first commit

Software/NodeJS/libs/sensors/base/sensor.js

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+var util         = require('util')
+var EventEmitter = require('events').EventEmitter
+var Board        = require('../../grovepi')
+
+var isEqual = function(a, b) {
+  if (typeof a == 'object') {
+    for (var i in a) {
+      if (a[i] !== b[i]) {
+        return false
+      }
+    }
+    return true
+  } else {
+    return a === b
+  }
+}
+
+function Sensor() {
+  this.board = new Board()
+  this.lastValue = 0
+  this.currentValue = 0
+  this.streamInterval = this.watchInterval = undefined
+  this.watchDelay = 100
+}
+
+util.inherits(Sensor, EventEmitter)
+
+Sensor.prototype.read = function() {}
+Sensor.prototype.write = function() {}
+Sensor.prototype.stream = function(delay, cb) {
+  var self = this
+  delay = typeof delay == 'undefined' ? self.watchDelay : delay
+
+  self.stopStream()
+  self.streamInterval = setInterval(function onStreamInterval() {
+    var res = self.read()
+    cb(res)
+  }, delay)
+}
+Sensor.prototype.stopStream = function() {
+  var self = this
+  if (typeof self.streamInterval != 'undefined')
+    clearInterval(self.streamInterval)
+}
+
+Sensor.prototype.watch = function(delay) {
+  var self = this
+  delay = typeof delay == 'undefined' ? self.watchDelay : delay
+
+  self.stopWatch()
+  self.watchInterval = setInterval(function onInterval() {
+    var res = self.read()
+
+    self.lastValue = self.currentValue
+    self.currentValue = res
+
+    if (!isEqual(self.currentValue, self.lastValue))
+      self.emit('change', self.currentValue)
+  }, delay)
+}
+Sensor.prototype.stopWatch = function() {
+  var self = this
+  if (typeof self.watchInterval != 'undefined')
+    clearInterval(self.watchInterval)
+}
+
+module.exports = Sensor