Add method Xml::encode()

Author: fdreamsu

src/Xml.php

@@ -1,22 +1,24 @@
 <?php
+use function Swlib\Http\stream_for;
 class Xml {
     private static function intoObject(SimpleXMLElement $data, array &$need_array, string $key) {
         $s = $data->__toString();
         if (str_replace([
-            ' ',
-            "\n",
-            "\r",
-            "\t"
-        ], '', $s) != '') {
+                ' ',
+                "\n",
+                "\r",
+                "\t"
+            ], '', $s) != '') {
             return $s;
         }
         $result = new stdClass();
         $flag = 0; // 0表示没有儿子 1表示有多个同键名儿子 2表示有儿子
         $map = [];
-        foreach ($data as $k=>$v) {
+        foreach ($data as $k => $v) {
             $child_need_to_be_array = in_array("$key.$k", $need_array);
-            if ($child_need_to_be_array && ! isset($result->{$k}))
+            if ($child_need_to_be_array && ! isset($result->{$k})) {
                 $result->{$k} = [];
+            }
 
             // 有两项相同健值，说明这里需要转换为数组
             if (! $child_need_to_be_array && $flag !== 1 && array_key_exists($k, $map)) {
@@ -47,11 +49,75 @@ private static function intoObject(SimpleXMLElement $data, array &$need_array, s
     }
     public static function decodeAsObject(string $data, array $need_array = []): stdClass {
         $xml = simplexml_load_string($data);
-        if ($xml === false)
+        if ($xml === false) {
             throw new XmlDecodeFailException();
+        }
         $name = $xml->getName();
         $ret = new stdClass();
         $ret->{$name} = self::intoObject($xml, $need_array, $name);
         return $ret;
     }
-}
+    private static function toXml(&$data, \Psr\Http\Message\StreamInterface $result, string $outer_key,
+                                  ?int $level): void {
+        $is_fixed_array = true;
+        $i = 0;
+        foreach ($data as $key => &$val) {
+            if ($key !== $i) {
+                $is_fixed_array = false;
+                break;
+            }
+            ++$i;
+        }
+        unset($val);
+
+        if (! $is_fixed_array && '' !== $outer_key) {
+            if ($level) {
+                $result->write(str_repeat('  ', $level));
+            }
+            $result->write("<$outer_key>");
+            if (isset($level)) {
+                $result->write("\n");
+            }
+        }
+        foreach ($data as $key => &$val) {
+            if (is_scalar($val)) {
+                if (isset($level)) {
+                    $result->write(str_repeat('  ', $is_fixed_array ? $level : $level + 1));
+                }
+                if ($is_fixed_array) {
+                    $result->write("<$outer_key><![CDATA[");
+                    $result->write($val);
+                    $result->write("]]></$outer_key>");
+                } else {
+                    $result->write("<$key><![CDATA[");
+                    $result->write($val);
+                    $result->write("]]></$key>");
+                }
+                if (isset($level)) {
+                    $result->write("\n");
+                }
+            } else {
+                self::toXml($val, $result, $is_fixed_array ? $outer_key : $key,
+                    isset($level) ? ($is_fixed_array ? $level : $level + 1) : null);
+            }
+        }
+        if (! $is_fixed_array && '' !== $outer_key) {
+            if ($level) {
+                $result->write(str_repeat('  ', $level));
+            }
+            $result->write("</$outer_key>");
+            if (isset($level)) {
+                $result->write("\n");
+            }
+        }
+        unset($val);
+    }
+    public static function encode($valueToEncode, bool $pretty_print = false): string {
+        if (is_scalar($valueToEncode)) {
+            throw new \Exception('Cannot xml encode scalar');
+        }
+        $res = stream_for('');
+        self::toXml($valueToEncode, $res, '', $pretty_print ? -1 : null);
+        return $res->__toString();
+    }
+}