chore(doc-gen, docs-app): generate "stable snapshot" for distTag=latest

The "stable snapshot" is the current state of the branch that has
distTag=latest, i.e. a preview of the next patch version of the stable branch.

Author: Narretz

docs/app/src/versions.js

@@ -12,10 +12,16 @@ angular.module('versions', ['currentVersionData', 'allVersionsData'])
             /** @this VersionPickerController */
             function VersionPickerController($location, $window, CURRENT_NG_VERSION, ALL_NG_VERSIONS) {
 
-      var versionStr = CURRENT_NG_VERSION.isSnapshot ? 'snapshot' : CURRENT_NG_VERSION.version;
+      var versionStr = CURRENT_NG_VERSION.version;
+
+      if (CURRENT_NG_VERSION.isSnapshot) {
+        versionStr = CURRENT_NG_VERSION.distTag === 'latest' ? 'snapshot-stable' : 'snapshot';
+      }
 
       this.versions  = ALL_NG_VERSIONS;
-      this.selectedVersion = find(ALL_NG_VERSIONS, function(value) { return value.version.version === versionStr; });
+      this.selectedVersion = find(ALL_NG_VERSIONS, function(value) {
+        return value.version.version === versionStr;
+      });
 
       this.jumpToDocsVersion = function(value) {
         var currentPagePath = $location.path().replace(/\/$/, '');

docs/config/processors/versions-data.js

@@ -55,6 +55,9 @@ module.exports = function generateVersionDocProcessor(gitData) {
 
         if (missesCurrentVersion) versions.push(currentVersion.version);
 
+        // Get the stable release with the highest version
+        var highestStableRelease = versions.reverse().find(semverIsStable);
+
         versions = versions
             .filter(function(versionStr) {
               return blacklist.indexOf(versionStr) === -1;
@@ -82,7 +85,21 @@ module.exports = function generateVersionDocProcessor(gitData) {
         var latest = sortObject(latestMap, reverse(semver.compare))
             .map(function(version) { return makeOption(version, 'Latest'); });
 
-        return [makeOption({version: 'snapshot'}, 'Latest', 'master')]
+        // Generate master and stable snapshots
+        var snapshots = [
+          makeOption(
+            {version: 'snapshot'},
+            'Latest',
+            'master-snapshot'
+          ),
+          makeOption(
+            {version: 'snapshot-stable'},
+            'Latest',
+            createSnapshotStableLabel(highestStableRelease)
+          )
+        ];
+
+        return snapshots
             .concat(latest)
             .concat(versions);
       }
@@ -112,6 +129,18 @@ module.exports = function generateVersionDocProcessor(gitData) {
       function sortObject(obj, cmp) {
         return Object.keys(obj).map(function(key) { return obj[key]; }).sort(cmp);
       }
+
+      // https://github.com/kaelzhang/node-semver-stable/blob/34dd29842409295d49889d45871bec55a992b7f6/index.js#L25
+      function semverIsStable(version) {
+        var semverObj = semver.parse(version);
+        return semverObj === null ? false : !semverObj.prerelease.length;
+      }
+
+      function createSnapshotStableLabel(version) {
+        var label = 'v' + version.replace(/.$/, 'x') + '-snapshot';
+
+        return label;
+      }
     }
   };
 };

lib/versions/version-info.js

@@ -210,6 +210,7 @@ var getSnapshotVersion = function() {
   version.format();
   version.full = version.version + '+' + version.build;
   version.branch = 'master';
+  version.distTag = currentPackage.distTag;
 
   return version;
 };