Return transactions from "differential.parsecommitmessage"

Summary:
Depends on D18740. Prepares `arc` to receive a `--draft` flag by letting us switch to "differential.revision.edit" instead of "differential.createrevision".

To "differential.revision.edit", we need a transaction list, but we can't automatically construct this list from a field map. Return the transaction list alongside the field map.

The next change uses this list (if available) to switch us to the modern API method.

Test Plan: Ran `arc diff` on the experiemntal branch with followup changes, got a new revision.

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D18741

src/applications/differential/conduit/DifferentialParseCommitMessageConduitAPIMethod.php

@@ -36,6 +36,7 @@ final class DifferentialParseCommitMessageConduitAPIMethod
     $field_map = $parser->parseFields($corpus);
 
     $errors = $parser->getErrors();
+    $xactions = $parser->getTransactions();
 
     $revision_id_value = idx(
       $field_map,
@@ -49,6 +50,7 @@ final class DifferentialParseCommitMessageConduitAPIMethod
         'value' => $revision_id_value,
         'validDomain' => $revision_id_valid_domain,
       ),
+      'transactions' => $xactions,
     );
   }
 

src/applications/differential/parser/DifferentialCommitMessageParser.php

@@ -28,6 +28,7 @@ final class DifferentialCommitMessageParser extends Phobject {
   private $errors;
   private $commitMessageFields;
   private $raiseMissingFieldErrors = true;
+  private $xactions;
 
   public static function newStandardParser(PhabricatorUser $viewer) {
     $key_title = DifferentialTitleCommitMessageField::FIELDKEY;
@@ -134,6 +135,7 @@ final class DifferentialCommitMessageParser extends Phobject {
    */
   public function parseCorpus($corpus) {
     $this->errors = array();
+    $this->xactions = array();
 
     $label_map = $this->getLabelMap();
     $key_title = $this->titleKey;
@@ -284,12 +286,25 @@ final class DifferentialCommitMessageParser extends Phobject {
       try {
         $result = $field->parseFieldValue($text_value);
         $result_map[$field_key] = $result;
+
+        try {
+          $xactions = $field->getFieldTransactions($result);
+          foreach ($xactions as $xaction) {
+            $this->xactions[] = $xaction;
+          }
+        } catch (Exception $ex) {
+          $this->errors[] = pht(
+            'Error extracting field transactions from "%s": %s',
+            $field->getFieldName(),
+            $ex->getMessage());
+        }
       } catch (DifferentialFieldParseException $ex) {
         $this->errors[] = pht(
           'Error parsing field "%s": %s',
           $field->getFieldName(),
           $ex->getMessage());
       }
+
     }
 
     if ($this->getRaiseMissingFieldErrors()) {
@@ -317,6 +332,14 @@ final class DifferentialCommitMessageParser extends Phobject {
   }
 
 
+  /**
+   * @task parse
+   */
+  public function getTransactions() {
+    return $this->xactions;
+  }
+
+
 /* -(  Support Methods  )---------------------------------------------------- */