Encoder: fixed encoding of control characters [Closes #72]

Author: ondrejmirtes

src/Neon/Node/StringNode.php

@@ -80,16 +80,18 @@ function (array $m): string {
 	public function toString(): string
 	{
 		if (strpos($this->value, "\n") === false) {
-			return "'" . str_replace("'", "''", $this->value) . "'";
+			return preg_match('~[\x00-\x08\x0B-\x1F]~', $this->value)
+				? json_encode($this->value, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES)
+				: "'" . str_replace("'", "''", $this->value) . "'";
 
-		} elseif (preg_match('~\n[\t ]+\'{3}~', $this->value)) {
-			$s = json_encode($this->value, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+		} elseif (preg_match('~[\x00-\x08\x0B-\x1F]|\n[\t ]+\'{3}~', $this->value)) {
+			$s = substr(json_encode($this->value, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES), 1, -1);
 			$s = preg_replace_callback(
 				'#[^\\\\]|\\\\(.)#s',
 				function ($m) {
 					return ['n' => "\n", 't' => "\t", '"' => '"'][$m[1] ?? ''] ?? $m[0];
 				},
-				substr($s, 1, -1)
+				$s
 			);
 			$s = str_replace('"""', '""\"', $s);
 			$delim = '"""';

tests/Neon/Encoder.phpt

@@ -164,3 +164,13 @@ Assert::same(
 	'[]',
 	Neon::encode([], Neon::BLOCK)
 );
+
+Assert::same(
+	'"special \u0000 chars"',
+	Neon::encode("special \x00 chars", true)
+);
+
+Assert::same(
+	"\"\"\"\n\tspecial\\r\n\tchars\n\"\"\"",
+	Neon::encode("special\r\nchars", true)
+);