--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/gumbo-parser/examples/serialize.cc	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,287 @@
+// Copyright 2015 Kevin B. Hendricks, Stratford, Ontario,  All Rights Reserved.
+// loosely based on a greatly simplified version of BeautifulSoup4 decode() routine
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Author: Kevin Hendricks
+//
+// Serialize back to html / xhtml making as few changes as possible (even in whitespace)
+
+#include <fstream>
+#include <iostream>
+#include <stdlib.h>
+#include <string>
+
+#include "gumbo.h"
+
+static std::string nonbreaking_inline  = "|a|abbr|acronym|b|bdo|big|cite|code|dfn|em|font|i|img|kbd|nobr|s|small|span|strike|strong|sub|sup|tt|";
+static std::string empty_tags          = "|area|base|basefont|bgsound|br|command|col|embed|event-source|frame|hr|image|img|input|keygen|link|menuitem|meta|param|source|spacer|track|wbr|";
+static std::string preserve_whitespace = "|pre|textarea|script|style|";
+static std::string special_handling    = "|html|body|";
+static std::string no_entity_sub       = "|script|style|";
+
+
+static inline void rtrim(std::string &s) 
+{
+  s.erase(s.find_last_not_of(" \n\r\t")+1);
+}
+
+
+static inline void ltrim(std::string &s)
+{
+  s.erase(0,s.find_first_not_of(" \n\r\t"));
+}
+
+
+static void replace_all(std::string &s, const char * s1, const char * s2)
+{
+  std::string t1(s1);
+  size_t len = t1.length();
+  size_t pos = s.find(t1);
+  while (pos != std::string::npos) {
+    s.replace(pos, len, s2);
+    pos = s.find(t1, pos + len);
+  }
+}
+
+
+static std::string substitute_xml_entities_into_text(const std::string &text)
+{
+  std::string result = text;
+  // replacing & must come first 
+  replace_all(result, "&", "&amp;");
+  replace_all(result, "<", "&lt;");
+  replace_all(result, ">", "&gt;");
+  return result;
+}
+
+
+static std::string substitute_xml_entities_into_attributes(char quote, const std::string &text)
+{
+  std::string result = substitute_xml_entities_into_text(text);
+  if (quote == '"') {
+    replace_all(result,"\"","&quot;");
+  }    
+  else if (quote == '\'') {
+    replace_all(result,"'","&apos;");
+  }
+ return result;
+}
+
+
+static std::string handle_unknown_tag(GumboStringPiece *text)
+{
+  std::string tagname = "";
+  if (text->data == NULL) {
+    return tagname;
+  }
+  // work with copy GumboStringPiece to prevent asserts 
+  // if try to read same unknown tag name more than once
+  GumboStringPiece gsp = *text;
+  gumbo_tag_from_original_text(&gsp);
+  tagname = std::string(gsp.data, gsp.length);
+  return tagname; 
+}
+
+
+static std::string get_tag_name(GumboNode *node)
+{
+  std::string tagname;
+  // work around lack of proper name for document node
+  if (node->type == GUMBO_NODE_DOCUMENT) {
+    tagname = "document";
+  } else {
+    tagname = gumbo_normalized_tagname(node->v.element.tag);
+  }
+  if (tagname.empty()) {
+    tagname = handle_unknown_tag(&node->v.element.original_tag);
+  }
+  return tagname;
+}
+
+
+static std::string build_doctype(GumboNode *node)
+{
+  std::string results = "";
+  if (node->v.document.has_doctype) {
+    results.append("<!DOCTYPE ");
+    results.append(node->v.document.name);
+    std::string pi(node->v.document.public_identifier);
+    if ((node->v.document.public_identifier != NULL) && !pi.empty() ) {
+        results.append(" PUBLIC \"");
+        results.append(node->v.document.public_identifier);
+        results.append("\" \"");
+        results.append(node->v.document.system_identifier);
+        results.append("\"");
+    }
+    results.append(">\n");
+  }
+  return results;
+}
+
+
+static std::string build_attributes(GumboAttribute * at, bool no_entities)
+{
+  std::string atts = " ";
+  atts.append(at->name);
+
+  // how do we want to handle attributes with empty values
+  // <input type="checkbox" checked />  or <input type="checkbox" checked="" /> 
+
+  if ( (!std::string(at->value).empty())   || 
+       (at->original_value.data[0] == '"') || 
+       (at->original_value.data[0] == '\'') ) {
+
+    // determine original quote character used if it exists
+    char quote = at->original_value.data[0];
+    std::string qs = "";
+    if (quote == '\'') qs = std::string("'");
+    if (quote == '"') qs = std::string("\"");
+    atts.append("=");
+    atts.append(qs);
+    if (no_entities) {
+      atts.append(at->value);
+    } else {
+      atts.append(substitute_xml_entities_into_attributes(quote, std::string(at->value)));
+    }
+    atts.append(qs);
+  }
+  return atts;
+}
+
+
+// forward declaration
+static std::string serialize(GumboNode*);
+
+
+// serialize children of a node
+// may be invoked recursively
+
+static std::string serialize_contents(GumboNode* node) {
+  std::string contents        = "";
+  std::string tagname         = get_tag_name(node);
+  std::string key             = "|" + tagname + "|";
+  bool no_entity_substitution = no_entity_sub.find(key) != std::string::npos;
+  bool keep_whitespace        = preserve_whitespace.find(key) != std::string::npos;
+  bool is_inline              = nonbreaking_inline.find(key) != std::string::npos;
+
+  // build up result for each child, recursively if need be
+  GumboVector* children = &node->v.element.children;
+
+  for (unsigned int i = 0; i < children->length; ++i) {
+    GumboNode* child = static_cast<GumboNode*> (children->data[i]);
+
+    if (child->type == GUMBO_NODE_TEXT) {
+      if (no_entity_substitution) {
+        contents.append(std::string(child->v.text.text));
+      } else {
+        contents.append(substitute_xml_entities_into_text(std::string(child->v.text.text)));
+      }
+
+    } else if (child->type == GUMBO_NODE_ELEMENT || child->type == GUMBO_NODE_TEMPLATE) {
+      contents.append(serialize(child));
+
+    } else if (child->type == GUMBO_NODE_WHITESPACE) {
+      // keep all whitespace to keep as close to original as possible
+      contents.append(std::string(child->v.text.text));
+
+    } else if (child->type != GUMBO_NODE_COMMENT) {
+      // Does this actually exist: (child->type == GUMBO_NODE_CDATA)
+      fprintf(stderr, "unknown element of type: %d\n", child->type); 
+    }
+  }
+  return contents;
+}
+
+
+// serialize a GumboNode back to html/xhtml
+// may be invoked recursively
+
+static std::string serialize(GumboNode* node) {
+  // special case the document node
+  if (node->type == GUMBO_NODE_DOCUMENT) {
+    std::string results = build_doctype(node);
+    results.append(serialize_contents(node));
+    return results;
+  }
+
+  std::string close = "";
+  std::string closeTag = "";
+  std::string atts = "";
+  std::string tagname            = get_tag_name(node);
+  std::string key                = "|" + tagname + "|";
+  bool need_special_handling     =  special_handling.find(key) != std::string::npos;
+  bool is_empty_tag              = empty_tags.find(key) != std::string::npos;
+  bool no_entity_substitution    = no_entity_sub.find(key) != std::string::npos;
+  bool is_inline                 = nonbreaking_inline.find(key) != std::string::npos;
+
+  // build attr string  
+  const GumboVector * attribs = &node->v.element.attributes;
+  for (int i=0; i< attribs->length; ++i) {
+    GumboAttribute* at = static_cast<GumboAttribute*>(attribs->data[i]);
+    atts.append(build_attributes(at, no_entity_substitution));
+  }
+
+  // determine closing tag type
+  if (is_empty_tag) {
+      close = "/";
+  } else {
+      closeTag = "</" + tagname + ">";
+  }
+
+  // serialize your contents
+  std::string contents = serialize_contents(node);
+
+  if (need_special_handling) {
+    ltrim(contents);
+    rtrim(contents);
+    contents.append("\n");
+  }
+
+  // build results
+  std::string results;
+  results.append("<"+tagname+atts+close+">");
+  if (need_special_handling) results.append("\n");
+  results.append(contents);
+  results.append(closeTag);
+  if (need_special_handling) results.append("\n");
+  return results;
+}
+
+
+int main(int argc, char** argv) {
+  if (argc != 2) {
+      std::cout << "serialize <html filename>\n";
+      exit(EXIT_FAILURE);
+  }
+  const char* filename = argv[1];
+
+  std::ifstream in(filename, std::ios::in | std::ios::binary);
+  if (!in) {
+    std::cout << "File " << filename << " not found!\n";
+    exit(EXIT_FAILURE);
+  }
+
+  std::string contents;
+  in.seekg(0, std::ios::end);
+  contents.resize(in.tellg());
+  in.seekg(0, std::ios::beg);
+  in.read(&contents[0], contents.size());
+  in.close();
+ 
+  GumboOptions options = kGumboDefaultOptions;
+
+  GumboOutput* output = gumbo_parse_with_options(&options, contents.data(), contents.length());
+  std::cout << serialize(output->document) << std::endl;
+  gumbo_destroy_output(&kGumboDefaultOptions, output);
+}