delpi::Expression Class Reference

Represents a symbolic form of an expression. More...

#include <Expression.h>

Public Member Functions
template<MapFromTo< Variable, mpq_class > T>
mpq_class	Evaluate (const T &env={}) const
	Evaluates using a given environment (by default, an empty environment).
Expression	Substitute (const SubstitutionMap &s) const
	Create a copy of this expression, replacing all occurrences of the variables in s with corresponding expressions in s.
Expression &	Add (const Variable &var, const mpq_class &coeff)
	Add a linear monomial \( c \cdot x \), where \( c \) is a constant and \( x \) is a Variable, to the current expression.
Expression &	Subtract (const Variable &var, const mpq_class &coeff)
	Subtract a linear monomial \( c \cdot x \), where \( c \) is a constant and \( x \) is a Variable, to the current expression.
std::ostream &	Print (std::ostream &os) const
	Print a string representation of this class to the provided os.

Private Attributes
intrusive_ptr< ExpressionCell >	ptr_
	Internal pointer to the ExpressionCell.

Detailed Description

Represents a symbolic form of an expression.

Its syntax tree is as follows:

E := Var | E + ... + E | Constant * E

To check structural equality between two expressions use Expression::equal_to.

Definition at line 37 of file Expression.h.

Member Function Documentation

Add()

Expression & delpi::Expression::Add	(	const Variable &	var,
		const mpq_class &	coeff )

Add a linear monomial \( c \cdot x \), where \( c \) is a constant and \( x \) is a Variable, to the current expression.

Parameters

var	variable of the linear monomial
coeff	coefficient of the linear monomial

Returns

reference to this object

Definition at line 76 of file Expression.cpp.

Evaluate()

template<MapFromTo< Variable, mpq_class > T>

template mpq_class delpi::Expression::Evaluate ( const T & env = {} ) const

nodiscard

Evaluates using a given environment (by default, an empty environment).

Template Parameters

T	map from variable to value (i.e. std::map<Variable, mpq_class>, std::unordered_map<Variable, mpq_class>)

Parameters

env	map between each variable and its value

Returns

value of the expression in the given environment

Exceptions

std::exception

if there exists variable in this expression whose assignment is not provided by env

Definition at line 45 of file Expression.cpp.

Print()

std::ostream & delpi::Expression::Print

(

std::ostream &

os

)

const

Print a string representation of this class to the provided os.

It is an alternative to the more standard operator<<.

Parameters

os	output stream

Returns

reference to the output stream

Definition at line 50 of file Expression.cpp.

Substitute()

Expression delpi::Expression::Substitute ( const SubstitutionMap & s ) const

nodiscard

Create a copy of this expression, replacing all occurrences of the variables in s with corresponding expressions in s.

Note that the substitutions occur simultaneously.

Expression e = x + 2 * y;
Substitution s = {{x, y}, {y, x}};
e.Substitute(s);  // returns y + 2 * x

Parameters

s	map of substitutions. Maps the old variable to the new one.

Returns

expression produced by the substitution

Definition at line 48 of file Expression.cpp.

Subtract()

Expression & delpi::Expression::Subtract	(	const Variable &	var,
		const mpq_class &	coeff )

Subtract a linear monomial \( c \cdot x \), where \( c \) is a constant and \( x \) is a Variable, to the current expression.

Parameters

var	variable of the linear monomial
coeff	coefficient of the linear monomial

Returns

reference to this object

Definition at line 84 of file Expression.cpp.

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

• delpi/symbolic/Expression.h
• delpi/symbolic/Expression.cpp