08-27-周三_17-09-29

node_modules/graphlib/lib/alg/topsort.js

@@ -0,0 +1,35 @@
+var _ = require("../lodash");
+
+module.exports = topsort;
+topsort.CycleException = CycleException;
+
+function topsort(g) {
+  var visited = {};
+  var stack = {};
+  var results = [];
+
+  function visit(node) {
+    if (_.has(stack, node)) {
+      throw new CycleException();
+    }
+
+    if (!_.has(visited, node)) {
+      stack[node] = true;
+      visited[node] = true;
+      _.each(g.predecessors(node), visit);
+      delete stack[node];
+      results.push(node);
+    }
+  }
+
+  _.each(g.sinks(), visit);
+
+  if (_.size(visited) !== g.nodeCount()) {
+    throw new CycleException();
+  }
+
+  return results;
+}
+
+function CycleException() {}
+CycleException.prototype = new Error(); // must be an instance of Error to pass testing