#include <deal.II/base/parameter_handler.h>

Inheritance diagram for ParameterHandler:

Public Types
enum	OutputStyle { Text = 1, LaTeX = 2, Description = 3, XML = 4, JSON = 5, ShortText = 193 }

Public Member Functions
	ParameterHandler ()

virtual	~ParameterHandler ()

virtual bool	read_input (std::istream &input, const std::string &filename="input file", const std::string &last_line="") 1

virtual void	parse_input (std::istream &input, const std::string &filename="input file", const std::string &last_line="")

virtual bool	read_input (const std::string &filename, const bool optional=false, const bool write_stripped_file=false, const std::string &last_line="") 1

virtual void	parse_input (const std::string &filename, const std::string &last_line="")

virtual bool	read_input_from_string (const char *s, const std::string &last_line="")

virtual void	parse_input_from_string (const char *s, const std::string &last_line="")

virtual bool	read_input_from_xml (std::istream &input) 1

virtual void	parse_input_from_xml (std::istream &input)

void	clear ()

void	declare_entry (const std::string &entry, const std::string &default_value, const Patterns::PatternBase &pattern=Patterns::Anything(), const std::string &documentation=std::string())

void	declare_alias (const std::string &existing_entry_name, const std::string &alias_name, const bool alias_is_deprecated=false)

void	enter_subsection (const std::string &subsection)

void	leave_subsection ()

std::string	get (const std::string &entry_string) const

long int	get_integer (const std::string &entry_string) const

double	get_double (const std::string &entry_name) const

bool	get_bool (const std::string &entry_name) const

void	set (const std::string &entry_name, const std::string &new_value)

void	set (const std::string &entry_name, const char *new_value)

void	set (const std::string &entry_name, const long int &new_value)

void	set (const std::string &entry_name, const double &new_value)

void	set (const std::string &entry_name, const bool &new_value)

std::ostream &	print_parameters (std::ostream &out, const OutputStyle style)

void	print_parameters_section (std::ostream &out, const OutputStyle style, const unsigned int indent_level, const bool include_top_level_elements=false)

void	log_parameters (LogStream &out)

void	log_parameters_section (LogStream &out)

std::size_t	memory_consumption () const

template<class Archive >
void	save (Archive &ar, const unsigned int version) const

template<class Archive >
void	load (Archive &ar, const unsigned int version)

bool	operator== (const ParameterHandler &prm2) const

Public Member Functions inherited from Subscriptor
	Subscriptor ()

	Subscriptor (const Subscriptor &)

	Subscriptor (Subscriptor &&)

virtual	~Subscriptor ()

Subscriptor &	operator= (const Subscriptor &)

Subscriptor &	operator= (Subscriptor &&)

void	subscribe (const char *identifier=0) const

void	unsubscribe (const char *identifier=0) const

unsigned int	n_subscriptions () const

void	list_subscribers () const

template<class Archive >
void	serialize (Archive &ar, const unsigned int version)

Static Public Member Functions
static ::ExceptionBase &	ExcEntryAlreadyExists (std::string arg1)

static ::ExceptionBase &	ExcValueDoesNotMatchPattern (std::string arg1, std::string arg2)

static ::ExceptionBase &	ExcAlreadyAtTopLevel ()

static ::ExceptionBase &	ExcEntryUndeclared (std::string arg1)

static ::ExceptionBase &	ExcUnbalancedSubsections (std::string arg1, std::string arg2)

static ::ExceptionBase &	ExcNoSubsection (int arg1, std::string arg2, std::string arg3)

static ::ExceptionBase &	ExcCannotParseLine (int arg1, std::string arg2, std::string arg3)

static ::ExceptionBase &	ExcInvalidEntryForPattern (int arg1, std::string arg2, std::string arg3, std::string arg4, std::string arg5)

static ::ExceptionBase &	ExcInvalidXMLParameterFile ()

static ::ExceptionBase &	ExcInvalidEntryForPatternXML (std::string arg1, std::string arg2, std::string arg3)

static ::ExceptionBase &	ExcCannotOpenIncludeStatementFile (int arg1, std::string arg2, std::string arg3)

Static Public Member Functions inherited from Subscriptor
static ::ExceptionBase &	ExcInUse (int arg1, char *arg2, std::string &arg3)

static ::ExceptionBase &	ExcNoSubscriber (char arg1, char arg2)

Private Member Functions
	ParameterHandler (const ParameterHandler &)

ParameterHandler &	operator= (const ParameterHandler &)

std::string	get_current_path () const

std::string	get_current_full_path (const std::string &name) const

void	scan_line (std::string line, const std::string &input_filename, const unsigned int current_line_n)

Static Private Member Functions
static std::string	mangle (const std::string &s)

static std::string	demangle (const std::string &s)

Private Attributes
std_cxx11::unique_ptr< boost::property_tree::ptree >	entries

std::vector< std_cxx11::shared_ptr< const Patterns::PatternBase > >	patterns

std::vector< std::string >	subsection_path

Static Private Attributes
static const char	path_separator = '.'

Friends
class	MultipleParameterLoop

Detailed Description

The ParameterHandler class provides a standard interface to an input file which provides at run-time for program parameters such as time step sizes, geometries, right hand sides etc. The input for the program is given in files, streams or strings in memory using text like

set Time step size = 0.3

set Geometry = [0,1]x[0,3]

Input may be sorted into subsection trees in order to give the input a logical structure, and input files may include other files.

The ParameterHandler class is discussed in detail in the step-19 example program, and is used in more realistic situations in step-29, step-33 and step-34.

Declaring entries

In order to use the facilities of a ParameterHandler object, one first has to make known the different entries the input file may or may not contain. This is done in the following way:

...
ParameterHandler prm;
prm.declare_entry ("Time step size",
                  "0.2",
                  Patterns::Double(),
                  "Some documentation");
prm.declare_entry ("Geometry",
                  "[0,1]x[0,1]",
                  Patterns::Anything());
...

Each entry is declared using the function declare_entry(). The first parameter is the name of the entry (in short: the entry). The second is the default answer to be taken in case the entry is not specified in the input file. The third parameter is a regular expression which the input (and the default answer) has to match. Several such regular expressions are defined in Patterns. This parameter can be omitted, in which case it will default to Patterns::Anything, i.e. a pattern that matches every input string. The fourth parameter can be used to document the intent or expected format of an entry; its value is printed as a comment when writing all entries of a ParameterHandler object using the print_parameters() function to allow for easier understanding of a parameter file. It can be omitted as well, in which case no such documentation will be printed.

Entries may be located in subsections which form a kind of input tree. For example input parameters for linear solver routines should be classified in a subsection named Linear solver or any other suitable name. This is accomplished in the following way:

...
  LinEq eq;
  eq.declare_parameters (prm);
...
void LinEq::declare_parameters (ParameterHandler &prm) {
  prm.enter_subsection("Linear solver");
  {
    prm.declare_entry ("Solver",
                       "CG",
                       Patterns::Selection("CG|GMRES|GaussElim"),
                       "Name of a linear solver for the inner iteration");
    prm.declare_entry ("Maximum number of iterations",
                       "20",
                       ParameterHandler::RegularExpressions::Integer());
    ...
  }
  prm.leave_subsection ();
}

Subsections may be nested. For example a nonlinear solver may have a linear solver as member object. Then the function call tree would be something like (if the class NonLinEq has a member variables eq of type LinEq):

void NonLinEq::declare_parameters (ParameterHandler &prm) {
  prm.enter_subsection ("Nonlinear solver");
  {
    prm.declare_entry ("Nonlinear method",
                       "Newton-Raphson",
                       ParameterHandler::RegularExpressions::Anything());
    eq.declare_parameters (prm);
  }
  prm.leave_subsection ();
}

For class member functions which declare the different entries we propose to use the common name declare_parameters. In normal cases this method can be static since the entries will not depend on any previous knowledge. Classes for which entries should logically be grouped into subsections should declare these subsections themselves. If a class has two or more member variables of the same type both of which should have their own parameters, this parent class' method declare_parameters is responsible to group them into different subsections:

void NonLinEq::declare_parameters (ParameterHandler &prm) {
  prm.enter_subsection ("Nonlinear solver");
  {
    prm.enter_subsection ("Linear solver 1");
    {
      eq1.declare_parameters (prm);
    }
    prm.leave_subsection ();
    prm.enter_subsection ("Linear solver 2");
    {
      eq2.declare_parameters (prm);
    }
    prm.leave_subsection ();
  }
  prm.leave_subsection ();
}

Input files and special characters

For the first example above the input file would look like the following:

...
subsection Nonlinear solver
  set Nonlinear method = Gradient
  # this is a comment
  subsection Linear solver
    set Solver                       = CG
    set Maximum number of iterations = 30
  end
end
...                       # other stuff

The words subsection, set and end may be either written in lowercase or uppercase letters. Leading and trailing whitespace is removed, multiple whitespace is condensed into only one. Since the latter applies also to the name of an entry, an entry name will not be recognized if in the declaration multiple whitespace is used.

In entry names and values the following characters are not allowed: #, {, }, |. Their use is reserved for the MultipleParameterLoop class.

Comments starting with # are skipped.

Continuation lines are allowed by means of the character \, which must be the last character (aside from whitespace, which is ignored) of the line. When a line is a continuation (i.e., the previous line ended in a \), then, unlike the default behavior of the C preprocessor, all whitespace at the beginning of the line is ignored.

We propose to use the following scheme to name entries: start the first word with a capital letter and use lowercase letters further on. The same applies to the possible entry values to the right of the = sign.

Including other input files

An input file can include other include files using the syntax

...
include some_other_file.prm
...

The file so referenced is searched for relative to the current directory (not relative to the directory in which the including parameter file is located, since this is not known to all three versions of the parse_input() function).

Reading data from input sources

In order to read input there are three possibilities: reading from an std::istream object, reading from a file of which the name is given and reading from a string in memory in which the lines are separated by \n characters. These possibilities are used as follows:

ParameterHandler prm;
...
// declaration of entries
...
prm.parse_input (std::cin); // read input from standard in,
// or
prm.parse_input ("simulation.prm");
// or
char *in = "set Time step size = 0.3 \n ...";
prm.parse_input_from_string (in);
...

You can use several sources of input successively. Entries which are changed more than once will be overwritten every time they are used.

You should not try to declare entries using declare_entry() and enter_subsection() with as yet unknown subsection names after using parse_input(). The results in this case are unspecified.

If an error occurs upon reading the input, error messages are written to std::cerr and the reader function returns with a return value of false. This is opposed to almost all other functions in deal.II, which would normally throw an exception if an error occurs; this difference in behavior is a relic of the fact that this class predates deal.II and had previously been written for a different project.

Using the ParameterHandler Graphical User Interface

An alternative to using the hand-written input files shown above is to use the graphical user interface (GUI) that accompanies this class.

See the parameter_gui github repository for further details.

Getting entry values out of a ParameterHandler object

Each class gets its data out of a ParameterHandler object by calling the get() member functions like this:

 void NonLinEq::get_parameters (ParameterHandler &prm) {
  prm.enter_subsection ("Nonlinear solver");
  std::string method = prm.get ("Nonlinear method");
  eq.get_parameters (prm);
  prm.leave_subsection ();
}

get() returns the value of the given entry. If the entry was not specified in the input source(s), the default value is returned. You have to enter and leave subsections exactly as you did when declaring subsection. You may chose the order in which to transverse the subsection tree.

It is guaranteed that only entries matching the given regular expression are returned, i.e. an input entry value which does not match the regular expression is not stored.

You can use get() to retrieve the parameter in text form, get_integer() to get an integer or get_double() to get a double. You can also use get_bool(). It will cause an internal error if the string could not be converted to an integer, double or a bool. This should, though, not happen if you correctly specified the regular expression for this entry; you should not try to get out an integer or a double from an entry for which no according regular expression was set. The internal error is raised through the Assert() macro family which only works in debug mode.

If you want to print out all user selectable features, use the print_parameters() function. It is generally a good idea to print all parameters at the beginning of a log file, since this way input and output are together in one file which makes matching at a later time easier. Additionally, the function also print those entries which have not been modified in the input file and are thus set to default values; since default values may change in the process of program development, you cannot know the values of parameters not specified in the input file.

Style guide for data retrieval

We propose that every class which gets data out of a ParameterHandler object provides a function named get_parameters. This should be declared virtual. get_parameters functions in derived classes should call the BaseClass::get_parameters function.

Experience with large parameter lists

Experience has shown that in programs defining larger numbers of parameters (more than, say, fifty) it is advantageous to define an additional class holding these parameters. This class is more like a C-style structure, having a large number of variables, usually public. It then has at least two functions, which declare and parse the parameters. In the main program, the main class has an object of this parameter class and delegates declaration and parsing of parameters to this object.

The advantage of this approach is that you can keep out the technical details (declaration and parsing) out of the main class and additionally don't clutter up your main class with dozens or more variables denoting the parameters.

Worked Example

This is the code:

#include <deal.II/base/parameter_handler.h>
#include <iostream>
#include <string>
using namespace dealii;
class LinearEquation
{
public:
  static void declare_parameters (ParameterHandler &prm);
  void get_parameters (ParameterHandler &prm);
private:
  std::string method;
  int         max_iterations;
};
class Problem
{
private:
  LinearEquation eq1, eq2;
  std::string matrix1, matrix2;
  std::string outfile;
public:
  static void declare_parameters (ParameterHandler &prm);
  void get_parameters (ParameterHandler &prm);
  void do_something ();
};
void LinearEquation::declare_parameters (ParameterHandler &prm)
{
  // declare parameters for the linear solver in a subsection
  prm.enter_subsection ("Linear solver");
  {
    prm.declare_entry ("Solver",
                       "CG",
                       Patterns::Selection("CG|BiCGStab|GMRES"),
                       "Name of a linear solver for the inner iteration");
    prm.declare_entry ("Maximum number of iterations",
                       "20",
                       Patterns::Integer());
  }
  prm.leave_subsection ();
}
void LinearEquation::get_parameters (ParameterHandler &prm)
{
  prm.enter_subsection ("Linear solver");
  {
    method         = prm.get ("Solver");
    max_iterations = prm.get_integer ("Maximum number of iterations");
  }
  prm.leave_subsection ();
  std::cout << "  LinearEquation: method=" << method
            << ", max_iterations=" << max_iterations
            << std::endl;
}
void Problem::declare_parameters (ParameterHandler &prm)
{
  // first some global parameter entries
  prm.declare_entry ("Output file",
                     "out",
                     Patterns::Anything(),
                     "Name of the output file, either relative to the present "
                     "path or absolute");
  prm.declare_entry ("Equation 1",
                     "Laplace",
                     Patterns::Anything(),
                     "String identifying the equation we want to solve");
  prm.declare_entry ("Equation 2",
                     "Elasticity",
                     Patterns::Anything());
  // declare parameters for the first equation
  prm.enter_subsection ("Equation 1 Settings");
  {
    prm.declare_entry ("Matrix type",
                       "Sparse",
                       Patterns::Selection("Full|Sparse|Diagonal"),
                       "Type of the matrix to be used, either full, "
                       "sparse, or diagonal");
    LinearEquation::declare_parameters (prm);  // for eq1
  }
  prm.leave_subsection ();
  // declare parameters for the second equation
  prm.enter_subsection ("Equation 2 Settings");
  {
    prm.declare_entry ("Matrix type",
                       "Sparse",
                       Patterns::Selection("Full|Sparse|Diagonal"));
    LinearEquation::declare_parameters (prm);  // for eq2
  }
  prm.leave_subsection ();
}
void Problem::get_parameters (ParameterHandler &prm)
{
  // entries of the problem class
  outfile = prm.get ("Output file");
  std::string equation1 = prm.get ("Equation 1"),
              equation2 = prm.get ("Equation 2");
  // get parameters for the first equation
  prm.enter_subsection ("Equation 1 Settings");
  {
    matrix1 = prm.get ("Matrix type");
    eq1.get_parameters (prm); // for eq1
  }
  prm.leave_subsection ();
  // get parameters for the second equation
  prm.enter_subsection ("Equation 2 Settings");
  {
    matrix2 = prm.get ("Matrix type");
    eq2.get_parameters (prm); // for eq2
  }
  prm.leave_subsection ();
  std::cout << "  Problem: outfile=" << outfile << '\n'
            << "           eq1="     << equation1 << ", eq2=" << equation2 << '\n'
            << "           matrix1=" << matrix1 << ", matrix2=" << matrix2
            << std::endl;
}
void Problem::do_something ()
{
  // While this example does nothing here, at this point in the program
  // all of the parameters are known so we can start doing computations.
}
int main ()
{
  ParameterHandler prm;
  Problem p;
  p.declare_parameters (prm);
  // read input from "prmtest.prm"; giving argv[1] would also be a
  // good idea
  prm.parse_input ("prmtest.prm");
  // print parameters to std::cout as ASCII text
  std::cout << "\n\n";
  prm.print_parameters (std::cout, ParameterHandler::Text);
  // get parameters into the program
  std::cout << "\n\n" << "Getting parameters:" << std::endl;
  p.get_parameters (prm);
  // now run the program with these input parameters
  p.do_something ();
}

This is the input file (named "prmtest.prm"):

# first declare the types of equations
set Equation 1 = Poisson
set Equation 2 = Stokes
subsection Equation 1 Settings
  set Matrix type = Sparse
  subsection Linear solver # parameters for linear solver 1
    set Solver                       = Gauss-Seidel
    set Maximum number of iterations = 40
  end
end
subsection Equation 2 Settings
  set Matrix type = Full
  subsection Linear solver
    set Solver                       = CG
    set Maximum number of iterations = 100
  end
end

And here is the output of the program:

Line <8> of file <prmtest.prm>:
    The entry value
        Gauss-Seidel
    for the entry named
        Solver
    does not match the given pattern
        [Selection CG|BiCGStab|GMRES ]
# Listing of Parameters
# ---------------------
# String identifying the equation we want to solve
set Equation 1  = Poisson # default: Laplace
set Equation 2  = Stokes  # default: Elasticity
# Name of the output file, either relative to the present path or absolute
set Output file = out
subsection Equation 1 Settings
  # Type of the matrix to be used, either full, sparse, or diagonal
  set Matrix type = Sparse
  subsection Linear solver
    set Maximum number of iterations = 40 # default: 20
    # Name of a linear solver for the inner iteration
    set Solver                       = CG
  end
end
subsection Equation 2 Settings
  set Matrix type = Full # default: Sparse
  subsection Linear solver
    set Maximum number of iterations = 100 # default: 20
    # Name of a linear solver for the inner iteration
    set Solver                       = CG
  end
end
Getting parameters:
  LinearEquation: method=CG, max_iterations=40
  LinearEquation: method=CG, max_iterations=100
  Problem: outfile=out
           eq1=Poisson, eq2=Stokes
           matrix1=Sparse, matrix2=Full

Representation of Parameters

Here is some more internal information about the representation of parameters:

Logically, parameters and the nested sections they are arranged in can be thought of as a hierarchical directory structure, or a tree. Take, for example, the following code declaring a set of parameters and sections they live in:

ParameterHandler prm;
prm.declare_entry ("Maximal number of iterations",
                   "10",
                   Patterns::Integer (1, 1000),
                   "A parameter that describes the maximal number of "
                   "iterations the CG method is to take before giving "
                   "up on a matrix.");
prm.enter_subsection ("Preconditioner");
{
  prm.declare_entry ("Kind",
                     "SSOR",
                     Patterns::Selection ("SSOR|Jacobi"),
                     "A string that describes the kind of preconditioner "
                     "to use.");
  prm.declare_entry ("Relaxation factor",
                     "1.0",
                     Patterns::Double (0, 1),
                     "The numerical value (between zero and one) for the "
                     "relaxation factor to use in the preconditioner.");
}
prm.leave_subsection ();

We can think of the parameters so arranged as a file system in which every parameter is a directory. The name of this directory is the name of the parameter, and in this directory lie files that describe the parameter. These files are:

value: The content of this file is the current value of this parameter; initially, the content of the file equals the default value of the parameter.
default_value: The content of this file is the default value value of the parameter.
pattern: A textual representation of the pattern that describes the parameter's possible values.
pattern_index: A number that indexes the Patterns::PatternBase object that is used to describe the parameter.
documentation: The content of this file is the documentation given for a parameter as the last argument of the ParameterHandler::declare_entry call. With the exception of the value file, the contents of files are never changed after declaration of a parameter.

Alternatively, a directory in this file system may not have a file called value in it. In that case, the directory represents a subsection as declared above, and the directory's name will correspond to the name of the subsection. It will then have no files in it at all, but it may have further directories in it: some of these directories will be parameters (indicates by the presence of files) or further nested subsections.

Given this explanation, the code above will lead to a hierarchical representation of data that looks like this (the content of files is indicated at the right in a different font):

Once parameters have been read in, the contents of the value "files" may be different while the other files remain untouched.

Using the ParameterHandler::print_parameters() function with ParameterHandler::XML as second argument, we can get a complete representation of this data structure in XML. It will look like this:

<?xml version="1.0" encoding="utf-8"?>
<ParameterHandler>
  <Maximal_20number_20of_20iterations>
    <value>10</value>
    <default_value>10</default_value>
    <documentation>A parameter that describes the maximal number of iterations the CG method is to take before giving up on a matrix.</documentation>
    <pattern>0</pattern>
    <pattern_description>[Integer range 1...1000 (inclusive)]</pattern_description>
  </Maximal_20number_20of_20iterations>
  <Preconditioner>
    <Kind><value>SSOR</value>
      <default_value>SSOR</default_value>
      <documentation>A string that describes the kind of preconditioner to use.</documentation>
      <pattern>1</pattern>
      <pattern_description>SSOR|Jacobi</pattern_description>
    </Kind>
    <Relaxation_20factor>
      <value>1.0</value>
      <default_value>1.0</default_value>
      <documentation>The numerical value (between zero and one) for the relaxation factor to use in the preconditioner.</documentation>
      <pattern>2</pattern>
      <pattern_description>[Floating point range 0...1 (inclusive)]</pattern_description>
    </Relaxation_20factor>
  </Preconditioner>
<ParameterHandler>

This representation closely resembles the directory/file structure discussed above. The only difference is that directory and file names are mangled: since they should only contain letters and numbers, every character in their names that is not a letter or number is replaced by an underscore followed by its two-digit hexadecimal representation. In addition, the special name "value" is mangled when used as the name of a parameter, given that this name is also used to name special files in the hierarchy structure. Finally, the entire tree is wrapped into a tag ParameterHandler to satisfy the XML requirement that there be only a single top-level construct in each file.

The tree structure (and its XML representation) is what the graphical user interface (see above) uses to represent parameters like a directory/file collection.

Author: Wolfgang Bangerth, October 1997, revised February 1998, 2010, 2011; Alberto Sartori, 2015; David Wells, 2016

Definition at line 1559 of file parameter_handler.h.

Member Enumeration Documentation

◆ OutputStyle

enum ParameterHandler::OutputStyle

List of possible output formats.

The formats down the list with prefix Short and bit 6 and 7 set reproduce the old behavior of not writing comments or original values to the files.

Enumerator
Text	Write human readable output suitable to be read by ParameterHandler again.
LaTeX	Write parameters as a LaTeX table.
Description	Write out declared parameters with description and possible values.
XML	Write out everything as an XML file. See the general documentation of this class for an example of output.
JSON	Write out everything as a JSON file.
ShortText	Write input for ParameterHandler without comments or changed default values.

Definition at line 1580 of file parameter_handler.h.

Constructor & Destructor Documentation

◆ ParameterHandler() [1/2]

ParameterHandler::ParameterHandler ( const ParameterHandler & )

private

Inhibit automatic CopyConstructor.

◆ ParameterHandler() [2/2]

ParameterHandler::ParameterHandler ( )

Constructor.

Definition at line 1374 of file parameter_handler.cc.

◆ ~ParameterHandler()

ParameterHandler::~ParameterHandler ( )

virtual

Destructor. Declare this only to have a virtual destructor, which is safer as we have virtual functions. It actually does nothing spectacular.

Definition at line 1381 of file parameter_handler.cc.

Member Function Documentation

◆ operator=()

ParameterHandler& ParameterHandler::operator= ( const ParameterHandler & )

private

Inhibit automatic assignment operator.

◆ read_input() [1/2]

bool ParameterHandler::read_input	(	std::istream &	input,
		const std::string &	filename = `"input file"`,
		const std::string &	last_line = `""`
	)

virtual

Read input from a stream until the stream returns the eof condition or error. The second argument can be used to denote the name of the file (if that's what the input stream represents) we are reading from; this is only used when creating output for error messages.

If non-empty last_line is provided, the ParameterHandler object will stop parsing lines after encountering last_line . This is handy when adding extra data that shall be parsed manually.

Deprecated:: This function has been deprecated in favor of the replacement ParameterHandler::parse_input, which raises exceptions to indicate errors instead of returning an error code.

Reimplemented in MultipleParameterLoop.

Definition at line 1616 of file parameter_handler.cc.

◆ parse_input() [1/2]

void ParameterHandler::parse_input	(	std::istream &	input,
		const std::string &	filename = `"input file"`,
		const std::string &	last_line = `""`
	)

virtual

Parse each line from a stream until the stream returns the eof condition or error to provide values for known parameter fields. The second argument can be used to denote the name of the file (if that's what the input stream represents) we are reading from; this is only used when creating output for exceptions.

If non-empty last_line is provided, the ParameterHandler object will stop parsing lines after encountering last_line . This is handy when adding extra data that shall be parsed manually.

Reimplemented in MultipleParameterLoop.

Definition at line 1641 of file parameter_handler.cc.

◆ read_input() [2/2]

bool ParameterHandler::read_input	(	const std::string &	filename,
		const bool	optional = `false`,
		const bool	write_stripped_file = `false`,
		const std::string &	last_line = `""`
	)

virtual

Read input from a file the name of which is given. The PathSearch class "PARAMETERS" is used to find the file.

Unless optional is true, this function will automatically generate the requested file with default values if the file did not exist. This file will not contain additional comments if write_stripped_file is true.

If non-empty last_line is provided, the ParameterHandler object will stop parsing lines after encountering last_line . This is handy when adding extra data that shall be parsed manually.

Deprecated:: This function has been deprecated in favor of the replacement ParameterHandler::parse_input, which raises exceptions to indicate errors instead of returning an error code. ParameterHandler::parse_input does not have the capability to write default values to a file on failure: if you wish to duplicate that old behavior then you should catch the PathSearch::ExcFileNotFound exception and then call ParameterHandler::print_parameters.

Definition at line 1744 of file parameter_handler.cc.

◆ parse_input() [2/2]

void ParameterHandler::parse_input	(	const std::string &	filename,
		const std::string &	last_line = `""`
	)

virtual

Parse the given file to provide values for known parameter fields. The PathSearch class "PARAMETERS" is used to find the file.

If non-empty last_line is provided, the ParameterHandler object will stop parsing lines after encountering last_line . This is handy when adding extra data that shall be parsed manually.

Definition at line 1777 of file parameter_handler.cc.

◆ read_input_from_string()

bool ParameterHandler::read_input_from_string	(	const char *	s,
		const std::string &	last_line = `""`
	)

virtual

Read input from a string in memory. The lines in memory have to be separated by \n characters.

If non-empty last_line is provided, the ParameterHandler object will stop parsing lines after encountering last_line . This is handy when adding extra data that shall be parsed manually.

Deprecated:: This function has been deprecated in favor of the replacement ParameterHandler::parse_input_from_string, which raises exceptions to indicate errors instead of returning an error code.

Definition at line 1790 of file parameter_handler.cc.

◆ parse_input_from_string()

void ParameterHandler::parse_input_from_string	(	const char *	s,
		const std::string &	last_line = `""`
	)

virtual

Parse input from a string to populate known parameter fields. The lines in the string must be separated by \n characters.

If non-empty last_line is provided, the ParameterHandler object will stop parsing lines after encountering last_line . This is handy when adding extra data that shall be parsed manually.

Definition at line 1815 of file parameter_handler.cc.

◆ read_input_from_xml()

bool ParameterHandler::read_input_from_xml ( std::istream & input )

virtual

Read a parameter file in XML format. This could be from a file originally written by the print_parameters() function using the XML output style and then modified by hand as necessary; or from a file written using this method and then modified by the graphical parameter GUI (see the general documentation of this class).

Deprecated:: This function has been deprecated in favor of the replacement ParameterHandler::parse_input_from_xml, which raises exceptions to indicate errors instead of returning an error code.

Definition at line 1908 of file parameter_handler.cc.

◆ parse_input_from_xml()

void ParameterHandler::parse_input_from_xml ( std::istream & input )

virtual

Parse input from an XML stream to populate known parameter fields. This could be from a file originally written by the print_parameters() function using the XML output style and then modified by hand as necessary, or from a file written using this method and then modified by the graphical parameter GUI (see the general documentation of this class).

Definition at line 1928 of file parameter_handler.cc.

◆ clear()

void ParameterHandler::clear ( )

Clear all contents.

Definition at line 1981 of file parameter_handler.cc.

◆ declare_entry()

void ParameterHandler::declare_entry	(	const std::string &	entry,
		const std::string &	default_value,
		const Patterns::PatternBase &	pattern = `Patterns::Anything()`,
		const std::string &	documentation = `std::string()`
	)

Declare a new entry with name entry, default and for which any input has to match the pattern (default: any pattern).

The last parameter defaulting to an empty string is used to add a documenting text to each entry which will be printed as a comment when this class is asked to write out all declarations to a stream using the print_parameters() function.

The function generates an exception of type ExcValueDoesNotMatchPattern if the default value doesn't match the given pattern, using the C++ throw mechanism. However, this exception is only generated after the entry has been created; if you have code where no sensible default value for a parameter is possible, you can then catch and ignore this exception.

Note: An entry can be declared more than once without generating an error, for example to override an earlier default value.

Definition at line 1989 of file parameter_handler.cc.

◆ declare_alias()

void ParameterHandler::declare_alias	(	const std::string &	existing_entry_name,
		const std::string &	alias_name,
		const bool	alias_is_deprecated = `false`
	)

Create an alias for an existing entry. This provides a way to refer to a parameter in the input file using an alternate name. The alias will be in the current section, and the referenced entry needs to be an existing entry in the current section.

The primary purpose of this function is to allow for a backward compatible way of changing names in input files of applications for which backward compatibility is important. This can be achieved by changing the name of the parameter in the call to declare_entry(), and then creating an alias that maps the old name to the new name. This way, old input files can continue to refer to parameters under the old name, and they will automatically be mapped to the new parameter name.

It is valid to set the same parameter multiple times in an input file. The value that will ultimately be chosen in such cases is simply the last value set. This rule also applies to aliases, where the final value of a parameter is the last value set either through the current name of the parameter or through any of its possible multiple aliases. For example, if you have an input file that looks like

set parm1 = 1

set parm1_alias = 2

where parm1_alias is an alias declared via

prm.declare_alias ("parm1", "parm1_alias");

then the final value for the parameter called parm1 will be 2, not 1.

Parameters

existing_entry_name	The name of an existing parameter in the current section that the alias should refer to.
alias_name	An alternate name for the parameter referenced by the first argument.
alias_is_deprecated	If true, mark the alias as deprecated. This will then be listed in the description of the alias if you call print_parameters(), and you will get a warning on the screen when reading an input file that contains this deprecated alias. The purpose of this argument is to be able to allow the use of an old name for a parameter (see above) but make it clear that this old name will eventually be removed.

Definition at line 2028 of file parameter_handler.cc.

◆ enter_subsection()

void ParameterHandler::enter_subsection ( const std::string & subsection )

Enter a subsection. If it does not yet exist, create it.

Definition at line 2086 of file parameter_handler.cc.

◆ leave_subsection()

void ParameterHandler::leave_subsection ( )

Leave present subsection.

Definition at line 2099 of file parameter_handler.cc.

◆ get()

std::string ParameterHandler::get ( const std::string & entry_string ) const

Return value of entry entry_string. If the entry was changed, then the changed value is returned, otherwise the default value. If the value of an undeclared entry is required, an exception will be thrown.

Definition at line 2112 of file parameter_handler.cc.

◆ get_integer()

long int ParameterHandler::get_integer ( const std::string & entry_string ) const

Return value of entry entry_string as long int. (A long int is chosen so that even very large unsigned values can be returned by this function).

Definition at line 2128 of file parameter_handler.cc.

◆ get_double()

double ParameterHandler::get_double ( const std::string & entry_name ) const

Return value of entry entry_name as double.

Definition at line 2148 of file parameter_handler.cc.

◆ get_bool()

bool ParameterHandler::get_bool ( const std::string & entry_name ) const

Return value of entry entry_name as bool. The entry may be "true" or "yes" for true, "false" or "no" for false respectively.

Definition at line 2168 of file parameter_handler.cc.

◆ set() [1/5]

void ParameterHandler::set	(	const std::string &	entry_name,
		const std::string &	new_value
	)

Change the value presently stored for entry_name to the one given in the second argument.

The parameter must already exist in the present subsection.

The function throws an exception of type ExcValueDoesNotMatchPattern if the new value does not conform to the pattern for this entry.

Definition at line 2188 of file parameter_handler.cc.

◆ set() [2/5]

void ParameterHandler::set	(	const std::string &	entry_name,
		const char *	new_value
	)

Same as above, but an overload where the second argument is a character pointer. This is necessary, since otherwise the call to set("abc","def") will be mapped to the function taking one string and a bool as arguments, which is certainly not what is most often intended.

The function throws an exception of type ExcValueDoesNotMatchPattern if the new value does not conform to the pattern for this entry.

Definition at line 2217 of file parameter_handler.cc.

◆ set() [3/5]

void ParameterHandler::set	(	const std::string &	entry_name,
		const long int &	new_value
	)

Change the value presently stored for entry_name to the one given in the second argument.

The parameter must already exist in the present subsection.

The function throws an exception of type ExcValueDoesNotMatchPattern if the new value does not conform to the pattern for this entry.

Definition at line 2241 of file parameter_handler.cc.

◆ set() [4/5]

void ParameterHandler::set	(	const std::string &	entry_name,
		const double &	new_value
	)

Change the value presently stored for entry_name to the one given in the second argument.

The parameter must already exist in the present subsection.

For internal purposes, the new value needs to be converted to a string. This is done using 16 digits of accuracy, so the set value and the one you can get back out using get_double() may differ in the 16th digit.

The function throws an exception of type ExcValueDoesNotMatchPattern if the new value does not conform to the pattern for this entry.

Definition at line 2226 of file parameter_handler.cc.

◆ set() [5/5]

void ParameterHandler::set	(	const std::string &	entry_name,
		const bool &	new_value
	)

Change the value presently stored for entry_name to the one given in the second argument.

The parameter must already exist in the present subsection.

The function throws an exception of type ExcValueDoesNotMatchPattern if the new value does not conform to the pattern for this entry.

Definition at line 2255 of file parameter_handler.cc.

◆ print_parameters()

std::ostream & ParameterHandler::print_parameters	(	std::ostream &	out,
		const OutputStyle	style
	)

Print all parameters with the given style to out. Presently only Text, LaTeX and XML are implemented.

In Text format, the output is formatted in such a way that it is possible to use it for later input again. This is most useful to record the parameters for a specific run, since if you output the parameters using this function into a log file, you can always recover the results by simply copying the output to your input file.

Besides the name and value of each entry, the output also contains the default value of entries if it is different from the actual value, as well as the documenting string given to the declare_entry() function if available.

In XML format, the output starts with one root element ParameterHandler in order to get a valid XML document and all subsections under it.

In LaTeX format, the output contains the same information but in a format so that the resulting file can be input into a latex document such as a manual for the code for which this object handles run-time parameters. The various sections of parameters are then represented by latex section and subsection commands as well as by nested enumerations.

In addition, all parameter names are listed with \index statements in two indices called prmindex (where the name of each parameter is listed in the index) and prmindexfull where parameter names are listed sorted by the section in which they exist. By default, the LaTeX program ignores these \index commands, but they can be used to generate an index by using the following commands in the preamble of the latex file :

\usepackage{imakeidx}
\makeindex[name=prmindex, title=Index of run-time parameter entries]
\makeindex[name=prmindexfull, title=Index of run-time parameters with section names]

and at the end of the file this:

\printindex[prmindex]

\printindex[prmindexfull]

Definition at line 2267 of file parameter_handler.cc.

◆ print_parameters_section()

void ParameterHandler::print_parameters_section	(	std::ostream &	out,
		const OutputStyle	style,
		const unsigned int	indent_level,
		const bool	include_top_level_elements = `false`
	)

Print out the parameters of the present subsection as given by the subsection_path member variable. This variable is controlled by entering and leaving subsections through the enter_subsection() and leave_subsection() functions.

If include_top_level_elements is true, also the higher subsection elements are printed. In XML format this is required to get a valid XML document and output starts with one root element ParameterHandler.

In most cases, you will not want to use this function directly, but have it called recursively by the previous function.

Definition at line 2356 of file parameter_handler.cc.

◆ log_parameters()

void ParameterHandler::log_parameters ( LogStream & out )

Print parameters to a logstream. This function allows to print all parameters into a log-file. Sections will be indented in the usual log- file style.

Definition at line 2859 of file parameter_handler.cc.

◆ log_parameters_section()

void ParameterHandler::log_parameters_section ( LogStream & out )

Log parameters in the present subsection. The subsection is determined by the subsection_path member variable. This variable is controlled by entering and leaving subsections through the enter_subsection() and leave_subsection() functions.

In most cases, you will not want to use this function directly, but have it called recursively by the previous function.

Definition at line 2872 of file parameter_handler.cc.

◆ memory_consumption()

std::size_t ParameterHandler::memory_consumption ( ) const

Determine an estimate for the memory consumption (in bytes) of this object.

Definition at line 3076 of file parameter_handler.cc.

◆ save()

template<class Archive >

void ParameterHandler::save	(	Archive &	ar,
		const unsigned int	version
	)		const

inline

Write the data of this object to a stream for the purpose of serialization.

Definition at line 2657 of file parameter_handler.h.

◆ load()

template<class Archive >

void ParameterHandler::load	(	Archive &	ar,
		const unsigned int	version
	)

inline

Read the data of this object from a stream for the purpose of serialization.

Definition at line 2677 of file parameter_handler.h.

◆ operator==()

bool ParameterHandler::operator== ( const ParameterHandler & prm2 ) const

Test for equality.

Definition at line 3085 of file parameter_handler.cc.

◆ mangle()

std::string ParameterHandler::mangle ( const std::string & s )

staticprivate

Mangle a string so that it doesn't contain any special characters or spaces.

Definition at line 1387 of file parameter_handler.cc.

◆ demangle()

std::string ParameterHandler::demangle ( const std::string & s )

staticprivate

Unmangle a string into its original form.

Definition at line 1426 of file parameter_handler.cc.

◆ get_current_path()

std::string ParameterHandler::get_current_path ( ) const

private

Return the string that identifies the current path into the property tree. This is only a path, i.e. it is not terminated by the path_separator character.

Definition at line 1584 of file parameter_handler.cc.

◆ get_current_full_path()

std::string ParameterHandler::get_current_full_path ( const std::string & name ) const

private

Given the name of an entry as argument, the function computes a full path into the parameter tree using the current subsection.

Definition at line 1603 of file parameter_handler.cc.

◆ scan_line()

void ParameterHandler::scan_line	(	std::string	line,
		const std::string &	input_filename,
		const unsigned int	current_line_n
	)

private

Scan one line of input. input_filename and current_line_n are the name of the input file and the number of the line presently scanned (these are used in exception messages to show where parse errors occurred). This function will raise an exception if the line contains an undeclared subsection or entry, if the line's entry does not match its given pattern, or if the line could not be understood as a valid parameter file expression.

The function modifies its argument, but also takes it by value, so the caller's variable is not changed.

Definition at line 2907 of file parameter_handler.cc.

Member Data Documentation

◆ path_separator

const char ParameterHandler::path_separator = '.'

staticprivate

The separator used when accessing elements of a path into the parameter tree.

Definition at line 2151 of file parameter_handler.h.

◆ entries

std_cxx11::unique_ptr<boost::property_tree::ptree> ParameterHandler::entries

private

The complete tree of sections and entries. See the general documentation of this class for a description how data is stored in this variable.

The variable is a pointer so that we can use an incomplete type, rather than having to include all of the property_tree stuff from boost. This works around a problem with gcc 4.5.

Definition at line 2161 of file parameter_handler.h.

◆ patterns

std::vector<std_cxx11::shared_ptr<const Patterns::PatternBase> > ParameterHandler::patterns

private

A list of patterns that are used to describe the parameters of this object. The are indexed by nodes in the property tree.

Definition at line 2167 of file parameter_handler.h.

◆ subsection_path

std::vector<std::string> ParameterHandler::subsection_path

private

Path of presently selected subsections; empty list means top level

Definition at line 2183 of file parameter_handler.h.

The documentation for this class was generated from the following files:

deal.II/base/parameter_handler.h
source/base/parameter_handler.cc

Public Types

Public Member Functions

Static Public Member Functions

Private Member Functions

Static Private Member Functions

Private Attributes

Static Private Attributes

Friends

Detailed Description

Declaring entries

Input files and special characters

Including other input files

Reading data from input sources

Using the ParameterHandler Graphical User Interface

Getting entry values out of a ParameterHandler object

Style guide for data retrieval

Experience with large parameter lists

Worked Example

Representation of Parameters

Member Enumeration Documentation

◆ OutputStyle

Constructor & Destructor Documentation

◆ ParameterHandler() [1/2]

◆ ParameterHandler() [2/2]

◆ ~ParameterHandler()

Member Function Documentation

◆ operator=()

◆ read_input() [1/2]

◆ parse_input() [1/2]

◆ read_input() [2/2]

◆ parse_input() [2/2]

◆ read_input_from_string()

◆ parse_input_from_string()

◆ read_input_from_xml()

◆ parse_input_from_xml()

◆ clear()

◆ declare_entry()

◆ declare_alias()

◆ enter_subsection()

◆ leave_subsection()

◆ get()

◆ get_integer()

◆ get_double()

◆ get_bool()

◆ set() [1/5]

◆ set() [2/5]

◆ set() [3/5]

◆ set() [4/5]

◆ set() [5/5]

◆ print_parameters()

◆ print_parameters_section()

◆ log_parameters()

◆ log_parameters_section()

◆ memory_consumption()

◆ save()

◆ load()

◆ operator==()

◆ mangle()

◆ demangle()

◆ get_current_path()

◆ get_current_full_path()

◆ scan_line()

Member Data Documentation

◆ path_separator

◆ entries

◆ patterns

◆ subsection_path