variables.hpp File Reference

#include <map>
#include <string>
#include "node.hpp"

Go to the source code of this file.

Classes
class	set_symbol_table
Typedefs
typedef std::map < std::string, node >	symbol_table
Functions
node	get_variable (std::string const &name)
node	get_function (std::string const &name)
void	set_variable (std::string const &name, node value)
void	set_function (std::string const &name, node definition)
void	save_library (std::string const &filename)
void	load_library (std::string const &filename)

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Typedef Documentation

typedef std::map<std::string, node> symbol_table

Represent a global or local symbol table, which stores variables and functions. In fact, there's no difference between a variable and a function of no arguments.

Definition at line 13 of file variables.hpp.

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Function Documentation

node get_function

(

std::string const &

name

)

Get the definition of a function.

Parameters:

name

The function name

Returns:

The definition of function named name

Exceptions:

no_such_function

if the function is not defined

Definition at line 65 of file variables.cpp.

References find_symbol().

{
  node result;
  if (not find_symbol(name, result))
    throw no_such_function(name);
  else
    return result;
}

node get_variable

(

std::string const &

name

)

Get the value of a variable.

Parameters:

name

The variable name

Returns:

The value of variable name or node() if the variable is undefined.

Definition at line 49 of file variables.cpp.

References find_symbol(), and node::get_parameters().

{
  node result;
  if (not find_symbol(name, result))
    return node();
  else if (result.get_parameters().empty())
    return result;
  else
    throw function_error(name, result.get_parameters().size(), 0);
}

void load_library

(

std::string const &

filename

)

Load variable and function definitions from a file. Definitions in the file overwrite existing definitions with the same name.

Parameters:

filename

The file name

Exceptions:

calc_error

for I/O errors

Definition at line 99 of file variables.cpp.

References set_variable().

{
  std::ifstream stream(filename.c_str());
  if (not stream)
    throw file_error(filename);
  std::string token;
  if (not std::getline(stream, token))
    throw calc_error(filename + ": is empty");
  if (token != ":library:")
    throw calc_error(filename + ": is not a calculator library file");
  while (stream >> token) {
    if (token == "*")
      return;
    else
      set_variable(token, node(stream));
  }
}

void save_library

(

std::string const &

filename

)

Save all variable and function definitions to a file. The file is a simple text file, so you can examine it in any text editor.

Parameters:

filename

The name of the file.

Exceptions:

calc_error

if the file cannot be created

Definition at line 79 of file variables.cpp.

References variables.

{
  std::ofstream stream(filename.c_str());
  if (not stream)
    throw file_error(filename);
  // Be sure to save numbers with maximum precision.
  stream.precision(std::numeric_limits<double>::digits10);
  stream << ":library:\n";
  for (symbol_table::iterator symbol(variables.begin()); symbol != variables.end(); ++symbol) {
    stream << symbol->first << ' ';
    symbol->second.save(stream);
    if (stream.fail())
      throw file_error(filename);
  }
  stream << "*\n";
  stream.close();
  if (stream.fail())
    throw file_error(filename);
}

void set_function	(	std::string const &	name,
		node	definition
	)

Set the definition of a function.

Parameters:

	name	The function name
	definition	The function definition

Definition at line 74 of file variables.cpp.

References set_variable().

{
  set_variable(name, value);
}

void set_variable	(	std::string const &	name,
		node	value
	)

Set the value of a variable.

Parameters:

	name	The variable name
	value	The value. if the variable is already defined, changes its value.

Definition at line 60 of file variables.cpp.

References variables.

{
  variables[name] = value;
}

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