Prevent deprecation notices for implode, json_encode and substr modifiers.

CHANGELOG.md

@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+- Using the `|implode`, `|json_encode` and `|substr` modifiers does not generate a deprecation warning anymore as they will continue to be supported in v5 [#939](https://github.com/smarty-php/smarty/issues/939) 
+
 ## [4.3.4] - 2023-09-14
 
 ## [4.3.3] - 2023-09-14

libs/plugins/modifier.implode.php

@@ -0,0 +1,15 @@
+<?php
+/**
+ * Smarty plugin
+ *
+ * @package    Smarty
+ * @subpackage PluginsModifier
+ */
+
+function smarty_modifier_implode($values, $separator = '')
+{
+	if (is_array($separator)) {
+		return implode((string) ($values ?? ''), (array) $separator);
+	}
+	return implode((string) ($separator ?? ''), (array) $values);
+}

libs/plugins/modifiercompiler.json_encode.php

@@ -0,0 +1,11 @@
+<?php
+
+/**
+ * Smarty plugin
+ *
+ * @package    Smarty
+ * @subpackage PluginsModifierCompiler
+ */
+function smarty_modifiercompiler_json_encode($params) {
+	return 'json_encode(' . $params[0] . (isset($params[1]) ? ', (int) ' . $params[1] : '') . ')';
+}

libs/plugins/modifiercompiler.substr.php

@@ -0,0 +1,12 @@
+<?php
+
+/**
+ * Smarty plugin
+ *
+ * @package    Smarty
+ * @subpackage PluginsModifierCompiler
+ */
+function smarty_modifiercompiler_substr($params) {
+	return 'substr((string) ' . $params[0] . ', (int) ' . $params[1] .
+		(isset($params[2]) ? ', (int) ' . $params[2] : '') . ')';
+}