本文整理汇总了C++中Ptree::get_child_optional方法的典型用法代码示例。如果您正苦于以下问题：C++ Ptree::get_child_optional方法的具体用法？C++ Ptree::get_child_optional怎么用？C++ Ptree::get_child_optional使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类Ptree的用法示例。
在下文中一共展示了Ptree::get_child_optional方法的2个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: write_xml_element
void write_xml_element(std::basic_ostream<typename Ptree::key_type::value_type> &stream,
const std::basic_string<typename Ptree::key_type::value_type> &key,
const Ptree &pt,
int indent,
const xml_writer_settings<typename Ptree::key_type::value_type> & settings)
{
typedef typename Ptree::key_type::value_type Ch;
typedef typename Ptree::const_iterator It;
bool want_pretty = settings.indent_count > 0;
// Find if elements present
bool has_elements = false;
bool has_attrs_only = pt.data().empty();
for (It it = pt.begin(), end = pt.end(); it != end; ++it)
{
if (it->first != xmlattr<Ch>() )
{
has_attrs_only = false;
if (it->first != xmltext<Ch>())
{
has_elements = true;
break;
}
}
}
// Write element
if (pt.data().empty() && pt.empty()) // Empty key
{
if (indent >= 0)
{
write_xml_indent(stream,indent,settings);
stream << Ch('<') << key <<
Ch('/') << Ch('>');
if (want_pretty)
stream << Ch('\n');
}
}
else // Nonempty key
{
// Write opening tag, attributes and data
if (indent >= 0)
{
// Write opening brace and key
write_xml_indent(stream,indent,settings);
stream << Ch('<') << key;
// Write attributes
if (optional<const Ptree &> attribs = pt.get_child_optional(xmlattr<Ch>()))
for (It it = attribs.get().begin(); it != attribs.get().end(); ++it)
stream << Ch(' ') << it->first << Ch('=')
<< Ch('"')
<< encode_char_entities(
it->second.template get_value<std::basic_string<Ch> >())
<< Ch('"');
if ( has_attrs_only )
{
// Write closing brace
stream << Ch('/') << Ch('>');
if (want_pretty)
stream << Ch('\n');
}
else
{
// Write closing brace
stream << Ch('>');
// Break line if needed and if we want pretty-printing
if (has_elements && want_pretty)
stream << Ch('\n');
}
}
// Write data text, if present
if (!pt.data().empty())
write_xml_text(stream,
pt.template get_value<std::basic_string<Ch> >(),
indent + 1, has_elements && want_pretty, settings);
// Write elements, comments and texts
for (It it = pt.begin(); it != pt.end(); ++it)
{
if (it->first == xmlattr<Ch>())
continue;
else if (it->first == xmlcomment<Ch>())
write_xml_comment(stream,
it->second.template get_value<std::basic_string<Ch> >(),
indent + 1, want_pretty, settings);
else if (it->first == xmltext<Ch>())
write_xml_text(stream,
it->second.template get_value<std::basic_string<Ch> >(),
indent + 1, has_elements && want_pretty, settings);
else
write_xml_element(stream, it->first, it->second,
indent + 1, settings);
}
//.........这里部分代码省略.........
示例2: write_xml_element
void write_xml_element(std::basic_ostream<typename Ptree::char_type> &stream,
const std::basic_string<typename Ptree::char_type> &key,
const Ptree &pt,
int indent)
{
typedef typename Ptree::char_type Ch;
typedef typename std::basic_string<Ch> Str;
typedef typename Ptree::const_iterator It;
// Find if elements present
bool has_elements = false;
for (It it = pt.begin(), end = pt.end(); it != end; ++it)
if (it->first != xmlattr<Ch>() &&
it->first != xmltext<Ch>())
{
has_elements = true;
break;
}
// Write element
if (pt.data().empty() && pt.empty()) // Empty key
{
if (indent >= 0)
stream << Str(4 * indent, Ch(' ')) << Ch('<') << key <<
Ch('/') << Ch('>') << std::endl;
}
else // Nonempty key
{
// Write opening tag, attributes and data
if (indent >= 0)
{
// Write opening brace and key
stream << Str(4 * indent, Ch(' '));
stream << Ch('<') << key;
// Write attributes
if (optional<const Ptree &> attribs = pt.get_child_optional(xmlattr<Ch>()))
for (It it = attribs.get().begin(); it != attribs.get().end(); ++it)
stream << Ch(' ') << it->first << Ch('=') <<
Ch('"') << it->second.template get_own<std::basic_string<Ch> >() << Ch('"');
// Write closing brace
stream << Ch('>');
// Break line if needed
if (has_elements)
stream << Ch('\n');
}
// Write data text, if present
if (!pt.data().empty())
write_xml_text(stream, pt.template get_own<std::basic_string<Ch> >(), indent + 1, has_elements);
// Write elements, comments and texts
for (It it = pt.begin(); it != pt.end(); ++it)
{
if (it->first == xmlattr<Ch>())
continue;
else if (it->first == xmlcomment<Ch>())
write_xml_comment(stream, it->second.template get_own<std::basic_string<Ch> >(), indent + 1);
else if (it->first == xmltext<Ch>())
write_xml_text(stream, it->second.template get_own<std::basic_string<Ch> >(), indent + 1, has_elements);
else
write_xml_element(stream, it->first, it->second, indent + 1);
}
// Write closing tag
if (indent >= 0)
{
if (has_elements)
stream << Str(4 * indent, Ch(' '));
stream << Ch('<') << Ch('/') << key << Ch('>') << std::endl;
}
}
}