Merge pull request #63 from jiminys/master

added isLeaf(v) function to graph

Author: zenkyomu

.gitignore

@@ -1,2 +1,3 @@
 /build
 /node_modules
+/.vscode

lib/graph.js

@@ -270,6 +270,16 @@ Graph.prototype.neighbors = function(v) {
   }
 };
 
+Graph.prototype.isLeaf = function (v) {
+  var neighbors;
+  if (this.isDirected()) {
+    neighbors = this.successors(v);
+  } else {
+    neighbors = this.neighbors(v);
+  }
+  return neighbors.length === 0;
+};
+
 Graph.prototype.filterNodes = function(filter) {
   var copy = new this.constructor({
     directed: this._isDirected,

test/graph-test.js

@@ -529,6 +529,37 @@ describe("Graph", function() {
     });
   });
 
+  describe("isLeaf", function() {
+    it("returns false for connected node in undirected graph", function() {
+      g = new Graph({directed: false});
+      g.setNode("a");
+      g.setNode("b");
+      g.setEdge("a", "b");
+      expect(g.isLeaf("b")).to.be.false;
+    });
+    it("returns true for an unconnected node in undirected graph", function() {
+      g = new Graph({directed: false});
+      g.setNode("a");
+      expect(g.isLeaf("a")).to.be.true;
+    });
+    it("returns true for unconnected node in directed graph", function() {
+      g.setNode("a");
+      expect(g.isLeaf("a")).to.be.true;
+    });
+    it("returns false for predecessor node in directed graph", function() {
+      g.setNode("a");
+      g.setNode("b");
+      g.setEdge("a", "b");
+      expect(g.isLeaf("a")).to.be.false;
+    });
+    it("returns true for successor node in directed graph", function() {
+      g.setNode("a");
+      g.setNode("b");
+      g.setEdge("a", "b");
+      expect(g.isLeaf("b")).to.be.true;
+    });
+  });
+
   describe("edges", function() {
     it("is empty if there are no edges in the graph", function() {
       expect(g.edges()).to.eql([]);