Version 1

[yaffs-website] / node_modules / pend / index.js

diff --git a/node_modules/pend/index.js b/node_modules/pend/index.js
new file mode 100644 (file)
index 0000000..3bf485e
--- /dev/null
+++ b/node_modules/pend/index.js
@@ -0,0 +1,55 @@
+module.exports = Pend;
+
+function Pend() {
+  this.pending = 0;
+  this.max = Infinity;
+  this.listeners = [];
+  this.waiting = [];
+  this.error = null;
+}
+
+Pend.prototype.go = function(fn) {
+  if (this.pending < this.max) {
+    pendGo(this, fn);
+  } else {
+    this.waiting.push(fn);
+  }
+};
+
+Pend.prototype.wait = function(cb) {
+  if (this.pending === 0) {
+    cb(this.error);
+  } else {
+    this.listeners.push(cb);
+  }
+};
+
+Pend.prototype.hold = function() {
+  return pendHold(this);
+};
+
+function pendHold(self) {
+  self.pending += 1;
+  var called = false;
+  return onCb;
+  function onCb(err) {
+    if (called) throw new Error("callback called twice");
+    called = true;
+    self.error = self.error || err;
+    self.pending -= 1;
+    if (self.waiting.length > 0 && self.pending < self.max) {
+      pendGo(self, self.waiting.shift());
+    } else if (self.pending === 0) {
+      var listeners = self.listeners;
+      self.listeners = [];
+      listeners.forEach(cbListener);
+    }
+  }
+  function cbListener(listener) {
+    listener(self.error);
+  }
+}
+
+function pendGo(self, fn) {
+  fn(pendHold(self));
+}