Feature: Commenting\DisallowEmptyComment sniff

Detects empty comments (doc-blocks, multiline and inline comments)
and redundant empty lines in comments.
Two empty lines next to each other are disallowed, also - empty lines
at the beginning and at the end of the comment are disallowed.

src/WebimpressCodingStandard/Sniffs/Commenting/DisallowEmptyCommentSniff.php

@@ -0,0 +1,149 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WebimpressCodingStandard\Sniffs\Commenting;
+
+use PHP_CodeSniffer\Files\File;
+use PHP_CodeSniffer\Sniffs\Sniff;
+use PHP_CodeSniffer\Util\Common;
+
+use function preg_match;
+use function preg_replace;
+use function strpos;
+use function trim;
+
+use const T_COMMENT;
+use const T_DOC_COMMENT_CLOSE_TAG;
+use const T_DOC_COMMENT_OPEN_TAG;
+use const T_DOC_COMMENT_STAR;
+use const T_DOC_COMMENT_WHITESPACE;
+use const T_WHITESPACE;
+
+class DisallowEmptyCommentSniff implements Sniff
+{
+    /**
+     * @return int[]
+     */
+    public function register() : array
+    {
+        return [
+            T_DOC_COMMENT_OPEN_TAG,
+            T_COMMENT,
+        ];
+    }
+
+    /**
+     * @param int $stackPtr
+     */
+    public function process(File $phpcsFile, $stackPtr) : int
+    {
+        $tokens = $phpcsFile->getTokens();
+
+        if ($tokens[$stackPtr]['code'] === T_DOC_COMMENT_OPEN_TAG) {
+            $next = $phpcsFile->findNext([T_DOC_COMMENT_WHITESPACE, T_DOC_COMMENT_STAR], $stackPtr + 1, null, true);
+
+            if ($tokens[$next]['code'] === T_DOC_COMMENT_CLOSE_TAG) {
+                $error = 'Empty doc-block comment';
+
+                $fix = $phpcsFile->addFixableError($error, $stackPtr, 'DocBlock');
+                if ($fix) {
+                    $after = $phpcsFile->findNext(T_WHITESPACE, $next + 1, null, true);
+                    $phpcsFile->fixer->beginChangeset();
+                    for ($i = $stackPtr; $i < $after; ++$i) {
+                        $phpcsFile->fixer->replaceToken($i, '');
+                    }
+                    $phpcsFile->fixer->endChangeset();
+                }
+            }
+
+            return $stackPtr + 1;
+        }
+
+        $line = $tokens[$stackPtr]['line'];
+        $comment = trim($tokens[$stackPtr]['content']);
+        if (strpos($comment, '/*') === 0) {
+            $i = $stackPtr;
+            $content = '';
+            do {
+                $content .= $tokens[$i]['content'];
+            } while ($tokens[++$i]['code'] === T_COMMENT);
+
+            $end = $i;
+
+            if (preg_replace('#[\s\*/]#', '', $content) === '') {
+                $fix = $phpcsFile->addFixableError('Empty comment', $stackPtr, 'Multiline');
+                if ($fix) {
+                    $next = $phpcsFile->findNext(T_WHITESPACE, $i, null, true) ?: $phpcsFile->numTokens;
+                    $phpcsFile->fixer->beginChangeset();
+                    for ($i = $stackPtr; $i < $next; ++$i) {
+                        $phpcsFile->fixer->replaceToken($i, '');
+                    }
+                    $phpcsFile->fixer->endChangeset();
+                }
+
+                return $end;
+            }
+
+            $newContent = preg_replace('#(^/\*\s*?$)(?:\n^[\s\*]*$)+#m', '\\1', $content);
+            $newContent = preg_replace('#(?:^[\s\*]*$\n)+(\s*?\*/)#m', '\\1', $newContent);
+            $newContent = preg_replace('#(^[\s\*]*$\n){2,}#m', '\\1', $newContent);
+
+            if ($newContent !== $content) {
+                $error = 'Redundant empty lines in comment; found: %s but expected %s';
+                $data = [
+                    Common::prepareForOutput($content),
+                    Common::prepareForOutput($newContent),
+                ];
+
+                $fix = $phpcsFile->addFixableError($error, $stackPtr, 'Lines', $data);
+                if ($fix) {
+                    $phpcsFile->fixer->beginChangeset();
+                    while (--$i >= $stackPtr) {
+                        $phpcsFile->fixer->replaceToken($i, '');
+                    }
+                    $phpcsFile->fixer->addContent($stackPtr, $newContent);
+                    $phpcsFile->fixer->endChangeset();
+                }
+            }
+
+            return $end;
+        }
+
+        if ($this->isEmptyComment($comment)) {
+            $before = $phpcsFile->findPrevious(T_WHITESPACE, $stackPtr - 1, null, true);
+            $after = $phpcsFile->findNext(T_WHITESPACE, $stackPtr + 1, null, true);
+
+            $hasBefore = false;
+            $hasAfter = false;
+
+            if ($tokens[$before]['code'] === T_COMMENT
+                && $tokens[$before]['line'] === $line - 1
+                && ! $this->isEmptyComment($tokens[$before]['content'])
+            ) {
+                $hasBefore = true;
+            }
+
+            if ($tokens[$after]['code'] === T_COMMENT
+                && $tokens[$after]['line'] === $line + 1
+                && ! $this->isEmptyComment($tokens[$after]['content'])
+            ) {
+                $hasAfter = true;
+            }
+
+            if (! $hasBefore || ! $hasAfter) {
+                $fix = $phpcsFile->addFixableError('Empty inline comment ' . $comment, $stackPtr, 'Inline');
+                if ($fix) {
+                    $phpcsFile->fixer->replaceToken($stackPtr, '');
+                }
+            }
+        }
+
+        return $stackPtr + 1;
+    }
+
+    private function isEmptyComment(string $comment) : bool
+    {
+        return preg_match('@^(//|#)[\s/#*-]*$@', $comment) === 1;
+    }
+}

test/Sniffs/Commenting/DisallowEmptyCommentUnitTest.inc

@@ -0,0 +1,101 @@
+<?php
+/**
+ * non empty doc-block comment
+ */
+
+/**
+ *
+ */
+
+/**
+
+ */
+
+/**  */
+
+/* */
+
+/* * */
+
+/*
+ */
+
+/*
+ *
+ */
+
+/*
+
+ */
+
+/*
+ *
+ *
+ */
+
+//
+
+#
+
+// Hello
+//
+// Above line can be empty
+
+# The same
+#
+# here
+
+/*
+ * Below line cannot be empty
+ *
+ */
+
+/*
+ *
+ * Above line cannot be empty
+ */
+
+//
+// Above line cannot be empty
+
+// Below line cannot be empty
+//
+
+// Mixed types: Below line cannot be empty.
+//
+#
+# Above and below lines cannot be empty.
+#
+/* something */
+
+/****
+ *
+ */
+
+/*
+
+ Remove empty lines above and below
+
+ */
+
+/*
+ *
+ *
+ * Multi-line
+ *
+ *
+ * comment
+ *
+ *
+ */
+
+// / / / / / / / / / / / /
+
+//////////////////////////
+
+///
+///
+
+# # # #
+
+#######

test/Sniffs/Commenting/DisallowEmptyCommentUnitTest.inc.fixed

@@ -0,0 +1,46 @@
+<?php
+/**
+ * non empty doc-block comment
+ */
+
+
+
+// Hello
+//
+// Above line can be empty
+
+# The same
+#
+# here
+
+/*
+ * Below line cannot be empty
+ */
+
+/*
+ * Above line cannot be empty
+ */
+
+// Above line cannot be empty
+
+// Below line cannot be empty
+
+// Mixed types: Below line cannot be empty.
+# Above and below lines cannot be empty.
+#
+/* something */
+
+/*
+ Remove empty lines above and below
+ */
+
+/*
+ * Multi-line
+ *
+ * comment
+ */
+
+
+
+
+

test/Sniffs/Commenting/DisallowEmptyCommentUnitTest.php

@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WebimpressCodingStandardTest\Sniffs\Commenting;
+
+use WebimpressCodingStandardTest\Sniffs\AbstractTestCase;
+
+class DisallowEmptyCommentUnitTest extends AbstractTestCase
+{
+    protected function getErrorList(string $testFile = '') : array
+    {
+        return [
+            6 => 1,
+            10 => 1,
+            14 => 1,
+            16 => 1,
+            18 => 1,
+            20 => 1,
+            23 => 1,
+            27 => 1,
+            31 => 1,
+            36 => 1,
+            38 => 1,
+            48 => 1,
+            53 => 1,
+            58 => 1,
+            62 => 1,
+            65 => 1,
+            66 => 1,
+            71 => 1,
+            75 => 1,
+            81 => 1,
+            92 => 1,
+            94 => 1,
+            96 => 1,
+            97 => 1,
+            99 => 1,
+            101 => 1,
+        ];
+    }
+
+    protected function getWarningList(string $testFile = '') : array
+    {
+        return [];
+    }
+}