Reduce complexity

src/controllers/controller.bar.js

@@ -118,7 +118,7 @@ function getMatchingVisibleMetas(scale) {
 	var isHorizontal = scale.isHorizontal();
 	return scale.chart._getSortedVisibleDatasetMetas()
 		.filter(function(meta) {
-			return meta.bar && isHorizontal ? meta.xAxisID === scale.id : meta.yAxisID === scale.id;
+			return meta.bar && (isHorizontal ? meta.xAxisID === scale.id : meta.yAxisID === scale.id);
 		});
 }
 
@@ -216,20 +216,22 @@ module.exports = DatasetController.extend({
 	 */
 	_getStacks: function(last) {
 		var me = this;
-		var chart = me.chart;
 		var scale = me._getIndexScale();
-		var metasets = chart._getSortedVisibleDatasetMetas();
+		var metasets = getMatchingVisibleMetas(scale);
 		var stacked = scale.options.stacked;
 		var ilen = metasets.length;
 		var stacks = [];
 		var i, meta;
 
 		for (i = 0; i < ilen; ++i) {
 			meta = metasets[i];
-			if (meta.bar &&
-				(stacked === false ||
-				(stacked === true && stacks.indexOf(meta.stack) === -1) ||
-				(stacked === undefined && (meta.stack === undefined || stacks.indexOf(meta.stack) === -1)))) {
+			// stacked   | meta.stack
+			//           | found | not found | undefined
+			// false     |   x   |     x     |     x
+			// true      |       |     x     |
+			// undefined |       |     x     |     x
+			if (stacked === false || stacks.indexOf(meta.stack) === -1 ||
+				(stacked === undefined && meta.stack === undefined)) {
 				stacks.push(meta.stack);
 			}
 			if (meta.index === last) {

src/scales/scale.linear.js

@@ -41,6 +41,19 @@ function getOrCreateStack(stacks, stacked, meta) {
 	return stacks[key];
 }
 
+function isInvalidOrHidden(value, meta, i) {
+	return isNaN(value.min) || isNaN(value.max) || meta.data[i].hidden;
+}
+
+function initStackIndex(pos, neg, i) {
+	pos[i] = pos[i] || 0;
+	neg[i] = neg[i] || 0;
+}
+
+function isNegative(value) {
+	return value.min < 0 || value.max < 0;
+}
+
 function stackData(scale, stacks, meta, data) {
 	var opts = scale.options;
 	var stacked = opts.stacked;
@@ -51,17 +64,16 @@ function stackData(scale, stacks, meta, data) {
 	var i, value;
 
 	for (i = 0; i < ilen; ++i) {
+		initStackIndex(pos, neg, i);
+
 		value = scale._parseValue(data[i]);
-		if (isNaN(value.min) || isNaN(value.max) || meta.data[i].hidden) {
+		if (isInvalidOrHidden(value, meta, i)) {
 			continue;
 		}
 
-		pos[i] = pos[i] || 0;
-		neg[i] = neg[i] || 0;
-
 		if (opts.relativePoints) {
 			pos[i] = 100;
-		} else if (value.min < 0 || value.max < 0) {
+		} else if (isNegative(value)) {
 			neg[i] += value.min;
 		} else {
 			pos[i] += value.max;
@@ -75,8 +87,7 @@ function updateMinMax(scale, meta, data) {
 
 	for (i = 0; i < ilen; ++i) {
 		value = scale._parseValue(data[i]);
-
-		if (isNaN(value.min) || isNaN(value.max) || meta.data[i].hidden) {
+		if (isInvalidOrHidden(value, meta, i)) {
 			continue;
 		}