Limit replacements to the beginning of the namespace string

Also: Rewrite the namespace regex to be more easily understandable

fixes #67

Author: markjaquith

src/Replace/NamespaceReplacer.php

@@ -9,11 +9,19 @@ class NamespaceReplacer extends BaseReplacer
 
     public function replace($contents)
     {
-        $searchNamespace = addslashes($this->autoloader->getSearchNamespace());
-        $dependencyNamespace = addslashes($this->dep_namespace);
+        $searchNamespace = preg_quote($this->autoloader->getSearchNamespace(), '/');
+        $dependencyNamespace = preg_quote($this->dep_namespace, '/');
 
-        return preg_replace_callback(
-            '/([^a-zA-Z0-9_\x7f-\xff])((?<!' . $dependencyNamespace . ')' . $searchNamespace . '[\\\|;])/U',
+        return preg_replace_callback("
+            /                                # Start the pattern
+              ([^a-zA-Z0-9_\x7f-\xff])       # Match the non-class character before the namespace
+                (                            # Start the namespace matcher
+                  (?<!$dependencyNamespace)  # Does NOT start with the prefix
+                  (?<![a-zA-Z0-9_]\\\\)      # Not a class-allowed character followed by a slash
+                  $searchNamespace           # The namespace we're looking for
+                  [\\\|;]                    # Backslash, semicolon, or pipe
+                )                            # End the namespace matcher
+            /Ux",
             function ($matches) {
                 return $matches[1] . $this->dep_namespace . $matches[2];
             },