Generate slightly shorter summaries in the typeahead browse dialog

Summary: Ref T11034. Try to produce a roughly-one-sentence summary instead of a roughly-one-paragraph summary for the browse dialog.

Test Plan:
  - Added unit tests, ran unit tests.
  - Wrote a longer summary for a project, browsed to it, saw a shorter summary.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11034

Differential Revision: https://secure.phabricator.com/D16892

src/__phutil_library_map__.php

@@ -2896,6 +2896,7 @@ phutil_register_library_map(array(
     'PhabricatorManiphestTaskTestDataGenerator' => 'applications/maniphest/lipsum/PhabricatorManiphestTaskTestDataGenerator.php',
     'PhabricatorMarkupCache' => 'applications/cache/storage/PhabricatorMarkupCache.php',
     'PhabricatorMarkupEngine' => 'infrastructure/markup/PhabricatorMarkupEngine.php',
+    'PhabricatorMarkupEngineTestCase' => 'infrastructure/markup/__tests__/PhabricatorMarkupEngineTestCase.php',
     'PhabricatorMarkupInterface' => 'infrastructure/markup/PhabricatorMarkupInterface.php',
     'PhabricatorMarkupOneOff' => 'infrastructure/markup/PhabricatorMarkupOneOff.php',
     'PhabricatorMarkupPreviewController' => 'infrastructure/markup/PhabricatorMarkupPreviewController.php',
@@ -7871,6 +7872,7 @@ phutil_register_library_map(array(
     'PhabricatorManiphestTaskTestDataGenerator' => 'PhabricatorTestDataGenerator',
     'PhabricatorMarkupCache' => 'PhabricatorCacheDAO',
     'PhabricatorMarkupEngine' => 'Phobject',
+    'PhabricatorMarkupEngineTestCase' => 'PhabricatorTestCase',
     'PhabricatorMarkupOneOff' => array(
       'Phobject',
       'PhabricatorMarkupInterface',

src/applications/project/typeahead/PhabricatorProjectDatasource.php

@@ -130,7 +130,7 @@ final class PhabricatorProjectDatasource
 
         $description = idx($descriptions, $phid);
         if (strlen($description)) {
-          $summary = PhabricatorMarkupEngine::summarize($description);
+          $summary = PhabricatorMarkupEngine::summarizeSentence($description);
           $proj_result->addAttribute($summary);
         }
       }

src/infrastructure/markup/PhabricatorMarkupEngine.php

@@ -607,6 +607,28 @@ final class PhabricatorMarkupEngine extends Phobject {
     return array_values($files);
   }
 
+  public static function summarizeSentence($corpus) {
+    $corpus = trim($corpus);
+    $blocks = preg_split('/\n+/', $corpus, 2);
+    $block = head($blocks);
+
+    $sentences = preg_split(
+      '/\b([.?!]+)\B/u',
+      $block,
+      2,
+      PREG_SPLIT_DELIM_CAPTURE);
+
+    if (count($sentences) > 1) {
+      $result = $sentences[0].$sentences[1];
+    } else {
+      $result = head($sentences);
+    }
+
+    return id(new PhutilUTF8StringTruncator())
+      ->setMaximumGlyphs(128)
+      ->truncateString($result);
+  }
+
   /**
    * Produce a corpus summary, in a way that shortens the underlying text
    * without truncating it somewhere awkward.

src/infrastructure/markup/__tests__/PhabricatorMarkupEngineTestCase.php

@@ -0,0 +1,43 @@
+<?php
+
+final class PhabricatorMarkupEngineTestCase
+  extends PhabricatorTestCase {
+
+  public function testRemarkupSentenceSummmaries() {
+    $this->assertSentenceSummary(
+      'The quick brown fox. Jumped over the lazy dog.',
+      'The quick brown fox.');
+
+    $this->assertSentenceSummary(
+      'Go to www.help.com for details. Good day.',
+      'Go to www.help.com for details.');
+
+    $this->assertSentenceSummary(
+      'Coxy lummox gives squid who asks for job pen.',
+      'Coxy lummox gives squid who asks for job pen.');
+
+    $this->assertSentenceSummary(
+      'DEPRECATED',
+      'DEPRECATED');
+
+    $this->assertSentenceSummary(
+      'Never use this! It is deadly poison.',
+      'Never use this!');
+
+    $this->assertSentenceSummary(
+      "a short poem\nmeow meow meow\nmeow meow meow\n\n- cat",
+      'a short poem');
+
+    $this->assertSentenceSummary(
+      'WOW!! GREAT PROJECT!',
+      'WOW!!');
+  }
+
+  private function assertSentenceSummary($corpus, $summary) {
+    $this->assertEqual(
+      $summary,
+      PhabricatorMarkupEngine::summarizeSentence($corpus),
+      pht('Summary of: %s', $corpus));
+  }
+
+}