Initial commit. Added single and recursive dereference utilities.

Author: ndobromirov

.gitignore

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+vendor
+nbproject
+composer.lock

README.md

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 # php-env-dereference
+
 Allow dereferencing of environment variables in PHP.
+
+## Overview
+
+This is generally useful, in cloud environments, where different backing
+services are injected into PHP with some strange names. At that point the
+developer is either using that strange names in his code or starting to do
+workarounds.
+
+This particular library solves this based on the idea from variable dereference
+feature that is (already in PHP engine)[http://php.net/manual/en/language.variables.variable.php].
+```
+<?php
+$a = 'hello';
+$$a = 'world';
+// Same output.
+echo "$a ${$a}\n", "hello world\n";
+```
+
+This is very similar to the (phpdotenv)[https://github.com/vlucas/phpdotenv]
+nested variables functionality, but exposing only it with a simpler syntax and
+allowing recursive dereferencing.
+
+## Library example
+```
+// We have this environment variables.
+putenv('MY_VAR_1=1');
+putenv('MY_VAR_2=#MY_VAR_1');
+putenv('MY_VAR=#MY_VAR_2');
+
+echo EnvDereference\Variable::get('MY_VAR'); // Should output '#MY_VAR_1'.
+echo EnvDereference\Variable::getRecursive('MY_VAR'); // Should output '1'.
+```
+
+## Install
+```
+composer require ndobromirov/php-env-dereference
+```
+
+## Contribute.
+
+The library complies with PSR-2. Validate with ```composer cs```.  
+The run tests with ```composer test```.

composer.json

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+{
+    "name": "ndobromirov/php-env-dereference",
+    "description": "LCache library.",
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Nikolay Dobromirov",
+            "email": "[email protected]"
+        }
+    ],
+    "autoload":{
+        "psr-4":{
+            "EnvDereference\\": "src/"
+        }
+    },
+    "autoload-dev":{
+        "psr-4":{
+            "EnvDereference\\": "tests/"
+        }
+    },
+    "require": {
+        "php": ">=5"
+    },
+    "require-dev": {
+        "phpunit/phpunit": "4.*",
+        "squizlabs/php_codesniffer": "2.*"
+    },
+    "scripts": {
+        "cs": "phpcs --standard=PSR2 -n src tests",
+        "test": "phpunit"
+    },
+     "extra": {
+        "branch-alias": {
+            "dev-master": "master"
+        }
+    }
+}

phpunit.xml.dist

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+<phpunit verbose="true">
+  <testsuites>
+    <testsuite>
+      <directory>tests</directory>
+    </testsuite>
+  </testsuites>
+  <php>
+    <includePath>.</includePath>
+  </php>
+  <logging>
+      <log type="coverage-clover" target="build/logs/clover.xml"/>
+  </logging>
+  <filter>
+    <whitelist processUncoveredFilesFromWhitelist="true">
+      <directory suffix=".php">src</directory>
+    </whitelist>
+  </filter>
+</phpunit>

src/Variable.php

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+<?php
+
+/**
+ * @file
+ * Utility library implementation.
+ */
+
+namespace EnvDereference;
+
+/**
+ * Class containing the static metods provided by the library.
+ *
+ * @author ndobromirov
+ */
+class Variable
+{
+    const DEFAULT_PREFIX = '#';
+
+    public static function get($name, $prefix = self::DEFAULT_PREFIX)
+    {
+        $value = getenv($name);
+        if (strpos($value, $prefix) === 0) {
+            $value = getenv(substr($value, strlen($prefix)));
+        }
+        return $value;
+    }
+
+    public static function getRecursive($name, $prefix = self::DEFAULT_PREFIX)
+    {
+        $value = getenv($name);
+        while (strpos($value, $prefix) === 0) {
+            $value = getenv(substr($value, strlen($prefix)));
+        }
+        return $value;
+    }
+}

tests/VariableTest.php

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+<?php
+
+/**
+ * @file
+ * Testing utility.
+ */
+
+namespace EnvDereference;
+
+/**
+ * Tests to ensure that the library works as expected.
+ *
+ * @todo: Have more tests added to cover customized prefixes.
+ * @author ndobromirov
+ */
+class VariableTest extends \PHPUnit\Framework\TestCase
+{
+    public static function setUpBeforeClass()
+    {
+        putenv('MY_VAR_1=1');
+        putenv('MY_VAR_2=#MY_VAR_1');
+        putenv('MY_VAR=#MY_VAR_2');
+    }
+
+    public static function tearDownAfterClass()
+    {
+        putenv('MY_VAR');
+        putenv('MY_VAR_1');
+        putenv('MY_VAR_2');
+    }
+
+    public function testSingleDereference()
+    {
+        $this->assertEquals('#MY_VAR_1', Variable::get('MY_VAR'));
+    }
+
+    public function testRecursiveDereference()
+    {
+        $this->assertEquals('1', Variable::getRecursive('MY_VAR'));
+    }
+}