Add a very basic Scala (SBT) linter.

Summary:
SBT is the most common Scala buildsystem. This adds an extremely basic and
slightly horrible linter to check SBT's output for warnings and errors.

Test Plan:
Tested this with a Scala project I've been working on for some time.
It seemed relatively sane.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4064

src/__phutil_library_map__.php

@@ -104,6 +104,7 @@ phutil_register_library_map(array(
     'ArcanistRepositoryAPI' => 'repository/api/ArcanistRepositoryAPI.php',
     'ArcanistRubyLinter' => 'lint/linter/ArcanistRubyLinter.php',
     'ArcanistRubyLinterTestCase' => 'lint/linter/__tests__/ArcanistRubyLinterTestCase.php',
+    'ArcanistScalaSBTLinter' => 'lint/linter/ArcanistScalaSBTLinter.php',
     'ArcanistScriptAndRegexLinter' => 'lint/linter/ArcanistScriptAndRegexLinter.php',
     'ArcanistSetConfigWorkflow' => 'workflow/ArcanistSetConfigWorkflow.php',
     'ArcanistSettings' => 'configuration/ArcanistSettings.php',
@@ -215,6 +216,7 @@ phutil_register_library_map(array(
     'ArcanistPyLintLinter' => 'ArcanistLinter',
     'ArcanistRubyLinter' => 'ArcanistLinter',
     'ArcanistRubyLinterTestCase' => 'ArcanistArcanistLinterTestCase',
+    'ArcanistScalaSBTLinter' => 'ArcanistLinter',
     'ArcanistScriptAndRegexLinter' => 'ArcanistLinter',
     'ArcanistSetConfigWorkflow' => 'ArcanistBaseWorkflow',
     'ArcanistShellCompleteWorkflow' => 'ArcanistBaseWorkflow',

src/lint/engine/ComprehensiveLintEngine.php

@@ -45,6 +45,9 @@ final class ComprehensiveLintEngine extends ArcanistLintEngine {
     $linters[] = id(new ArcanistRubyLinter())
       ->setPaths(preg_grep('/\.rb$/', $paths));
 
+    $linters[] = id(new ArcanistScalaSBTLinter())
+      ->setPaths(preg_grep('/\.scala$/', $paths));
+
     $linters[] = id(new ArcanistJSHintLinter())
       ->setPaths(preg_grep('/\.js$/', $paths));
 

src/lint/linter/ArcanistScalaSBTLinter.php

@@ -0,0 +1,106 @@
+<?php
+
+/**
+ * Uses `sbt compile` to detect various warnings/errors in Scala code.
+ *
+ * @group linter
+ */
+final class ArcanistScalaSBTLinter extends ArcanistLinter {
+
+  public function willLintPaths(array $paths) {
+    return;
+  }
+
+  public function getLinterName() {
+    return 'ScalaSBT';
+  }
+
+  public function getLintSeverityMap() {
+    return array();
+  }
+
+  public function getLintNameMap() {
+    return array();
+  }
+
+  public function canRun() {
+    // Check if this looks like a SBT project. If it doesn't, throw, because
+    // we rely fairly heavily on `sbt compile` working, below. We don't want
+    // to call out to scalac ourselves, because then we'll end up in Class Path
+    // Hell. We let the build system handle this for us.
+    if (!Filesystem::pathExists('project/Build.scala') &&
+      !Filesystem::pathExists('build.sbt')) {
+      throw new ArcanistUsageException(
+        "This directory does not appear to be maintained by SBT, as we can't ".
+        "seem to find a working build file (project/Build.scala or ".
+        "build.sbt).");
+    }
+    return true;
+  }
+
+  private function getSBTPath() {
+    $sbt_bin = "sbt";
+
+    // Use the SBT prefix specified in the config file
+    $working_copy = $this->getEngine()->getWorkingCopy();
+    $prefix = $working_copy->getConfig('lint.scala_sbt.prefix');
+    if ($prefix !== null) {
+      $sbt_bin = $prefix . $sbt_bin;
+    }
+
+    if (!Filesystem::pathExists($sbt_bin)) {
+
+      list($err) = exec_manual('which %s', $sbt_bin);
+      if ($err) {
+        throw new ArcanistUsageException(
+          "SBT does not appear to be installed on this system. Install it or ".
+          "add 'lint.scala_sbt.prefix' in your .arcconfig to point to ".
+          "the directory where it resides.");
+      }
+    }
+
+    return $sbt_bin;
+  }
+
+  private function getMessageCodeSeverity($type_of_error) {
+    switch ($type_of_error) {
+      case 'warn':
+        return ArcanistLintSeverity::SEVERITY_WARNING;
+      case 'error':
+        return ArcanistLintSeverity::SEVERITY_ERROR;
+    }
+  }
+
+  public function lintPath($path) {
+    $sbt = $this->getSBTPath();
+
+    // Tell SBT to not use color codes so our regex life is easy.
+    // TODO: Should this be "clean compile" instead of "compile"?
+    $f = new ExecFuture("%s -Dsbt.log.noformat=true compile", $sbt);
+    list($err, $stdout, $stderr) = $f->resolve();
+
+    $lines = explode("\n", $stdout);
+    $messages = array();
+    foreach ($lines as $line) {
+      $matches = null;
+      if (!preg_match(
+        "/\[(warn|error)\] (.*?):(\d+): (.*?)$/",
+        $line,
+        $matches)) {
+        continue;
+      }
+      foreach ($matches as $key => $match) {
+        $matches[$key] = trim($match);
+      }
+
+      $message = new ArcanistLintMessage();
+      $message->setPath($matches[2]);
+      $message->setLine($matches[3]);
+      $message->setCode($this->getLinterName());
+      $message->setDescription($matches[4]);
+      $message->setSeverity($this->getMessageCodeSeverity($matches[1]));
+      $this->addLintMessage($message);
+    }
+  }
+
+}