diff --git a/.travis.yml b/.travis.yml
index 0416daa..d80fdb6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,8 +17,6 @@ matrix:
       env: 'HIGHEST_LOWEST="update"'
     - php: 7.0.11
     - php: 5.6
-    - php: 5.5
-    - php: 5.4
       env: 'SCENARIO=symfony2 HIGHEST_LOWEST="update --prefer-lowest'
 
 sudo: false
diff --git a/composer.json b/composer.json
index f671ee4..b18c09c 100644
--- a/composer.json
+++ b/composer.json
@@ -3,9 +3,10 @@
     "description": "Expands internal property references in a yaml file.",
     "type": "library",
     "require": {
-        "php": ">=5.4",
-        "symfony/yaml":                   "^2.8.11|^3|^4",
-        "dflydev/dot-access-data":        "^1.1.0"
+        "php": ">=5.6",
+        "dflydev/dot-access-data": "^1.1.0",
+        "grasmash/expander": "^1.0.0",
+        "symfony/yaml": "^2.8.11|^3|^4"
     },
     "license": "MIT",
     "authors": [
@@ -16,7 +17,7 @@
     "minimum-stability": "stable",
     "autoload": {
         "psr-4": {
-            "Grasmash\\YamlExpander\\":        "src/"
+            "Grasmash\\YamlExpander\\": "src/"
         }
     },
     "require-dev": {
@@ -48,12 +49,12 @@
         "optimize-autoloader": true,
         "sort-packages": true,
         "platform": {
-            "php": "5.5.9"
+            "php": "7.1"
         }
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "1.x-dev"
+            "dev-master": "2.x-dev"
         }
     }
 }
diff --git a/composer.lock b/composer.lock
index 7f1268a..a9dfd33 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "ae81b9e7daa60d332450889eb23e80a9",
+    "content-hash": "7930cf3afdba0b8dc84256478b201fcb",
     "packages": [
         {
             "name": "dflydev/dot-access-data",
@@ -65,18 +65,65 @@
             ],
             "time": "2017-01-20T21:14:22+00:00"
         },
+        {
+            "name": "grasmash/expander",
+            "version": "1.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/grasmash/expander.git",
+                "reference": "95d6037344a4be1dd5f8e0b0b2571a28c397578f"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/grasmash/expander/zipball/95d6037344a4be1dd5f8e0b0b2571a28c397578f",
+                "reference": "95d6037344a4be1dd5f8e0b0b2571a28c397578f",
+                "shasum": ""
+            },
+            "require": {
+                "dflydev/dot-access-data": "^1.1.0",
+                "php": ">=5.4"
+            },
+            "require-dev": {
+                "greg-1-anderson/composer-test-scenarios": "^1",
+                "phpunit/phpunit": "^4|^5.5.4",
+                "satooshi/php-coveralls": "^1.0.2|dev-master",
+                "squizlabs/php_codesniffer": "^2.7"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Grasmash\\Expander\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Matthew Grasmick"
+                }
+            ],
+            "description": "Expands internal property references in PHP arrays file.",
+            "time": "2017-12-21T22:14:55+00:00"
+        },
         {
             "name": "symfony/yaml",
-            "version": "v3.4.0",
+            "version": "v3.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/yaml.git",
-                "reference": "b3d0c9c11be3831b84825967dc6b52b5a7b84e04"
+                "reference": "afe0cd38486505c9703707707d91450cfc1bd536"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/yaml/zipball/b3d0c9c11be3831b84825967dc6b52b5a7b84e04",
-                "reference": "b3d0c9c11be3831b84825967dc6b52b5a7b84e04",
+                "url": "https://api.github.com/repos/symfony/yaml/zipball/afe0cd38486505c9703707707d91450cfc1bd536",
+                "reference": "afe0cd38486505c9703707707d91450cfc1bd536",
                 "shasum": ""
             },
             "require": {
@@ -121,38 +168,38 @@
             ],
             "description": "Symfony Yaml Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-29T13:28:14+00:00"
+            "time": "2017-12-11T20:38:23+00:00"
         }
     ],
     "packages-dev": [
         {
             "name": "doctrine/instantiator",
-            "version": "1.0.5",
+            "version": "1.1.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/doctrine/instantiator.git",
-                "reference": "8e884e78f9f0eb1329e445619e04456e64d8051d"
+                "reference": "185b8868aa9bf7159f5f953ed5afb2d7fcdc3bda"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/doctrine/instantiator/zipball/8e884e78f9f0eb1329e445619e04456e64d8051d",
-                "reference": "8e884e78f9f0eb1329e445619e04456e64d8051d",
+                "url": "https://api.github.com/repos/doctrine/instantiator/zipball/185b8868aa9bf7159f5f953ed5afb2d7fcdc3bda",
+                "reference": "185b8868aa9bf7159f5f953ed5afb2d7fcdc3bda",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.3,<8.0-DEV"
+                "php": "^7.1"
             },
             "require-dev": {
                 "athletic/athletic": "~0.1.8",
                 "ext-pdo": "*",
                 "ext-phar": "*",
-                "phpunit/phpunit": "~4.0",
-                "squizlabs/php_codesniffer": "~2.0"
+                "phpunit/phpunit": "^6.2.3",
+                "squizlabs/php_codesniffer": "^3.0.2"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.0.x-dev"
+                    "dev-master": "1.2.x-dev"
                 }
             },
             "autoload": {
@@ -177,20 +224,20 @@
                 "constructor",
                 "instantiate"
             ],
-            "time": "2015-06-14T21:17:01+00:00"
+            "time": "2017-07-22T11:58:36+00:00"
         },
         {
             "name": "greg-1-anderson/composer-test-scenarios",
-            "version": "1.0.0",
+            "version": "1.0.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/greg-1-anderson/composer-test-scenarios.git",
-                "reference": "00ff9f3af3132f0c6b2fb9e0906efee402f0c703"
+                "reference": "dc81660f44a8b126d7fa947156c98e34f45af3e9"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/greg-1-anderson/composer-test-scenarios/zipball/00ff9f3af3132f0c6b2fb9e0906efee402f0c703",
-                "reference": "00ff9f3af3132f0c6b2fb9e0906efee402f0c703",
+                "url": "https://api.github.com/repos/greg-1-anderson/composer-test-scenarios/zipball/dc81660f44a8b126d7fa947156c98e34f45af3e9",
+                "reference": "dc81660f44a8b126d7fa947156c98e34f45af3e9",
                 "shasum": ""
             },
             "bin": [
@@ -209,7 +256,7 @@
                 }
             ],
             "description": "Useful scripts for testing multiple sets of Composer dependencies.",
-            "time": "2017-12-01T21:34:53+00:00"
+            "time": "2017-12-13T18:41:24+00:00"
         },
         {
             "name": "guzzlehttp/guzzle",
@@ -392,6 +439,51 @@
             ],
             "time": "2017-03-20T17:10:46+00:00"
         },
+        {
+            "name": "myclabs/deep-copy",
+            "version": "1.7.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/myclabs/DeepCopy.git",
+                "reference": "3b8a3a99ba1f6a3952ac2747d989303cbd6b7a3e"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/myclabs/DeepCopy/zipball/3b8a3a99ba1f6a3952ac2747d989303cbd6b7a3e",
+                "reference": "3b8a3a99ba1f6a3952ac2747d989303cbd6b7a3e",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.6 || ^7.0"
+            },
+            "require-dev": {
+                "doctrine/collections": "^1.0",
+                "doctrine/common": "^2.6",
+                "phpunit/phpunit": "^4.1"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "DeepCopy\\": "src/DeepCopy/"
+                },
+                "files": [
+                    "src/DeepCopy/deep_copy.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "description": "Create deep copies (clones) of your objects",
+            "keywords": [
+                "clone",
+                "copy",
+                "duplicate",
+                "object",
+                "object graph"
+            ],
+            "time": "2017-10-19T19:58:43+00:00"
+        },
         {
             "name": "phpdocumentor/reflection-common",
             "version": "1.0.1",
@@ -448,29 +540,35 @@
         },
         {
             "name": "phpdocumentor/reflection-docblock",
-            "version": "3.2.2",
+            "version": "4.2.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/ReflectionDocBlock.git",
-                "reference": "4aada1f93c72c35e22fb1383b47fee43b8f1d157"
+                "reference": "66465776cfc249844bde6d117abff1d22e06c2da"
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             "dist": {
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-                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/4aada1f93c72c35e22fb1383b47fee43b8f1d157",
-                "reference": "4aada1f93c72c35e22fb1383b47fee43b8f1d157",
+                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/66465776cfc249844bde6d117abff1d22e06c2da",
+                "reference": "66465776cfc249844bde6d117abff1d22e06c2da",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.5",
-                "phpdocumentor/reflection-common": "^1.0@dev",
-                "phpdocumentor/type-resolver": "^0.3.0",
+                "php": "^7.0",
+                "phpdocumentor/reflection-common": "^1.0.0",
+                "phpdocumentor/type-resolver": "^0.4.0",
                 "webmozart/assert": "^1.0"
             },
             "require-dev": {
-                "mockery/mockery": "^0.9.4",
-                "phpunit/phpunit": "^4.4"
+                "doctrine/instantiator": "~1.0.5",
+                "mockery/mockery": "^1.0",
+                "phpunit/phpunit": "^6.4"
             },
             "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "4.x-dev"
+                }
+            },
             "autoload": {
                 "psr-4": {
                     "phpDocumentor\\Reflection\\": [
@@ -489,20 +587,20 @@
                 }
             ],
             "description": "With this component, a library can provide support for annotations via DocBlocks or otherwise retrieve information that is embedded in a DocBlock.",
-            "time": "2017-08-08T06:39:58+00:00"
+            "time": "2017-11-27T17:38:31+00:00"
         },
         {
             "name": "phpdocumentor/type-resolver",
-            "version": "0.3.0",
+            "version": "0.4.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/TypeResolver.git",
-                "reference": "fb3933512008d8162b3cdf9e18dba9309b7c3773"
+                "reference": "9c977708995954784726e25d0cd1dddf4e65b0f7"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/TypeResolver/zipball/fb3933512008d8162b3cdf9e18dba9309b7c3773",
-                "reference": "fb3933512008d8162b3cdf9e18dba9309b7c3773",
+                "url": "https://api.github.com/repos/phpDocumentor/TypeResolver/zipball/9c977708995954784726e25d0cd1dddf4e65b0f7",
+                "reference": "9c977708995954784726e25d0cd1dddf4e65b0f7",
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             },
             "require": {
@@ -536,7 +634,7 @@
                     "email": "me@mikevanriel.com"
                 }
             ],
-            "time": "2017-06-03T08:32:36+00:00"
+            "time": "2017-07-14T14:27:02+00:00"
         },
         {
             "name": "phpspec/prophecy",
@@ -603,39 +701,40 @@
         },
         {
             "name": "phpunit/php-code-coverage",
-            "version": "2.2.4",
+            "version": "4.0.8",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-code-coverage.git",
-                "reference": "eabf68b476ac7d0f73793aada060f1c1a9bf8979"
+                "reference": "ef7b2f56815df854e66ceaee8ebe9393ae36a40d"
             },
             "dist": {
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-                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/eabf68b476ac7d0f73793aada060f1c1a9bf8979",
-                "reference": "eabf68b476ac7d0f73793aada060f1c1a9bf8979",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/ef7b2f56815df854e66ceaee8ebe9393ae36a40d",
+                "reference": "ef7b2f56815df854e66ceaee8ebe9393ae36a40d",
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             },
             "require": {
-                "php": ">=5.3.3",
-                "phpunit/php-file-iterator": "~1.3",
-                "phpunit/php-text-template": "~1.2",
-                "phpunit/php-token-stream": "~1.3",
-                "sebastian/environment": "^1.3.2",
-                "sebastian/version": "~1.0"
+                "ext-dom": "*",
+                "ext-xmlwriter": "*",
+                "php": "^5.6 || ^7.0",
+                "phpunit/php-file-iterator": "^1.3",
+                "phpunit/php-text-template": "^1.2",
+                "phpunit/php-token-stream": "^1.4.2 || ^2.0",
+                "sebastian/code-unit-reverse-lookup": "^1.0",
+                "sebastian/environment": "^1.3.2 || ^2.0",
+                "sebastian/version": "^1.0 || ^2.0"
             },
             "require-dev": {
-                "ext-xdebug": ">=2.1.4",
-                "phpunit/phpunit": "~4"
+                "ext-xdebug": "^2.1.4",
+                "phpunit/phpunit": "^5.7"
             },
             "suggest": {
-                "ext-dom": "*",
-                "ext-xdebug": ">=2.2.1",
-                "ext-xmlwriter": "*"
+                "ext-xdebug": "^2.5.1"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.2.x-dev"
+                    "dev-master": "4.0.x-dev"
                 }
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             "autoload": {
@@ -661,7 +760,7 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2015-10-06T15:47:00+00:00"
+            "time": "2017-04-02T07:44:40+00:00"
         },
         {
             "name": "phpunit/php-file-iterator",
@@ -802,29 +901,29 @@
         },
         {
             "name": "phpunit/php-token-stream",
-            "version": "1.4.11",
+            "version": "2.0.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-token-stream.git",
-                "reference": "e03f8f67534427a787e21a385a67ec3ca6978ea7"
+                "reference": "791198a2c6254db10131eecfe8c06670700904db"
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-                "url": "https://api.github.com/repos/sebastianbergmann/php-token-stream/zipball/e03f8f67534427a787e21a385a67ec3ca6978ea7",
-                "reference": "e03f8f67534427a787e21a385a67ec3ca6978ea7",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-token-stream/zipball/791198a2c6254db10131eecfe8c06670700904db",
+                "reference": "791198a2c6254db10131eecfe8c06670700904db",
                 "shasum": ""
             },
             "require": {
                 "ext-tokenizer": "*",
-                "php": ">=5.3.3"
+                "php": "^7.0"
             },
             "require-dev": {
-                "phpunit/phpunit": "~4.2"
+                "phpunit/phpunit": "^6.2.4"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.4-dev"
+                    "dev-master": "2.0-dev"
                 }
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@@ -847,44 +946,54 @@
             "keywords": [
                 "tokenizer"
             ],
-            "time": "2017-02-27T10:12:30+00:00"
+            "time": "2017-11-27T05:48:46+00:00"
         },
         {
             "name": "phpunit/phpunit",
-            "version": "4.8.36",
+            "version": "5.7.26",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit.git",
-                "reference": "46023de9a91eec7dfb06cc56cb4e260017298517"
+                "reference": "7fbc25c13309de0c4c9bb48b7361f1eca34c7fbd"
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-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/46023de9a91eec7dfb06cc56cb4e260017298517",
-                "reference": "46023de9a91eec7dfb06cc56cb4e260017298517",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/7fbc25c13309de0c4c9bb48b7361f1eca34c7fbd",
+                "reference": "7fbc25c13309de0c4c9bb48b7361f1eca34c7fbd",
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                 "ext-json": "*",
-                "ext-pcre": "*",
-                "ext-reflection": "*",
-                "ext-spl": "*",
-                "php": ">=5.3.3",
-                "phpspec/prophecy": "^1.3.1",
-                "phpunit/php-code-coverage": "~2.1",
+                "ext-libxml": "*",
+                "ext-mbstring": "*",
+                "ext-xml": "*",
+                "myclabs/deep-copy": "~1.3",
+                "php": "^5.6 || ^7.0",
+                "phpspec/prophecy": "^1.6.2",
+                "phpunit/php-code-coverage": "^4.0.4",
                 "phpunit/php-file-iterator": "~1.4",
                 "phpunit/php-text-template": "~1.2",
                 "phpunit/php-timer": "^1.0.6",
-                "phpunit/phpunit-mock-objects": "~2.3",
-                "sebastian/comparator": "~1.2.2",
-                "sebastian/diff": "~1.2",
-                "sebastian/environment": "~1.3",
-                "sebastian/exporter": "~1.2",
-                "sebastian/global-state": "~1.0",
-                "sebastian/version": "~1.0",
-                "symfony/yaml": "~2.1|~3.0"
+                "phpunit/phpunit-mock-objects": "^3.2",
+                "sebastian/comparator": "^1.2.4",
+                "sebastian/diff": "^1.4.3",
+                "sebastian/environment": "^1.3.4 || ^2.0",
+                "sebastian/exporter": "~2.0",
+                "sebastian/global-state": "^1.1",
+                "sebastian/object-enumerator": "~2.0",
+                "sebastian/resource-operations": "~1.0",
+                "sebastian/version": "~1.0.3|~2.0",
+                "symfony/yaml": "~2.1|~3.0|~4.0"
+            },
+            "conflict": {
+                "phpdocumentor/reflection-docblock": "3.0.2"
+            },
+            "require-dev": {
+                "ext-pdo": "*"
             },
             "suggest": {
+                "ext-xdebug": "*",
                 "phpunit/php-invoker": "~1.1"
             },
             "bin": [
@@ -893,7 +1002,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "4.8.x-dev"
+                    "dev-master": "5.7.x-dev"
                 }
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             "autoload": {
@@ -919,30 +1028,33 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2017-06-21T08:07:12+00:00"
+            "time": "2017-12-17T06:14:38+00:00"
         },
         {
             "name": "phpunit/phpunit-mock-objects",
-            "version": "2.3.8",
+            "version": "3.4.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit-mock-objects.git",
-                "reference": "ac8e7a3db35738d56ee9a76e78a4e03d97628983"
+                "reference": "a23b761686d50a560cc56233b9ecf49597cc9118"
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                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit-mock-objects/zipball/ac8e7a3db35738d56ee9a76e78a4e03d97628983",
-                "reference": "ac8e7a3db35738d56ee9a76e78a4e03d97628983",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit-mock-objects/zipball/a23b761686d50a560cc56233b9ecf49597cc9118",
+                "reference": "a23b761686d50a560cc56233b9ecf49597cc9118",
                 "shasum": ""
             },
             "require": {
                 "doctrine/instantiator": "^1.0.2",
-                "php": ">=5.3.3",
-                "phpunit/php-text-template": "~1.2",
-                "sebastian/exporter": "~1.2"
+                "php": "^5.6 || ^7.0",
+                "phpunit/php-text-template": "^1.2",
+                "sebastian/exporter": "^1.2 || ^2.0"
+            },
+            "conflict": {
+                "phpunit/phpunit": "<5.4.0"
             },
             "require-dev": {
-                "phpunit/phpunit": "~4.4"
+                "phpunit/phpunit": "^5.4"
             },
             "suggest": {
                 "ext-soap": "*"
@@ -950,7 +1062,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "2.3.x-dev"
+                    "dev-master": "3.2.x-dev"
                 }
             },
             "autoload": {
@@ -975,7 +1087,7 @@
                 "mock",
                 "xunit"
             ],
-            "time": "2015-10-02T06:51:40+00:00"
+            "time": "2017-06-30T09:13:00+00:00"
         },
         {
             "name": "psr/http-message",
@@ -1080,12 +1192,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/php-coveralls/php-coveralls.git",
-                "reference": "c9d3fe2327c8539f1105dc19954673ba993e4ad9"
+                "reference": "a9c356100c095e07b004d32942c9ff5731459b49"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/php-coveralls/php-coveralls/zipball/c9d3fe2327c8539f1105dc19954673ba993e4ad9",
-                "reference": "c9d3fe2327c8539f1105dc19954673ba993e4ad9",
+                "url": "https://api.github.com/repos/php-coveralls/php-coveralls/zipball/a9c356100c095e07b004d32942c9ff5731459b49",
+                "reference": "a9c356100c095e07b004d32942c9ff5731459b49",
                 "shasum": ""
             },
             "require": {
@@ -1155,7 +1267,52 @@
                 "github",
                 "test"
             ],
-            "time": "2017-10-14T23:16:28+00:00"
+            "time": "2017-12-08T13:59:48+00:00"
+        },
+        {
+            "name": "sebastian/code-unit-reverse-lookup",
+            "version": "1.0.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/code-unit-reverse-lookup.git",
+                "reference": "4419fcdb5eabb9caa61a27c7a1db532a6b55dd18"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/code-unit-reverse-lookup/zipball/4419fcdb5eabb9caa61a27c7a1db532a6b55dd18",
+                "reference": "4419fcdb5eabb9caa61a27c7a1db532a6b55dd18",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.6 || ^7.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^5.7 || ^6.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de"
+                }
+            ],
+            "description": "Looks up which function or method a line of code belongs to",
+            "homepage": "https://github.com/sebastianbergmann/code-unit-reverse-lookup/",
+            "time": "2017-03-04T06:30:41+00:00"
         },
         {
             "name": "sebastian/comparator",
@@ -1275,28 +1432,28 @@
         },
         {
             "name": "sebastian/environment",
-            "version": "1.3.8",
+            "version": "2.0.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/environment.git",
-                "reference": "be2c607e43ce4c89ecd60e75c6a85c126e754aea"
+                "reference": "5795ffe5dc5b02460c3e34222fee8cbe245d8fac"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/environment/zipball/be2c607e43ce4c89ecd60e75c6a85c126e754aea",
-                "reference": "be2c607e43ce4c89ecd60e75c6a85c126e754aea",
+                "url": "https://api.github.com/repos/sebastianbergmann/environment/zipball/5795ffe5dc5b02460c3e34222fee8cbe245d8fac",
+                "reference": "5795ffe5dc5b02460c3e34222fee8cbe245d8fac",
                 "shasum": ""
             },
             "require": {
-                "php": "^5.3.3 || ^7.0"
+                "php": "^5.6 || ^7.0"
             },
             "require-dev": {
-                "phpunit/phpunit": "^4.8 || ^5.0"
+                "phpunit/phpunit": "^5.0"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.3.x-dev"
+                    "dev-master": "2.0.x-dev"
                 }
             },
             "autoload": {
@@ -1321,25 +1478,25 @@
                 "environment",
                 "hhvm"
             ],
-            "time": "2016-08-18T05:49:44+00:00"
+            "time": "2016-11-26T07:53:53+00:00"
         },
         {
             "name": "sebastian/exporter",
-            "version": "1.2.2",
+            "version": "2.0.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/exporter.git",
-                "reference": "42c4c2eec485ee3e159ec9884f95b431287edde4"
+                "reference": "ce474bdd1a34744d7ac5d6aad3a46d48d9bac4c4"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/exporter/zipball/42c4c2eec485ee3e159ec9884f95b431287edde4",
-                "reference": "42c4c2eec485ee3e159ec9884f95b431287edde4",
+                "url": "https://api.github.com/repos/sebastianbergmann/exporter/zipball/ce474bdd1a34744d7ac5d6aad3a46d48d9bac4c4",
+                "reference": "ce474bdd1a34744d7ac5d6aad3a46d48d9bac4c4",
                 "shasum": ""
             },
             "require": {
                 "php": ">=5.3.3",
-                "sebastian/recursion-context": "~1.0"
+                "sebastian/recursion-context": "~2.0"
             },
             "require-dev": {
                 "ext-mbstring": "*",
@@ -1348,7 +1505,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.3.x-dev"
+                    "dev-master": "2.0.x-dev"
                 }
             },
             "autoload": {
@@ -1388,7 +1545,7 @@
                 "export",
                 "exporter"
             ],
-            "time": "2016-06-17T09:04:28+00:00"
+            "time": "2016-11-19T08:54:04+00:00"
         },
         {
             "name": "sebastian/global-state",
@@ -1441,18 +1598,64 @@
             ],
             "time": "2015-10-12T03:26:01+00:00"
         },
+        {
+            "name": "sebastian/object-enumerator",
+            "version": "2.0.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/object-enumerator.git",
+                "reference": "1311872ac850040a79c3c058bea3e22d0f09cbb7"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/object-enumerator/zipball/1311872ac850040a79c3c058bea3e22d0f09cbb7",
+                "reference": "1311872ac850040a79c3c058bea3e22d0f09cbb7",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.6",
+                "sebastian/recursion-context": "~2.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "~5"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de"
+                }
+            ],
+            "description": "Traverses array structures and object graphs to enumerate all referenced objects",
+            "homepage": "https://github.com/sebastianbergmann/object-enumerator/",
+            "time": "2017-02-18T15:18:39+00:00"
+        },
         {
             "name": "sebastian/recursion-context",
-            "version": "1.0.5",
+            "version": "2.0.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/recursion-context.git",
-                "reference": "b19cc3298482a335a95f3016d2f8a6950f0fbcd7"
+                "reference": "2c3ba150cbec723aa057506e73a8d33bdb286c9a"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/recursion-context/zipball/b19cc3298482a335a95f3016d2f8a6950f0fbcd7",
-                "reference": "b19cc3298482a335a95f3016d2f8a6950f0fbcd7",
+                "url": "https://api.github.com/repos/sebastianbergmann/recursion-context/zipball/2c3ba150cbec723aa057506e73a8d33bdb286c9a",
+                "reference": "2c3ba150cbec723aa057506e73a8d33bdb286c9a",
                 "shasum": ""
             },
             "require": {
@@ -1464,7 +1667,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.0.x-dev"
+                    "dev-master": "2.0.x-dev"
                 }
             },
             "autoload": {
@@ -1492,23 +1695,73 @@
             ],
             "description": "Provides functionality to recursively process PHP variables",
             "homepage": "http://www.github.com/sebastianbergmann/recursion-context",
-            "time": "2016-10-03T07:41:43+00:00"
+            "time": "2016-11-19T07:33:16+00:00"
+        },
+        {
+            "name": "sebastian/resource-operations",
+            "version": "1.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/resource-operations.git",
+                "reference": "ce990bb21759f94aeafd30209e8cfcdfa8bc3f52"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/resource-operations/zipball/ce990bb21759f94aeafd30209e8cfcdfa8bc3f52",
+                "reference": "ce990bb21759f94aeafd30209e8cfcdfa8bc3f52",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.6.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de"
+                }
+            ],
+            "description": "Provides a list of PHP built-in functions that operate on resources",
+            "homepage": "https://www.github.com/sebastianbergmann/resource-operations",
+            "time": "2015-07-28T20:34:47+00:00"
         },
         {
             "name": "sebastian/version",
-            "version": "1.0.6",
+            "version": "2.0.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/version.git",
-                "reference": "58b3a85e7999757d6ad81c787a1fbf5ff6c628c6"
+                "reference": "99732be0ddb3361e16ad77b68ba41efc8e979019"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/version/zipball/58b3a85e7999757d6ad81c787a1fbf5ff6c628c6",
-                "reference": "58b3a85e7999757d6ad81c787a1fbf5ff6c628c6",
+                "url": "https://api.github.com/repos/sebastianbergmann/version/zipball/99732be0ddb3361e16ad77b68ba41efc8e979019",
+                "reference": "99732be0ddb3361e16ad77b68ba41efc8e979019",
                 "shasum": ""
             },
+            "require": {
+                "php": ">=5.6"
+            },
             "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.0.x-dev"
+                }
+            },
             "autoload": {
                 "classmap": [
                     "src/"
@@ -1527,7 +1780,7 @@
             ],
             "description": "Library that helps with managing the version number of Git-hosted PHP projects",
             "homepage": "https://github.com/sebastianbergmann/version",
-            "time": "2015-06-21T13:59:46+00:00"
+            "time": "2016-10-03T07:35:21+00:00"
         },
         {
             "name": "squizlabs/php_codesniffer",
@@ -1609,16 +1862,16 @@
         },
         {
             "name": "symfony/config",
-            "version": "v3.4.0",
+            "version": "v3.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/config.git",
-                "reference": "1de51a6c76359897ab32c309934b93d036bccb60"
+                "reference": "e57211b88aa889fefac1cb36866db04100b0f21c"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/config/zipball/1de51a6c76359897ab32c309934b93d036bccb60",
-                "reference": "1de51a6c76359897ab32c309934b93d036bccb60",
+                "url": "https://api.github.com/repos/symfony/config/zipball/e57211b88aa889fefac1cb36866db04100b0f21c",
+                "reference": "e57211b88aa889fefac1cb36866db04100b0f21c",
                 "shasum": ""
             },
             "require": {
@@ -1667,20 +1920,20 @@
             ],
             "description": "Symfony Config Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-19T20:09:36+00:00"
+            "time": "2017-12-14T19:40:10+00:00"
         },
         {
             "name": "symfony/console",
-            "version": "v3.4.0",
+            "version": "v3.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/console.git",
-                "reference": "9468ad3fba3a5e1f0dc12a96e50e84cddb923cf0"
+                "reference": "9f21adfb92a9315b73ae2ed43138988ee4913d4e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/console/zipball/9468ad3fba3a5e1f0dc12a96e50e84cddb923cf0",
-                "reference": "9468ad3fba3a5e1f0dc12a96e50e84cddb923cf0",
+                "url": "https://api.github.com/repos/symfony/console/zipball/9f21adfb92a9315b73ae2ed43138988ee4913d4e",
+                "reference": "9f21adfb92a9315b73ae2ed43138988ee4913d4e",
                 "shasum": ""
             },
             "require": {
@@ -1736,20 +1989,20 @@
             ],
             "description": "Symfony Console Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-29T13:28:14+00:00"
+            "time": "2017-12-14T19:40:10+00:00"
         },
         {
             "name": "symfony/debug",
-            "version": "v3.4.0",
+            "version": "v3.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/debug.git",
-                "reference": "fb2001e5d85f95d8b6ab94ae3be5d2672df128fd"
+                "reference": "543deab3ffff94402440b326fc94153bae2dfa7a"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/debug/zipball/fb2001e5d85f95d8b6ab94ae3be5d2672df128fd",
-                "reference": "fb2001e5d85f95d8b6ab94ae3be5d2672df128fd",
+                "url": "https://api.github.com/repos/symfony/debug/zipball/543deab3ffff94402440b326fc94153bae2dfa7a",
+                "reference": "543deab3ffff94402440b326fc94153bae2dfa7a",
                 "shasum": ""
             },
             "require": {
@@ -1792,20 +2045,20 @@
             ],
             "description": "Symfony Debug Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-21T09:01:46+00:00"
+            "time": "2017-12-12T08:27:14+00:00"
         },
         {
             "name": "symfony/filesystem",
-            "version": "v3.4.0",
+            "version": "v3.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/filesystem.git",
-                "reference": "de56eee71e0a128d8c54ccc1909cdefd574bad0f"
+                "reference": "25b135bea251829e3db6a77d773643408b575ed4"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/filesystem/zipball/de56eee71e0a128d8c54ccc1909cdefd574bad0f",
-                "reference": "de56eee71e0a128d8c54ccc1909cdefd574bad0f",
+                "url": "https://api.github.com/repos/symfony/filesystem/zipball/25b135bea251829e3db6a77d773643408b575ed4",
+                "reference": "25b135bea251829e3db6a77d773643408b575ed4",
                 "shasum": ""
             },
             "require": {
@@ -1841,7 +2094,7 @@
             ],
             "description": "Symfony Filesystem Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-19T18:59:05+00:00"
+            "time": "2017-12-14T19:40:10+00:00"
         },
         {
             "name": "symfony/polyfill-mbstring",
@@ -1904,7 +2157,7 @@
         },
         {
             "name": "symfony/stopwatch",
-            "version": "v3.4.0",
+            "version": "v3.4.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/stopwatch.git",
@@ -2014,6 +2267,6 @@
     },
     "platform-dev": [],
     "platform-overrides": {
-        "php": "5.5.9"
+        "php": "7.1"
     }
 }
diff --git a/scenarios/install b/scenarios/install
index 5bc73b7..e921ec0 100755
--- a/scenarios/install
+++ b/scenarios/install
@@ -15,9 +15,14 @@ if [ ! -d "$dir" ] ; then
   exit 1
 fi
 
-echo "Switch to ${SCENARIO} scenario"
+echo
+echo "::"
+echo ":: Switch to ${SCENARIO} scenario"
+echo "::"
+echo
 
 set -ex
 
+composer -n validate --working-dir=$dir --no-check-all --ansi
 composer -n --working-dir=$dir ${ACTION} --prefer-dist --no-scripts
 composer -n --working-dir=$dir info
diff --git a/scenarios/symfony2/composer.json b/scenarios/symfony2/composer.json
index 43e4e96..356a3ac 100644
--- a/scenarios/symfony2/composer.json
+++ b/scenarios/symfony2/composer.json
@@ -4,8 +4,9 @@
     "type": "library",
     "require": {
         "php": ">=5.4",
-        "symfony/yaml":                   "^2.8.11|^3|^4",
-        "dflydev/dot-access-data":        "^1.1.0"
+        "dflydev/dot-access-data": "^1.1.0",
+        "grasmash/expander": "^1.0.0",
+        "symfony/yaml": "^2.8.11|^3|^4"
     },
     "license": "MIT",
     "authors": [
@@ -16,7 +17,7 @@
     "minimum-stability": "stable",
     "autoload": {
         "psr-4": {
-            "Grasmash\\YamlExpander\\":        "src/"
+            "Grasmash\\YamlExpander\\": "src/"
         }
     },
     "require-dev": {
@@ -55,7 +56,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "1.x-dev"
+            "dev-master": "2.x-dev"
         }
     }
 }
diff --git a/scenarios/symfony4/composer.json b/scenarios/symfony4/composer.json
index 3052d4e..96f70bf 100644
--- a/scenarios/symfony4/composer.json
+++ b/scenarios/symfony4/composer.json
@@ -4,8 +4,9 @@
     "type": "library",
     "require": {
         "php": ">=5.4",
-        "symfony/yaml":                   "^2.8.11|^3|^4",
-        "dflydev/dot-access-data":        "^1.1.0"
+        "dflydev/dot-access-data": "^1.1.0",
+        "grasmash/expander": "^1.0.0",
+        "symfony/yaml": "^2.8.11|^3|^4"
     },
     "license": "MIT",
     "authors": [
@@ -16,7 +17,7 @@
     "minimum-stability": "stable",
     "autoload": {
         "psr-4": {
-            "Grasmash\\YamlExpander\\":        "src/"
+            "Grasmash\\YamlExpander\\": "src/"
         }
     },
     "require-dev": {
@@ -55,7 +56,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "1.x-dev"
+            "dev-master": "2.x-dev"
         }
     }
 }
diff --git a/scenarios/symfony4/composer.lock b/scenarios/symfony4/composer.lock
index d0fe611..df03b4b 100644
--- a/scenarios/symfony4/composer.lock
+++ b/scenarios/symfony4/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "content-hash": "d2caa274a8dbc1766b1756b440be19a0",
+    "content-hash": "bc5e8004383b21b8ff51fb59bc6dcf67",
     "packages": [
         {
             "name": "dflydev/dot-access-data",
@@ -65,18 +65,65 @@
             ],
             "time": "2017-01-20T21:14:22+00:00"
         },
+        {
+            "name": "grasmash/expander",
+            "version": "1.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/grasmash/expander.git",
+                "reference": "95d6037344a4be1dd5f8e0b0b2571a28c397578f"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/grasmash/expander/zipball/95d6037344a4be1dd5f8e0b0b2571a28c397578f",
+                "reference": "95d6037344a4be1dd5f8e0b0b2571a28c397578f",
+                "shasum": ""
+            },
+            "require": {
+                "dflydev/dot-access-data": "^1.1.0",
+                "php": ">=5.4"
+            },
+            "require-dev": {
+                "greg-1-anderson/composer-test-scenarios": "^1",
+                "phpunit/phpunit": "^4|^5.5.4",
+                "satooshi/php-coveralls": "^1.0.2|dev-master",
+                "squizlabs/php_codesniffer": "^2.7"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Grasmash\\Expander\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Matthew Grasmick"
+                }
+            ],
+            "description": "Expands internal property references in PHP arrays file.",
+            "time": "2017-12-21T22:14:55+00:00"
+        },
         {
             "name": "symfony/yaml",
-            "version": "v4.0.0",
+            "version": "v4.0.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/yaml.git",
-                "reference": "7be8741ce5dce9943f41a9269f6828b66e726776"
+                "reference": "a5ee52d155f06ad23b19eb63c31228ff56ad1116"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/yaml/zipball/7be8741ce5dce9943f41a9269f6828b66e726776",
-                "reference": "7be8741ce5dce9943f41a9269f6828b66e726776",
+                "url": "https://api.github.com/repos/symfony/yaml/zipball/a5ee52d155f06ad23b19eb63c31228ff56ad1116",
+                "reference": "a5ee52d155f06ad23b19eb63c31228ff56ad1116",
                 "shasum": ""
             },
             "require": {
@@ -121,7 +168,7 @@
             ],
             "description": "Symfony Yaml Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-29T13:42:03+00:00"
+            "time": "2017-12-12T08:41:51+00:00"
         }
     ],
     "packages-dev": [
@@ -181,16 +228,16 @@
         },
         {
             "name": "greg-1-anderson/composer-test-scenarios",
-            "version": "1.0.0",
+            "version": "1.0.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/greg-1-anderson/composer-test-scenarios.git",
-                "reference": "00ff9f3af3132f0c6b2fb9e0906efee402f0c703"
+                "reference": "dc81660f44a8b126d7fa947156c98e34f45af3e9"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/greg-1-anderson/composer-test-scenarios/zipball/00ff9f3af3132f0c6b2fb9e0906efee402f0c703",
-                "reference": "00ff9f3af3132f0c6b2fb9e0906efee402f0c703",
+                "url": "https://api.github.com/repos/greg-1-anderson/composer-test-scenarios/zipball/dc81660f44a8b126d7fa947156c98e34f45af3e9",
+                "reference": "dc81660f44a8b126d7fa947156c98e34f45af3e9",
                 "shasum": ""
             },
             "bin": [
@@ -209,7 +256,7 @@
                 }
             ],
             "description": "Useful scripts for testing multiple sets of Composer dependencies.",
-            "time": "2017-12-01T21:34:53+00:00"
+            "time": "2017-12-13T18:41:24+00:00"
         },
         {
             "name": "guzzlehttp/guzzle",
@@ -903,16 +950,16 @@
         },
         {
             "name": "phpunit/phpunit",
-            "version": "5.7.25",
+            "version": "5.7.26",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit.git",
-                "reference": "4b1c822a68ae6577df38a59eb49b046712ec0f6a"
+                "reference": "7fbc25c13309de0c4c9bb48b7361f1eca34c7fbd"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/4b1c822a68ae6577df38a59eb49b046712ec0f6a",
-                "reference": "4b1c822a68ae6577df38a59eb49b046712ec0f6a",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/7fbc25c13309de0c4c9bb48b7361f1eca34c7fbd",
+                "reference": "7fbc25c13309de0c4c9bb48b7361f1eca34c7fbd",
                 "shasum": ""
             },
             "require": {
@@ -981,7 +1028,7 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2017-11-14T14:50:51+00:00"
+            "time": "2017-12-17T06:14:38+00:00"
         },
         {
             "name": "phpunit/phpunit-mock-objects",
@@ -1145,12 +1192,12 @@
             "source": {
                 "type": "git",
                 "url": "https://github.com/php-coveralls/php-coveralls.git",
-                "reference": "c9d3fe2327c8539f1105dc19954673ba993e4ad9"
+                "reference": "a9c356100c095e07b004d32942c9ff5731459b49"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/php-coveralls/php-coveralls/zipball/c9d3fe2327c8539f1105dc19954673ba993e4ad9",
-                "reference": "c9d3fe2327c8539f1105dc19954673ba993e4ad9",
+                "url": "https://api.github.com/repos/php-coveralls/php-coveralls/zipball/a9c356100c095e07b004d32942c9ff5731459b49",
+                "reference": "a9c356100c095e07b004d32942c9ff5731459b49",
                 "shasum": ""
             },
             "require": {
@@ -1220,7 +1267,7 @@
                 "github",
                 "test"
             ],
-            "time": "2017-10-14T23:16:28+00:00"
+            "time": "2017-12-08T13:59:48+00:00"
         },
         {
             "name": "sebastian/code-unit-reverse-lookup",
@@ -1815,16 +1862,16 @@
         },
         {
             "name": "symfony/config",
-            "version": "v4.0.0",
+            "version": "v4.0.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/config.git",
-                "reference": "6e6dbc6d2beff8117b974d74274bff02e43c32a6"
+                "reference": "0356e6d5298e9e72212c0bad65c2f1b49e42d622"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/config/zipball/6e6dbc6d2beff8117b974d74274bff02e43c32a6",
-                "reference": "6e6dbc6d2beff8117b974d74274bff02e43c32a6",
+                "url": "https://api.github.com/repos/symfony/config/zipball/0356e6d5298e9e72212c0bad65c2f1b49e42d622",
+                "reference": "0356e6d5298e9e72212c0bad65c2f1b49e42d622",
                 "shasum": ""
             },
             "require": {
@@ -1871,20 +1918,20 @@
             ],
             "description": "Symfony Config Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-20T18:22:57+00:00"
+            "time": "2017-12-14T19:48:22+00:00"
         },
         {
             "name": "symfony/console",
-            "version": "v4.0.0",
+            "version": "v4.0.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/console.git",
-                "reference": "5cd0dd461dfc72f59c8405cac32d31e82c7348e8"
+                "reference": "de8cf039eacdec59d83f7def67e3b8ff5ed46714"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/console/zipball/5cd0dd461dfc72f59c8405cac32d31e82c7348e8",
-                "reference": "5cd0dd461dfc72f59c8405cac32d31e82c7348e8",
+                "url": "https://api.github.com/repos/symfony/console/zipball/de8cf039eacdec59d83f7def67e3b8ff5ed46714",
+                "reference": "de8cf039eacdec59d83f7def67e3b8ff5ed46714",
                 "shasum": ""
             },
             "require": {
@@ -1939,20 +1986,20 @@
             ],
             "description": "Symfony Console Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-29T13:42:03+00:00"
+            "time": "2017-12-14T19:48:22+00:00"
         },
         {
             "name": "symfony/filesystem",
-            "version": "v4.0.0",
+            "version": "v4.0.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/filesystem.git",
-                "reference": "c9d4a26759ff75a077e4e334315cb632739b661a"
+                "reference": "8c2868641d0c4885eee9c12a89c2b695eb1985cd"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/filesystem/zipball/c9d4a26759ff75a077e4e334315cb632739b661a",
-                "reference": "c9d4a26759ff75a077e4e334315cb632739b661a",
+                "url": "https://api.github.com/repos/symfony/filesystem/zipball/8c2868641d0c4885eee9c12a89c2b695eb1985cd",
+                "reference": "8c2868641d0c4885eee9c12a89c2b695eb1985cd",
                 "shasum": ""
             },
             "require": {
@@ -1988,7 +2035,7 @@
             ],
             "description": "Symfony Filesystem Component",
             "homepage": "https://symfony.com",
-            "time": "2017-11-21T14:14:53+00:00"
+            "time": "2017-12-14T19:48:22+00:00"
         },
         {
             "name": "symfony/polyfill-mbstring",
@@ -2051,7 +2098,7 @@
         },
         {
             "name": "symfony/stopwatch",
-            "version": "v4.0.0",
+            "version": "v4.0.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/stopwatch.git",
diff --git a/src/Expander.php b/src/Expander.php
index d922db5..c94ae83 100644
--- a/src/Expander.php
+++ b/src/Expander.php
@@ -2,8 +2,10 @@
 
 namespace Grasmash\YamlExpander;
 
-use Dflydev\DotAccessData\Data;
+use Psr\Log\LoggerInterface;
+use Psr\Log\NullLogger;
 use Symfony\Component\Yaml\Yaml;
+use Grasmash\Expander\Expander as GrasmashExpander;
 
 /**
  * Class Expander
@@ -11,6 +13,28 @@
  */
 class Expander
 {
+    /**
+     * @var \Psr\Log\LoggerInterface
+     */
+    protected $logger;
+
+    /**
+     * @var \Grasmash\Expander\Expander
+     */
+    protected $expander;
+
+    /**
+     * Expander constructor.
+     *
+     * @param \Psr\Log\LoggerInterface $logger
+     */
+    public function __construct(LoggerInterface $logger)
+    {
+        $this->logger = $logger;
+        $this->expander =  new GrasmashExpander();
+        $this->expander->setLogger($logger);
+        $this->expander->setStringifier(new Stringifier());
+    }
 
     /**
      * Parses a YAML string and expands property placeholders.
@@ -27,13 +51,12 @@ class Expander
      *   The modified array in which placeholders have been replaced with
      *   values.
      */
-    public static function parse($yaml_string, $reference_array = [])
+    public function parse($yaml_string, $reference_array = [])
     {
         $array = Yaml::parse($yaml_string);
-        return self::expandArrayProperties($array, $reference_array);
+        return $this->expander->expandArrayProperties($array, $reference_array);
     }
 
-
     /**
      * Expands property placeholders in an array.
      *
@@ -46,228 +69,8 @@ public static function parse($yaml_string, $reference_array = [])
      *   The modified array in which placeholders have been replaced with
      *   values.
      */
-    public static function expandArrayProperties($array, $reference_array = [])
-    {
-        $data = new Data($array);
-        if ($reference_array) {
-            $reference_data = new Data($reference_array);
-            self::doExpandArrayProperties($data, $array, '', $reference_data);
-        } else {
-            self::doExpandArrayProperties($data, $array);
-        }
-
-        return $data->export();
-    }
-
-    /**
-     * Performs the actual property expansion.
-     *
-     * @param Data $data
-     *   A data object, containing the $array.
-     * @param array $array
-     *   The original, unmodified array.
-     * @param string $parent_keys
-     *   The parent keys of the current key in dot notation. This is used to
-     *   track the absolute path to the current key in recursive cases.
-     * @param Data|null $reference_data
-     *   A reference data object. This is not operated upon but is used as a
-     *   reference to provide supplemental values for property expansion.
-     */
-    protected static function doExpandArrayProperties(
-        $data,
-        $array,
-        $parent_keys = '',
-        $reference_data = null
-    ) {
-        foreach ($array as $key => $value) {
-            // Boundary condition(s).
-            if (is_null($value) || is_bool($value)) {
-                continue;
-            }
-            // Recursive case.
-            if (is_array($value)) {
-                self::doExpandArrayProperties($data, $value, $parent_keys . "$key.", $reference_data);
-            } // Base case.
-            else {
-                self::expandStringProperties($data, $parent_keys, $reference_data, $value, $key);
-            }
-        }
-    }
-
-    /**
-     * Expand a single property.
-     *
-     * @param Data $data
-     *   A data object, containing the $array.
-     * @param string $parent_keys
-     *   The parent keys of the current key in dot notation. This is used to
-     *   track the absolute path to the current key in recursive cases.
-     * @param Data|null $reference_data
-     *   A reference data object. This is not operated upon but is used as a
-     *   reference to provide supplemental values for property expansion.
-     * @param string $value
-     *   The unexpanded property value.
-     * @param string $key
-     *   The immediate key of the property.
-     *
-     * @return mixed
-     */
-    protected static function expandStringProperties(
-        $data,
-        $parent_keys,
-        $reference_data,
-        $value,
-        $key
-    ) {
-        // We loop through all placeholders in a given string.
-        // E.g., '${placeholder1} ${placeholder2}' requires two replacements.
-        while (strpos($value, '${') !== false) {
-            $original_value = $value;
-            $value = preg_replace_callback(
-                '/\$\{([^\$}]+)\}/',
-                function ($matches) use ($data, $reference_data) {
-                    return self::expandStringPropertiesCallback(
-                        $matches,
-                        $data,
-                        $reference_data
-                    );
-                },
-                $value
-            );
-
-            // If no replacement occurred at all, break to prevent
-            // infinite loop.
-            if ($original_value == $value) {
-                break;
-            }
-
-            // Set value on $data object.
-            if ($parent_keys) {
-                $full_key = $parent_keys . "$key";
-            } else {
-                $full_key = $key;
-            }
-            $data->set($full_key, $value);
-        }
-        return $value;
-    }
-
-    /**
-     * Expansion callback used by preg_replace_callback() in expandProperty().
-     *
-     * @param array $matches
-     *   An array of matches created by preg_replace_callback().
-     * @param Data $data
-     *   A data object containing the complete array being operated upon.
-     * @param Data|null $reference_data
-     *   A reference data object. This is not operated upon but is used as a
-     *   reference to provide supplemental values for property expansion.
-     *
-     * @return mixed
-     */
-    public static function expandStringPropertiesCallback(
-        $matches,
-        $data,
-        $reference_data = null
-    ) {
-        $property_name = $matches[1];
-        $unexpanded_value = $matches[0];
-
-        // Use only values within the subject array's data.
-        if (!$reference_data) {
-            return self::expandProperty($property_name, $unexpanded_value, $data);
-        } // Search both the subject array's data and the reference data for a value.
-        else {
-            return self::expandPropertyWithReferenceData(
-                $property_name,
-                $unexpanded_value,
-                $data,
-                $reference_data
-            );
-        }
-    }
-
-    /**
-     * Searches both the subject data and the reference data for value.
-     *
-     * @param string $property_name
-     *   The name of the value for which to search.
-     * @param string $unexpanded_value
-     *   The original, unexpanded value, containing the placeholder.
-     * @param Data $data
-     *   A data object containing the complete array being operated upon.
-     * @param Data|null $reference_data
-     *   A reference data object. This is not operated upon but is used as a
-     *   reference to provide supplemental values for property expansion.
-     *
-     * @return string
-     *   The expanded string.
-     */
-    public static function expandPropertyWithReferenceData(
-        $property_name,
-        $unexpanded_value,
-        $data,
-        $reference_data
-    ) {
-        $expanded_value = self::expandProperty(
-            $property_name,
-            $unexpanded_value,
-            $data
-        );
-        // If the string was not changed using the subject data, try using
-        // the reference data.
-        if ($expanded_value == $unexpanded_value) {
-            $expanded_value = self::expandProperty(
-                $property_name,
-                $unexpanded_value,
-                $reference_data
-            );
-        }
-
-        return $expanded_value;
-    }
-
-    /**
-     * Searches a data object for a value.
-     *
-     * @param string $property_name
-     *   The name of the value for which to search.
-     * @param string $unexpanded_value
-     *   The original, unexpanded value, containing the placeholder.
-     * @param Data $data
-     *   A data object containing possible replacement values.
-     *
-     * @return mixed
-     */
-    public static function expandProperty($property_name, $unexpanded_value, $data)
-    {
-        if (strpos($property_name, "env.") === 0 &&
-          !$data->has($property_name)) {
-            $env_key = substr($property_name, 4);
-            if (getenv($env_key)) {
-                $data->set($property_name, getenv($env_key));
-            }
-        }
-
-        if (!$data->has($property_name)) {
-            self::log("Property \${'$property_name'} could not be expanded.");
-            return $unexpanded_value;
-        } else {
-            $expanded_value = $data->get($property_name);
-            if (is_array($expanded_value)) {
-                $expanded_value = Yaml::dump($expanded_value, 0);
-                return $expanded_value;
-            }
-            self::log("Expanding property \${'$property_name'} => $expanded_value.");
-            return $expanded_value;
-        }
-    }
-
-    /**
-     * @param $message
-     */
-    public static function log($message)
+    public function expandArrayProperties($array, $reference_array = [])
     {
-        // print "$message\n";
+        return $this->expander->expandArrayProperties($array, $reference_array);
     }
 }
diff --git a/src/Stringifier.php b/src/Stringifier.php
new file mode 100644
index 0000000..a420999
--- /dev/null
+++ b/src/Stringifier.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace Grasmash\YamlExpander;
+
+use Grasmash\Expander\StringifierInterface;
+use Symfony\Component\Yaml\Yaml;
+
+class Stringifier implements StringifierInterface
+{
+    /**
+     * Converts array to string.
+     *
+     * @param array $array
+     *   The array to convert.
+     *
+     * @return string
+     *   The resultant string.
+     */
+    public static function stringifyArray(array $array)
+    {
+        return Yaml::dump($array, 0);
+    }
+}
diff --git a/tests/phpunit/ExpanderTest.php b/tests/phpunit/ExpanderTest.php
index 291d00c..6b1b1dc 100644
--- a/tests/phpunit/ExpanderTest.php
+++ b/tests/phpunit/ExpanderTest.php
@@ -4,7 +4,9 @@
 
 use Dflydev\DotAccessData\Data;
 use Grasmash\YamlExpander\Expander;
+use Grasmash\YamlExpander\Stringifier;
 use Grasmash\YamlExpander\Tests\TestBase;
+use Psr\Log\NullLogger;
 use Symfony\Component\Yaml\Yaml;
 
 class ExpanderTest extends \PHPUnit_Framework_TestCase
@@ -22,7 +24,8 @@ public function testExpandArrayProperties($filename, $reference_array)
     {
         $array = Yaml::parse(file_get_contents(__DIR__ . "/../resources/$filename"));
         putenv("test=gomjabbar");
-        $expanded = Expander::expandArrayProperties($array);
+        $expander = new Expander(new NullLogger());
+        $expanded = $expander->expandArrayProperties($array);
         $this->assertEquals('gomjabbar', $expanded['env-test']);
         $this->assertEquals('Frank Herbert 1965', $expanded['book']['copyright']);
         $this->assertEquals('Paul Atreides', $expanded['book']['protaganist']);
@@ -31,7 +34,7 @@ public function testExpandArrayProperties($filename, $reference_array)
         $this->assertEquals('Dune', $expanded['product-name']);
         $this->assertEquals(Yaml::dump($array['inline-array'], 0), $expanded['expand-array']);
 
-        $expanded = Expander::expandArrayProperties($array, $reference_array);
+        $expanded = $expander->expandArrayProperties($array, $reference_array);
         $this->assertEquals('Dune Messiah, and others.', $expanded['sequels']);
         $this->assertEquals('Dune Messiah', $expanded['book']['nested-reference']);
     }
@@ -47,13 +50,14 @@ public function testExpandArrayProperties($filename, $reference_array)
     public function testParse($filename, $reference_array)
     {
         $yaml_string = file_get_contents(__DIR__ . "/../resources/$filename");
-        $expanded = Expander::parse($yaml_string);
+        $expander = new Expander(new NullLogger());
+        $expanded = $expander->parse($yaml_string);
         $this->assertEquals('Frank Herbert 1965', $expanded['book']['copyright']);
         $this->assertEquals('Paul Atreides', $expanded['book']['protaganist']);
         $this->assertEquals('Dune by Frank Herbert', $expanded['summary']);
         $this->assertEquals('${book.media.1}, hardcover', $expanded['available-products']);
 
-        $expanded = Expander::parse($yaml_string, $reference_array);
+        $expanded = $expander->parse($yaml_string, $reference_array);
         $this->assertEquals('Dune Messiah, and others.', $expanded['sequels']);
         $this->assertEquals('Dune Messiah', $expanded['book']['nested-reference']);
     }
@@ -75,25 +79,15 @@ public function providerYaml()
 
     /**
      * Tests Expander::expandProperty().
-     *
-     * @dataProvider providerTestExpandProperty
      */
-    public function testExpandProperty($array, $property_name, $unexpanded_string, $expected)
+    public function testStringifyArray()
     {
-        $data = new Data($array);
-        $expanded_value = Expander::expandProperty($property_name, $unexpanded_string, $data);
-
-        $this->assertEquals($expected, $expanded_value);
-    }
-
-    /**
-     * @return array
-     */
-    public function providerTestExpandProperty()
-    {
-        return [
-            [ ['author' => 'Frank Herbert'], 'author', '${author}', 'Frank Herbert' ],
-            [ ['book' =>  ['author' => 'Frank Herbert' ]], 'book.author', '${book.author}', 'Frank Herbert' ],
+        $array =  [
+          0 => 'one',
+          1 => 'two',
+          2 => 'three',
         ];
+        $string = Stringifier::stringifyArray($array);
+        $this->assertEquals('[one, two, three]', $string);
     }
 }