replicate the git behvaiour to resolve a feature's version for mercurial

src/Composer/Package/Loader/RootPackageLoader.php

@@ -160,9 +160,21 @@ class RootPackageLoader extends ArrayLoader
     }
 
     private function guessVersion(array $config)
+    {
+        if (function_exists('proc_open')) {
+            $version = $this->guessGitVersion($config);
+            if (null !== $version) {
+                return $version;
+            }
+
+            return $this->guessHgVersion($config);
+        }
+    }
+
+    private function guessGitVersion(array $config)
     {
         // try to fetch current version from git branch
-        if (function_exists('proc_open') && 0 === $this->process->execute('git branch --no-color --no-abbrev -v', $output)) {
+        if (0 === $this->process->execute('git branch --no-color --no-abbrev -v', $output)) {
             $branches = array();
             $isFeatureBranch = false;
             $version = null;
@@ -193,6 +205,43 @@ class RootPackageLoader extends ArrayLoader
                 return $version;
             }
 
+            // try to find the best (nearest) version branch to assume this feature's version
+            $version = $this->guessFeatureVersion($config, $version, $branches, 'git rev-list %candidate%..%branch%');
+
+            return $version;
+        }
+    }
+
+    private function guessHgVersion(array $config)
+    {
+        // try to fetch current version from hg branch
+        if (0 === $this->process->execute('hg branch', $output)) {
+            $branch = trim($output);
+            $version = $this->versionParser->normalizeBranch($branch);
+            $isFeatureBranch = 0 === strpos($version, 'dev-');
+
+            if ('9999999-dev' === $version) {
+                $version = 'dev-'.$branch;
+            }
+
+            if (!$isFeatureBranch) {
+                return $version;
+            }
+
+            // re-use the HgDriver to fetch branches (this properly includes bookmarks)
+            $config = array('url' => getcwd());
+            $driver = new HgDriver($config, new NullIO(), $this->config, $this->process);
+            $branches = array_keys($driver->getBranches());
+
+            // try to find the best (nearest) version branch to assume this feature's version
+            $version = $this->guessFeatureVersion($config, $version, $branches, 'hg log -r "not ancestors(\'%candidate%\') and ancestors(\'%branch%\')" --template "{node}\\n"');
+
+            return $version;
+        }
+    }
+
+    private function guessFeatureVersion(array $config, $version, array $branches, $scmCmdline)
+    {
         // ignore feature branches if they have no branch-alias or self.version is used
         // and find the branch they came from to use as a version instead
         if ((isset($config['extra']['branch-alias']) && !isset($config['extra']['branch-alias'][$version]))
@@ -205,9 +254,12 @@ class RootPackageLoader extends ArrayLoader
                 if ($candidate === $branch || !preg_match('{^(master|trunk|default|develop|\d+\..+)$}', $candidate, $match)) {
                     continue;
                 }
-                    if (0 !== $this->process->execute('git rev-list '.$candidate.'..'.$branch, $output)) {
+
+                $cmdLine = str_replace(array('%candidate%', '%branch%'), array($candidate, $branch), $scmCmdline);
+                if (0 !== $this->process->execute($cmdLine, $output)) {
                     continue;
                 }
+
                 if (strlen($output) < $length) {
                     $length = strlen($output);
                     $version = $this->versionParser->normalizeBranch($candidate);
@@ -220,5 +272,4 @@ class RootPackageLoader extends ArrayLoader
 
         return $version;
     }
-    }
 }