Add PHP to S6323 (#650)

Co-authored-by: Nils Werner <64034005+nils-werner-sonarsource@users.noreply.github.com>

rules/S6323/description.adoc

@@ -0,0 +1 @@
+Alternation is used to match a single regular expression out of several possible regular expressions. If one of the alternatives is empty it would match any input, which is most probably a mistake.

rules/S6323/javascript/metadata.json

@@ -1,20 +1,2 @@
 {
-  "title": "Alternation in regular expressions should not contain empty alternatives",
-  "type": "BUG",
-  "status": "ready",
-  "remediation": {
-    "func": "Constant\/Issue",
-    "constantCost": "5min"
-  },
-  "tags": [
-    "regex"
-  ],
-  "defaultSeverity": "Major",
-  "ruleSpecification": "RSPEC-6323",
-  "sqKey": "S6323",
-  "scope": "Main",
-  "defaultQualityProfiles": [
-    "Sonar way"
-  ],
-  "quickfix": "unknown"
 }

rules/S6323/javascript/rule.adoc

@@ -1,4 +1,4 @@
-Alternation is used to match a single regular expression out of several possible regular expressions. If one of the alternatives is empty it would match any input, which is most probably a mistake.
+include::../description.adoc[]
 
 == Noncompliant Code Example
 ----

rules/S6323/metadata.json

@@ -1,2 +1,21 @@
 {
-}
+    "title": "Alternation in regular expressions should not contain empty alternatives",
+    "type": "BUG",
+    "status": "ready",
+    "remediation": {
+      "func": "Constant\/Issue",
+      "constantCost": "5min"
+    },
+    "tags": [
+      "regex"
+    ],
+    "defaultSeverity": "Major",
+    "ruleSpecification": "RSPEC-6323",
+    "sqKey": "S6323",
+    "scope": "Main",
+    "defaultQualityProfiles": [
+      "Sonar way"
+    ],
+    "quickfix": "unknown"
+  }
+  

rules/S6323/php/metadata.json

@@ -0,0 +1,2 @@
+{
+}

rules/S6323/php/rule.adoc

@@ -0,0 +1,38 @@
+include::../description.adoc[]
+
+== Noncompliant Code Example
+----
+preg_match("/Jack|Peter|/", "John"); // Noncompliant - returns 1
+preg_match("/Jack||Peter/", "John"); // Noncompliant - returns 1
+----
+== Compliant Solution
+----
+preg_match("/Jack|Peter/", "John"); // returns 0
+----
+
+== Exceptions
+
+One could use an empty alternation to make a regular expression group optional. Rule will not report on such cases.
+
+----
+preg_match("/mandatory(-optional|)/", "mandatory"); // returns 1
+preg_match("/mandatory(-optional|)/", "mandatory-optional"); // returns 1
+----
+
+ifdef::env-github,rspecator-view[]
+
+'''
+== Implementation Specification
+(visible only on this page)
+
+== Message
+
+Remove this empty alternative.
+
+== Highlighting
+
+The | should be highlighted.
+
+'''
+
+endif::env-github,rspecator-view[]