Add cmXMLWriter class to consolidate XML generation

Explicitly track XML generation state (indentation, element closure,
etc.) so that clients can avoid manually/implicitly maintaining it.

Source/cmXMLWriter.h

@@ -0,0 +1,120 @@
+/*============================================================================
+  CMake - Cross Platform Makefile Generator
+  Copyright 2015 Daniel Pfeifer <daniel@pfeifer-mail.de>
+
+  Distributed under the OSI-approved BSD License (the "License");
+  see accompanying file Copyright.txt for details.
+
+  This software is distributed WITHOUT ANY WARRANTY; without even the
+  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the License for more information.
+============================================================================*/
+#ifndef cmXMLWiter_h
+#define cmXMLWiter_h
+
+#include "cmStandardIncludes.h"
+#include "cmXMLSafe.h"
+
+#include <ostream>
+#include <stack>
+#include <string>
+#include <vector>
+
+class cmXMLWriter
+{
+public:
+  cmXMLWriter(std::ostream& output, std::size_t level = 0);
+  ~cmXMLWriter();
+
+  void StartDocument(const char* encoding = "UTF-8");
+  void EndDocument();
+
+  void StartElement(std::string const& name);
+  void EndElement();
+
+  void BreakAttributes();
+
+  template <typename T>
+  void Attribute(const char* name, T const& value)
+    {
+    this->PreAttribute();
+    this->Output << name << "=\"" << SafeAttribute(value) << '"';
+    }
+
+  template <typename T>
+  void Element(std::string const& name, T const& value)
+    {
+    this->StartElement(name);
+    this->Content(value);
+    this->EndElement();
+    }
+
+  template <typename T>
+  void Content(T const& content)
+    {
+    this->PreContent();
+    this->Output << SafeContent(content);
+    }
+
+  void Comment(const char* comment);
+
+  void CData(std::string const& data);
+
+  void ProcessingInstruction(const char* target, const char* data);
+
+  void FragmentFile(const char* fname);
+
+private:
+  cmXMLWriter(const cmXMLWriter&);
+  cmXMLWriter& operator=(const cmXMLWriter&);
+
+  void ConditionalLineBreak(bool condition, std::size_t indent);
+
+  void PreAttribute();
+  void PreContent();
+
+  void CloseStartElement();
+
+private:
+  static cmXMLSafe SafeAttribute(const char* value)
+    {
+    return cmXMLSafe(value);
+    }
+
+  static cmXMLSafe SafeAttribute(std::string const& value)
+    {
+    return cmXMLSafe(value);
+    }
+
+  template <typename T>
+  static T SafeAttribute(T value)
+    {
+    return value;
+    }
+
+  static cmXMLSafe SafeContent(const char* value)
+    {
+    return cmXMLSafe(value).Quotes(false);
+    }
+
+  static cmXMLSafe SafeContent(std::string const& value)
+    {
+    return cmXMLSafe(value).Quotes(false);
+    }
+
+  template <typename T>
+  static T SafeContent(T value)
+    {
+    return value;
+    }
+
+private:
+  std::ostream& Output;
+  std::stack<std::string, std::vector<std::string> > Elements;
+  std::size_t Level;
+  bool ElementOpen;
+  bool BreakAttrib;
+  bool IsContent;
+};
+
+#endif