org.expressionj.util

Class ExpressionCombiner

java.lang.Object

org.expressionj.util.ExpressionCombiner

public class ExpressionCombiner
extends java.lang.Object

This class allows to combine two expressions. This class provide several method:

• replace(Expression, java.lang.String, Expression): Change a value in an Expression. The change consist in replacing a Variable by an Expression, which may contain Variables.
• add(Expression, Expression): Add two expressions.
• substract(Expression, Expression): Substract two expressions.
• multiply(Expression, Expression): Multiply two expressions.
• divide(Expression, Expression): Divide two expressions.

More simple methods also exist to easily add, subtract, multiply, or divide an expression with an int or a float.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEEP_COPY
static int	DONT_COPY
static int	SHALLOW_COPY

Constructor Summary

Constructors

Constructor and Description
ExpressionCombiner()

Method Summary

Modifier and Type	Method and Description
Expression	add(Expression expr1, Expression expr2) Add an expression to another.
Expression	add(Expression expr, float value) Add an expression and a float constant.
Expression	add(Expression expr, int value) Add an expression and an integer constant.
Expression	add(Expression expr, java.lang.String value) Add an expression and a String constant.
Expression	createArray(Expression... exprs) Create an array expression.
Expression	divide(Expression expr1, Expression expr2) Divide an expression by another.
Expression	divide(Expression expr, float value) Divide an expression by a float constant.
Expression	divide(Expression expr, int value) Divide an expression by an integer constant.
int	getCopyBehavior() Return the copy behavior of this ExpressionCombiner.
Expression	multiply(Expression expr1, Expression expr2) Multiply an expression with another.
Expression	multiply(Expression expr, float value) Multiply an expression by a float constant.
Expression	multiply(Expression expr, int value) Multiply an expression by an integer constant.
Expression	replace(Expression expr, java.lang.String varName, Expression replacedExpr) Replace a variable in an expression by another sub-expression.
Expression	replaceVariable(Expression expr, java.lang.String varName, java.lang.String varToReplace) Replace a variable in an expression by another variable.
void	setCopyBehavior(int copyBehavior) Set the copy behavior of this ExpressionCombiner.
Expression	substract(Expression expr1, Expression expr2) Subtract an expression to another.
Expression	substract(Expression expr, float value) Subtract an expression by a float constant.
Expression	substract(Expression expr, int value) Subtract an expression and an integer constant.

Methods inherited from class java.lang.Object

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

Field Detail

DONT_COPY

public static final int DONT_COPY

See Also:

Constant Field Values

SHALLOW_COPY

public static final int SHALLOW_COPY

See Also:

Constant Field Values

DEEP_COPY

public static final int DEEP_COPY

See Also:

Constant Field Values

Constructor Detail

ExpressionCombiner

public ExpressionCombiner()

Method Detail

setCopyBehavior

public void setCopyBehavior(int copyBehavior)

Set the copy behavior of this ExpressionCombiner.

• DONT_COPY: return the expression (no copy)
• SHALLOW_COPY: return a shallow copy of the expression
• DEEP_COPY: return a deep copy of the expression

Parameters:

copyBehavior - the copy behavior

getCopyBehavior

public int getCopyBehavior()

Return the copy behavior of this ExpressionCombiner.

Returns:

the copy behavior

See Also:

setCopyBehavior(int)

add

public Expression add(Expression expr,
                      int value)

Add an expression and an integer constant.

Parameters:

expr - the expression

value - the integer constant

Returns:

the new expression

add

public Expression add(Expression expr,
                      float value)

Add an expression and a float constant.

Parameters:

expr - the expression

value - the float constant

Returns:

the new expression

add

public Expression add(Expression expr,
                      java.lang.String value)

Add an expression and a String constant.

Parameters:

expr - the expression

value - the String constant

Returns:

the new expression

substract

public Expression substract(Expression expr,
                            int value)

Subtract an expression and an integer constant.

Parameters:

expr - the expression

value - the integer constant

Returns:

the new expression

substract

public Expression substract(Expression expr,
                            float value)

Subtract an expression by a float constant.

Parameters:

expr - the expression

value - the float constant

Returns:

the new expression

multiply

public Expression multiply(Expression expr,
                           int value)

Multiply an expression by an integer constant.

Parameters:

expr - the expression

value - the int constant

Returns:

the new expression

multiply

public Expression multiply(Expression expr,
                           float value)

Multiply an expression by a float constant.

Parameters:

expr - the expression

value - the float constant

Returns:

the new expression

divide

public Expression divide(Expression expr,
                         int value)

Divide an expression by an integer constant.

Parameters:

expr - the expression

value - the int constant

Returns:

the new expression

divide

public Expression divide(Expression expr,
                         float value)

Divide an expression by a float constant.

Parameters:

expr - the expression

value - the float constant

Returns:

the new expression

createArray

public Expression createArray(Expression... exprs)

Create an array expression.

Parameters:

exprs - the expressions

Returns:

the array of expressions

add

public Expression add(Expression expr1,
                      Expression expr2)

Add an expression to another.

Parameters:

expr1 - the first expression

expr2 - the expression to add

Returns:

expr1 + expr2

substract

public Expression substract(Expression expr1,
                            Expression expr2)

Subtract an expression to another.

Parameters:

expr1 - the first expression

expr2 - the expression to substract

Returns:

expr1 - expr2

multiply

public Expression multiply(Expression expr1,
                           Expression expr2)

Multiply an expression with another.

Parameters:

expr1 - the first expression

expr2 - the expression to multiply

Returns:

expr1 * expr2

divide

public Expression divide(Expression expr1,
                         Expression expr2)

Divide an expression by another.

Parameters:

expr1 - the first expression

expr2 - the expression to divide

Returns:

expr1 / expr2

replaceVariable

public Expression replaceVariable(Expression expr,
                                  java.lang.String varName,
                                  java.lang.String varToReplace)

Replace a variable in an expression by another variable. For example, if we have:

 expr = sin(a + b)
 varName = a
 varToReplace = b
 

then the result is sin(b + b) Note that:

• If the initial variable does not exist, then the initial expression will not be modified
• If the replacing variable does not already exist, then the replacing variable will be created

Parameters:

expr - the expression

varName - the name of the variable which must be replaced

varToReplace - the name of the variable to use

Returns:

the new expression

replace

public Expression replace(Expression expr,
                          java.lang.String varName,
                          Expression replacedExpr)

Replace a variable in an expression by another sub-expression. For example, if we have:

 expr = sin(a + 2)
 varName = a
 replacedExpr = b * c
 

then the result is sin((b * c) + 2) Note that:

• The method will return the first expression if the sub-expression is equal to the first
• The method will also return the first expression if the variable is not present in the first expression

Parameters:

expr - the expression

varName - the name of the variable which must be replaced

replacedExpr - the expression which must replace the variable

Returns:

the new expression