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chrome/common/libxml_utils.h

-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef CHROME_COMMON_LIBXML_UTILS_H__
-#define CHROME_COMMON_LIBXML_UTILS_H__
-#pragma once
-
-#include <string>
-
-#include "libxml/xmlreader.h"
-#include "libxml/xmlwriter.h"
-
-class FilePath;
-
-// Converts a libxml xmlChar* into a UTF-8 std::string.
-// NULL inputs produce an empty string.
-std::string XmlStringToStdString(const xmlChar* xmlstring);
-
-// libxml uses a global error function pointer for reporting errors.
-// A ScopedXmlErrorFunc object lets you change the global error pointer
-// for the duration of the object's lifetime.
-class ScopedXmlErrorFunc {
- public:
-  ScopedXmlErrorFunc(void* context, xmlGenericErrorFunc func) {
-    old_error_func_ = xmlGenericError;
-    old_error_context_ = xmlGenericErrorContext;
-    xmlSetGenericErrorFunc(context, func);
-  }
-  ~ScopedXmlErrorFunc() {
-    xmlSetGenericErrorFunc(old_error_context_, old_error_func_);
-  }
-
- private:
-  xmlGenericErrorFunc old_error_func_;
-  void* old_error_context_;
-};
-
-// XmlReader is a wrapper class around libxml's xmlReader,
-// providing a simplified C++ API.
-class XmlReader {
- public:
-  XmlReader();
-  ~XmlReader();
-
-  // Load a document into the reader from memory.  |input| must be UTF-8 and
-  // exist for the lifetime of this object.  Returns false on error.
-  // TODO(evanm): handle encodings other than UTF-8?
-  bool Load(const std::string& input);
-
-  // Load a document into the reader from a file.  Returns false on error.
-  bool LoadFile(const FilePath& file_path);
-
-  // Wrappers around libxml functions -----------------------------------------
-
-  // Read() advances to the next node.  Returns false on EOF or error.
-  bool Read() { return xmlTextReaderRead(reader_) == 1; }
-
-  // Next(), when pointing at an opening tag, advances to the node after
-  // the matching closing tag.  Returns false on EOF or error.
-  bool Next() { return xmlTextReaderNext(reader_) == 1; }
-
-  // Return the depth in the tree of the current node.
-  int Depth() { return xmlTextReaderDepth(reader_); }
-
-  // Returns the "local" name of the current node.
-  // For a tag like <foo:bar>, this is the string "foo:bar".
-  std::string NodeName() {
-    return XmlStringToStdString(xmlTextReaderConstLocalName(reader_));
-  }
-
-  // When pointing at a tag, retrieves the value of an attribute.
-  // Returns false on failure.
-  // E.g. for <foo bar:baz="a">, NodeAttribute("bar:baz", &value)
-  // returns true and |value| is set to "a".
-  bool NodeAttribute(const char* name, std::string* value);
-
-  // Helper functions not provided by libxml ----------------------------------
-
-  // Return the string content within an element.
-  // "<foo>bar</foo>" is a sequence of three nodes:
-  // (1) open tag, (2) text, (3) close tag.
-  // With the reader currently at (1), this returns the text of (2),
-  // and advances past (3).
-  // Returns false on error.
-  bool ReadElementContent(std::string* content);
-
-  // Skip to the next opening tag, returning false if we reach a closing
-  // tag or EOF first.
-  // If currently on an opening tag, doesn't advance at all.
-  bool SkipToElement();
-
-  // Returns the errors reported by libxml, if any.
-  // (libxml normally just dumps these errors to stderr.)
-  const std::string& errors() const { return errors_; }
-
- private:
-  // A callback for libxml to report errors.
-  static void GenericErrorCallback(void* context, const char* msg, ...);
-
-  // Returns the libxml node type of the current node.
-  int NodeType() { return xmlTextReaderNodeType(reader_); }
-
-  // The underlying libxml xmlTextReader.
-  xmlTextReaderPtr reader_;
-
-  // error_func_ is used to reassign libxml's global error function
-  // to report errors into |errors_| for the lifetime of this object.
-  ScopedXmlErrorFunc error_func_;
-  std::string errors_;
-};
-
-// XmlWriter is a wrapper class around libxml's xmlWriter,
-// providing a simplified C++ API.
-// StartWriting must be called before other methods, and StopWriting
-// must be called before GetWrittenString() will return results.
-class XmlWriter {
- public:
-  XmlWriter();
-  ~XmlWriter();
-
-  // Allocates the xmlTextWriter and an xmlBuffer and starts an XML document.
-  // This must be called before any other functions. By default, indenting is
-  // set to true.
-  void StartWriting();
-
-  // Ends the XML document and frees the xmlTextWriter.
-  // This must be called before GetWrittenString() is called.
-  void StopWriting();
-  // Wrappers around libxml functions -----------------------------------------
-
-  // All following elements will be indented to match their depth.
-  void StartIndenting() { xmlTextWriterSetIndent(writer_, 1); }
-
-  // All follow elements will not be indented.
-  void StopIndenting() { xmlTextWriterSetIndent(writer_, 0); }
-
-  // Start an element with the given name. All future elements added will be
-  // children of this element, until it is ended. Returns false on error.
-  bool StartElement(const std::string& element_name) {
-    return xmlTextWriterStartElement(writer_,
-                                     BAD_CAST element_name.c_str()) >= 0;
-  }
-
-  // Ends the current open element. Returns false on error.
-  bool EndElement() {
-    return xmlTextWriterEndElement(writer_) >= 0;
-  }
-
-  // Adds an attribute to the current open element. Returns false on error.
-  bool AddAttribute(const std::string& attribute_name,
-                    const std::string& attribute_value) {
-    return xmlTextWriterWriteAttribute(writer_,
-                                       BAD_CAST attribute_name.c_str(),
-                                       BAD_CAST attribute_value.c_str()) >= 0;
-  }
-
-  // Adds a new element with name |element_name| and content |content|
-  // to the buffer. Example: <|element_name|>|content|</|element_name|>
-  // Returns false on errors.
-  bool WriteElement(const std::string& element_name,
-                    const std::string& content) {
-    return xmlTextWriterWriteElement(writer_,
-                                     BAD_CAST element_name.c_str(),
-                                     BAD_CAST content.c_str()) >= 0;
-  }
-
-  // Helper functions not provided by xmlTextWriter ---------------------------
-
-  // Returns the string that has been written to the buffer.
-  std::string GetWrittenString() {
-    if (buffer_ == NULL)
-      return "";
-    return XmlStringToStdString(buffer_->content);
-  }
-
- private:
-  // The underlying libxml xmlTextWriter.
-  xmlTextWriterPtr writer_;
-
-  // Stores the output.
-  xmlBufferPtr buffer_;
-};
-
-#endif  // CHROME_COMMON_LIBXML_UTILS_H__