEqual(set.values(), []);
+      set.add("foo");
+      assert.deepEqual(set.values(), ["foo"]);
+      set.remove("foo");
+      assert.deepEqual(set.values(), []);
+    },
+    "values are returned in arbitrary order": function() {
+      var set = d3.set(["foo", "bar"]);
+      assert.deepEqual(set.values().sort(d3.ascending()), ["bar", "foo"]);
+      var set = d3.set(["bar", "foo"]);
+      assert.deepEqual(set.values().sort(d3.ascending()), ["bar", "foo"]);
+    },
+    "observes changes via add and remove": function() {
+      var set = d3.set(["foo", "bar"]);
+      assert.deepEqual(set.values().sort(d3.ascending()), ["bar", "foo"]);
+      set.remove("foo");
+      assert.deepEqual(set.values(), ["bar"]);
+      set.add("bar");
+      assert.deepEqual(set.values(), ["bar"]);
+      set.add("foo");
+      assert.deepEqual(set.values().sort(d3.ascending()), ["bar", "foo"]);
+      set.remove("bar");
+      assert.deepEqual(set.values(), ["foo"]);
+      set.remove("foo");
+      assert.deepEqual(set.values(), []);
+      set.remove("foo");
+      assert.deepEqual(set.values(), []);
+    }
+  },
+  "values": {
+    "returns an array of string values": function() {
+      var set = d3.set(["foo", "bar"]);
+      assert.deepEqual(set.values().sort(), ["bar", "foo"]);
+    }
+  },
+  "has": {
+    "empty sets do not have object built-ins": function() {
+      var set = d3.set();
+      assert.isFalse(set.has("__proto__"));
+      assert.isFalse(set.has("hasOwnProperty"));
+    },
+    "coerces values to strings": function() {
+      var set = d3.set(["42", "null", "undefined"]);
+      assert.isTrue(set.has(42));
+      assert.isTrue(set.has(null));
+      assert.isTrue(set.has(undefined));
+    },
+    "observes changes via add and remove": function() {
+      var set = d3.set(["foo"]);
+      assert.isTrue(set.has("foo"));
+      set.add("foo");
+      assert.isTrue(set.has("foo"));
+      set.remove("foo");
+      assert.isFalse(set.has("foo"));
+      set.add("foo");
+      assert.isTrue(set.has("foo"));
+    },
+    "returns undefined for missing values": function() {
+      var set = d3.set(["foo"]);
+      assert.isFalse(set.has("bar"));
+    }
+  },
+  "add": {
+    "returns the set value": function() {
+      var set = d3.set();
+      assert.equal(set.add("foo"), "foo");
+    },
+    "can add values using built-in names": function() {
+      var set = d3.set();
+      set.add("__proto__");
+      assert.isTrue(set.has("__proto__"));
+    },
+    "coerces values to strings": function() {
+      var set = d3.set();
+      set.add(42);
+      assert.isTrue(set.has(42));
+      set.add(null);
+      assert.isTrue(set.has(null));
+      set.add(undefined);
+      assert.isTrue(set.has(undefined));
+      assert.deepEqual(set.values().sort(), ["42", "null", "undefined"]);
+    },
+    "can add null, undefined or empty string values": function() {
+      var set = d3.set();
+      set.add("");
+      set.add("null");
+      set.add("undefined");
+      assert.isTrue(set.has(""));
+      assert.isTrue(set.has("null"));
+      assert.isTrue(set.has("undefined"));
+    }
+  },
+  "remove": {
+    "returns true if the value was removed": function() {
+      var set = d3.set(["foo"]);
+      assert.isTrue(set.remove("foo"));
+    },
+    "returns false if the value is not an element": function() {
+      var set = d3.set();
+      assert.isFalse(set.remove("foo"));
+    }
+  }
+});
+
+suite.export(module);