Environment Class Reference

Represents a symbolic environment (mapping from a variable to a value). More...

#include </home/soonhokong/work/dreal4/third_party/com_github_robotlocomotion_drake/dreal/symbolic/symbolic_environment.h>

Public Types
typedef Variable	key_type
typedef double	mapped_type
typedef std::unordered_map< key_type, mapped_type, hash_value< key_type > >	map
typedef map::value_type	value_type
	std::pair<key_type, mapped_type>
typedef map::iterator	iterator
typedef map::const_iterator	const_iterator

Public Member Functions
	Environment (const Environment &)=default
Environment &	operator= (const Environment &)=default
	Environment (Environment &&)=default
Environment &	operator= (Environment &&)=default
	Environment ()=default
	Default constructor. More...
	~Environment ()=default
	Default destructor. More...
	Environment (std::initializer_list< value_type > init)
	List constructor. More...
	Environment (std::initializer_list< key_type > vars)
	List constructor. More...
	Environment (map m)
	Constructs an environment from m.
iterator	begin ()
	Returns an iterator to the beginning. More...
iterator	end ()
	Returns an iterator to the end. More...
const_iterator	begin () const
	Returns a const iterator to the beginning. More...
const_iterator	end () const
	Returns a const iterator to the end. More...
const_iterator	cbegin () const
	Returns a const iterator to the beginning. More...
const_iterator	cend () const
	Returns a const iterator to the end. More...
void	insert (const key_type &key, const mapped_type &elem)
	Inserts a pair (key, elem). More...
bool	empty () const
	Checks whether the container is empty. More...
size_t	size () const
	Returns the number of elements. More...
iterator	find (const key_type &key)
	Finds element with specific key. More...
const_iterator	find (const key_type &key) const
	Finds element with specific key. More...
Variables	domain () const
	Returns the domain of this environment. More...
std::string	to_string () const
	Returns string representation. More...
mapped_type &	operator[] (const key_type &key)
	Returns a reference to the value that is mapped to a key equivalent to key, performing an insertion if such key does not already exist.
const mapped_type &	operator[] (const key_type &key) const
	As above, but returns a constref and does not perform an insertion (throwing a runtime error instead) if the key does not exist. More...

Friends
std::ostream &	operator<< (std::ostream &os, const Environment &env)

Detailed Description

Represents a symbolic environment (mapping from a variable to a value).

This class is used when we evaluate symbolic expressions or formulas which include unquantified (free) variables. Here are examples:

const Variable var_x{"x"};
const Variable var_y{"y"};
const Expression x{var_x};
const Expression y{var_x};
const Expression e1{x + y};
const Expression e2{x - y};
const Formula f{e1 > e2};

// env maps var_x to 2.0 and var_y to 3.0
const Environment env{{var_x, 2.0}, {var_y, 3.0}};

const double res1 = e1.Evaluate(env);  // x + y => 2.0 + 3.0 =>  5.0
const double res2 = e2.Evaluate(env);  // x - y => 2.0 - 3.0 => -1.0
const bool res = f.Evaluate(env);  // x + y > x - y => 5.0 >= -1.0 => True

Note that it is not allowed to have a dummy variable in an environment. It throws std::runtime_error for the attempts to create an environment with a dummy variable, to insert a dummy variable to an existing environment, or to take a reference to a value mapped to a dummy variable. See the following examples.

Variable    var_dummy{};           // OK to have a dummy variable
Environment e1{var_dummy};         // throws std::runtime_error exception
Environment e2{{var_dummy, 1.0}};  // throws std::runtime_error exception
Environment e{};
e.insert(var_dummy, 1.0);          // throws std::runtime_error exception
e[var_dummy] = 3.0;                // throws std::runtime_error exception

Constructor & Destructor Documentation

Environment() [1/3]

Environment ( )

default

Default constructor.

~Environment()

~Environment ( )

default

Default destructor.

Environment() [2/3]

Environment

(

std::initializer_list< value_type >

init

)

List constructor.

Constructs an environment from a list of (Variable * double).

Environment() [3/3]

Environment

(

std::initializer_list< key_type >

vars

)

List constructor.

Constructs an environment from a list of Variable. Initializes the variables with 0.0.

Member Function Documentation

begin() [1/2]

iterator begin ( )

inline

Returns an iterator to the beginning.

begin() [2/2]

const_iterator begin ( ) const

inline

Returns a const iterator to the beginning.

cbegin()

const_iterator cbegin ( ) const

inline

Returns a const iterator to the beginning.

cend()

const_iterator cend ( ) const

inline

Returns a const iterator to the end.

domain()

Variables domain

(

)

const

Returns the domain of this environment.

empty()

bool empty ( ) const

inline

Checks whether the container is empty.

end() [1/2]

iterator end ( )

inline

Returns an iterator to the end.

end() [2/2]

const_iterator end ( ) const

inline

Returns a const iterator to the end.

find() [1/2]

iterator find ( const key_type &  key )

inline

Finds element with specific key.

find() [2/2]

const_iterator find ( const key_type &  key ) const

inline

Finds element with specific key.

insert()

void insert	(	const key_type &	key,
		const mapped_type &	elem
	)

Inserts a pair (key, elem).

operator[]()

const Environment::mapped_type & operator[]

(

const key_type &

key

)

const

As above, but returns a constref and does not perform an insertion (throwing a runtime error instead) if the key does not exist.

size()

size_t size ( ) const

inline

Returns the number of elements.

to_string()

string to_string

(

)

const

Returns string representation.

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

• /home/soonhokong/work/dreal4/third_party/com_github_robotlocomotion_drake/dreal/symbolic/symbolic_environment.h
• /home/soonhokong/work/dreal4/third_party/com_github_robotlocomotion_drake/dreal/symbolic/symbolic_environment.cc