org.cryptimeleon.math.expressions.exponent

Class ExponentSumExpr

java.lang.Object

org.cryptimeleon.math.expressions.exponent.ExponentSumExpr

All Implemented Interfaces:

ExponentExpr, Expression

public class ExponentSumExpr
extends java.lang.Object
implements ExponentExpr

An ExponentExpr representing the sum of two exponent expressions.

Field Summary

Fields

Modifier and Type	Field and Description
protected ExponentExpr	lhs The left hand side of this sum.
protected ExponentExpr	rhs The right hand side of this sum.

Constructor Summary

Constructors

Constructor and Description
ExponentSumExpr(ExponentExpr lhs, ExponentExpr rhs)

Method Summary

Modifier and Type	Method and Description
java.math.BigInteger	evaluate() Evaluates the expression.
Zn.ZnElement	evaluate(Zn zn) Evaluates the expression in the given ring Zn.
void	forEachChild(java.util.function.Consumer<Expression> action) Calls action on every (direct) child of this expression.
ExponentExpr	getLhs() Retrieves the left hand side of this sum.
ExponentExpr	getRhs() Retrieves the right hand side of this sum.
ExponentSumExpr	linearize() Returns an equivalent expression of the form y + f(variables), where y is constant (no variables), and the expression f is linear.
ExponentExpr	substitute(Substitution substitutions) Substitutes variables using the given function.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.cryptimeleon.math.expressions.exponent.ExponentExpr

add, add, add, add, add, evaluate, evaluate, invert, isEqualTo, isEqualTo, isEqualTo, mul, mul, mul, mul, mul, negate, pow, pow, pow, pow, pow, sub, sub, sub, sub, sub, substitute, substitute

Methods inherited from interface org.cryptimeleon.math.expressions.Expression

accumulate, containsExprMatchingPredicate, containsVariables, getVariables, treeWalk

Field Detail

lhs

protected final ExponentExpr lhs

The left hand side of this sum.

rhs

protected final ExponentExpr rhs

The right hand side of this sum.

Constructor Detail

ExponentSumExpr

public ExponentSumExpr(ExponentExpr lhs,
                       ExponentExpr rhs)

Method Detail

getLhs

public ExponentExpr getLhs()

Retrieves the left hand side of this sum.

getRhs

public ExponentExpr getRhs()

Retrieves the right hand side of this sum.

evaluate

public java.math.BigInteger evaluate()

Description copied from interface: Expression

Evaluates the expression.

Specified by:

evaluate in interface ExponentExpr

Specified by:

evaluate in interface Expression

Returns:

the result of evaluation

forEachChild

public void forEachChild(java.util.function.Consumer<Expression> action)

Description copied from interface: Expression

Calls action on every (direct) child of this expression. For example, for a GroupOpExpr, this would call action on the left- and right-hand-side and then return.

Specified by:

forEachChild in interface Expression

evaluate

public Zn.ZnElement evaluate(Zn zn)

Description copied from interface: ExponentExpr

Evaluates the expression in the given ring Zn.

Specified by:

evaluate in interface ExponentExpr

Parameters:

zn - the Zn to evaluate in

Returns:

the result of evaluation as a Zn.ZnElement

substitute

public ExponentExpr substitute(Substitution substitutions)

Description copied from interface: Expression

Substitutes variables using the given function.

Specified by:

substitute in interface ExponentExpr

Specified by:

substitute in interface Expression

Parameters:

substitutions - a function mapping variable expressions to their replacement expressions

Returns:

the expression after substitution

linearize

public ExponentSumExpr linearize()
                          throws java.lang.IllegalArgumentException

Description copied from interface: ExponentExpr

Returns an equivalent expression of the form y + f(variables), where y is constant (no variables), and the expression f is linear. Linearity means that

 f(variables) + f(variables2) = f(variables + variables2)
 

The exact result is a ExponentSumExpr where the left-hand-side y fulfills y.containsVariables() == false and the right-hand side is linear.

Specified by:

linearize in interface ExponentExpr

Throws:

java.lang.IllegalArgumentException - if it's not possible to form the desired output (e.g., the input is something like \(g^{x_1 \cdot x_2}\) for variables \(x_1, x_2\)).