Add a linter rule for object operator spacing

Summary: Add a linter rule to check that there is no whitespace surrounding the object operator, `->`.

Test Plan: Added test case.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D13798

src/__phutil_library_map__.php

@@ -171,6 +171,7 @@ phutil_register_library_map(array(
     'ArcanistNoLintLinterTestCase' => 'lint/linter/__tests__/ArcanistNoLintLinterTestCase.php',
     'ArcanistNoParentScopeXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistNoParentScopeXHPASTLinterRule.php',
     'ArcanistNoneLintRenderer' => 'lint/renderer/ArcanistNoneLintRenderer.php',
+    'ArcanistObjectOperatorSpacingXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistObjectOperatorSpacingXHPASTLinterRule.php',
     'ArcanistPEP8Linter' => 'lint/linter/ArcanistPEP8Linter.php',
     'ArcanistPEP8LinterTestCase' => 'lint/linter/__tests__/ArcanistPEP8LinterTestCase.php',
     'ArcanistPHPCloseTagXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistPHPCloseTagXHPASTLinterRule.php',
@@ -445,6 +446,7 @@ phutil_register_library_map(array(
     'ArcanistNoLintLinterTestCase' => 'ArcanistLinterTestCase',
     'ArcanistNoParentScopeXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
     'ArcanistNoneLintRenderer' => 'ArcanistLintRenderer',
+    'ArcanistObjectOperatorSpacingXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
     'ArcanistPEP8Linter' => 'ArcanistExternalLinter',
     'ArcanistPEP8LinterTestCase' => 'ArcanistExternalLinterTestCase',
     'ArcanistPHPCloseTagXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',

src/lint/linter/__tests__/xhpast/object-operating-spacing.lint-test

@@ -0,0 +1,12 @@
+<?php
+$x -> doSomething();
+id(new Something())
+  ->doSomething();
+~~~~~~~~~~
+warning:2:3
+warning:2:6
+~~~~~~~~~~
+<?php
+$x->doSomething();
+id(new Something())
+  ->doSomething();

src/lint/linter/xhpast/rules/ArcanistObjectOperatorSpacingXHPASTLinterRule.php

@@ -0,0 +1,47 @@
+<?php
+
+final class ArcanistObjectOperatorSpacingXHPASTLinterRule
+  extends ArcanistXHPASTLinterRule {
+
+  const ID = 74;
+
+  public function getLintName() {
+    return pht('Object Operator Spacing');
+  }
+
+  public function getLintSeverity() {
+    return ArcanistLintSeverity::SEVERITY_WARNING;
+  }
+
+  public function process(XHPASTNode $root) {
+    $operators = $root->selectTokensOfType('T_OBJECT_OPERATOR');
+
+    foreach ($operators as $operator) {
+      $before = $operator->getNonsemanticTokensBefore();
+      $after  = $operator->getNonsemanticTokensAfter();
+
+      if ($before) {
+        $value = implode('', mpull($before, 'getValue'));
+
+        if (strpos($value, "\n") !== false) {
+          continue;
+        }
+
+        $this->raiseLintAtOffset(
+          head($before)->getOffset(),
+          pht('There should be no whitespace before the object operator.'),
+          $value,
+          '');
+      }
+
+      if ($after) {
+        $this->raiseLintAtOffset(
+          head($after)->getOffset(),
+          pht('There should be no whitespace after the object operator.'),
+          implode('', mpull($before, 'getValue')),
+          '');
+      }
+    }
+  }
+
+}