#include <XmlReader.hpp>
Public Member Functions | |
| XmlReader (const std::string &xml_file_name, const std::string &root_element) | |
| ~XmlReader () | |
| XmlReader & | operator>> (const stream_command &command) |
| template<size_t N, class data_t> | |
| XmlReader & | operator>> (ublas::fixed_vector< data_t, N > &value) |
| template<size_t N, class data_t> | |
| XmlReader & | operator>> (std::vector< ublas::fixed_vector< data_t, N > > &vector) |
| XmlReader & | operator>> (std::vector< float_t > &vector) |
| XmlReader & | operator>> (float_t &value) |
| XmlReader & | operator>> (size_t &value) |
| XmlReader & | operator>> (int &value) |
| XmlReader & | operator>> (bool &value) |
| XmlReader & | operator>> (std::string &string) |
| XmlReader & | operator>> (std::vector< std::string > &vector) |
| template<class data_t> | |
| XmlReader & | operator>> (const default_value< data_t > &command) |
| template<class data_t> | |
| XmlReader & | operator>> (const try_read< data_t > &command) |
| template<class data_t> | |
| XmlReader & | operator>> (std::vector< data_t > &vector) |
| template<class data_t> | |
| XmlReader & | operator>> (std::vector< boost::shared_ptr< data_t > > &vector) |
| template<class data_t> | |
| XmlReader & | operator>> (data_t &object) |
| size_t | n_elements () const |
| size_t | n_child_elements () const |
| std::string | current_element_name () const |
Static Public Attributes | |
| static const stream_command | end_element |
| Stream command to end an element. | |
Classes | |
| class | attribute |
| Stream command to select an attribute at the current path. More... | |
| class | child_element |
| Stream command to add a child element to the current path. More... | |
| class | default_value |
| Stream command to read an object if it is present at the current path and to retrieve an default value if not. More... | |
| class | element |
| Stream command to add an element to the current path. More... | |
| class | try_read |
| Stream command to read an object if it is present at the current path and to keep it unchanged if not. More... | |
| class | XmlNoTagException |
| This exception is throw if the attempt to read an object fails. More... | |
This class enables you to read an XML file using an interface which loosely resembles the stream interface used in iostream to read from input streams. An XmlReader object is initialized by an XML file and then represents an XML stream which you can read using operator>>(data_t &), where data_t is the type of the object to be read. XmlReader provides the stream operator for the built-in data types. If called for other types, XmlReader calls the function xml_handler<data_t>::read_object() which then reads the object from the stream. I.e. by specializing xml_handler for custom data types the user enables XmlReader to read these types. Implementations of xml_handler for various classes of the imaging2 modules can be found in the files xmlio.hpp and xmlio.cxx in the module subdirectories.
Consider the following XML file:
<imaging2>
<person age="50">Franz</person>
<person age="50">Arne</person>
<some_float>0.5</some_float>
<some_float>1.0</some_float>
<some_float>1.5</some_float>
</imaging2>
An XmlReader object reads objects at the position of its current path. This path is the sequence of element names (and possibly indices) which leads to a given node in an XML file. This concept is very similiar to the idea of XPath. The current path of a XmlReader can be altered by passing stream commands to the input stream. An example is given below:
using imaging; XmlReader xml_in("some_file.xml", "imaging2"); // read some_file.xml; "imaging2" is the root element std::string name; unsigned int age = 0; xml_in >> XmlReader::element("person"); // select element "person" xml_in >> XmlReader::attribute("age") >> age; // read attribute "age" xml_in >> name >> XmlReader::end_element; // read the person's name and close element "person" std::vector<float_t> some_floats; xml_in >> XmlReader::element("some_float"); // select element "some_float" xml_in >> some_floats; // read the floats // there is no need to pass XmlReader::end_element here, because float is a built-in type
Assume further that the user has implemented a class Person and xml_handler<Person> which reads a person's data as above. Assuming that the class declaration and the declaration of xml_handler<Person> both reside in "Person.h", then she can use XmlReader in the following way:
#include "Person.h" XmlReader xml_in("some_file.xml", "imaging2"); // read some_file.xml; "imaging2" is the root element Person person; std::vector<Person> people; xml_in >> person; // read person (note that there is no need to select the element "person") xml_in >> people; // read all the people at the current path
Note reading a vector of floats is different from a custom data type. For the custom data Person neither XmlReader::element() nor XmlReader::end_element have to be passed to the stream. In case of a vector of floats XmlReader::element() must be passed, but not XmlReader::end_element. The reason for this behavior is that XmlReader does not know which element name identifies the floats. Introducing a standard element name (such as <float> </float>) would often be inconvenient because it makes intuitive element names like <super_parameter>10^9</super_parameter> impossible. This behavior is the same for all built-in types.
| imaging::XmlReader::XmlReader | ( | const std::string & | xml_file_name, | |
| const std::string & | root_element | |||
| ) |
Constructs an XML input stream from file file_name and sets the current path to root_element. An XML file can only have one root node, so it is okay to fix it during construction.
References imaging::MessageInterface::DEBUG_ONLY, and imaging::MessageInterface::out.
| imaging::XmlReader::~XmlReader | ( | ) |
Destructor. Closes the input file.
| XmlReader & imaging::XmlReader::operator>> | ( | const stream_command & | command | ) |
Passes any other stream command to the stream.
| XmlReader& imaging::XmlReader::operator>> | ( | ublas::fixed_vector< data_t, N > & | value | ) | [inline] |
Reads a ublas::fixed_vector from the stream.
| XmlReader& imaging::XmlReader::operator>> | ( | std::vector< ublas::fixed_vector< data_t, N > > & | vector | ) | [inline] |
Reads a vector of fixed size vectors from the stream. The function assumes that each vector is enclosed by element tags identified by the last XmlReader::element() passed to the input stream. In this respect this function is different from the generic version operator>>(data_t &).
References end_element.
Reads a vector of floats from the stream. The function assumes that each string is enclosed by element tags identified by the last XmlReader::element() passed to the input stream. In this respect this function is different from the generic version operator>>(data_t &).
Reads a floating point value from the stream.
Reads an unsigned integer from the stream.
| XmlReader & imaging::XmlReader::operator>> | ( | int & | value | ) |
Reads an integer from the stream.
| XmlReader & imaging::XmlReader::operator>> | ( | bool & | value | ) |
Reads a bool from the stream.
| XmlReader & imaging::XmlReader::operator>> | ( | std::string & | string | ) |
Reads string from the stream.
| XmlReader & imaging::XmlReader::operator>> | ( | std::vector< std::string > & | vector | ) |
Reads a vector of strings from the stream. The function assumes that each string is enclosed by element tags identified by the last XmlReader::element() passed to the input stream. In this respect this function is different from the generic version operator>>(data_t &).
| XmlReader& imaging::XmlReader::operator>> | ( | const default_value< data_t > & | command | ) | [inline] |
Passes an XmlReader::default_value() command to the stream.
References imaging::XmlReader::default_value< data_t >::_default_object, and imaging::XmlReader::default_value< data_t >::_object.
| XmlReader& imaging::XmlReader::operator>> | ( | const try_read< data_t > & | command | ) | [inline] |
Passes an XmlReader::try_read() command to the stream.
References imaging::XmlReader::try_read< data_t >::_object.
| XmlReader& imaging::XmlReader::operator>> | ( | std::vector< data_t > & | vector | ) | [inline] |
Reads a vector of data_t objects from the stream. The class specialization xml_handler<data_t> has to be defined.
References end_element.
| XmlReader& imaging::XmlReader::operator>> | ( | std::vector< boost::shared_ptr< data_t > > & | vector | ) | [inline] |
Constructs data_t objects in vector and reads data_t objects from the stream. The class specialization xml_handler<data_t> has to be defined.
References end_element.
| XmlReader& imaging::XmlReader::operator>> | ( | data_t & | object | ) | [inline] |
Reads a data_t object from the stream. The class specialization xml_handler<data_t>::read_object() has to be defined.
References end_element.
| size_t imaging::XmlReader::n_elements | ( | ) | const |
Returns the number of different nodes in the document which are referenced by the current path. If the current path uniquely determines an object this function returns 1. If no object exists at the current path it returns 0.
| size_t imaging::XmlReader::n_child_elements | ( | ) | const |
Returns the number of child nodes of elements in the document which are referenced by the current path.
| std::string imaging::XmlReader::current_element_name | ( | ) | const |
const XmlReader::stream_command imaging::XmlReader::end_element [static] |
Stream command to end an element.
Stream command to remove the last element from the current path. Every XmlReader::element(std::string &) and XmlReader::element(std::string &, size_t) command passed to the input stream has to be followed by an Xml::end_element command. This is not true for XmlReader::element(size_t) and XmlReader::attribute() commands.
Referenced by operator>>().
1.5.5