add ability for nested language definition

system/Language/Language.php

@@ -149,7 +149,19 @@ public function getLine(string $line, array $args = [])
 			$parsedLine,
 		] = $this->parseLine($line, $this->locale);
 
-		$output = $this->language[$this->locale][$file][$parsedLine] ?? null;
+		foreach (explode('.', $parsedLine) as $row)
+		{
+			if (! isset($current))
+			{
+				$current = $this->language[$this->locale][$file] ?? null;
+			}
+
+			$output = $current[$row] ?? null;
+			if (is_array($output))
+			{
+				$current = $output;
+			}
+		}
 
 		if ($output === null && strpos($this->locale, '-'))
 		{

tests/_support/Language/en/Nested.php

@@ -0,0 +1,11 @@
+<?php
+
+return [
+   'a' => [
+	   'b' => [
+		   'c' => [
+			   'd' => 'e',
+		   ],
+	   ],
+   ],
+];

tests/system/Language/LanguageTest.php

@@ -313,4 +313,12 @@ public function testAllTheWayFallbacks()
 		$this->assertEquals('Hanging Gardens of Babylon', $language->getLine('Allin.sev'));
 	}
 
+	public function testLanguageNestedArrayDefinition()
+	{
+		$lang = new SecondMockLanguage('en');
+		$lang->loadem('Nested', 'en');
+
+		$this->assertEquals('e', $lang->getLine('Nested.a.b.c.d'));
+	}
+
 }

user_guide_src/source/outgoing/localization.rst

@@ -113,10 +113,18 @@ Languages do not have any specific naming convention that are required. The file
 describe the type of content it holds. For example, let's say you want to create a file containing error messages.
 You might name it simply: **Errors.php**.
 
-Within the file, you would return an array, where each element in the array has a language key and the string to return::
+Within the file, you would return an array, where each element in the array has a language key and can have string to return::
 
         'language_key' => 'The actual message to be shown.'
 
+It also support nested definition:
+
+        'language_key' => [
+            'nested' => [
+                'key' => 'The actual message to be shown.'
+            ],
+        ],
+
 .. note:: It's good practice to use a common prefix for all messages in a given file to avoid collisions with
     similarly named items in other files. For example, if you are creating error messages you might prefix them
     with error\_
@@ -127,6 +135,11 @@ Within the file, you would return an array, where each element in the array has
         'errorEmailMissing'    => 'You must submit an email address',
         'errorURLMissing'      => 'You must submit a URL',
         'errorUsernameMissing' => 'You must submit a username',
+        'nested'             => [
+            'error' => [
+                'message' => 'A specific error message',
+            ],
+        ],
     ];
 
 Basic Usage
@@ -138,8 +151,12 @@ filename and the language key as the first parameter, separated by a period (.).
 
     echo lang('Errors.errorEmailMissing');
 
+For nested definition, you would do the following::
+
+    echo lang('Errors.nested.error.message');
+
 If the requested language key doesn't exist in the file for the current locale, the string will be passed
-back, unchanged. In this example, it would return 'Errors.errorEmailMissing' if it didn't exist.
+back, unchanged. In this example, it would return 'Errors.errorEmailMissing' or 'Errors.nested.error.message' if it didn't exist.
 
 Replacing Parameters
 --------------------