Implemented fixed length prefix matching functionality

src/Matchers/PrefixMatcher.php

@@ -12,13 +12,16 @@ class PrefixMatcher implements Matcher
      */
     private $prefix;
 
+    private $fixedLength;
+
     /**
      * PrefixMatcher constructor.
      * @param string $prefix
      */
-    public function __construct($prefix)
+    public function __construct($prefix, $fixedLength = null)
     {
         $this->prefix = $prefix;
+        $this->fixedLength = $fixedLength;
     }
 
     /**
@@ -71,6 +74,10 @@ public function stringToEntity($match_string)
      */
     private function getRegex()
     {
+        if($this->fixedLength){
+            return '/'.$this->prefix.'(.{'.intval($this->fixedLength).'})/';
+        }
+
         return '/(?:^|\s)'.$this->prefix.'{1}([^\s]+)/';
     }
 }

tests/Matching/PrefixMatcherWithFixedLengthTest.php

@@ -0,0 +1,34 @@
+<?php
+
+class PrefixMatcherWithFixedLengthTest extends \PHPUnit\Framework\TestCase
+{
+    public function testMatchesStrings()
+    {
+        $matcher = new \SebastianWalker\Statement\Matchers\PrefixMatcher("PFIX-", 4);
+        $transaction = new \SebastianWalker\Statement\Transaction(10, "PAYMENT FOR PFIX-1234SOME OTHER STUFF");
+
+        $matches = $matcher->getEntities($transaction);
+
+        $this->assertSame(["1234"], $matches);
+    }
+
+    public function testMatchesMultipleStrings()
+    {
+        $matcher = new \SebastianWalker\Statement\Matchers\PrefixMatcher("PFIX-", 4);
+        $transaction = new \SebastianWalker\Statement\Transaction(10, "PAYMENT FOR PFIX-1234SOME OTHER STUFF AND PFIX-5678SOME MORE STUFF");
+
+        $matches = $matcher->getEntities($transaction);
+
+        $this->assertSame(["1234","5678"], $matches);
+    }
+
+    public function testMatchesNothing()
+    {
+        $matcher = new \SebastianWalker\Statement\Matchers\PrefixMatcher("PFIX-", 4);
+        $transaction = new \SebastianWalker\Statement\Transaction(10, "PAYMENT FOR SOMETHING ELSE");
+
+        $matches = $matcher->getEntities($transaction);
+
+        $this->assertSame([], $matches);
+    }
+}